A Phase 2, Single Arm Study of Mirvetuximab Soravtansine in Recurrent Platinum-Sensitive, High-Grade Epithelial Ovarian, Primary Peritoneal, or Fallopian Tube Cancers With High Folate Receptor-Alpha Expression
Phase: PHASE2
Conditions: Ovarian Cancer, Peritoneal Cancer, Fallopian Tube Cancer
Sponsor: AbbVie

CLINICAL STUDY PROTOCOL 
Study Title: 
PICCOLO: A Phase 2, Single Arm Study of Mirvetuximab Soravtansine 
in Recurrent Platinum-Sensitive, High-Grade Epithelial Ovarian, Primary 
Peritoneal, or Fallopian Tube Cancers with High Folate Receptor-Alpha 
Expression 
Study Number: 
IMGN853-0419 
Study Phase: 
2
Product Name: 
Mirvetuximab Soravtansine (IMGN853) 
Indication: 
Recurrent platinum-sensitive, high-grade epithelial ovarian, primary 
peritoneal, or fallopian tube cancers with high folate receptor-alpha 
expression  
Sponsor: 
ImmunoGen, Inc. 
830 Winter Street 
Waltham, MA 02451 USA 
Sponsor Contact: 
 
Phone: 
 
Email: 
 
Original Protocol Date 
(Version 1.0): 
16 April 2021 
Amendment 1 Date 
(Version 2.0) 
23 August 2021 
Confidentiality Statement 
This document is the proprietary and confidential property of ImmunoGen, Inc. 
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NCT #: NCT05041257

Mirvetuximab Soravtansine (IMGN853) 
Dated 23 August 2021 
Protocol Number IMGN853-0419 v2.0 
 
 
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SPONSOR SIGNATURE PAGE 
 
 
 
 
 
 
Aug 23, 2021 | 9:04:11 PM EDT
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SPONSOR CONTACT LIST 
 
Primary Medical Monitor 
 
Phone: 
 
Email: 
 
Clinical Scientist 
 
Phone: 
 
Email: 
 
Trial Management  
 
Phone: 
 
Email: 
 
 
 
 
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INVESTIGATOR’S AGREEMENT 
 
I have received and read the Investigator Brochure for mirvetuximab soravtansine.  
I have read the ImmunoGen Protocol IMGN853-0419 and agree to conduct the study as outlined 
and in conformance with International Conference on Harmonisation (ICH) E6 Good Clinical 
Practice (GCP) and applicable regulatory requirements. I agree to maintain the confidentiality of 
all information received or developed in connection with this protocol. 
 
 
Printed Name of Investigator 
 
Signature of Investigator 
Date 
 
 
 
 
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LIST OF ABBREVIATIONS 
Table 1: 
List of Abbreviations and Definitions of Terms 
Abbreviation 
Term 
ADA 
antidrug antibodies 
ADC 
antibody drug conjugate 
AE 
adverse event 
AIBW 
adjusted ideal body weight 
ALT 
alanine aminotransferase  
ANC 
absolute neutrophil count 
ASCO 
American Society of Clinical Oncology 
AST 
aspartate aminotransferase  
BICR 
blinded independent central review 
BRCA 
breast cancer susceptibility gene 
C1D1 
Cycle 1 Day 1 
cfDNA 
cell-free DNA 
CTC 
circulating tumor cells 
ctDNA 
circulating tumor DNA 
CNS 
central nervous system 
CR 
complete response/remission 
CRO 
contract research organization 
CT 
computed tomography 
CTCAE  
Common Terminology Criteria for Adverse Events 
DM4 
N2’-[4-[(3-carboxypropyl)dithio]-4-methyl-1-oxo-2-sulfopentyl]-N2’-
deacetylmaytansine 
S-methyl DM4 
methylated N2’-[4-[(3-carboxypropyl)dithio]-4-methyl-1-oxo-2-
sulfopentyl]-N2’-deacetylmaytansine 
DOR 
duration of response 
ECG 
electrocardiogram 
ECOG 
Eastern Cooperative Oncology Group 
eCRF 
electronic case report form 
EOC 
epithelial ovarian cancer 
EOS 
End of Study 
EOT 
End of Treatment 
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Abbreviation 
Term 
ERB 
Ethics Review Board 
FDA 
Food and Drug Administration 
FFPE 
formalin-fixed paraffin-embedded 
FIH 
first-in-human 
FOLR1, FRα 
folate receptor 1/folate receptor alpha 
GCIG 
Gynecologic Cancer Intergroup  
GCP 
Good Clinical Practice 
HRD 
homologous recombination deficient 
IC 
Investigator’s choice 
ICF 
informed consent form 
ICH 
International Conference on Harmonisation  
IDMC 
Independent Data Monitoring Committee 
IEC 
Independent Ethics Committee 
IHC 
Immunohistochemistry 
ILD 
interstitial lung disease 
IMGN 
ImmunoGen 
IRB 
Institutional Review Board 
IRR 
infusion-related reaction 
ITT 
intent-to-treat 
IV 
intravenous 
mAb 
monoclonal antibody 
MedDRA 
Medical Dictionary for Regulatory Activities 
MIRV 
mirvetuximab soravtansine (IMGN853) 
MRI 
magnetic resonance imaging 
MS 
multiple sclerosis 
MTD 
maximum tolerated dose 
NCCN 
National Comprehensive Cancer Network 
NCI 
National Cancer Institute 
nM 
nanomolar 
ORR 
objective response rate 
OS 
overall survival 
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Abbreviation 
Term 
PARP 
poly (ADP-ribose) polymerase 
PD 
progressive disease 
PE 
physical examination 
PET 
positron emission testing 
PFS 
progression-free survival 
PI 
Principal Investigator 
PK 
pharmacokinetics 
PO 
orally 
PR 
partial response/remission 
PRN 
as needed  
PS 
performance status 
PT 
prothrombin time 
Q3W 
every 3 weeks 
REC 
Research Ethics Committee 
RECIST 
Response Evaluation Criteria in Solid Tumors 
RP2D 
recommended phase 2 dose 
rPSOC 
recurrent platinum-sensitive ovarian cancer 
RT 
radiotherapy 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
SC 
Steering Committee 
SoD 
sum of diameters 
SUSAR 
suspected unexpected serious adverse reaction 
TMT 
thiol s-methyltransferase 
TEAE 
treatment-emergent adverse event 
ULN 
upper limit of normal 
US 
United States 
Ventana FOLR1 Assay 
Ventana FOLR1 (FOLR1-2.1) CDx assay 
WBC 
white blood cell (count) 
WCBP 
woman of childbearing potential 
WHO-DD 
World Health Organization-Drug Dictionary 
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PROTOCOL SYNOPSIS 
Name of Sponsor/Company: ImmunoGen, Inc. 
Name of Investigational Product: mirvetuximab soravtansine (MIRV; IMGN853) 
Name of Active Ingredient: mirvetuximab soravtansine (MIRV; IMGN853) 
Title of Study: PICCOLO: A Phase 2, Single Arm Study of Mirvetuximab Soravtansine in Recurrent 
Platinum-Sensitive, High-Grade Epithelial Ovarian, Primary Peritoneal, or Fallopian Tube Cancers 
with High Folate Receptor-Alpha Expression 
Number of Patients (planned): Approximately 75 patients  
Study Center(s): Approximately 75 centers globally 
Studied Period (months): Approximately 30 months, 
including follow-up 
Phase of Development: 2 
Objectives: 
Primary Objective 
• 
To determine the efficacy of MIRV in patients with recurrent platinum-sensitive ovarian 
cancer (rPSOC) and high folate receptor alpha (FRα) expression  
Key Secondary Objective 
• 
To determine the durability of response to MIRV in patients with rPSOC and high FRα 
expression 
Additional Secondary Objectives 
• 
To evaluate the safety and tolerability of MIRV 
• 
To characterize the clinical activity of MIRV in patients with rPSOC and high FRα expression 
Exploratory Objectives 
• 
To assess the immunogenicity of MIRV  
• 
To evaluate potential blood-based biomarkers predictive of response to MIRV 
• 
To evaluate potential tumor-based biomarkers predictive of response to MIRV 
• 
To evaluate whether gene mutation(s) and/or homologous recombination status correlate with 
FRα levels 
Endpoints: 
Primary Endpoint 
• 
Objective response rate (ORR), which includes confirmed best response of complete response 
(CR) or partial response (PR) as assessed by the Investigator 
Key Secondary Endpoint 
• 
Duration of response (DOR), defined as the time from initial Investigator-assessed response 
(CR or PR) until progressive disease (PD) as assessed by the Investigator  
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Additional Secondary Endpoints 
• 
Treatment-emergent adverse events (TEAEs) and laboratory test results, physical examination, 
or vital signs 
• 
CA-125 response determined using the Gynecologic Cancer Intergroup (GCIG) criteria 
defined in Appendix C 
• 
Progression-free survival (PFS), defined as the time from first dose of MIRV until 
Investigator-assessed radiological PD or death, whichever occurs first  
• 
Overall survival (OS), defined as the time from first dose of MIRV until death 
• 
ORR, DOR, and PFS by blinded independent central review (BICR) will be summarized as 
sensitivity analysis 
Exploratory Endpoints 
• 
Incidence of seroconversion of antidrug antibodies (ADA) to MIRV and association with 
safety and efficacy 
• 
Identification of blood-based biomarkers potentially predictive of responsiveness to treatment 
• 
Identification of tumor DNA mutational status and the expression level of genes and pathways 
involved in cancer development, progression, and responsiveness to treatment 
• 
Correlation of gene mutation(s) and/or homologous recombination status with tumor FRα 
levels and soluble FRα levels in blood 
Study Design Overview: 
This Phase 2 study is designed to evaluate the efficacy and safety of MIRV in patients with recurrent 
platinum-sensitive, high-grade serous epithelial ovarian cancer (EOC), primary peritoneal, or fallopian 
tube cancer, whose tumors express a high-level of FRα, referred to throughout as rPSOC (recurrent 
platinum-sensitive ovarian cancer). Patients will have had at least 2 prior lines of therapy. These will 
include at least 2 lines of platinum-containing therapy or 1 line with a documented platinum allergy. 
All patients will be, in the opinion of the Investigator, appropriate for non-platinum single-agent 
therapy for their next line of therapy. FRα positivity will be defined by the Ventana FOLR1 (FOLR1-
2.1) CDx assay (Ventana FOLR1 Assay). 
Approximately 75 patients will be enrolled so that a total of 69 patients will be efficacy evaluable.  
Efficacy evaluable patients include those who have at least 1 measurable lesion (per Response 
Evaluation Criteria in Solid Tumors version 1.1 [RECIST v1.1]) at baseline and received at least 1 
dose of MIRV. 
All patients will receive single-agent MIRV at 6 mg/kg adjusted ideal body weight (AIBW) 
(Appendix D) administered through intravenous (IV) infusion on Day 1 of every 3-week cycle (Q3W). 
Tumor response will be evaluated by the Investigator using RECIST v1.1. 
Computerized tomography (CT) or magnetic resonance imaging (MRI) scans will be collected for 
sensitivity analysis by BICR. 
Patients will continue to receive MIRV until PD, unacceptable toxicity, withdrawal of consent, death, 
or until the Sponsor terminates the study (whichever comes first).  
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Tumor assessments, including radiological assessments by CT/MRI scans, will be performed at 
Screening and subsequently every 6 weeks (± 1 week) from Cycle 1 Day 1 (C1D1) for the first 
36 weeks then every 12 weeks (± 3 weeks) until PD, death, the start of new anticancer therapy, or 
patient’s withdrawal of consent (whichever occurs first).  
Patients who discontinue MIRV for reasons other than PD will continue with tumor assessments until 
documentation of PD or the start of a new anticancer therapy, whichever comes first. Prior to Week 36 
(from C1D1), assessments should occur every 6 weeks (± 1 week) as allowed by local requirements 
but must occur at an interval of no more than 12 weeks. After Week 36, assessments will occur every 
12 weeks (± 3 weeks) until documentation of PD per RECIST v1.1 or the start of new anticancer 
therapy.  
All patients who discontinue MIRV will be followed for survival every 3 months (± 1 month) until 
death, lost to follow-up, withdrawal of consent for survival follow-up, or End of Study (EOS) 
(whichever comes first). Additional survival follow-up calls may occur periodically, if needed.  
Statistical Considerations 
The primary endpoint of this study is ORR as assessed by the Investigator. The study is designed to 
test the null hypothesis that the ORR is ≤ 28% using an optimal Simon’s two-stage design (Simon 
1989) without a planned pause in enrollment given preliminary efficacy and established safety of 
MIRV. 
The optimal two-stage design to test the null hypothesis that the ORR is ≤ 28% versus the alternative 
that the ORR is ≥ 48%, has an expected sample size of 37.74, and a probability of early termination of 
0.762. If the ORR is ≤ 28%, there is a 0.024 probability of rejecting the null hypothesis (the target 
1-sided alpha value was 0.025). If the ORR is ≥ 48%, there is a 0.9 probability of rejecting the null 
hypothesis. After testing the drug on 28 efficacy evaluable patients in the first stage, the study will be 
terminated for futility if 9 or fewer patients respond. If the study goes on to the second stage, a total of 
69 efficacy evaluable patients will be enrolled. If the total number responding is more than 26, the null 
hypothesis is rejected. A total of approximately 75 patients will be enrolled to achieve 69 efficacy 
evaluable patients.  
Study Eligibility  
Inclusion Criteria 
1. Patients ≥ 18 years of age 
2. Patients must have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) 
of 0 or 1 
3. Patients must have a confirmed diagnosis of high-grade serous EOC, primary peritoneal 
cancer, or fallopian tube cancer  
4. Patients must have platinum-sensitive disease defined as radiographic progression greater than 
6 months from last dose of most recent platinum therapy 
Note: Progression should be calculated from the date of the last administered dose of platinum 
therapy to the date of the radiographic imaging showing progression  
5. Patients must have progressed radiographically on or after their most recent line of anticancer 
therapy 
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6. Patients must have at least 1 lesion that meets the definition of measurable disease by 
RECIST v1.1 (radiologically measured by the Investigator) 
7. Patients must be willing to provide an archival tumor tissue block or slides, or undergo 
procedure to obtain a new biopsy using a low-risk, medically routine procedure for 
immunohistochemistry (IHC) confirmation of FRα positivity  
8. Patient’s tumor must be positive for FRα expression as defined by the Ventana FOLR1 Assay 
9. Prior anticancer therapy 
a. Patients must have received at least 2 prior systemic lines of platinum therapy and be 
considered by the Investigator as appropriate for single-agent non-platinum therapy 
(documentation required – eg, high risk of hypersensitivity reaction; risk of further 
cumulative toxicity with additional platinum, including but not limited to 
myelosuppression, neuropathy, renal insufficiency or other) 
Note: Patients who have had a documented platinum allergy may have had only 1 prior 
line of platinum 
b. Patients may have received up to but no more than 1 prior independent non-platinum 
cytotoxic therapy 
c. Patients must have had testing for breast cancer susceptibility gene (BRCA) mutation 
(tumor or germline) and, if positive, must have received a prior poly (ADP-ribose) 
polymerase (PARP) inhibitor as either treatment or maintenance therapy 
d. Neoadjuvant ± adjuvant therapies are considered 1 line of therapy 
e. Maintenance therapy (eg, bevacizumab, PARP inhibitors) will be considered part of the 
preceding line of therapy (ie, not counted independently) 
f. Therapy changed due to toxicity in the absence of progression will be considered part of 
the same line (ie, not counted independently) 
10. Patients must have completed prior therapy within the specified times below: 
a. Systemic antineoplastic therapy within 5 half-lives or 4 weeks (whichever is shorter) prior 
to first dose of MIRV 
b. Focal radiation completed at least 2 weeks prior to first dose of MIRV 
11. Patients must have stabilized or recovered (Grade 1 or baseline) from all prior therapy-related 
toxicities (except alopecia) 
12. Patients must have completed any major surgery at least 4 weeks prior to first dose of MIRV 
and have recovered or stabilized from the side effects of prior surgery prior to first dose of 
MIRV 
13. Patients must have adequate hematologic, liver and kidney functions defined as: 
a. Absolute neutrophil count (ANC) ≥ 1.5 x 109/L (1500/μL) without granulocyte colony-
stimulating factor (G-CSF) in the prior 10 days or long-acting white blood cell (WBC) 
growth factors in the prior 20 days 
b. Platelet count ≥ 100 x 109/L (100,000/μL) without platelet transfusion in the prior 10 days 
c. Hemoglobin ≥ 9.0 g/dL without packed red blood cell (PRBC) transfusion in the prior 
21 days 
d. Serum creatinine ≤ 1.5 x upper limit of normal (ULN) 
e. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3.0 x ULN  
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f. Serum bilirubin ≤ 1.5 x ULN (patients with documented diagnosis of Gilbert syndrome are 
eligible if total bilirubin < 3.0 x ULN) 
g. Serum albumin ≥ 2 g/dL 
14. Patients must be willing and able to sign the informed consent form (ICF) and to adhere to the 
protocol requirements 
15. Women of childbearing potential (WCBP) must agree to use highly effective contraceptive 
method(s) while on MIRV and for at least 3 months after the last dose 
16. WCBP must have a negative pregnancy test within the 4 days prior to the first dose of MIRV 
 
Exclusion Criteria  
1. Patients with endometrioid, clear cell, mucinous, or sarcomatous histology, mixed tumors 
containing any of the above histologies, or low-grade/borderline ovarian tumor 
2. Patients with prior wide-field radiotherapy (RT) affecting at least 20% of the bone marrow 
3. Patients with > Grade 1 peripheral neuropathy per Common Terminology Criteria for Adverse 
Events (CTCAE) 
4. Patients with active or chronic corneal disorders, history of corneal transplantation, or active 
ocular conditions requiring ongoing treatment/monitoring, such as uncontrolled glaucoma, wet 
age-related macular degeneration requiring intravitreal injections, active diabetic retinopathy 
with macular edema, macular degeneration, presence of papilledema, and/or monocular vision 
5. Patients with serious concurrent illness or clinically relevant active infection, including, but 
not limited to the following: 
a. Active hepatitis B or C infection (whether or not on active antiviral therapy)  
b. HIV infection 
c. Active cytomegalovirus infection  
d. Any other concurrent infectious disease requiring IV antibiotics within 2 weeks prior to the 
first dose of MIRV 
Note: Testing at screening is not required for the above infections unless clinically indicated. 
6. Patients with a history of multiple sclerosis (MS) or other demyelinating disease and/or 
Lambert-Eaton syndrome (paraneoplastic syndrome) 
7. Patients with clinically significant cardiac disease including, but not limited to, any of the 
following: 
a. Myocardial infarction ≤ 6 months prior to first dose 
b. Unstable angina pectoris 
c. Uncontrolled congestive heart failure (New York Heart Association > class II) 
d. Uncontrolled ≥ Grade 3 hypertension (per CTCAE) 
e. Uncontrolled cardiac arrhythmias 
8. Patients with a history of hemorrhagic or ischemic stroke within 6 months prior to enrollment 
9. Patients with a history of cirrhotic liver disease (Child-Pugh Class B or C) 
10. Patients with a previous clinical diagnosis of noninfectious interstitial lung disease (ILD), 
including noninfectious pneumonitis 
11. Patients requiring use of folate-containing supplements (eg, folate deficiency) 
12. Patients with prior hypersensitivity to monoclonal antibodies (mAb) 
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13. Women who are pregnant or breastfeeding 
14. Patients who received prior treatment with MIRV or other FRα-targeting agents 
15. Patients with untreated or symptomatic central nervous system (CNS) metastases 
16. Patients with a history of other malignancy within 3 years prior to enrollment  
Note: patients with tumors with a negligible risk for metastasis or death (eg, adequately 
controlled basal-cell carcinoma or squamous-cell carcinoma of the skin, or carcinoma in situ of 
the cervix or breast) are eligible. 
17. Prior known hypersensitivity reactions to study drugs and/or any of their excipients 
Prohibited Concomitant Medications:  
Any non-study anticancer agents, including but not limited to antineoplastic agents, biologics, mAbs, 
hormonal therapy, or palliative RT during study treatment. Folate supplements are also prohibited 
during the course of the trial. 
Investigational Product, Dosage and Mode of Administration:  
Patients will receive MIRV 6 mg/kg AIBW IV Q3W.  
Duration of Study Participation:  
The duration of study participation for each patient extends from the signing of the ICF until the final 
follow-up study visit, termination from study, death, or withdrawal of consent.  
Study Committees: 
An Independent Data Monitoring Committee (IDMC) will not be utilized in this open-label, single-arm 
study of MIRV. 
 
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Table 2: 
Schedule of Assessments 
Procedure 
Pre-
screening 
Screening 
Cycle 1 
C=3 weeks 
C2+ 
C3/C5 
EOT 
30-Day  
Follow-up 
Survival  
Follow-up 
D1 
D1 
D1 
≤ 7d from 
discon. 
30 (+14) days 
from last dose 
Every 3 months 
(±1 month) 
from EOT 
Pre-screening Informed 
Consent 
● 
 
 
 
 
 
 
 
Informed Consent 
 
●a 
 
 
 
 
 
 
Eligibility 
 
●a  
 
 
 
 
 
 
Demographics 
 
●a  
 
 
 
 
 
 
Medical History 
 
●a  
 
 
 
 
 
 
Confirm Disease 
Diagnosis/Current Stage  
 
●a 
 
 
 
 
 
 
12-Lead ECG 
 
●b 
●b  
 
 
 
 
 
Coagulation  
(PT or INR/aPTT)  
 
●c 
 
 
 
 
 
 
Urinalysis  
 
●c  
 
 
 
 
 
 
FFPE Archived Tumor 
Tissue and/or New Biopsyd 
●d  
 
 
 
 
 
 
 
Physical Examinatione 
 
●c  
●f 
● 
● 
● 
● 
 
Weight 
 
●c  
● 
● 
● 
● 
● 
 
Vital Signsg 
 
●c  
● 
● 
● 
● 
● 
 
ECOG PS  
 
●c  
●f  
● 
● 
● 
● 
 
Hematology and Chemistryh 
 
●c  
●f  
● 
● 
● 
● 
 
Blood Sample for 
Biomarkers 
● 
 
● 
● 
● 
● 
● 
●i 
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Procedure 
Pre-
screening 
Screening 
Cycle 1 
C=3 weeks 
C2+ 
C3/C5 
EOT 
30-Day  
Follow-up 
Survival  
Follow-up 
D1 
D1 
D1 
≤ 7d from 
discon. 
30 (+14) days 
from last dose 
Every 3 months 
(±1 month) 
from EOT 
Pregnancy Testj 
 
●j  
●f  
● 
● 
 
●j  
 
Ophthalmic Examk 
 
●c  
Every other cycle from time 
treatment-emergent  
eye disorder first reported 
 
●k  
●k  
 
Ocular Symptom 
Assessmentl 
 
●c 
● 
● 
● 
● 
● 
 
Radiologic Tumor 
Assessmentm 
 
●a 
Every 6 (±1) weeks from 
C1D1 for first 36 weeks, then 
every 12 (±3) weeks 
 
●n 
●n  
 
CA-125o 
 
●c 
Collect at each radiologic 
tumor assessment (± 4 days) 
 
●n  
●n  
 
MIRV Administration  
 
 
● 
● 
● 
 
 
 
Record AE/SAEs and 
Concomitant Medicationsp 
●q  
● 
Collected continuously while patients are on study 
 
Blood Samples for 
Immunogenicityr 
 
 
● 
● 
● 
● 
●  
 
Survival Phone Screen, 
Including New Anticancer 
Therapys 
 
 
 
 
 
 
 
● 
Abbreviations: AE = adverse event; aPTT = activated partial thromboplastin time; BP = blood pressure; C = cycle; CA = cancer antigen; CT = computed 
tomography; CTCAE = Common Terminology Criteria for Adverse Events; D = day; ECG = electrocardiogram; ECOG PS = Eastern Cooperative Oncology 
Group; EOT = End of Treatment; FFPE = formalin-fixed paraffin-embedded; GCIC = Gynecologic Cancer Intergroup; INR = international normalized ratio; 
MIRV = mirvetuximab soravtansine MRI = magnetic resonance imaging; PD = progressive disease; PE = physical examination; PT = prothrombin time; 
RECIST = Response Evaluation Criteria in Solid Tumors; SAE = serious adverse event; WCBP = woman of childbearing potential 
a Must be within 28 days before C1D1 unless otherwise specified. 
b ECG assessment may be performed predose at C1D1 if not performed previously up to 28 days prior to first dose of MIRV. 
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c Must be within 14 days before C1D1. 
d Testing for FRα expression is required for all patients. All patients must submit tumor tissue block or fresh cut slides from available block (FFPE slides). 
Those who do not have archival tumor tissue to submit will be required to undergo procedures to obtain a new biopsy using a low-risk, medically routine 
procedure during the Pre-screening period to confirm eligibility. If the archival tumor tissue does not meet FRα criteria, a new biopsy tumor sample may be 
submitted and used to confirm this criterion. 
e Complete PE is required at Screening and the 30-Day Follow-up visit. At all other study visits while on MIRV, patients will have symptom-directed PEs. 
f ECOG, PE, pregnancy test for WCBP, and hematology and chemistry labs (if all parameters are within normal range) do not need to be repeated at C1D1 if 
performed within the previous 4 days during Screening. 
g Vital signs (BP and body temperature) will be measured before start of infusion; post infusion vital signs should be collected as clinically indicated for 
potential infusion-related reaction. 
h Hematology and chemistry labs may be performed up to 4 days prior to D1 of each cycle, and as clinically indicated while on treatment, with results reviewed 
before each MIRV administration. In the event of severe toxicity, laboratory tests must be repeated as clinically necessary until the toxicity resolves or 
stabilizes to baseline level. 
i Performed between 3 and 6 months after EOT based on patient availability or until documented progression (as measured by CA-125 GCIG criteria and/or 
RECIST-defined measurable disease). 
j For WCBP, a urine or serum pregnancy test must be performed within the 4 days prior to D1 of each cycle, and at the 30-Day Follow-up visit. It is 
recommended to perform monthly pregnancy tests for 3 months after the last dose of MIRV. Additional testing may be performed in accordance with 
institutional requirements or local regulation. 
k Baseline ophthalmic exams will be performed by an ophthalmologist within 14 days before C1D1 and will include the following: visual acuity (with/without 
corrective lens; whichever best reflects the patient’s usual functioning), slit lamp examination, and intraocular pressure measurement. All patients who have 
an ophthalmic exam on study treatment (post-baseline) due to emergence of visual signs or symptoms will have a complete ophthalmological examination 
performed at EOT visit or 30-Day Follow-up visit. 
l Ocular symptoms assessment will be performed by the treating physician or other qualified individual before the start of each cycle. For patients reporting 
> CTCAE Grade 1 ocular symptoms, treatment will be held until the patient is evaluated by an ophthalmologist for a complete examination. 
m Radiologic tumor assessment by CT/MRI scan. The same method of radiographic assessment used at Screening must be used at all subsequent radiographic 
assessments. 
n If a patient discontinues before documentation of PD, a tumor assessment and CA-125 will be assessed at the EOT or 30-Day Follow-up visit, if not 
performed within the previous 6 weeks. Tumor assessments and CA-125 will continue to be performed every 12 (± 3) weeks until PD is documented per 
RECIST v1.1 or the patient starts new anticancer therapy. Patients who discontinue MIRV for reasons other than PD will continue with tumor assessments 
until documentation of PD or the start of a new anticancer therapy, whichever comes first. Prior to Week 36 (from C1D1), assessments should occur every 6 
weeks (± 1 week) as allowed by local requirements but must occur at an interval of no more than 12 weeks. After Week 36, assessment will occur every 12 
weeks (± 3 weeks) until documentation of PD, death, the start of new anticancer therapy, or patient’s withdrawal of consent (whichever occurs first). 
o CA-125 will be measured at the time of every tumor assessment (± 4 days) (responses will be confirmed according to GCIG criteria Appendix C). 
p All SAEs, and those AEs assessed by the Investigator as at least possibly related to study drug should continue to be followed until they resolve or stabilize, 
whichever comes first. 
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q Only AEs/SAEs which are considered related to a study procedure (ie, blood draw or fresh tumor biopsy) will be captured during the Pre-screening period, ie, 
from the time of signing the Pre-screening consent (if one is utilized) until the signing of the main study informed consent, or until the patient is determined to 
be a screen failure.  
r Immunogenicity will be assessed in samples collected prior to dosing (predose) on C1D1, C2D1, C3D1, C5D1, at EOT, and 30-Day Follow-up. 
s Survival follow-up assessments will occur every 3 months (±1 month) until death, the patient is lost to follow-up or withdrawal of consent for survival follow-
up, or EOS (whichever comes first). These assessments may be conducted by telephone. Information on the start of new anticancer therapy (including start 
date, therapy type/name, and response on treatment) should be collected. Additional survival follow-up calls may occur periodically if needed for regulatory 
requests or at time of database lock for either primary or final analysis. 
 
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TABLE OF CONTENTS 
SPONSOR SIGNATURE PAGE ....................................................................................................2 
SPONSOR CONTACT LIST ..........................................................................................................3 
INVESTIGATOR’S AGREEMENT ...............................................................................................4 
LIST OF ABBREVIATIONS ..........................................................................................................5 
PROTOCOL SYNOPSIS ................................................................................................................8 
1.
INTRODUCTION ......................................................................................................25 
1.1. 
Target Background .....................................................................................................25 
1.2. 
Mirvetuximab Soravtansine ........................................................................................25 
1.3. 
Epithelial Ovarian Cancer and Treatment Options for Recurrent Platinum-
Sensitive Disease ........................................................................................................26 
1.4. 
Non-Clinical Studies of Mirvetuximab Soravtansine .................................................28 
1.4.1. 
Impact of FRα Expression ..........................................................................................28 
1.4.2. 
Pharmacology .............................................................................................................29 
1.4.3. 
Pharmacokinetics ........................................................................................................29 
1.4.4. 
Toxicology ..................................................................................................................29 
1.5. 
Clinical Studies of Mirvetuximab Soravtansine .........................................................29 
1.5.1. 
First-in-Human Phase 1 Clinical Trial: Study IMGN853-0401 .................................30 
1.5.2. 
Phase 3 Study IMGN853-0403 ...................................................................................30 
1.5.3. 
Conclusion ..................................................................................................................31 
1.6. 
Rationale for the Selection of Drug Dose Levels and Dosing Schedules ...................31 
1.6.1. 
Mirvetuximab Soravtansine ........................................................................................31 
1.7. 
Rationale for the Study Plan .......................................................................................32 
2.
STUDY OBJECTIVES AND ENDPOINTS ..............................................................32 
2.1. 
Objectives ...................................................................................................................32 
2.1.1. 
Primary Objective .......................................................................................................32 
2.1.2. 
Key Secondary Objective ...........................................................................................32 
2.1.3. 
Additional Secondary Objectives ...............................................................................32 
2.1.4. 
Exploratory Objectives ...............................................................................................32 
2.2. 
Endpoints ....................................................................................................................33 
2.2.1. 
Primary Endpoint ........................................................................................................33 
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2.2.2. 
Key Secondary Endpoint ............................................................................................33 
2.2.3. 
Additional Secondary Endpoints ................................................................................33 
2.2.4. 
Exploratory Endpoints ................................................................................................33 
3. 
STUDY POPULATION .............................................................................................34 
3.1. 
Criteria for Selection of Patient Population ................................................................34 
3.1.1. 
Inclusion Criteria ........................................................................................................34 
3.1.2. 
Exclusion Criteria .......................................................................................................35 
4. 
INVESTIGATIONAL PLAN .....................................................................................37 
4.1. 
Study Design ...............................................................................................................37 
4.1.1. 
Overview and Schema ................................................................................................37 
4.1.2. 
Dose and Schedule for Mirvetuximab Soravtansine ..................................................38 
5. 
STUDY TREATMENT ..............................................................................................38 
5.1. 
Mirvetuximab Soravtansine ........................................................................................38 
5.1.1. 
Mirvetuximab Soravtansine Packaging ......................................................................38 
5.1.2. 
Mirvetuximab Soravtansine Accountability ...............................................................38 
5.1.3. 
Mirvetuximab Soravtansine Study Treatment Compliance ........................................38 
5.2. 
Assignment of Patient Number ...................................................................................39 
5.2.1. 
Enrolled Patient Definition .........................................................................................39 
5.2.2. 
Patient Assignment to Dosing Regimens ...................................................................39 
5.3. 
Blinding Methods .......................................................................................................39 
5.4. 
Study Treatment Administration ................................................................................39 
5.4.1. 
Premedication for Study Treatment ............................................................................39 
5.4.2. 
Prophylactic use of Eye Drops ...................................................................................39 
5.4.2.1. 
Corticosteroid Eye Drops ...........................................................................................39 
5.4.2.2. 
Lubricating Artificial Tears ........................................................................................40 
5.4.3. 
Preparation and Administration of Mirvetuximab Soravtansine ................................40 
5.4.3.1. 
Calculation for Adjusted Ideal Body Weight .............................................................40 
5.5. 
Dose Modification Guidelines ....................................................................................41 
5.5.1. 
Treatment Criteria .......................................................................................................41 
5.5.1.1. 
Mirvetuximab Soravtansine-Related Adverse Events ................................................42 
5.5.1.2. 
Mirvetuximab Soravtansine Dose Reduction Dose Levels ........................................43 
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5.5.1.3. 
Monitoring and Management of Nausea and Vomiting .............................................43 
5.5.1.4. 
Monitoring and Management of Diarrhea ..................................................................44 
5.5.2. 
Ocular Disorders .........................................................................................................44 
5.5.2.1. 
Monitoring and Preventive Measures .........................................................................44 
5.5.2.2. 
Management and Dose Modification Guidelines .......................................................44 
5.5.3. 
Monitoring of Noninfectious Pneumonitis .................................................................46 
5.5.4. 
Management of Electrolytes Imbalance .....................................................................48 
5.5.5. 
Potential Infusion-related Reactions ...........................................................................48 
5.5.6. 
Discontinuation of Mirvetuximab Soravtansine Due to Toxicity...............................50 
5.6. 
Discontinuation of the Patients from the Study or Study Treatment ..........................50 
5.6.1. 
End of Treatment ........................................................................................................50 
5.6.2. 
End of Study ...............................................................................................................50 
5.6.3. 
Withdrawal of Consent ...............................................................................................50 
5.6.4. 
Lost to Follow-up .......................................................................................................51 
5.7. 
Period of Observation .................................................................................................51 
5.8. 
Concomitant Medications and Procedures .................................................................52 
5.8.1. 
Vaccine Administration ..............................................................................................52 
5.8.2. 
Antiemetic and Antidiarrheal Medications .................................................................52 
5.8.3. 
Folate-Containing Supplements ..................................................................................52 
5.8.4. 
Antineoplastic Therapy ...............................................................................................52 
5.8.5. 
Hematopoietic Growth Factors ...................................................................................52 
5.8.6. 
Anticoagulants ............................................................................................................52 
5.8.7. 
Methods of Contraception ..........................................................................................52 
5.8.8. 
Other Concomitant Medications .................................................................................53 
5.8.9. 
Medications That Are CYP3A or MDR1 Substrates or CYP3A Substrates 
with Narrow Therapeutic Index ..................................................................................54 
5.9. 
Overdose and Medication Error ..................................................................................54 
5.9.1. 
Overdose .....................................................................................................................54 
5.9.2. 
Medication Error .........................................................................................................54 
6. 
IMMUNOGENICITY AND BIOMARKER ASSESSMENTS .................................54 
6.1. 
Immunogenicity Assessments – Mirvetuximab Soravtansine ....................................54 
6.2. 
Evaluation of FRα Expression in Tumor Tissue ........................................................55 
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6.3. 
Potential Predictive Markers of Drug Response .........................................................55 
6.3.1. 
Blood Biomarkers .......................................................................................................55 
6.3.2. 
Tumor Biomarkers ......................................................................................................55 
6.3.3. 
BRCA and Homologous Recombination Deficient Status ..........................................56 
7. 
STUDY PROCEDURES ............................................................................................56 
7.1. 
Informed Consent .......................................................................................................56 
7.2. 
Inclusion and Exclusion Criteria ................................................................................56 
7.3. 
Confirmation of Disease Diagnosis ............................................................................57 
7.4. 
BRCA Mutation Status ................................................................................................57 
7.5. 
Demographic/Medical History ...................................................................................57 
7.6. 
Physical Examination, Weight, and Height ................................................................57 
7.7. 
Vital Signs ..................................................................................................................57 
7.8. 
Electrocardiogram .......................................................................................................57 
7.9. 
Ocular Symptom Assessment and Ophthalmic Examination .....................................58 
7.9.1. 
Ocular Symptom Assessment .....................................................................................58 
7.9.2. 
Ophthalmic Examination ............................................................................................58 
7.10. 
Laboratory Assessments .............................................................................................58 
7.10.1. 
Clinical Laboratory Panels .........................................................................................59 
7.11. 
Pregnancy Screen ........................................................................................................59 
7.12. 
Eastern Cooperative Oncology Group Performance Status ........................................59 
7.13. 
Tumor Response Assessment .....................................................................................60 
7.13.1. 
Radiological Imaging ..................................................................................................60 
7.13.2. 
CA-125 .......................................................................................................................60 
8. 
ASSESSMENT OF SAFETY .....................................................................................60 
8.1. 
Recording Adverse Events and Serious Adverse Events ...........................................60 
8.1.1. 
Definition of Adverse Events .....................................................................................61 
8.1.1.1. 
Adverse Event .............................................................................................................61 
8.1.1.2. 
Serious Adverse Event ................................................................................................62 
8.1.1.3. 
Adverse Events of Special Interest .............................................................................62 
8.1.2. 
Classification of Adverse Events ................................................................................63 
8.2. 
Adverse Events ...........................................................................................................64 
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8.2.1. 
Reporting Serious Adverse Events .............................................................................64 
8.2.1.1. 
Reporting of Disease Progression ...............................................................................65 
8.2.2. 
Reporting a Pregnancy ................................................................................................65 
9. 
STUDY ACTIVITIES ................................................................................................65 
9.1. 
Screening Visit ............................................................................................................65 
9.1.1. 
Standard of Care Assessments ....................................................................................66 
9.2. 
End of Treatment Visit ...............................................................................................66 
9.3. 
Follow-up Assessments ..............................................................................................66 
9.3.1. 
30-Day Follow-up Visit ..............................................................................................66 
9.3.2. 
Response Follow-up ...................................................................................................66 
9.3.3. 
Survival Follow-up .....................................................................................................67 
10. 
STATISTICAL METHODS .......................................................................................67 
10.1. 
Sample Size ................................................................................................................67 
10.2. 
Safety Analyses ..........................................................................................................68 
10.3. 
Efficacy .......................................................................................................................68 
10.3.1. 
Primary Efficacy Analysis ..........................................................................................68 
10.3.1.1. 
Objective Response Rate ............................................................................................68 
10.3.2. 
Key Secondary Efficacy Endpoint ..............................................................................68 
10.3.3. 
Additional Secondary Efficacy Endpoints ..................................................................69 
10.4. 
Interim Analysis ..........................................................................................................69 
11. 
QUALITY CONTROL AND ASSURANCE ............................................................69 
11.1. 
Recording of Data and Data Quality Assurance .........................................................69 
12. 
ETHICAL CONSIDERATIONS AND ADMINISTRATIVE 
PROCEDURES ..........................................................................................................69 
12.1. 
Ethical and Regulatory ...............................................................................................69 
12.1.1. 
Institutional Review Board or Independent Ethics Committee Approval ..................70 
12.1.2. 
Patient Information and Consent ................................................................................70 
12.2. 
Investigators and Study Administrative Structure ......................................................71 
12.3. 
Patient Confidentiality ................................................................................................71 
12.4. 
Study Monitoring ........................................................................................................71 
12.5. 
Study Committees .......................................................................................................72 
12.5.1. 
Steering Committee ....................................................................................................72 
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12.5.2. 
Independent Data Monitoring Committee ..................................................................72 
12.6. 
Case Report Forms and Study Reports .......................................................................72 
12.7. 
Protocol Adherence ....................................................................................................73 
12.8. 
End of Study ...............................................................................................................73 
12.9. 
Study Termination ......................................................................................................74 
12.10. 
Site Termination .........................................................................................................74 
12.11. 
Access to Source Documentation ...............................................................................74 
12.12. 
Audits and Inspections ................................................................................................75 
12.13. 
Data Generation and Analysis ....................................................................................75 
12.14. 
Retention of Data ........................................................................................................75 
12.15. 
Financial Disclosure ...................................................................................................75 
12.16. 
Insurance Compensation .............................................................................................75 
12.17. 
Publication and Disclosure Policy ..............................................................................76 
13. 
LIST OF REFERENCES ............................................................................................77 
APPENDIX A. EASTERN COOPERATIVE ONCOLOGY GROUP 
PERFORMANCE STATUS SCALE .........................................................................81 
APPENDIX B. RESPONSE DEFINITIONS (RECIST V1.1) ...................................................82 
APPENDIX C. GYNECOLOGIC CANCER INTERGROUP CRITERIA FOR 
EVALUATION OF CA-125 ......................................................................................88 
APPENDIX D. ADJUSTED IDEAL BODY WEIGHT CALCULATION ...............................91 
 
LIST OF TABLES 
Table 1: 
List of Abbreviations and Definitions of Terms ...........................................................5 
Table 2: 
Schedule of Assessments ............................................................................................14 
Table 3: 
Dose Modifications for Mirvetuximab Soravtansine-related Adverse Events ...........42 
Table 4: 
Mirvetuximab Soravtansine Dose Reduction Dose Levels ........................................43 
Table 5: 
Management of Ocular Symptoms .............................................................................45 
Table 6: 
Management of Noninfectious Pneumonitis ..............................................................47 
Table 7: 
Management Guidelines for Potential Infusion-related Reactions .............................49 
Table 8: 
Clinical Laboratory Tests ...........................................................................................59 
Table 9: 
Adverse Event Severity ..............................................................................................63 
Table 10: Adverse Event Causal Relatedness .............................................................................63 
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LIST OF FIGURES 
Figure 1: 
Mirvetuximab Soravtansine Structure ........................................................................26 
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1. 
INTRODUCTION 
1.1. 
Target Background 
Folate receptor alpha (FRα) is a glycosylphosphatidylinositol-anchored cell surface protein 
encoded by the folate receptor 1 (FOLR1) gene. FRα internalizes folate, which is an essential 
cofactor for one-carbon transfer reactions that are required for DNA and RNA synthesis, cell 
growth, and proliferation. Marked upregulation of FRα occurs during neonatal development and 
in cancer, suggesting that the receptor functions primarily under conditions of high folate 
demand. In contrast, normal adult tissues generally lack FRα expression and employ alternative 
transporters such as folate receptor β, reduced folate carrier and proton-coupled folate transporter 
for folate uptake (Weitman 1992, Mantovani 1994, Elnakat 2004, Kelemen 2006, and 
Investigator Brochure).  
Published studies have demonstrated FRα overexpression by immunohistochemistry (IHC) in 
various epithelial tumors, particularly the serous and endometrioid histologic subtypes of ovarian 
and endometrial cancers (Scorer 2010, Garin-Chesa 1993, Kalli 2008, Crane 2012, Dainty 2007, 
Jones 2008, Ab 2015, and Allard 2007). IHC results obtained from patients screened or enrolled 
in the Phase 1 Study IMGN853-0401 and Phase 3 Study IMGN853-403 are generally consistent 
with the literature (Investigator Brochure). Assessment of the FRα distribution in the expansion 
cohorts of IMGN853-0401 demonstrated that approximately 40% of patients have high 
expression (the threshold for positivity in this study).  
Several additional studies have further validated FRα as a target in serous epithelial ovarian 
cancer (EOC). First, quantitative polymerase chain reaction studies show ubiquitous FRα mRNA 
expression in serous EOC (Hanker 2012, Hoskins 1998, Hough 2001) and high levels of FRα 
mRNA correlate with poor response to chemotherapy and decreased disease-free survival 
(Chen 2012). Second, both Kalli et al and Crane et al have demonstrated that recurrent tumors 
retain FRα expression comparably to primary tumors as shown by serial biopsy sampling and 
IHC (Kalli 2008, Crane 2012). Third, studies with FRα-specific imaging agents have 
demonstrated real-time FRα expression at primary and metastatic tumor sites (Fisher 2008, 
Gaillard 2018, Garcia 2013, Garin-Chesa 1993, and van Dam 2011). Finally, a truncated form of 
FRα has been detected in ascites and blood of EOC patients (Basal 2009, Mantovani 1994), 
further confirming expression in this disease and suggesting that the receptor may serve as a 
circulating biomarker. Collectively, these data suggest that FRα is a promising target in solid 
tumors, particularly EOC. 
1.2. 
Mirvetuximab Soravtansine 
Because of its tumor-specific expression and capacity to internalize small and large molecule 
ligands, FRα has emerged as a biologically rational target for antibody drug conjugate (ADC) 
therapy. ADCs combine the specificity of monoclonal antibody (mAb) to tumor antigens with 
the extraordinary cytotoxicity of maytansine derivatives, which are potent antimicrotubule agents 
that target proliferating cells. MIRV is an ADC designed to target FRα. It consists of the 
chimeric anti-FRα mAb M9346A attached via a cleavable linker to the cytotoxic maytansinoid, 
DM4 (Figure 1). 
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Figure 1: 
Mirvetuximab Soravtansine Structure 
 
DM4 is ~2% by weight relative to mAb. 
Due to the nature of the conjugation process, the number of DM4 molecules attached to the mAb 
ranges from 1 to 7 molecules per Ab, with an average of 3 or 4 DM4 molecules per Ab. 
Conjugation of the maytansinoid to the tumor-targeting Ab ensures that the cytotoxic component 
remains inactive in the circulation. Release of the cytotoxic payload requires binding, 
internalization, and degradation of the Ab. The released payload then kills the cell by inducing 
G2-M arrest and cell death. Cellular processing of maytansinoid conjugates can also generate 
lipophilic catabolites that cross cell membranes and kill neighboring cells (Erickson 2006).  
In vitro, MIRV binds cell surface FRα with high apparent affinity (≤ 0.1 nM) and shows potent 
(half maximal inhibitory concentration [IC50] ≤ 1 nM) and selective cytotoxicity against tumor 
cells expressing FRα. Cytotoxic effects of MIRV in vitro is related to the level of cell-surface 
expression of FRα (Ab 2015). MIRV additionally demonstrates significant activity against FRα 
positive xenografts, with partial and complete remissions observed in ovarian models (Ab 2015). 
Together with the selective upregulation of FRα in solid tumors, these results provide the 
rationale for exploring the clinical utility of MIRV. 
1.3. 
Epithelial Ovarian Cancer and Treatment Options for Recurrent 
Platinum-Sensitive Disease 
Ovarian cancer is a lethal disease with 21,750 new cases and 13,940 deaths expected in 2020 in 
the US (SEER Cancer Statistics Factsheet 2020). The estimated number of new EOC cases in the 
EU (EU27) in 2020 was 39,414 with 27,138 deaths (EUCAN Cancer Fact Sheet: Ovary 2020). 
The overall 5-year survival for EOC patients is only 44% (Cannistra 2004, Baldwin 2012). 
Recent studies indicate that ovarian, peritoneal, and fallopian tube cancers are not distinct 
entities, but represent a spectrum of diagnoses that originate in the Mullerian tissue. Primary 
fallopian tube carcinoma and peritoneal cancers are now included in the ovarian cancer staging 
classification (Cobb 2015, Grant 2010, Naumann 2011, O’Shannessy 2013), and are considered 
to be part of EOC with the same treatment and outcomes.  
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Despite considerable improvements in primary therapy, 80% of the patients with advanced EOC 
are expected to relapse during or after treatment with platinum-containing regimens 
(Armstrong 2019). Disease recurring within 6 months of platinum-based chemotherapy is 
classified as platinum-resistant, whereas disease recurring longer than 6 months after therapy is 
termed platinum-sensitive.  
Platinum remains the most active treatment for earlier lines of ovarian cancer. The benefit of 
retreatment with platinum is generally less with each subsequent line of therapy, as evidenced by 
objective response rate (ORR) and median progression-free survival (PFS) reported for 
platinum-based doublets in the following settings: frontline (~70% [Sandercock 2002], 12-17 
months [Burger 2011 and Table 15 (GOG-0218)] in Avastin US Package Insert 2020, ICON3 
2002); second-line (56% to 57%, 8.4 to 10.4 months [Aghajanian 2012, Coleman 2017]); and a 
mixed population of second-line and third-line patients (~80% of patients were second-line and 
~ 20% were third-line) with partially platinum-sensitive disease with a platinum free interval of 6 
to 12 months (39% to 45%, 8.8 to 9.4 months [Gladieff 2012]). 
While platinum-based doublets predominate treatment for front- and second-line patients based on 
results from randomized trials, there is no generally accepted standard of care with a clear efficacy 
benchmark based on prospective trials in third-line or later patients. While patients with 
platinum-sensitive disease after 2 prior lines of therapy may benefit from further platinum-based 
treatment, by the time they have completed 2 prior lines of platinum-based therapy, they are at risk 
for cumulative platinum-associated toxicities, including increased risk of hypersensitivity 
reactions, bone marrow suppression, renal insufficiency, and neuropathy. Patients who receive 
multiple courses of platinum have an increased rate of potentially fatal hypersensitivity reactions 
(Navo 2006, Zweizig 1994). More than 27% of patients who receive more than 7 cycles of 
carboplatin have reactions, and half of those are moderate to severe (Markman 1999). Physicians 
must choose, therefore, the most appropriate next therapy from a range of options. For example, 
symptomatic patients in need of a rapid response might be offered a platinum-based doublet, 
despite the risks of toxicities from this approach, whereas patients with a slower tempo of 
progression might be offered single-agent chemotherapy, choosing the next treatment with a side 
effect profile least likely to interfere with their goals of care. For those patients with a prior 
hypersensitivity reaction, while desensitization protocols can be undertaken, particularly at 
academic institutions, they are cumbersome and not always successful (Castells 2008, O’Malley 
2017, Navo 2006). For such patients, as well as those who those who are at risk of having a 
hypersensitivity reaction based on prior cumulative exposure to platinum, the availability of other 
active, well-tolerated treatment options would be important. Given these considerations, it is not 
surprising that a majority of third-line recurrent platinum-sensitive ovarian cancer (rPSOC) 
patients do not receive a platinum-based regimen. In particular, real world data show that over 
60% of these patients receive non-platinum therapy, including 34% treated with non-platinum 
based single-agent chemotherapy, 12% with a non-platinum bevacizumab chemotherapy 
combination, and the remainder with other regimens such as hormonal therapy, checkpoint poly 
(ADP-ribose) polymerase inhibitors, PARP inhibitors, and clinical trials (Flatiron Health Ovarian 
Cancer Cohort, 2017-2020).  
Although PARPi are approved for third- or greater-line treatment of breast cancer susceptibility 
gene (BRCA) mutation or homologous recombination deficiency positive ovarian cancer, the low 
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use of PARPi (4%; Flatiron Health Ovarian Cancer Cohort, 2017-2020) in this setting illustrates 
the evolving paradigm where patients are increasingly assessed for mutational status in the 
frontline setting and receive PARPi earlier in their course of therapy as part of maintenance. It is 
noted that studies supporting the efficacy claims for PARPi in the treatment setting are based on 
populations who were PARPi naïve (Rucaparib Multi-Discipline Review 2016, Olaparib Medical 
Review 2014, niraparib US package insert 2019). Thus, in BRCA mutation patients who have 
received prior PARPi maintenance, the efficacy of subsequent PARPi treatment is unknown. A 
diminished response is likely, based on an acquired resistance such as that reported by Lin (Lin 
2019), that referenced resistance related to the conversion of mutational status back to wildtype. 
Ovarian cancer patients without known BRCA mutations tend to have a worse outcome than 
those with BRCA mutations, both in terms of response to platinum therapy and overall survival in 
general (Neff 2017). In the general ovarian cancer population, retrospective studies have shown 
that efficacy diminishes with each line of therapy regardless of platinum status (Hanker 2012, 
Bruchim 2013). Consistent with data from those retrospective studies, a randomized trial of 
topotecan versus paclitaxel in the second-line setting demonstrated that the overall response rate 
to chemotherapy diminishes with subsequent lines of therapy (ORR of 28% to 29% in the 
platinum-sensitive subset; and an ORR of 10% to 13% for patients who crossed over and 
therefore have 2 priors [Gordon 2001, Gore 2001]). Thus, a reasonable estimate of response rates 
associated with non-platinum regimens in the third-line setting, based on limited data from the 
pre-PARPi era, range from 10% 13% for single agents (Gore 2001, Bruchim 2013). 
In summary, the range of available therapies for patients with platinum-sensitive disease and two 
or more prior lines of therapy (including those with BRCA mutations who had a prior PARPi) 
provide limited benefit and the potential for significant cumulative toxicity. Furthermore, with 
the introduction of PARPi maintenance early in the ovarian cancer treatment paradigm, the 
population of patients with recurrent disease that remains potentially platinum-sensitive based on 
platinum-free interval is increasing, representing a growing unmet need. Because rPSOC remains 
a significant unmet medical need, the National Comprehensive Cancer Network (NCCN) 
guidelines recommend that patients with recurrent platinum-sensitive disease participate in 
clinical trials (NCCN Guidelines 2021). 
1.4. 
Non-Clinical Studies of Mirvetuximab Soravtansine 
Please refer to the Investigator Brochure for further detail of nonclinical studies in MIRV. 
1.4.1. 
Impact of FRα Expression 
Nonclinical studies revealed a positive correlation between the level of FRα expression on the 
cell surface, the amount of maytansinoid catabolites generated, and the degree of sensitivity of 
the cells to MIRV in vitro. MIRV is not active against low and negative FRα expressing cells. 
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1.4.2. 
Pharmacology 
Nonclinical pharmacology studies are further detailed in the Investigator Brochure. In summary, 
results of nonclinical pharmacology studies demonstrate the following: 
• FRα has limited normal tissue expression and marked expression in solid tumors, 
particularly cancers of the ovary and endometrium (Investigator Brochure).  
• In vitro cytotoxicity studies suggest that cells sensitive to MIRV express higher levels 
of FRα and release 10- to 100-fold more cytotoxic maytansinoid than cells resistant to 
MIRV.  
• MIRV retains the inherent activities of its Ab moiety, M9346A, including binding 
affinity (apparent affinity ≤ 0.1 nM) and selectivity for FRα, capacity for uptake, 
internalization and degradation by FRα-positive target cells, and ability to induce Ab-
dependent cell-mediated cytotoxicity (ADCC) in vitro.  
• MIRV demonstrates significant activity against FRα-positive xenografts. Partial 
and/or complete regressions in xenograft models of EOC were seen at doses of MIRV 
well below its maximum tolerated dose (MTD).  
1.4.3. 
Pharmacokinetics 
Nonclinical data indicated that the pharmacokinetics (PK) of MIRV were approximately dose 
proportional within the ranges evaluated (1 to 10 mg/kg). These studies are further detailed in the 
Investigator Brochure.  
1.4.4. 
Toxicology 
Results of nonclinical toxicology studies supported the first-in-human (FIH) study exploring the 
safety and tolerability of MIRV when administered once every 3 weeks to patients with 
advanced solid tumors. Toxicology studies are further detailed in the Investigator Brochure. 
1.5. 
Clinical Studies of Mirvetuximab Soravtansine 
To date, MIRV has been evaluated in 5 clinical studies, 2 of which are currently ongoing: 
• a completed, Phase 1, single-agent, first-in-human, dose escalation, and dose 
expansion study in patients (n = 206) with FRα-positive solid tumors (IMGN853-
0401);  
• a completed, randomized, open-label, pivotal Phase 3 study in patients (n = 366) with 
FRα-positive platinum-resistant ovarian cancer (PROC; which includes epithelial 
ovarian, fallopian tube, and primary peritoneal cancer) treated with single-agent 
MIRV versus Investigator’s choice (IC) chemotherapy (IMGN853-0403); 
• a completed, combination (with bevacizumab [BEV], carboplatin [Carbo], pegylated 
liposomal doxorubicin [PLD], pembrolizumab [Pembro], or BEV + Carbo), dose 
escalation, dose expansion, Phase 1b/2 study in patients (n = 311) with FRα-positive 
EOC, primary peritoneal, or fallopian tube cancer (IMGN853-0402); 
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• an ongoing, randomized, open-label, Phase 3 study in patients (estimated n = 430) 
with FRα-positive PROC treated with single-agent MIRV versus IC chemotherapy 
(IMGN853-0416); 
• an ongoing, monotherapy, Phase 3 study in patients (estimated n = 110) with FRα-
positive EOC, primary peritoneal, or fallopian tube cancer (IMGN853-0417);  
Section 1.5.1 provides further details of Study IMGN853-0401, which evaluated MIRV in 
11 patients with rPSOC. 
1.5.1. 
First-in-Human Phase 1 Clinical Trial: Study IMGN853-0401 
The FIH, Phase 1 study evaluated the safety, PK, and pharmacodynamics of single-agent MIRV 
in patients with EOC and other FRα-positive tumors. The recommended Phase 2 dose (RP2D) 
for single-agent MIRV administered every 3 weeks (Q3W) was determined to be 6.0 mg/kg 
adjusted ideal body weight (AIBW). Data from this study are detailed in the Investigator 
Brochure.  
In EOC, initial antitumor activity was observed with MIRV monotherapy in Study 
IMGN853-0401 regardless of platinum sensitivity. A total of 113 patients with EOC were 
enrolled in 3 separate expansion cohorts (46 patients with PROC; 27 patients with 
biopsy-accessible relapsed/refractory EOC; and 40 patients with relapsed EOC). Of these 
113 patients, 11 had rPSOC with at least 2 prior lines of therapy, 5 of whom were enrolled in the 
biopsy-accessible cohort and 6 of whom were enrolled in the cohort with relapsed EOC. Within 
the 11 patients with rPSOC, MIRV was associated with a confirmed Investigator-assessed ORR 
of 63.6% (95% CI: 30.8, 89.1); with 2 patients (18.2%) with complete response (CR) (median 
duration of response [DOR] of 15.71 months), and 5 patients (45.5%) with partial response (PR) 
(median DOR of 4.11 months), representing a potential improvement over the ORR of available 
third-line treatment options. 
Safety data suggested that MIRV was well tolerated, with a safety profile primarily consisting of 
low-grade gastrointestinal adverse events (AEs) and blurred vision related to corneal 
keratopathy. The treatment-emergent adverse events (TEAEs) were manageable with standard 
medical care and/or dose modification, with a low rate (10%) of patients discontinuing MIRV 
due to a treatment-related TEAE.  
1.5.2. 
Phase 3 Study IMGN853-0403 
Study IMGN853-0403 was a randomized, open-label, pivotal Phase 3 study in patients with 
FRα-positive platinum-resistant ovarian cancer (PROC; which includes epithelial ovarian, 
fallopian tube, and primary peritoneal cancer) treated with single-agent MIRV versus IC 
chemotherapy. A total of 366 patients were randomized and assigned to the MIRV group or the 
IC chemotherapy groups (248 and 118, respectively) and were included in the intent-to-treat 
(ITT) analysis. A total of 352 patients received at least 1 dose of MIRV or IC chemotherapy (243 
and 109, respectively), and were included in the Safety population analysis. 
While Study IMGN853-0403 did not meet the primary efficacy endpoint, MIRV showed 
consistently favorable efficacy when compared to IC chemotherapy in measures of PFS, ORR, 
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overall survival (OS), DOR, PFS2, cancer antigen 125 (CA-125), and primary patient reported 
outcome (PRO) endpoints. 
The safety profile of MIRV demonstrated in Study IMGN853-0403 was consistent with that 
observed in Phase 1 and was favorable relative to that of IC chemotherapy. The MIRV safety 
profile was predominantly characterized by low-grade nausea (51%), diarrhea (40%), and 
blurred vision (40%). These TEAEs are generally managed and mitigated with antiemetics, 
antidiarrheals, and lubricating/steroid eye drops. In the MIRV group, there were fewer ≥ Grade 3 
TEAEs, and fewer TEAEs leading to dose reduction or delay and treatment discontinuation 
(46%, 37%, and 12%, respectively) compared with the IC chemotherapy group (61%, 45%, and 
19%, respectively). While myelosuppression is an important safety issue with pegylated 
liposomal doxorubicin and topotecan, MIRV is associated with less myelosuppression compared 
to IC chemotherapy, with lower rates of neutropenia (7% versus 39% all grades; 0% versus 21% 
≥ Grade 3), thrombocytopenia (11% versus 16% all grades; 0% versus 4% ≥ Grade 3) and 
anemia (14% versus 29% all grades; 2% versus 11% ≥ Grade 3). Similarly, neurotoxicity is an 
important safety issue with paclitaxel; MIRV, an ADC with the tubulin-directed payload DM4, is 
associated with less peripheral neuropathy than paclitaxel (15% versus 28% ≥ Grade 2) and less 
alopecia (3% versus 22% all grades). The safety profile of MIRV in the high FRα subset is 
consistent with that observed in the overall MIRV safety population. 
1.5.3. 
Conclusion 
Safety and efficacy data were available in 737 patients who received MIRV as a single-agent or 
in combination and are consistent with a positive risk benefit assessment. The potential benefit of 
the antitumor activity demonstrated by MIRV in patients with FRα high, recurrent 
platinum-sensitive EOC with at least 2 prior lines of therapy, a population with high unmet need, 
outweighs the risks associated with the well tolerated safety profile, as summarized above. 
1.6. 
Rationale for the Selection of Drug Dose Levels and Dosing 
Schedules 
1.6.1. 
Mirvetuximab Soravtansine 
The selection of the Phase 2 dose of 6 mg/kg AIBW intravenous (IV) Q3W was based on data 
obtained from Study IMGN853-0401, an FIH study designed to establish the MTD and 
determine the RP2D of MIRV when administered IV as a single-agent in adult patients with 
FRα-positive solid tumors who have relapsed or are refractory to standard therapies. This dose 
and schedule are well tolerated in patients with PROC, based on the results from 243 patients 
who received MIRV in Study IMGN853-0403 (Section 1.5.2). In addition, this full dose and 
schedule of mirvetuximab soravtansine was able to be combined with full doses of each of the 
combination agents in Study IMGN853-0402. The safety data for the 11 patients with rPSOC 
who received MIRV in Study IMGN853-0401 are consistent with the overall safety profile 
(Section 1.5.1). Therefore, 6 mg/kg AIBW IV Q3W was chosen for further evaluation in rPSOC 
in this study. For more information, please see the Investigator Brochure.  
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1.7. 
Rationale for the Study Plan 
The design of this study is based on safety data obtained from the Phase 3 study 
(IMGN853-0403), as well as safety and efficacy data from the Phase 1 study (IMGN853-0401), 
which showed a potential for a clinically meaningful ORR and DOR for MIRV (ORR of 63.6% 
[95% CI: 30.8, 89.1]; with 2 patients [18.2%] with CR [both had a DOR of 15.7+ months], and 
5 patients [45.5%] with PR [median DOR of 4.1 months]). These data represent a potential 
improvement over the ORR of available third-line treatment options, as summarized in 
Section 1.3. 
This single-arm Phase 2 study is designed to evaluate the efficacy and safety of MIRV 
administered at 6 mg/kg AIBW IV Q3W in patients with rPSOC, primary peritoneal, or fallopian 
tube cancer, whose tumors express a high level of FRα. Patients will be, in the opinion of the 
Investigator, appropriate for single-agent therapy for their next line of therapy. FRα positivity 
(high FRα) will be defined by the Ventana FOLR1 Assay. Please see Section 6.2 for details 
regarding scoring methodology used for patient selection. 
2. 
STUDY OBJECTIVES AND ENDPOINTS 
2.1. 
Objectives 
2.1.1. 
Primary Objective 
• To determine the efficacy of MIRV in patients with recurrent platinum-sensitive 
ovarian cancer (rPSOC) and high folate receptor alpha (FRα) expression.  
2.1.2. 
Key Secondary Objective 
• To determine the durability of response to MIRV in patients with rPSOC and high 
FRα expression 
2.1.3. 
Additional Secondary Objectives 
• To evaluate the safety and tolerability of MIRV 
• To characterize the clinical activity of MIRV in patients with rPSOC and high FRα 
expression 
2.1.4. 
Exploratory Objectives 
• To assess the immunogenicity of MIRV 
• To evaluate potential blood-based biomarkers predictive of response to MIRV  
• To evaluate potential tumor-based biomarkers predictive of response to MIRV 
• To evaluate whether gene mutation(s) and/or homologous recombination status 
correlate with FRα levels 
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2.2. 
Endpoints 
2.2.1. 
Primary Endpoint 
• ORR, which includes confirmed best response of CR or PR as assessed by the 
Investigator 
2.2.2. 
Key Secondary Endpoint 
• DOR, defined as the time from initial Investigator-assessed response (CR or PR) until 
progressive disease (PD) as assessed by the Investigator 
2.2.3. 
Additional Secondary Endpoints 
• TEAEs and laboratory test results, physical examination, or vital signs 
• CA-125 response determined using the Gynecologic Cancer Intergroup (GCIG) 
criteria defined in Appendix C 
• PFS, defined as the time from first dose of MIRV until Investigator-assessed 
radiological PD or death, whichever occurs first  
• OS, defined as the time from first dose of MIRV until death 
• ORR, DOR, and PFS by blinded independent central review (BICR) will be 
summarized as sensitivity analysis 
2.2.4. 
Exploratory Endpoints 
Exploratory endpoints are provided below. The analysis and subsequent results of these 
assessments may be reported in separate documents and not included in the statistical analysis 
plan (SAP) or clinical study report, respectively. 
• Incidence of seroconversion of antidrug antibodies (ADA) to MIRV and association 
with safety and efficacy 
• Identification of blood-based biomarkers potentially predictive of responsiveness to 
treatment 
• Identification of tumor DNA mutational status and the expression level of genes and 
pathways involved in cancer development, progression, and responsiveness to 
treatment 
• Correlation of gene mutation(s) and/or homologous recombination status with tumor 
FRα levels and soluble FRα levels in blood 
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3. 
STUDY POPULATION 
3.1. 
Criteria for Selection of Patient Population 
3.1.1. 
Inclusion Criteria 
1. Patients ≥ 18 years of age 
2. Patients must have an Eastern Cooperative Oncology Group Performance Status (ECOG 
PS) of 0 or 1 
3. Patients must have a confirmed diagnosis of high-grade serous EOC, primary peritoneal 
cancer, or fallopian tube cancer 
4. Patients must have platinum-sensitive disease defined as radiographic progression greater 
than 6 months from last dose of most recent platinum therapy 
Note: Progression should be calculated from the date of the last administered dose of 
platinum therapy to the date of the radiographic imaging showing progression  
5. Patients must have progressed radiographically on or after their most recent line of 
anticancer therapy 
6. Patients must have at least 1 lesion that meets the definition of measurable disease by 
Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) (radiologically 
measured by the Investigator) 
7. Patients must be willing to provide an archival tumor tissue block or slides, or undergo 
procedure to obtain a new biopsy using a low-risk, medically routine procedure for 
immunohistochemistry (IHC) confirmation of FRα positivity  
8. Patient’s tumor must be positive for FRα expression as defined by the Ventana FOLR1 
Assay 
9. Prior anticancer therapy 
a. Patients must have received at least 2 prior systemic lines of platinum therapy and be 
considered by the Investigator as appropriate for single-agent non-platinum therapy 
(documentation required – eg, high risk of hypersensitivity reaction; risk of further 
cumulative toxicity with additional platinum, including but not limited to 
myelosuppression, neuropathy, renal insufficiency or other) 
Note: Patients who have had a documented platinum allergy may have had only 1 
prior line of platinum 
b. Patients may have received up to but no more than 1 prior independent non-platinum 
cytotoxic therapy  
c. Patients must have had testing for BRCA mutation (tumor or germline) and, if 
positive, must have received a prior PARP inhibitor as either treatment or 
maintenance therapy 
d. Neoadjuvant ± adjuvant therapies are considered 1 line of therapy 
e. Maintenance therapy (eg, bevacizumab, PARP inhibitors) will be considered part of 
the preceding line of therapy (ie, not counted independently) 
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f. Therapy changed due to toxicity in the absence of progression will be considered part 
of the same line (ie, not counted independently) 
10. Patients must have completed prior therapy within the specified times below: 
a. Systemic antineoplastic therapy within 5 half-lives or 4 weeks (whichever is shorter) 
prior to first dose of MIRV 
b. Focal radiation completed at least 2 weeks prior to first dose of MIRV 
11. Patients must have stabilized or recovered (Grade 1 or baseline) from all prior therapy-
related toxicities (except alopecia) 
12. Patients must have completed any major surgery at least 4 weeks prior to first dose of 
MIRV and have recovered or stabilized from the side effects of prior surgery prior to first 
dose of MIRV 
13. Patients must have adequate hematologic, liver and kidney functions defined as: 
a. Absolute neutrophil count (ANC) ≥ 1.5 x 109/L (1500/μL) without granulocyte 
colony-stimulating factor (G-CSF) in the prior 10 days or long-acting white blood cell 
(WBC) growth factors in the prior 20 days 
b. Platelet count ≥ 100 x 109/L (100,000/μL) without platelet transfusion in the prior 10 
days 
c. Hemoglobin ≥ 9.0 g/dL without packed red blood cell (PRBC) transfusion in the prior 
21 days 
d. Serum creatinine ≤ 1.5 x upper limit of normal (ULN) 
e. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3.0 x ULN  
f. Serum bilirubin ≤ 1.5 x ULN (patients with documented diagnosis of Gilbert 
syndrome are eligible if total bilirubin < 3.0 x ULN) 
g. Serum albumin ≥ 2 g/dL 
14. Patients must be willing and able to sign the informed consent form (ICF) and to adhere 
to the protocol requirements 
15. Women of childbearing potential (WCBP) must agree to use highly effective 
contraceptive method(s) while on MIRV and for at least 3 months after the last dose 
16. WCBP must have a negative pregnancy test within the 4 days prior to the first dose of 
MIRV 
3.1.2. 
Exclusion Criteria 
1. Patients with endometrioid, clear cell, mucinous, or sarcomatous histology, mixed tumors 
containing any of the above histologies, or low-grade/borderline ovarian tumor 
2. Patients with prior wide-field radiotherapy (RT) affecting at least 20% of the bone 
marrow 
3. Patients with > Grade 1 peripheral neuropathy per Common Terminology Criteria for 
Adverse Events (CTCAE) 
4. Patients with active or chronic corneal disorders, history of corneal transplantation, or 
active ocular conditions requiring ongoing treatment/monitoring, such as uncontrolled 
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glaucoma, wet age-related macular degeneration requiring intravitreal injections, active 
diabetic retinopathy with macular edema, macular degeneration, presence of papilledema, 
and/or monocular vision 
5. Patients with serious concurrent illness or clinically relevant active infection, including, 
but not limited to the following: 
a. Active hepatitis B or C infection (whether or not on active antiviral therapy)  
b. HIV infection 
c. Active cytomegalovirus infection  
d. Any other concurrent infectious disease requiring IV antibiotics within 2 weeks prior 
to the first dose of MIRV 
Note: Testing at screening is not required for the above infections unless clinically 
indicated. 
6. Patients with a history of multiple sclerosis (MS) or other demyelinating disease and/or 
Lambert-Eaton syndrome (paraneoplastic syndrome) 
7. Patients with clinically significant cardiac disease including, but not limited to, any of the 
following: 
a. Myocardial infarction ≤ 6 months prior to first dose 
b. Unstable angina pectoris 
c. Uncontrolled congestive heart failure (New York Heart Association > class II) 
d. Uncontrolled ≥ Grade 3 hypertension (per CTCAE) 
e. Uncontrolled cardiac arrhythmias 
8. Patients with a history of hemorrhagic or ischemic stroke within 6 months prior to 
enrollment 
9. Patients with a history of cirrhotic liver disease (Child-Pugh Class B or C) 
10. Patients with a previous clinical diagnosis of noninfectious interstitial lung disease (ILD), 
including noninfectious pneumonitis 
11. Patients requiring use of folate-containing supplements (eg, folate deficiency) 
12. Patients with prior hypersensitivity to monoclonal antibodies (mAb) 
13. Women who are pregnant or breastfeeding 
14. Patients who received prior treatment with MIRV or other FRα-targeting agents 
15. Patients with untreated or symptomatic central nervous system (CNS) metastases 
16. Patients with a history of other malignancy within 3 years prior to enrollment  
Note: patients with tumors with a negligible risk for metastasis or death (eg, adequately 
controlled basal-cell carcinoma or squamous-cell carcinoma of the skin, or carcinoma in 
situ of the cervix or breast) are eligible. 
17. Prior known hypersensitivity reactions to study drugs and/or any of their excipients 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also known as 
protocol waivers or exemptions, is not permitted. 
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4. 
INVESTIGATIONAL PLAN 
4.1. 
Study Design 
4.1.1. 
Overview and Schema 
This Phase 2 study is designed to evaluate the efficacy and safety of MIRV in patients with 
recurrent platinum-sensitive, high-grade serous EOC, primary peritoneal, or fallopian tube 
cancer, whose tumors express a high level of FRα. Patients will have had at least 2 prior lines of 
therapy. These will include at least 2 lines of platinum-containing therapy or 1 line with a 
documented platinum allergy. All patients will be, in the opinion of the Investigator, appropriate 
for non-platinum single-agent therapy for their next line of therapy. FRα positivity will be 
defined by the Ventana FOLR1 (FOLR1-2.1) CDx assay (Ventana FOLR1 Assay). 
The study is designed to test the null hypothesis that the ORR is ≤ 28% using an optimal Simon’s 
two-stage design (Simon 1989) without a planned pause in enrollment given preliminary efficacy 
and established safety of MIRV. Approximately 75 patients will be enrolled so that a total of 
69 patients will be efficacy evaluable.  
Efficacy evaluable patients include those who have at least 1 measurable lesion (per RECIST 
v1.1) at baseline and received at least 1 dose of MIRV. 
All patients will receive single-agent MIRV at 6 mg/kg AIBW (Appendix D) administered 
through IV infusion on Day 1 of every 3-week cycle (Q3W). 
Computerized tomography (CT) or magnetic resonance imaging (MRI) scans will be collected 
for sensitivity analysis by BICR. 
Patients will continue to receive MIRV until PD, unacceptable toxicity, withdrawal of consent, 
death, or until the Sponsor terminates the study (whichever comes first).  
Tumor assessments, including radiological assessment by CT/MRI scans, will be performed at 
Screening and subsequently every 6 weeks (± 1 week) from Cycle 1 Day 1 (C1D1) for the first 
36 weeks then every 12 weeks (± 3 weeks) until PD, death, the start of new anticancer therapy, 
or patient’s withdrawal of consent, whichever occurs first.  
Patients who discontinue MIRV for reasons other than progressive disease (PD) will continue 
with tumor assessments until documentation of PD or the start of a new anticancer therapy, 
whichever comes first. Prior to Week 36 (from C1D1), assessments should occur every 6 weeks 
(± 1 week) as allowed by local requirements but must occur at an interval of no more than 12 
weeks. After Week 36, assessments will occur every 12 weeks (± 3 weeks) until documentation 
of PD per RECIST v1.1 or the start of new anticancer therapy.  
All patients who discontinue MIRV will be followed for survival every 3 months (± 1 month) 
until death, lost to follow-up, withdrawal of consent for survival follow-up, or End of Study 
(EOS), whichever comes first. Additional survival follow-up calls may occur periodically, if 
needed. 
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4.1.2. 
Dose and Schedule for Mirvetuximab Soravtansine 
MIRV will be administered at 6 mg/kg IV on Day 1 of every 3-week cycle (Q3W). 
5. 
STUDY TREATMENT 
5.1. 
Mirvetuximab Soravtansine 
The investigational study drug, MIRV, will be provided by ImmunoGen, at a protein 
concentration of 5.0 mg/mL in an aqueous pH 5.0 buffered solution. See the Investigator 
Brochure for complete list of excipients. 
5.1.1. 
Mirvetuximab Soravtansine Packaging 
MIRV will be provided in a 20 mL glass, single-use Type I vial. The container closure for the 
Type I glass vials will consist of a 20 mm ethylene tetrafluoroethylene (ETFE)-coated serum 
stopper (Flurotec®) with a 20 mm aluminum TruEdge® seal with blue Flip-off® top.  
Refer to the Pharmacy Manual for labeling and storage information. 
5.1.2. 
Mirvetuximab Soravtansine Accountability 
Specific details regarding storage and handling of MIRV can be found in the Pharmacy Manual. 
Accountability and shipping documents for MIRV must be maintained by the Principal 
Investigator (PI) or designee (eg, the study pharmacist). The Investigator or designee must 
maintain an accurate record of all MIRV received, stored, dispensed, destroyed, and used in an 
Investigational Product Dispensing/Accountability Log or equivalent. These records must always 
be available for inspection, and a copy will be supplied to ImmunoGen on request. Information 
recorded on the Accountability Log will include dates and quantities of drug received, dates and 
quantities of drug dispensed, patient number and initials to whom drug is administered, lot 
number of drug administered, the recorder’s initials, and dates and quantities of drug destroyed 
or returned. Upon receipt, vials should be visually inspected for vial integrity (ie, cracks or leaks) 
and a record of any damaged or suspect drug should be kept on the Accountability Log. 
Upon completion of the study, all MIRV dispatched to a site must be accounted for and unused 
supplies destroyed according to the site’s standard operating procedures (SOPs) or returned to 
depot (refer to Pharmacy Manual). The original drug reconciliation records shall be maintained 
at the site and a copy collected and sent to ImmunoGen or designee once a representative of the 
company has confirmed the drug accountability.  
Drug accountability will be monitored. 
5.1.3. 
Mirvetuximab Soravtansine Study Treatment Compliance 
MIRV supplied for the study may not be used for any purpose other than the study or 
administered other than as described in this protocol.  
If necessary, MIRV from different drug lots may be mixed in a single-dose administration. 
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Under no circumstances is the Investigator allowed to release study drug supplies to any 
physician not named in the Food and Drug Administration (FDA) Form 1572 (or equivalent) to 
administer these supplies to a patient not enrolled in this study. If investigational supplies are to 
be dispensed from any facility other than that supervised directly by the PI (ie, hospital 
pharmacy, satellite pharmacy), it is the responsibility of the PI to ensure that all study drug is 
stored and administered as described (refer to Pharmacy Manual for instructions). 
5.2. 
Assignment of Patient Number 
Patient numbers are assigned in sequential order as patients sign the pre-screening informed 
consent to participate.  
5.2.1. 
Enrolled Patient Definition 
Patients who have consented to the study and have received at least 1 dose of study drug, are 
considered enrolled. Patients who are issued a patient number, but who do not successfully 
complete the screening process and are not treated will be considered screen failures. Patient 
numbers for patients who screen fail will not be re-issued. 
5.2.2. 
Patient Assignment to Dosing Regimens 
All patients will receive MIRV 6 mg/kg AIBW IV Q3W.  
5.3. 
Blinding Methods 
Not applicable as this is an open-label, single-arm study. 
5.4. 
Study Treatment Administration 
5.4.1. 
Premedication for Study Treatment 
All patients must receive 325 to 650 mg of acetaminophen/paracetamol (orally [PO] or IV), 
10 mg IV dexamethasone, and 25 to 50 mg diphenhydramine (IV or PO) (equivalent drugs of 
similar drug classes is also acceptable) approximately 30 min before each infusion of MIRV. If 
individual patients require more intensive treatment to prevent infusion-related reactions (IRRs), 
investigators may modify the regimen accordingly. An antiemetic medication (eg, 5-HT3 
serotonin receptor antagonists such as palonosetron, granisetron or ondansetron or appropriate 
alternatives) is recommended before each MIRV dose and may be used any time at the discretion 
of the treating physician. 
5.4.2. 
Prophylactic use of Eye Drops 
5.4.2.1. 
Corticosteroid Eye Drops 
All patients will be mandated to use corticosteroid eye drops as prescribed by the treating 
physician unless the risk outweighs the benefit as per the ophthalmologist/physician. All patients 
will be instructed to self-administer 1% prednisolone (Pred Forte® or generic equivalent) 6 times 
daily on Days -1 to 4 and 4 times daily (QID) on Days 5 to 8 of each cycle during the study. For 
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individual patients who cannot tolerate the preservative contained in 1% prednisolone, other 
corticosteroid eye drops may be substituted (eg, difluprednate 0.05%; Durezol®) and 
administered on Days -1 to 8 of each cycle at a frequency prescribed by the ophthalmologist. If 
prednisolone eye drops cannot be obtained, alternate steroid eye drops are acceptable. 
5.4.2.2. 
Lubricating Artificial Tears 
Patients will be mandated to use lubricating artificial tears on a daily basis (as directed by the 
product label or the treating physician). Preservative-free lubricating drops are recommended. 
Patients should be advised to wait at least 15 minutes after corticosteroid eye drop administration 
before instilling lubricating eye drops.  
5.4.3. 
Preparation and Administration of Mirvetuximab Soravtansine 
5.4.3.1. 
Calculation for Adjusted Ideal Body Weight 
The total dose of MIRV is calculated based on each patient’s AIBW using the following 
formula: 
Adjusted Ideal Body Weight (AIBW)  
AIBW = IBW1 + 0.4 (Actual weight – IBW1) 
Where: 
Ideal Body Weight (IBW)  
IBW1 (female) = 0.9H1-92 
1H=height in cm; W=weight in kg) 
The weight used for calculation should be obtained before study drug administration on C1D1 
(-14 days). Dosing may be modified per institutional standard of care for changes in body weight 
on subsequent cycles. Dosing must be modified for significant (≥ 10%) changes in body weight 
(not influenced by weight gain or loss attributed to fluid retention). 
5.4.3.1.1. Preparation 
MIRV is an experimental anticancer drug, and, as with other potentially toxic compounds, 
caution should be exercised when handling this compound. It is recommended that gloves and 
protective garments be worn during preparation. The desired amount of drug should be 
withdrawn from the vial(s) and diluted using 5% dextrose to a final concentration as outlined in 
the Pharmacy Manual.  
Note: MIRV is incompatible with saline (0.9% sodium chloride). Therefore, dilutions 
should be made using 5% dextrose. Infusion bags must be labeled with the protocol number, 
patient number, storage temperature, dose, and volume of MIRV filtered into the bag, or labeled 
according to institutional protocol. Once the solution is prepared, the infusion bag should be 
stored at room temperature protected from direct sunlight, and the infusion must be completed 
within eight hours of preparation. Please refer to Pharmacy Manual for further details. 
If necessary, MIRV from different drug lots may be mixed in a single-dose administration. 
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5.4.3.1.2. Administration 
MIRV is administered at 6 mg/kg AIBW as an IV infusion following preparation as outlined in 
the Pharmacy Manual. Details on required and compatible infusion materials are also included in 
the Pharmacy Manual.  
At C1D1 MIRV should be administered at a rate of 1 mg/min; after 30 min, the rate can be 
increased to 3 mg/min if well tolerated. If well tolerated after 30 min at 3 mg/min, the MIRV 
infusion rate may be increased to 5 mg/min. Subsequent infusions may be delivered at the 
tolerated rate. Therefore, the overall length of infusion will vary depending on dose and patient 
tolerability. After infusion, the IV line should be flushed with 5% dextrose as needed (PRN) to 
ensure delivery of the full dose.  
Patients will be carefully observed during each infusion and vital signs are taken as outlined in 
the Schedule of Assessments (Table 2). Patients will remain in the clinic under observation for 
4 hours after the first infusion, and for at least 1 hour after each subsequent infusion. While in the 
treatment area, patients are closely monitored for AEs. 
5.5. 
Dose Modification Guidelines 
Detailed MIRV dose modification guidelines are described below.  
5.5.1. 
Treatment Criteria 
In the absence of a TEAE that requires dose modification (as specified in the management 
guidance for a particular toxicity, see Section 5.5.1.1), a patient must meet the following criteria 
to receive MIRV at any cycle: 
• ANC must be ≥ 1.5 x 109/L (1,500/µL) 
• Platelet count must be ≥ 100 x 109/L (100,000/µL) 
• All non-hematologic toxicities for which a causal association to study drug cannot be 
ruled out, must be ≤ Grade 2 or returned to baseline; the exceptions to this rule being: 
− Treatment-emergent ocular disorders, which must have recovered to < Grade 1 or 
baseline 
− Treatment emergent pneumonitis which must have recovered to ≤ Grade 1 
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5.5.1.1. 
Mirvetuximab Soravtansine-Related Adverse Events 
Dose modifications for MIRV-related AEs are described in Table 3.  
Table 3: 
Dose Modifications for Mirvetuximab Soravtansine-related Adverse Events 
Severity Grade 
(CTCAE v5.0) 
Dose Modifications for MIRV a 
Hematological  
Neutropenia 
Grade 2 and Grade 3  
Hold drug until ANC is ≥ 1.5 x109/L (1500 /µL) and 
resume at the same dose level  
Grade 4 
Hold drug until ANC is ≥ 1.5 x109/L (1500 /µL) and 
then resume at one lower dose level 
Febrile neutropenia Grade 3 or 4 
(with a single temperature reading ≥ 38.3°C or a 
sustained temperature of > 38°C for > 1 hour 
Hold drug until ANC is ≥ 1.5 x109/L (1500 /µL) and 
then resume at one lower dose level 
Thrombocytopenia 
 
Grade 2 and Grade 3  
Hold drug until PLT count is ≥ 100 x 109/L 
(100,000/µL) and resume at same dose level  
Grade 3 associated with clinically significant 
bleeding that requires transfusion therapy and 
Grade 4 
Hold drug until PLT count is ≥ 100 x 109/L 
(100,000/µL) and then resume at one lower level 
Non-hematological 
Nausea and Vomiting 
Grade 3 (despite use of optimal antiemetics) 
Hold drug until resolved to ≤ Grade 1, then resume 
at one lower level 
Grade 4  
Permanently discontinue 
Diarrhea 
Grade 3 (despite use of optimal antidiarrheal 
treatment) 
Hold drug until resolved to ≤ Grade 1, then resume 
at one lower level 
Grade 4 
Permanently discontinue 
Ocular Disorders  
Refer to Section 5.5.2  
Noninfectious Pneumonitis 
Refer to Section 5.5.3 
Infusion-related Reactions 
Refer to Section 5.5.5 
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Table 3: 
Dose Modifications for Mirvetuximab Soravtansine-related Adverse Events 
(Continued) 
Severity Grade 
(CTCAE v5.0) 
Dose Modifications for MIRV a 
All Other Non-hematological Toxicities  
(except AEs related to underlying disease, Grade 3 fatigue, isolated symptomatic Grade 3 biochemistry 
laboratory abnormalities that last for < 7 days including electrolyte abnormalities that respond to 
medical intervention) 
Grade 3  
Hold drug until resolved to ≤ Grade 1, then resume 
at one lower level 
For any Grade 3 hepatic toxicity that does not 
resolve to baseline within 7 days, an abdominal CT 
scan must be performed to assess whether it is 
related to PD. 
≥ Grade 3 Cardiac events (excluding Grade 3 
hypertension)  
Permanently discontinue 
Grade 4 non-hematological toxicities 
Permanently discontinue 
Abbreviations: AE = adverse event; ANC = absolute neutrophil count; CT = computed tomography; 
CTCAE = common terminology criteria for adverse events; MIRV = mirvetuximab soravtansine; PD = progressive 
disease; PLT = platelets. 
a Failure to meet retreatment criteria within 1 cycle (21 days) after the missed dose due to insufficient recovery from 
a treatment-related toxicity will result in treatment discontinuation unless otherwise specified in the management 
guidance for a particular toxicity.  
5.5.1.2. 
Mirvetuximab Soravtansine Dose Reduction Dose Levels 
MIRV dose reduction will be as described in Table 4.  
Table 4: 
Mirvetuximab Soravtansine Dose Reduction Dose Levels 
If the patient was receiving MIRV at: 
Dose should be reduced to: 
6.0 mg/kg AIBW 
5.0 mg/kg AIBW 
5.0 mg/kg AIBW 
4.0 mg/kg AIBW 
4.0 mg/kg AIBW 
Permanently discontinue 
Reduction of MIRV below 4.0 mg/kg will not be permitted. Dose re-escalation is not permitted.  
Abbreviations: AIBW = adjusted ideal body weight; MIRV = mirvetuximab soravtansine. 
5.5.1.3. 
Monitoring and Management of Nausea and Vomiting 
Treatment-related nausea (46% all grades; 1% ≥ Grade 3) and vomiting (16% all grades; 
1% ≥ Grade 3) have been reported in patients treated with MIRV, despite premedication with 
dexamethasone. Therefore, it is recommended that an antiemetic (eg, 5-HT3 serotonin receptor 
antagonists such as palonosetron, granisetron, or ondansetron) medication is provided before 
each MIRV dose (Section 5.8.2). Additional antiemetics may be used any time at the discretion 
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of the treating physician, according to institutional or other practice guidelines, American 
Society of Clinical Oncology (ASCO), European Society for Medical Oncology (ESMO), and 
NCCN. Patients should be advised to contact their treating physician at the first sign of vomiting 
or worsening nausea.  
5.5.1.4. 
Monitoring and Management of Diarrhea 
Mild to moderate diarrhea has been reported in patients treated with MIRV. Patients should be 
advised to contact their treating physician at the first sign of diarrhea. Patients may then be 
treated according to standard institutional practice. One suggested regimen would be the 
administration of loperamide 2 mg at the first sign of loose stool, with repeat dosing every 
two hours until symptoms resolve (Wadler 1998). 
5.5.2. 
Ocular Disorders 
Changes in visual acuity resulting from reversible keratopathy have been reported in other 
studies of DM4-containing immunoconjugates that use the SPDB linker (Younes 2012). Patients 
receiving MIRV in the Phase 1 and 3 trials (IMGN853-0401, IMGN853-0403) reported ocular 
AEs consistent with reversible keratopathy/corneal epitheliopathy.  
5.5.2.1. 
Monitoring and Preventive Measures 
In early dose escalation of Study IMGN853-0401, a relationship was observed between MIRV 
plasma exposure and likelihood of an ocular event and response. Exposure-response modeling 
suggested that a dose of 6.0 mg/kg AIBW provided adequate exposure for response while also 
maintaining overall exposure within a range that decreased the potential for ocular AEs. Due to 
the observation of ocular disorders consistent with reversible keratopathy/corneal epitheliopathy 
in patients treated with MIRV, ocular function will be carefully monitored. Ocular symptom 
assessments will be performed at baseline and at Day 1 of every cycle thereafter (Table 2). 
Complete ophthalmologic exams will be performed in all patients at baseline and every other 
cycle thereafter if there is a TEAE reported. 
Patients are advised to avoid using contact lenses while on MIRV. Baby shampoo and a soft 
cloth should be used to clean the eyes, and a warm compress at bedtime may be used to decrease 
any possible inflammation on the eyelid’s surface. Please refer to Section 5.4.2.1 and 
Section 5.4.2.2 for details on the prophylactic use of steroid eye drops and lubricating artificial 
tears. The use of UVA/UVB sunglasses is recommended in full daylight during the study. The 
use of temporary lower punctal plugs to increase lubrication of the eyes is optional if lubricating 
artificial tears and corticosteroid eye drops are not sufficient. If patients report signs or 
symptoms of ocular disorders, including, but not limited to, blurred vision or eye irritation, the 
management and dose modification guidelines outlined in Table 5 should be followed.  
5.5.2.2. 
Management and Dose Modification Guidelines 
If a patient develops ocular symptoms of any grade, the patient is required to have a complete 
examination by an ophthalmologist. If a patient develops ≥ CTCAE Grade 2 ocular symptoms, 
treatment with MIRV must be interrupted. Treatment should not be interrupted solely for Grade 
2 ocular signs (eg, Grade 2 keratopathy) unless they are also associated with Grade 2 ocular 
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symptoms. Treatment with MIRV may resume if ocular symptoms improve to Grade 1 or 
baseline within 28 days of the next scheduled MIRV dose (refer to Table 5 for details). If ocular 
symptoms last longer than 28 days, resumption of MIRV, with or without dose reduction, may be 
considered for those patients who have experienced clinical benefit if agreed upon between the 
Sponsor and the Investigator. Subsequent eye examinations will be scheduled to occur in every 
other cycle going forward, from the time that the AE was initially reported and at either the End 
of Treatment (EOT) Visit or 30-Day Follow-up Visit after treatment discontinuation, even if the 
results of the patient’s ocular exam show no obvious clinical findings. Management of treatment-
emergent ocular AEs with inflammatory characteristics should include corticosteroid eye drops 
and/or other measures as indicated by an ophthalmologist. 
Table 5: 
Management of Ocular Symptoms 
Severity Grade 
(CTCAE v5.0) 
Management 
Guidelines for MIRV Dose 
Modifications 
Grade 1  
Complete eye exam as outlined in Schedule of 
Assessments (Table 2) 
Monitor for worsening symptoms 
Continue MIRV dosing 
Grade 2 
Complete eye exam as outlined in Schedule of 
Assessments (Table 2) 
Repeat complete exam as clinically indicated  
Patients should have weekly symptomatic 
ocular assessments by the Investigator until the 
symptoms resolve to Grade 1 or baseline or are 
deemed to be irreversible by the Investigator 
Hold MIRV dosing until AE has 
resolved to Grade 1 or better  
Patients with ocular symptoms lasting 
< 14 days may be allowed to resume 
MIRV at the same dose level 
Patients with ocular symptoms lasting 
≥ 14 days but no more than 28 days 
may resume MIRV at one lower dose 
level  
Recurrence of Grade 2 toxicity on 
subsequent cycles despite best 
supportive care will require a MIRV 
dose reduction of one dose level 
Grade 3  
Complete eye exam as outlined in Schedule of 
Assessments (Table 2). Repeat complete exam 
as clinically indicated 
Patients should have weekly symptomatic 
ocular assessments by the Investigator until the 
symptoms resolve to Grade 1 or baseline or are 
deemed to be irreversible by the Investigator 
Hold MIRV dosing  
Patients may be allowed to resume 
MIRV at a lower dose after AE has 
resolved to Grade 1 or better within 28 
days 
Recurrence of Grade 3 toxicity on 
subsequent cycles despite best 
supportive care will require a MIRV 
dose reduction of one dose level 
Grade 4  
Complete eye exam as outlined in Schedule of 
Assessments (Table 2). Repeat complete exam 
as clinically indicated 
Patients should have weekly symptomatic 
ocular assessments by the Investigator until the 
symptoms resolve to Grade 1 or baseline or are 
deemed irreversible by the Investigator 
Permanently discontinue MIRV 
Abbreviations: AE = adverse event; CTCAE = common terminology criteria for adverse events; MIRV = 
mirvetuximab soravtansine. 
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5.5.3. 
Monitoring of Noninfectious Pneumonitis 
Noninfectious pneumonitis has been observed after the administration of MIRV. Noninfectious 
pneumonitis may result in fatigue, shortness of breath, cough, or respiratory distress. Drug-
induced pneumonitis may be immediately life threatening. If a patient presents with signs or 
symptoms consistent with pneumonitis and/or other clinically meaningful signs or symptoms of 
pulmonary toxicity, the patient should be immediately evaluated. Patients are advised to notify 
their treating physician immediately if they experience new or worsening shortness of breath, 
cough, or respiratory distress. Patients who are asymptomatic may continue dosing of MIRV 
with close monitoring. 
The management and treatment guidelines outlined in Table 6 should be followed. 
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Table 6: 
Management of Noninfectious Pneumonitis 
CTCAE 
v5.0 
Grade 
CTCAE v5.0 
Definition 
Medical Management of 
Pneumonitis 
Guidelines for Dose 
Modificationsa 
Grade 1 
Asymptomatic; 
clinical or 
diagnostic 
observations 
only; 
intervention not 
indicated 
• 
Radiologic assessments (CT scan 
and/or chest x-ray) should be 
performed as clinically indicated. 
• 
Monitor for pulmonary 
symptoms. 
• 
Continue dosing in 
asymptomatic patients 
and monitor closely.  
Grade 2 
Symptomatic; 
medical 
intervention 
indicated; 
limiting 
instrumental 
ADL 
• 
Radiologic assessments (CT scan 
and/or chest x-ray) should be 
performed as clinically indicated. 
• 
Patient must be evaluated by a 
pulmonary specialist.  
• 
Treatment with corticosteroids 
may be indicated as 
recommended by a pulmonary 
specialist and/or institutional 
guidelines. 
• 
Hold dosing until 
symptoms resolve to  
≤ Grade 1. 
• 
MIRV may be resumed 
at same dose level or 
one dose level lower 
after discussion with the 
Sponsor. 
Grade 3 
Severe 
symptoms; 
limiting self-
care ADL; 
oxygen 
indicated 
• 
Radiologic assessments (CT scan 
and/or chest x-ray) should be 
performed as clinically indicated.  
• 
Patient must be evaluated by a 
pulmonary specialist.  
• 
Treatment with corticosteroids 
until resolution of symptoms may 
be indicated as recommended by 
a pulmonary specialist and/or 
institutional guidelines.  
• 
Bronchoscopy with lavage and/or 
biopsy when clinically feasible 
should be performed.  
• 
The pneumonitis event must be 
followed until resolution. 
• 
Permanently discontinue 
MIRV.  
Grade 4 
Life-threatening 
respiratory 
compromise; 
urgent 
intervention 
indicated (eg, 
tracheotomy or 
intubation) 
Abbreviations: ADL = activities of daily living; AE = adverse event; CT = computed tomography; MIRV = 
mirvetuximab soravtansine. 
a Failure to meet retreatment criteria within 1 cycle (21 days) after the missed dose due to insufficient recovery from 
a treatment-related toxicity will result in treatment discontinuation unless otherwise specified in the management 
guidance for a particular toxicity.  
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5.5.4. 
Management of Electrolytes Imbalance 
Prompt attention should be given to the correction of potential electrolytes imbalance, especially 
hypokalemia and hypomagnesemia. 
5.5.5. 
Potential Infusion-related Reactions 
Some patients treated with IV infusions of therapeutic drugs have experienced concurrent IRR 
(see CTCAE Version 5.0). The signs and symptoms may vary and include, for example, 
headache, fever, facial flushing, pruritus, myalgia, nausea, chest tightness, dyspnea, vomiting, 
erythema, abdominal discomfort, diaphoresis, shivers, lightheadedness, hypotension, 
palpitations, and somnolence. Anaphylaxis might occur at any time during an infusion. Before 
any infusion is started, appropriate medical personnel, medication (eg, epinephrine, inhaled beta 
agonists, antihistamines, and corticosteroids), and other required resources to treat anaphylaxis 
must be readily available. In general, Investigators should manage acute allergic or 
hypersensitivity reactions according to Institutional practices. General guidelines for the 
management of acute IRRs and for subsequent retreatment are provided in Table 7. Delayed 
IRRs may occur; therefore, patients should be advised to seek immediate medical treatment if 
symptoms newly develop and/or recur after discharge from clinic. 
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Table 7: 
Management Guidelines for Potential Infusion-related Reactions  
Infusion Reaction 
CTCAE v5.0 Severity 
Grade 
Management 
Grade 1: Mild, transient 
reaction 
• 
Maintain infusion rate unless progression of symptoms to ≥ Grade 2; if 
symptoms worsen, refer to guidelines below. 
• 
Promethazine (or equivalent) 150 mg PO per day (Q4h) PRN for nausea  
• 
Diphenhydramine (or equivalent) 25-50 mg PO or IV PRN 
• 
Methylprednisolone (or equivalent) 125 mg IV PRN 
Grade 2: Moderate  
• 
Interrupt infusion and disconnect infusion tubing from patient 
• 
Promethazine (or equivalent) 150 mg PO per day (Q4h) PRN for nausea 
• 
Diphenhydramine (or equivalent) 25-50 mg PO or IV PRN 
• 
Acetaminophen (or equivalent) 650 mg PO PRN 
• 
Methylprednisolone (or equivalent) 125 mg IV PRN 
• 
After recovery from symptoms, resume the infusion at 50% of the 
previous rate and if no further symptoms appear, gradually increase rate 
until infusion is completed. 
• 
For subsequent dosing in future cycles, patients should be pre-medicated 
with Dex (or equivalent) 8 mg PO BID the day before drug 
administration and acetaminophen (or equivalent) 650 mg PO and 
diphenhydramine (or equivalent) 25-50 mg PO 30-60 min before dosing.  
Grade 3: Severe, 
prolonged reaction not 
rapidly responsive to 
symptomatic 
medication and/or brief 
interruption of infusion; 
recurrence of 
symptoms after initial 
improvement; 
hospitalization 
indicated for clinical 
sequelae 
OR 
Grade 4: Life-
threatening 
consequences, urgent 
intervention indicated 
• 
Immediately stop infusion and disconnect infusion tubing from patient. 
• 
Administer diphenhydramine (25-50 mg) IV (or equivalent) 
• 
Administer IV steroids (methylprednisolone (or equivalent) up to 
0.5 mg/kg Q 6h) to treat ongoing reaction and prevent recurrence 
• 
Administer bronchodilators (nebulized albuterol/salbutamol, 2.5-5 mg in 
3 mL of saline or equivalent) as medically indicated 
• 
Administer normal saline as medically indicated 
• 
Administer epinephrine (0.2-0.5 mL of a 1:1000 dilution (0.2-0.5 mg) 
SQ or IM) as medically indicated. Epinephrine should only be used if all 
other treatment methods fail to manage the IRR. 
• 
Advise patient to seek emergency treatment and notify 
Investigator/clinic if the infusion-related symptoms recur after discharge 
from clinic. 
• 
Report as an SAE (see Section 8.1.1.2). 
• 
Permanently discontinue study medication treatment 
Abbreviations: BID = twice a day; CTCAE = common terminology criteria for adverse events; Dex = 
dexamethasone; IM = intramuscular; IRR = infusion-related reaction; IV = intravenously; PO = orally; PRN = as 
needed; SAE = serious adverse event; SQ = subcutaneous.  
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5.5.6. 
Discontinuation of Mirvetuximab Soravtansine Due to Toxicity 
MIRV should be discontinued in the case of the following treatment-related events: 
• ≥ Grade 3 cardiac event (excluding Grade 3 hypertension) (Section 5.5.1.1) 
• ≥ Grade 3 pneumonitis event (Section 5.5.3) 
• Non-hematologic events of Grade 4 severity (Section 5.5.1.1) 
• Ocular events of Grade 4 severity (Section 5.5.2.2)  
• Failure to meet re-treatment criteria within 1 cycle (21 days) after the missed dose 
due to insufficient recovery from a treatment-related toxicity unless otherwise 
specified in the management guidance for a particular toxicity. In such cases, 
continuation of MIRV may be considered for those patients who have experienced 
clinical benefit if agreed upon between the Sponsor and the Investigator. 
5.6. 
Discontinuation of the Patients from the Study or Study Treatment 
5.6.1. 
End of Treatment 
Patients will continue to receive MIRV until they present with PD per RECIST v1.1, as assessed 
by study Investigator, unacceptable toxicity, withdraw consent, or death, whichever comes first, 
or until the Sponsor terminates the study. Study treatment and/or participation in the study may 
be discontinued at any time at the discretion of the Investigator. The following may be reasons 
for the Investigator to remove a patient from the study drug: 
• The patient suffers an intolerable AE 
• Noncompliance, including failure to appear at one or more study visits 
• The patient was erroneously included in the study 
The reason for treatment discontinuation must be captured in the clinical trial database. Any AEs 
experienced up to the point of discontinuation and 30 days thereafter must be documented. All 
serious adverse events (SAEs), and those AEs assessed by the Investigator as at least possibly 
related to study drug should continue to be followed until they resolve or stabilize, whichever 
comes first. Patients will continue to be followed for OS, after discontinuing study drug 
(Section 9.3.3).  
5.6.2. 
End of Study  
Discontinuation from participation in the study will be documented in the clinical trial database. 
Reasons for EOS include withdrawal of consent, lost to follow-up, death, or study termination by 
Sponsor.  
5.6.3. 
Withdrawal of Consent 
The patient is free to withdraw consent to study treatment and/or participation in the study at any 
time irrespective of the reason. The Investigator must make every effort (eg, telephone, email, 
letter) to determine the primary reason for this decision and record this information. Study 
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treatment must be discontinued, and no further assessments conducted. Further attempts to 
contact the patient are not allowed unless safety findings require communication or follow-up. If 
the patient withdraws consent for disclosure of future information, the Sponsor may retain and 
continue to use any data collected before withdrawal of consent. All biological samples that have 
been already collected will be retained and analyzed at a later date. The patient may request 
destruction of any samples, and the Investigator must document this in the site study records. 
The SAP will specify how early withdrawals from treatment will be accounted for in the 
analyses of efficacy endpoints. Patients who have withdrawn from the study cannot be re-treated 
in the study and their inclusion and patient number must not be reused. 
5.6.4. 
Lost to Follow-up 
A study patient will be considered lost to follow-up if the patient repeatedly fails to return for 
scheduled visits and is unable to be contacted by the study site. The Investigator should make all 
efforts to contact the patient and to determine the patient’s health status, including at least her 
vital status (in accordance with applicable regulations related to privacy and confidentiality). A 
patient should not be considered lost to follow-up until due diligence has been completed and 
documented. The following actions must be taken if a patient fails to return to the clinic for a 
required study visit: 
• The site must attempt to contact the patient and reschedule the missed visit as soon as 
possible and counsel the patient on the importance of maintaining the assigned visit 
schedule and ascertain whether or not the patient wishes to and/or should continue in 
the study. 
• In cases in which the patient is deemed lost to follow-up, the Investigator or designee 
must make every effort to regain contact with the patient (where possible, 3 telephone 
calls and, if necessary, a certified letter to the patient’s last known mailing address or 
local equivalent methods). These contact attempts should be documented in the 
patient’s medical record. 
Should the patient continue to be unreachable, she will be considered to have withdrawn from 
the study with a primary reason of lost to follow-up. 
5.7. 
Period of Observation 
For purposes of this study, the period of safety observation extends from the time of informed 
consent until the 30-Day Follow-up visit unless additional follow-up safety information is 
requested as described in Section 9.3. Short-term follow-up for patients who discontinue study 
drug without documented PD will be followed per RECIST v1.1 every 6 weeks (± 1 week) from 
C1D1 for the first 36 weeks then every 12 weeks (± 3 weeks) until PD, until the patient starts 
new anticancer treatment, the patient dies, or the patient withdraws consent, whichever comes 
first. All patients will be followed every 3 months (± 1 month) for survival until death, lost to 
follow-up, withdrawal of consent for survival follow up, or until EOS, whichever comes first. 
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5.8. 
Concomitant Medications and Procedures 
All concomitant medications and supportive therapy taken within 4 weeks of C1D1 and through 
30 days after last study treatment must be recorded in the clinical database. 
5.8.1. 
Vaccine Administration 
To avoid potential overlap of vaccine-related adverse events with study-related adverse events, 
ImmunoGen is issuing the following recommendations: 
• the use of live viral vaccines while on study should be avoided 
• a vaccine (including COVID-19 vaccines) should be administered 5+ days before 
study drug administration, or 5+ days after study drug administration 
5.8.2. 
Antiemetic and Antidiarrheal Medications 
An antiemetic (eg, 5-HT3 serotonin receptor antagonists such as palonosetron, granisetron or 
ondansetron) medication is recommended before each MIRV dose; additional antiemetics and/or 
antidiarrheal (eg, loperamide) medications may be used any time at the discretion of the treating 
physician. 
5.8.3. 
Folate-Containing Supplements 
Folate-containing supplements should not be taken during the study. 
5.8.4. 
Antineoplastic Therapy 
All non-study related antineoplastic therapy, including but not limited to cytotoxic, 
immunotherapy, and vascular endothelial growth factor (VEGF)-targeted therapy, is prohibited 
while on study drug.  
5.8.5. 
Hematopoietic Growth Factors 
Patients receiving recombinant erythropoietin (EPO) or darbepoetin-α before study start may 
continue to receive pretreatment doses.  
The use of erythropoietic and granulocyte growth factors in accordance with ASCO guidelines 
may be implemented at the discretion of the treating physician. 
5.8.6. 
Anticoagulants 
The use of anticoagulant agents is allowed as clinically indicated.  
5.8.7. 
Methods of Contraception 
Women of childbearing potential must agree to use highly effective contraceptive method(s) 
while on study drug and for at least 3 months after the last dose of MIRV. A woman of 
childbearing potential is a woman who is considered fertile, following menarche and until 
becoming post-menopausal unless permanently sterile. Permanent sterilization methods include 
hysterectomy, bilateral salpingectomy, and bilateral oophorectomy. 
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The following birth control methods may be considered highly effective (failure rate of less than 
1% per year): 
• Combined (estrogen and progesterone) hormonal contraception associated with 
inhibition of ovulation 
− Oral 
− Intravaginal 
− Transdermal 
• Progesterone-only hormonal contraception associated with inhibition of ovulation: 
− Oral 
− Injectable 
− Implantable 
• Intrauterine device (IUD) 
• Intrauterine hormone-releasing system (IUS) 
• Bilateral tubal occlusion 
• Vasectomized partner  
• Sexual abstinence 
Abstinence (relative to heterosexual activity) can be used as the sole method of contraception if 
it is consistently employed as the patient’s preferred and usual lifestyle and if considered 
acceptable by local regulatory agencies and Institutional Review Board/Independent Ethics 
Committee (IECs /IRBs). Periodic abstinence (eg, calendar, ovulation, symptom-thermal, post-
ovulation methods, etc.) and withdrawal are not acceptable methods of contraception.  
If a contraceptive method listed above is restricted by local regulations/guidelines, then it does 
not qualify as an acceptable method of contraception for patients participating at sites in this 
country/region. 
Patients should be informed that taking the study medication may involve unknown risks to the 
fetus (unborn baby) if pregnancy were to occur during the study. To participate in the study 
WCBP must adhere to the contraception requirement (described above) from the day of study 
medication initiation (or 14 days before the initiation of study medication for oral contraception) 
through the duration of study treatment and for at least 3 months after the last dose of MIRV. If 
there is any question that a WCBP will not reliably comply with the requirements for 
contraception, that patient should not be entered into the study. 
5.8.8. 
Other Concomitant Medications 
Medications for the treatment of AEs or cancer symptoms (eg, packed red blood cells and pain 
medications), are allowed. Prophylactic use of steroids and/or antihistamines will be considered 
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if needed. Additionally, medications (not addressed above) used to treat underlying medical 
conditions at study entry including antiemetics and antidiarrheals will be allowed to continue.  
5.8.9. 
Medications That Are CYP3A or MDR1 Substrates or CYP3A Substrates with 
Narrow Therapeutic Index 
In vitro metabolism studies demonstrated that DM4 is predominantly metabolized by thiol 
s-methyltransferase (TMT) to form S-methyl DM4, which is further metabolized into 
sulfoxide-methyl-DM4. As S-methyl DM4 has been shown to be primarily metabolized by 
CYP3A, its exposure could potentially be increased in the presence of strong CYP3A inhibitors. 
Drinking greater than one serving (250 mL) of grapefruit juice per day should be avoided. 
Both DM4 and S-methyl DM4 are substrates for MDR1 efflux transporter. Their exposure could 
potentially increase in the presence of MDR1 efflux transporter. In vitro metabolism data also 
indicates that DM4 is a time-dependent inhibitor of CYP3A4. The risk of a significant in vivo 
drug-drug interaction caused by inhibition of CYP3A4 or MDR1 is unknown. Treatment of 
patients with concomitant medications that are inhibitors of MDR1, sensitive substrates of 
CYP3A or are CYP3A substrates with a narrow therapeutic index should be used with caution 
and carefully monitored. Please refer to the current listing of clinical substrates for 
P450-mediated metabolism for concomitant use clinical DDI studies and/or drug labeling 
(https://www.fda.gov/drugs/drug-interactions-labeling/drug-development-and-drug-interactions-
table-substrates-inhibitors-and-inducers#table3-1). 
5.9. 
Overdose and Medication Error 
5.9.1. 
Overdose 
There is no known treatment/antidote available for MIRV. Supportive measures should be 
instituted if an instance arises in which a patient suffers an overdose of study drug. 
5.9.2. 
Medication Error 
The Sponsor must be notified within 24 hours of any error leading to the administration of either 
10% more or 10% less than the intended dose; in such cases, the event must be reported in the 
clinical trial database. If an error resulted in a SAE, a Serious Adverse Event form must be 
submitted within 24 hours of the event (see Section 8.2.1). 
6. 
IMMUNOGENICITY AND BIOMARKER ASSESSMENTS 
6.1. 
Immunogenicity Assessments – Mirvetuximab Soravtansine 
The potential immunogenicity against MIRV will be assessed at C1D1, C2D1, C3D1, C5D1, 
EOT, and 30-Day Follow-up, as outlined in Table 2. The potential impact of immunogenicity on 
the safety and efficacy of MIRV and total Ab will be explored.  
An ADA sample should be collected prior to dosing on C1D1. The sample for ADA analysis is 
taken predose on Day 1 of Cycles 2, 3, and 5 and at the EOT and 30-Day Follow-up visits.  
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6.2. 
Evaluation of FRα Expression in Tumor Tissue 
FRα expression varies with tumor histology, as reported in the literature and demonstrated in 
preclinical studies (Section 1.1 and Investigator Brochure). FRα expression in tumor samples 
will be analyzed using the Ventana FOLR1 Assay, an immunohistochemical assay developed to 
detect FRα in cut slide specimens of formalin-fixed paraffin-embedded (FFPE) epithelial ovarian 
cancer tissue stained on the BenchMark ULTRA automated staining instrument using the 
Ventana OptiView DAB IHC Detection Kit. This assay will be conducted at a central laboratory. 
All patients must submit tumor tissue block or fresh cut slides from available block (FFPE 
slides) for analysis of FRα expression prior to enrollment.  
PS2+ is the terminology used to reference a scoring method based on membrane stain intensity 
level of 2 or greater. The PS2+ scoring method requires the pathologist (at the central laboratory) 
to assess the percentage of tumor cells with moderate (2) and/or strong (3) membrane staining 
compared to the total number of viable tumor cells. To be considered positive for FRα 
expression and eligibility for the study, ≥ 75% of viable tumor cells must exhibit level 2 and/or 3 
membrane staining intensity (see Ventana Assay details within the Investigator Brochure). 
Only patients with the required FRα expression levels by Ventana FOLR1 Assay are eligible to 
enroll in the study. If a patient wishes to enroll and does not have archival material available for 
analysis, she must undergo a biopsy to assess FRα expression. Patients for whom the only sites 
of disease would require biopsy procedures considered to be of significant risk must not be 
enrolled in the study. These procedures include (but are not limited to) biopsies of the brain, 
lung/mediastinum, pancreas, or endoscopic procedures extending beyond the esophagus, 
stomach, or bowel.  
Instructions regarding processing and shipment of all samples for FRα testing are detailed in the 
applicable Laboratory Manual. 
6.3. 
Potential Predictive Markers of Drug Response 
6.3.1. 
Blood Biomarkers 
An exploratory endpoint of the study is to assess if soluble FRα levels in blood at Pre-screening 
are predictive of tumor FRα levels and/or expression. For patients who receive MIRV, 
Pre-screening and on-treatment FRα levels may be correlated to MIRV response and survival. 
Remaining sera will be preserved for future analysis of additional biomarkers (as they become 
available) and/or circulating tumor cells (CTC), circulating tumor DNA (ctDNA), and/or 
cell-free DNA (cfDNA). Samples for FRα testing will be collected as outlined in Table 2. 
6.3.2. 
Tumor Biomarkers 
Cancer is a disease driven by molecular level changes, which include mutations, DNA 
rearrangements and copy number changes, as well as changes in gene expression of key 
oncogenic pathways. Many of these changes determine or influence the aggressiveness of the 
disease, how the cancer responds to standard of care and/or novel therapeutic agents, and 
development of resistance to treatment. To evaluate how tumor molecular changes are associated 
with response to MIRV we will characterize the genomic profile (gene mutations, genomic 
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translocations, etc.) as well as gene expression levels of archival tumor samples using a fit for 
purpose technology such as next generation sequencing (NGS).  
6.3.3. 
BRCA and Homologous Recombination Deficient Status 
An inclusion criterion for this trial is the BRCA status of patients. This will be determined by 
local testing prior to enrollment. An exploratory endpoint of this study is to determine the BRCA 
mutational status and the homologous recombination deficient (HRD) status of all screened, 
consenting patients (in tumor and/or sera). Due to the variability in techniques and sensitivities 
of assays used to determine BRCA/HRD status, a central lab will be used to obtain consistent 
data. This analysis will be carried out on all patient samples submitted for screening with the 
goal of correlating BRCA/HRD status to both tumor and circulating FRα levels. For patients who 
ultimately receive MIRV treatment, this data will additionally be used to correlate BRCA/HRD 
status with MIRV safety and efficacy. 
7. 
STUDY PROCEDURES 
7.1. 
Informed Consent 
Each patient will sign an Institutional Review Board (IRB)/Independent Ethics Committee 
(IEC)-approved ICF before any study-required procedures are conducted unless those procedures 
are performed as part of the patient’s standard care (Table 2). Participants must be re-consented 
to the most current version of the ICF(s) per IRB/IEC guidelines during their participation in the 
study. 
Patients will sign a pre-screening ICF to allow testing of fresh or archival tumor tissue by the 
assay required for study inclusion. If patients meet entry criteria for FRα positivity (high FRα) 
they will sign the main study ICF and proceed with remaining screening procedures per the 
Schedule of Assessments. In some cases, the pre-screening ICF and main study ICF may be 
merged into a single ICF based on site-specific guidelines or preference. 
7.2. 
Inclusion and Exclusion Criteria 
The inclusion and exclusion criteria are assessed during Screening (within 28 days before the 
first dose of MIRV on C1D1). All screening evaluations must be completed and reviewed to 
confirm that potential patients meet all eligibility criteria. The Investigator will maintain a 
screening log to record details of all participants screened and to confirm eligibility or record 
reasons for screening failure, as applicable. Procedures conducted as part of the patient’s routine 
clinical management and obtained before signing an ICF may be utilized for screening or 
baseline purposes provided the procedure met the protocol-specified criteria and were performed 
within the timeframe defined in the Schedule of Assessments (Table 2). A patient is considered 
enrolled when they have received their first dose of MIRV (Section 5.2.1). 
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7.3. 
Confirmation of Disease Diagnosis 
At Screening, disease diagnosis, and current disease status are confirmed from information in the 
source record (Table 2). 
7.4. 
BRCA Mutation Status 
The BRCA mutation status from prior testing (information in the source record) will be recorded 
(Table 2). Patients with a BRCA mutation (germline mutation or somatic mutation in tumor 
tissue) are classified as positive and patients who were tested and shown to not have a BRCA 
mutation will be classified as negative. 
An exploratory endpoint of this study is to determine the BRCA mutational status and the HRD 
status of all screened, consenting patients (in tumor and/or sera). Due to the variability in 
techniques and sensitivities of assays used to determine BRCA/HRD status, a central lab will be 
used to obtain consistent data. This analysis will be carried out on all patient samples submitted 
for screening with the goal of correlating BRCA/HRD status to both tumor and circulating FRα 
levels. For patients who ultimately receive MIRV treatment, this data will additionally be used to 
correlate BRCA/HRD status with MIRV safety and efficacy. 
7.5. 
Demographic/Medical History 
The age, sex, race, and ethnicity of the patient are to be recorded during Screening for all patients 
who consent to the study (Table 2). 
During the Screening period, a complete medical history will be compiled for each patient. The 
history will include the background and progress of the patient’s primary malignancy and 
include a description of all prior therapies for the primary malignancy. 
7.6. 
Physical Examination, Weight, and Height 
Physical examination (PE), height (Screening only) and weight must be performed as indicated 
in the Schedule of Assessments (Table 2). A complete PE, including assessments of general 
appearance, skin, head (eyes, ears, nose, and throat), neck, lungs, heart, abdomen, back, lymph 
nodes, extremities, and neurological system, will be completed at Screening and at the 30-Day 
Follow-up Visit. Directed PEs will be completed at additional time points as specified in the 
Schedule of Assessments. 
7.7. 
Vital Signs 
Vital signs include blood pressure and body temperature. These signs are measured as outlined in 
Table 2. 
7.8. 
Electrocardiogram  
A standard, single 12-lead electrocardiogram (ECG) will be performed within 28 days prior to 
first dose.  
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7.9. 
Ocular Symptom Assessment and Ophthalmic Examination 
7.9.1. 
Ocular Symptom Assessment 
Ocular symptom assessment will be performed before the start of each cycle by the treating 
physician or other qualified individual. For patients reporting CTCAE > Grade 1 ocular 
symptoms, study drug will be held until the patient is evaluated by an ophthalmologist for a 
complete examination. The ocular symptom assessment will also be performed at EOT and the 
30-Day Follow-up visits. All SAEs, and those AEs assessed by the Investigator as at least 
possibly related to study drug, should continue to be followed until they resolve or stabilize, 
whichever comes first. 
7.9.2. 
Ophthalmic Examination 
An ophthalmic examination will be performed at Screening (within 14 days prior to first dose of 
study drug) by an ophthalmologist and will include the following: distant visual acuity, best 
corrected visual acuity, slit lamp examination, and intraocular pressure measurement. Patients 
who experience ocular TEAEs while on study will have a complete ophthalmologic exam 
performed at the emergence of the symptoms and at every other cycle thereafter. All patients 
who have an ophthalmic exam on study treatment (post-baseline) will have a complete 
ophthalmologic exam performed at the EOT Visit or 30-Day Follow-up Visit (Table 2). 
7.10. 
Laboratory Assessments 
Local laboratories will be used for the analysis of scheduled hematology, biochemistry, 
coagulation, and other tests collected as part of safety monitoring. Sites will be asked to provide 
a copy of local laboratory reports to a third-party vendor contracted by the Sponsor for inclusion 
in the final data set for the study. Screening labs (Table 8) will be performed within 14 days of 
first dose. Repeat testing on C1D1 is not required if tests were obtained within 4 days of dosing 
and are within acceptable ranges. Repeat testing will be performed as outlined in the Schedule of 
Assessments (Table 2) and as clinically indicated.  
Note that before each administration of study drug, laboratory results must be reviewed to 
evaluate for potential toxicity.  
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7.10.1. 
Clinical Laboratory Panels 
A list of clinical laboratory tests may be found in Table 8. 
Table 8: 
Clinical Laboratory Tests 
Hematology 
Serum Chemistry 
Urinalysis 
(Screening only) 
Coagulation 
(Screening only) 
• 
Hematocrit 
• 
Hemoglobin 
• 
WBC (with 5-part 
differential)  
• 
Platelet count 
• 
Albumin 
• 
Alkaline 
phosphatase 
• 
ALT 
• 
AST 
• 
BUN or Urea 
• 
Calcium 
• 
Chloride 
• 
Creatinine 
• 
Glucose 
• 
Magnesium 
• 
Phosphorus 
• 
Potassium  
• 
Sodium 
• 
Total bilirubin 
• 
pH 
• 
Ketones 
• 
Protein 
• 
Glucose 
• 
Occult blood 
• 
Leukocyte esterase 
• 
Nitrite 
• 
PT or INR 
• 
aPTT 
Abbreviations: ALT = alanine aminotransferase; aPTT = activated partial thromboplastin time; AST = aspartate 
aminotransferase; BUN = blood urea nitrogen; INR = international normalized ratio; PT = prothrombin time; WBC 
= white blood cell count.  
7.11. 
Pregnancy Screen 
All WCBP will complete a serum beta-human chorionic gonadotropin (β-hCG) or urine 
pregnancy test within 4 days before the first dose of study drug and urine or serum pregnancy 
tests within 4 days of each study drug administration and at the 30-Day Follow-up visit. It is 
recommended to perform monthly pregnancy tests for 3 months after the last dose of MIRV. 
Additional testing may be performed in accordance with institutional requirements or local 
regulation. Pregnancy tests must be negative for the patient to be enrolled and to continue to 
receive the study drug (Table 2). 
If a patient becomes pregnant or suspects pregnancy while participating in this study, the 
Investigator and Sponsor must be informed immediately (Section 8.2.2) and the patient will be 
withdrawn from study drug. See Section 8.2.2 for more details.  
7.12. 
Eastern Cooperative Oncology Group Performance Status 
ECOG PS (Appendix A) will be assessed during Screening and at other times specified in the 
Schedule of Assessments (Table 2). An assessment is not necessary on C1D1 if the Screening 
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assessment was obtained within the prior 4 days. ECOG is also assessed at EOT and 30-Day 
Follow-up Visit. 
7.13. 
Tumor Response Assessment 
7.13.1. 
Radiological Imaging 
Radiologic tumor evaluation by CT or MRI of chest, abdomen, and pelvis will be performed 
within 28 days before first dose of study drug and every 6 weeks (±1 week) from C1D1 for the 
first 36 weeks on study and every 12 weeks (± 3 weeks) thereafter (Table 2). Patients who 
discontinue study treatment for reasons other than PD will continue with tumor assessments until 
documentation of PD or the start of a new anticancer therapy, whichever comes first. Prior to 
Week 36 (from C1D1), assessments should occur every 6 weeks (± 1 week) as allowed by local 
requirements but must occur at an interval of no more than 12 weeks. After Week 36, assessment 
will occur every 12 weeks (± 3 weeks) until documentation of PD or the start of new anticancer 
therapy. The same method of radiographic assessment used at Screening must be used at all 
subsequent radiographic evaluations. Copies of all imaging scans must be obtained and sent to a 
central imaging vendor designated by ImmunoGen as outlined in the Imaging Manual. The 
central imaging vendor will assess the quality of the images. The imaging vendor will be 
responsible for the formation and management of the BICR which will be used as a sensitivity 
analysis of ORR, DOR, and PFS by the Investigator. 
Tumor response will be assessed by the Investigator using RECIST v1.1 (Eisenhauer 2009). 
Response as determined by the Investigator will be recorded in the clinical trial database.  
The central imaging vendor will ensure that the central radiologists remain blinded to the local 
assessment from the Investigator and other unblinding information. This and all other imaging 
procedures will be documented in an independent review charter agreed upon between 
ImmunoGen and the imaging vendor before initiation of any BICR reviews. 
Note: It is very important that the same method of radiologic assessment be used 
throughout the study and that the same lesions are followed.  
7.13.2. 
CA-125 
Serum CA-125 assessments will be performed within 14 days prior to the first dose of study 
drug, and at each radiologic tumor assessment (± 4 days) (Table 2). CA-125 should be assessed 
by the same laboratory throughout the study.  
8. 
ASSESSMENT OF SAFETY 
8.1. 
Recording Adverse Events and Serious Adverse Events 
AEs, including those attributed to study procedures, will be documented in the clinical trial 
database and monitored continuously throughout the study from the time of informed consent 
until 30 days after the patient’s last study treatment. 
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Only AEs/SAEs which are considered related to a study procedure (ie, blood draw or fresh tumor 
biopsy) will be captured during the pre-screening period, ie, from the time of signing of the pre-
screening informed consent (if one is utilized) until the time of signing of the main study 
informed consent, or until the patient is determined to be a screen failure. All AEs and SAEs, 
regardless of causality, will be captured after the main study ICF has been signed. 
SAEs will continue to be followed by ImmunoGen Pharmacovigilance until resolution, 
stabilization, or return to baseline. Beyond this defined reporting period, any unsolicited SAE 
assessed as related to the study drug by the Investigator and reported to ImmunoGen will be 
collected and processed. Additional information obtained after database lock, will reside solely 
in the safety database. 
The Investigator should follow and provide updates for all AEs until clinical recovery is 
complete, laboratory values return to normal, the patient stabilizes, or death occurs, to ensure the 
safety of the patients. This may mean that observations continue beyond the last planned visit per 
protocol and that additional investigations may be requested by the Sponsor. 
8.1.1. 
Definition of Adverse Events 
8.1.1.1. 
Adverse Event 
An AE is any noxious, pathologic, or unintended change in anatomical, physiologic, or 
metabolic function as indicated by physical signs, symptoms, or laboratory changes occurring in 
any phase of a clinical study, whether or not considered study drug-related. This includes an 
exacerbation of a pre-existing condition. AEs include: 
• Worsening (change in nature, severity, or frequency) of conditions present at the 
onset of the study 
• Intercurrent illnesses 
• Drug interactions 
• Events related to or possibly related to concomitant medications 
• Abnormal laboratory values (this includes significant shifts from baseline within the 
range of normal that the Investigator considers to be clinically important) 
• Clinically significant abnormalities in PE, vital signs, and weight 
Note that PD should not be reported as an AE unless it is considered to be drug-related by the 
Investigator. 
All AEs, including AEs attributed to study procedures, occurring from the time of study 
informed consent until 30 days after last study treatment must be reported in the clinical 
database, regardless of the severity or relationship to study drug. Only AEs which are considered 
related to a study procedure (ie, blood draw or fresh tumor biopsy) will be captured during the 
pre-screening period, ie, from the time of signing the pre-screening consent (if one is utilized) 
until the signing of the main study informed consent, or until the patient is determined to be a 
screen failure. The Investigator should treat patients with AEs appropriately and observe them at 
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suitable intervals until the events stabilize, return to baseline, or resolve. AEs may be discovered 
through observation or examination of the patient, questioning of the patient, complaint by the 
patient, or by abnormal clinical laboratory values. 
In addition, AEs may also include laboratory values that become significantly out of range. Such 
abnormal laboratory values or test results constitute AEs if they induce clinical signs or 
symptoms, are considered clinically significant (eg, cause study drug discontinuation or 
constitutes in and of itself an SAE, or require therapy), and should be recorded in the clinical 
database under the signs, symptoms, or diagnosis associated with them. In the event of an out-of-
range value, the laboratory test should be repeated until it returns to normal or baseline or can be 
explained and the patient’s safety is not at risk.  
8.1.1.2. 
Serious Adverse Event 
An SAE is any AE occurring at any dose that results in any of the following outcomes: 
• Death 
• Is life-threatening 
• Requires inpatient hospitalization 
• Requires prolongation of existing hospitalization 
• A persistent or significant disability or incapacity or substantial disruption of the 
ability to conduct normal life functions 
• A congenital anomaly or birth defect 
• Important medical events that may not result in death, be life-threatening, or require 
hospitalization may be considered an SAE when, based upon appropriate medical 
judgment, they may jeopardize the patient and may require medical or surgical 
intervention to prevent one of the outcomes listed in this definition. Examples of such 
medical events include allergic bronchospasm requiring intensive treatment in an 
emergency room or at home, blood dyscrasias or convulsions that do not result in 
inpatient hospitalization 
Note that hospitalization is defined as admission to treat a clinical AE. The following events 
would not be considered hospitalizations for SAE reporting purposes: 23-hour hold for 
observation, admission to a hospice facility or nursing home, respite care, outpatient surgery, 
social admission (eg, a homeless patient) or admission not associated with a precipitating clinical 
AE (eg, elective or pre-planned surgery, or in-patient administration of subsequent 
chemotherapy, etc.). 
8.1.1.3. 
Adverse Events of Special Interest 
There are no AEs of special interest (serious or nonserious) associated with MIRV.  
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8.1.2. 
Classification of Adverse Events 
All AEs will be evaluated according to the NCI CTCAE v5.0 (effective 27 November 2017). If 
the AE is not listed in the CTCAE v5.0, it should be graded based on the description given in 
Table 9. 
Table 9: 
Adverse Event Severity 
Severity 
Definition 
Grade 1 (Mild) 
No limitation of usual activities. 
Grade 2 (Moderate) 
Some limitation of usual activities. 
Grade 3 (Severe) 
Inability to carry out usual activities. 
Grade 4 (Life-threatening) 
Immediate risk of death. 
Grade 5 (Fatal) 
Resulting in death. 
Relationship of an AE or SAE to study medication is to be determined by the Investigator based 
on the definitions in Table 10. 
Table 10: 
Adverse Event Causal Relatedness 
Relationship to Product(s) 
Definition 
Not Related 
No relationship between the event, including laboratory test abnormality, and 
the administration of study drug. There is no temporal relationship and there is 
unambiguous evidence supporting another cause.  
Unlikely Related 
A clinical event, including laboratory test abnormality, with a temporal 
relationship to study drug administration which makes a causal relationship 
improbable, and in which other drugs, chemicals or underlying disease provide 
plausible explanations.  
Possibly Related 
A clinical event, including laboratory test abnormality, with a reasonable time 
sequence to administration of study drug, but which could also be explained by 
concurrent disease or other drugs or chemicals. Information on study drug 
withdrawal may be lacking or unclear.  
Probably Related 
A clinical event, including laboratory test abnormality, with a reasonable time 
sequence to administration of study drug, unlikely to be attributed to 
concurrent disease or other drugs or chemicals, and which follows a clinically 
reasonable response on withdrawal of study drug. The association of the 
clinical event, including laboratory test abnormality, must also have some 
biologic plausibility, at least on theoretical grounds. 
Definitely Related 
A clinical event, including laboratory test abnormality occurring in a plausible 
time relationship to study drug administration, and which cannot be explained 
by concurrent disease or other drugs or chemicals. The response to withdrawal 
of the study drug should be clinically plausible. The event must be definitive 
pharmacologically or phenomenologically, using a satisfactory re-challenge 
procedure if necessary.  
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8.2. 
Adverse Events 
8.2.1. 
Reporting Serious Adverse Events 
Any SAE, regardless of relationship to study medication, which occurs in a patient from the time 
of study informed consent until 30 days after the last study treatment, must be recorded by the 
clinical site on an SAE report form. Only SAEs which are considered related to a study 
procedure (ie, blood draw or fresh tumor biopsy) will be captured during the pre-screening 
period, ie, from the time of signing the pre-screening consent (if one is utilized) until the signing 
of the main study informed consent, or until the patient is determined to be a screen failure. The 
SAE must also be recorded in the clinical trial database, including the Investigator’s assessment 
regarding the relationship of the SAE to the study drug. The Investigator will promptly supply all 
information requested by the Sponsor (or contract research organization [CRO]) regarding the 
SAE.  
The Investigator must submit the SAE Report Form to ImmunoGen Pharmacovigilance (or 
designee). This form must be completed and submitted within 24 hours of the Investigator’s 
learning of the event using the contact information printed on the SAE form and contained 
within the SAE form completion instructions. Follow-up information must also be submitted 
using a new SAE Report Form. 
When reporting SAEs, the following additional points should be noted:  
• The underlying diagnosis or syndrome should be reported as the primary SAE term, 
rather than the signs or symptoms (signs and symptoms may be described in the 
narrative). 
• An event term of “Death” should not be reported as an SAE, but rather be recorded as 
an outcome of a specific SAE term. Initially, the event term of “death” can be used 
until the actual cause of death is known. If an autopsy was performed, the autopsy 
report should be provided. 
It is the responsibility of the Sponsor to ensure that each Investigator receives a copy of any 
suspected unexpected serious adverse reaction (SUSAR) report (CIOMS/MedWatch) regarding 
the study drug and that the report is submitted to the appropriate national regulatory agencies.  
The Investigator (or Sponsor or contracted designee) must promptly report all SUSARs to the 
IRB/IEC for review in accordance with their local IRB/EC requirements and national 
regulations. IRB/IEC notification of the SUSAR may take the form of a submission of a copy of 
the CIOMS/MedWatch report or other format accepted by the IRB/IEC. A copy of the 
CIOMS/MedWatch report and notification to IRB/IEC should be retained in the site’s study files.  
In addition to CIOMS/MedWatch reports, the Sponsor will also notify (through annual updates 
to the Investigator Brochure) the Investigators and IRBs/IECs of all deaths that occur during the 
study, irrespective of relationship to study medication. 
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8.2.1.1. 
Reporting of Disease Progression 
Progressive disease (PD) is an anticipated occurrence in oncology drug development and is not 
an AE unto itself.  
Progression of disease should not be reported as an SAE term; any serious medical 
event/condition that results from progression of underlying disease, if untoward, should be 
reported as the SAE.  
Progression of disease with a fatal outcome does not need to be reported as an AE term. The 
applicable protocol CRF page(s) pertaining to death should be appropriately completed however, 
as PD. 
8.2.2. 
Reporting a Pregnancy 
Pregnancy and lactation are exclusion criteria. Women of child bearing potential, defined as a 
sexually mature woman who has not undergone surgical sterilization or who has not been 
naturally postmenopausal for at least 12 consecutive months (ie, who has had menses any time in 
the preceding 12 consecutive months) must agree to use highly effective contraceptive methods 
(as defined in Section 5.8.7) while on study drug and for at least 3 months after the last dose of 
MIRV. In addition, it is recommended that patients undergo monthly pregnancy test for at least 
3 months after the last dose of MIRV. 
The Sponsor must be immediately notified in the event of a pregnancy occurring during the 
study and through 30 days after a patient’s last dose of MIRV. If a patient becomes pregnant the 
patient will be withdrawn from study drug. Pregnancy is not an AE unto itself and therefore 
should not be reported as an AE. 
All pregnancies will be recorded on a Pregnancy report form and submitted according to the 
contact information on the form and in the completion guidelines. 
Pregnancies, with the permission of the mother, will be followed to completion or termination 
using the designated sections of the Pregnancy report form. 
Any SAE, occurring during the pregnancy to the mother or fetus, would require that a study SAE 
form also be completed/submitted. 
9. 
STUDY ACTIVITIES 
All study visits and assessments that must be performed during the study and follow-up are 
included in Table 2. 
9.1. 
Screening Visit 
The Investigator is responsible for keeping a record of all patients screened for entry into the 
study, including those who are subsequently excluded. The reason(s) for exclusion must be 
recorded.  
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9.1.1. 
Standard of Care Assessments 
In some cases, clinical assessments performed before obtaining informed consent may be used to 
qualify the patient for the study if performed within the screening window. These include 
radiologic tumor assessment, PEs, laboratory results, urinalysis, or other assessments which may 
be considered part of standard of care. In these cases, repeat assessments may not be necessary 
before enrollment, unless individual parameters require further study or confirmation and are 
clinically appropriate.  
Note that safety blood tests, and PE do not need to be repeated if normal and conducted within 
4 days prior to C1D1. 
9.2. 
End of Treatment Visit 
Patients may voluntarily withdraw from the study drug at any time for any reason, and without 
prejudice to further treatment. In addition, patients may be withdrawn by the Investigator if they 
do not feel the patient is deriving clinical benefit or because the patient is experiencing 
unacceptable toxicity. The reasons for which a patient may be prematurely discontinued are 
listed in Section 5.6. The clinical trial database will capture reasons for withdrawal. 
Patients who withdraw or are removed from the study treatment will have an EOT visit within 
7 days of the decision to discontinue study drug. Patients will undergo assessments as outlined in 
Table 2.  
9.3. 
Follow-up Assessments 
9.3.1. 
30-Day Follow-up Visit 
A 30-Day Follow-up visit will occur 30 days (+14 days) after last dose of MIRV and should 
occur prior to the start of new anticancer therapy.  
In some cases, nonserious AE observations may continue beyond the safety visit. All ocular AEs 
will be followed until resolution, stabilization, or return to baseline. In these instances, additional 
information may be requested by ImmunoGen to adequately categorize the nature of the toxicity. 
All SAEs will be followed until they resolve, stabilize, or return to baseline, regardless of time 
from last dose or last visit. 
9.3.2. 
Response Follow-up 
Patients who discontinued MIRV for reasons other than PD will continue with tumor 
assessments until documentation of PD or the start of a new anticancer therapy, whichever 
comes first. Prior to Week 36 (from C1D1), assessments should occur every 6 weeks (± 1 week) 
as allowed by local requirements but must occur at an interval of no more than 12 weeks. After 
Week 36, assessment will occur every 12 weeks (± 3 weeks) until documentation of PD or the 
start of new anticancer therapy. 
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9.3.3. 
Survival Follow-up 
All patients who discontinue MIRV for any reason will be followed for survival after PD as per 
Investigator, or after start of a new anticancer therapy. Survival status will be assessed every 3 
months (± 1 month) until death, lost to follow-up, withdrawal of consent for survival follow-up, 
or until EOS, whichever comes first. Additional survival follow-up calls may occur periodically 
if needed. 
10. 
STATISTICAL METHODS 
This is a Phase 2 study designed to evaluate the ORR of MIRV in patients with high FRα 
expressing, high-grade serous rPSOC. 
All patients who have received at least 1 dose of MIRV will comprise the Safety Analysis 
Population.  
The Efficacy Evaluable Population will include all patients who have received at least 1 dose of 
MIRV and have measurable lesions at baseline (per RECIST v1.1). The primary efficacy 
analysis of ORR and all other efficacy analyses will be based on the Efficacy Evaluable 
Population. 
The safety analyses will be based on Safety Analysis Population. 
All statistical analyses will be performed using SAS statistical software Version 9.4 or later, 
unless otherwise noted. For categorical variables, the number (n) and percent of each category 
within a parameter will be presented. For continuous variables, the sample size (n), mean, 
median, and standard deviation, as well as the minimum and maximum values, will be presented. 
Missing data will not be imputed unless otherwise stated. There will be a detailed description of 
patient disposition, patient demographics, and baseline characteristics. 
A SAP will fully describe the planned analyses for this trial and will be finalized prior to 
database lock.  
10.1. 
Sample Size 
The primary endpoint of this study is ORR as assessed by the Investigator. The study is designed 
to test the null hypothesis that the ORR is ≤ 28% using an optimal Simon’s two-stage design 
(Simon 1989) without a planned pause in enrollment given preliminary efficacy and established 
safety of MIRV. 
The optimal two-stage design to test the null hypothesis that the ORR is ≤ 28% versus the 
alternative that the ORR is ≥ 48%, has an expected sample size of 37.74, and a probability of 
early termination of 0.762. If the ORR is ≤ 28%, there is a 0.024 probability of rejecting the null 
hypothesis (the target 1 sided alpha value was 0.025). If the ORR is ≥ 48%, there is a 
0.9 probability of rejecting the null hypothesis. After testing the drug on 28 efficacy evaluable 
patients in the first stage, the study will be terminated for futility if 9 or fewer patients respond. If 
the study goes on to the second stage, a total of 69 efficacy evaluable patients will be enrolled. If 
the total number responding is more than 26, the null hypothesis is rejected.  
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Approximately 75 patients will be enrolled so that a total of 69 patients will be efficacy 
evaluable.  
10.2. 
Safety Analyses 
Safety analyses will be based on the Safety Analysis Population. 
AEs and concomitant medication will be listed.  
AEs will be coded using the latest Medical Dictionary for Regulatory Activities (MedDRA) 
version and summarized per system organ class (SOC) and preferred term. 
Concomitant medications will be coded using the World Health Organization-Drug Dictionary 
(WHO-DD; 01 September 2019 or later version). A dictionary listing of all unique concomitant 
medications used in the study will be provided. 
All hematology, blood chemistry, and vital signs will be listed per patient for each assessment 
and descriptive statistics will be tabulated for select criteria. Changes from baseline in 
hematology, blood chemistry, and vital signs will be summarized by treatment. Shifts in 
hematology and blood chemistry from baseline values will be summarized. Plasma also will be 
evaluated for the presence of ADA.  
10.3. 
Efficacy 
Unless stated otherwise in the SAP, efficacy analyses will be performed on the Efficacy 
Evaluable Population. 
10.3.1. 
Primary Efficacy Analysis 
10.3.1.1. Objective Response Rate 
The primary endpoint is ORR, which includes confirmed best response of CR or PR. 
The primary endpoint of ORR (objective response = CR + PR) will be estimated along with a 
95% CI by the Clopper-Pearson method based on the efficacy evaluable population.  
The primary analysis of ORR will be conducted after all efficacy evaluable patients have:  
• undergone at least 4 post-baseline tumor assessments, or 
• experienced radiological PD, or  
• died or had clinical progression within 105 days of first dose of study drug, or 
• withdrawn from study for other reasons 
10.3.2. 
Key Secondary Efficacy Endpoint 
The key secondary endpoint of Investigator-assessed DOR will be estimated using Kaplan-Meier 
method for survival function estimate.  
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The initial analysis of DOR will be conducted at the time of primary analysis of ORR. An 
updated analysis of DOR will be conducted 12 months after the primary analysis of ORR, at the 
end of the study. 
10.3.3. 
Additional Secondary Efficacy Endpoints 
The additional secondary endpoints of Investigator-assessed PFS and OS will be estimated using 
Kaplan-Meier method for survival function estimate and CA-125 response will be determined 
using the GCIG criteria defined in Appendix C. 
10.4. 
Interim Analysis 
In this Simon’s two-stage design, 28 efficacy evaluable patients will be enrolled in the first stage. 
If 9 or fewer patients have achieved a confirmed response (CR or PR), the study will be 
terminated for futility. If the study goes on to the second stage, a total of 69 efficacy evaluable 
patients will be enrolled. 
11. 
QUALITY CONTROL AND ASSURANCE 
11.1. 
Recording of Data and Data Quality Assurance 
Data will be documented in various source documents (eg, the patient medical chart) and then 
manually entered into the clinical trial database. Clinical sites will be monitored by ImmunoGen 
or its designee to ensure the accuracy of data against source documents. If necessary, the study 
site will be contacted for corrections or clarifications. 
Adverse events will be coded using the latest MedDRA version. Concomitant medications will 
be coded using the WHO-DD; 01 September 2019 or later version. Training will occur at an 
Investigator meeting or at the site initiation visit or both. Remote web-based training may be 
provided. Instruction manuals (eg, laboratory manuals and pharmacy manuals) will be provided 
to aid consistency in data collection and reporting across sites. 
This clinical study will be conducted according to ICH-GCP E6 (R2) guidelines. Quality 
oversight shall be maintained through proactive and continual risk assessment and mitigation at 
the operational level. GCP quality assurance audits will be conducted as needed as continued 
compliance oversight.  
12. 
ETHICAL CONSIDERATIONS AND ADMINISTRATIVE 
PROCEDURES 
12.1. 
Ethical and Regulatory 
This clinical study will be conducted by the Sponsor, the Investigator, delegated Investigator 
staff and sub-Investigator(s), in accordance with the protocol, the Declaration of Helsinki, the 
International Conference on Harmonisation (ICH) Harmonised Tripartite Guideline for GCP, and 
all applicable local regulatory requirements. 
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This clinical study will be recorded in a free, publicly accessible, internet-based registry, no later 
than 21 days after the first patient enrollment, in compliance with applicable regulatory 
requirements and with ImmunoGen public disclosure commitments. 
12.1.1. 
Institutional Review Board or Independent Ethics Committee Approval 
Before initiation of the study, the Investigator must provide the Sponsor with a copy of the 
written IRB/IEC approval of the protocol, the main study ICF and the pre-screening ICF (latter 
ICF is applicable for sites requesting permission to pre-screen for FRα positivity (high FRα) 
before performing any additional study related tests). This approval must refer to the ICF(s) and 
to the study title, study number, and version and date of issue of the study protocol, as given by 
the Sponsor on the cover page of the protocol. 
Status reports must be submitted to the IRB/IEC at least once per year or as per institutional 
guidelines. The IRB/IEC must be notified of completion of the study and a final report must be 
provided to the IRB/IEC. A copy of these reports will be sent to the study clinical monitor or 
designee. The Investigators must maintain an accurate and complete record of all submissions 
made to the IRB/IEC, including a list of all reports and documents submitted. AEs, which are 
subject to expedited reporting to the FDA or other regulatory agencies (SUSARs), must be 
submitted promptly to the IRB/IEC. 
12.1.2. 
Patient Information and Consent 
An ICF that includes information about the study will be prepared and given to the patient. The 
ICF will contain all FDA and ICH required elements and be approved by an IRB/IEC. The ICF 
must be in a language understandable to the patient. Before enrolling in the clinical study, the 
nature, scope, and possible consequences of the clinical study will be explained to the patient in a 
form understandable to him or her. After the patient has been given ample time to read and ask 
questions regarding the ICF and has been informed that participation is voluntary, the patient 
must give consent in writing. If the patient is unable to read, oral presentation and explanation of 
the written ICF and information to be supplied must take place in the presence of an impartial 
witness. Consent must be confirmed orally and by the personally dated signature of the patient. 
The witness and the person conducting the informed consent discussions must also sign and 
personally date the informed consent document. The informed consent process must be recorded 
and dated in the patient’s source document. 
A copy of the signed and dated consent document(s) must be given to the patient. The original 
signed and dated consent document will be retained by the Investigator. Patient confidentiality 
will be maintained as outlined in Section 12.3. 
The Investigator must not undertake any measures specifically required solely for the clinical 
study until valid informed consent has been obtained. 
A model of the pre-screening and the main study ICF will be provided to the sites separately for 
this protocol. The main study consent can be used to confirm a patient’s consent to all study 
procedures and all study-specific screening tests. The pre-screening ICF can be used to 
pre-screen patients for FRα status via tumor FRα levels and soluble FRα levels in blood. If a 
patient is eligible based on FRα expression level, the patient will be provided the main study 
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consent and only after signing the main study ICF will additional study-specific screening tests 
be performed. Alternatively, the patient can be consented on both pre-screening and main study 
ICF at the same time; and FRα testing and study-specific screening assessments can be carried 
out in parallel.  
Patients must be consented to the most current version of the ICF during their participation in the 
study.  
12.2. 
Investigators and Study Administrative Structure 
Before initiation of the study, the Investigators must provide the Sponsor with a completed Form 
FDA 1572 or equivalent form. Study medications must be administered only under the 
supervision of the Investigators listed on this form. Curriculum vitae must be provided for the 
Investigators and sub-investigators listed on Form FDA 1572 or equivalent form. 
The Investigator must ensure that all persons assisting with the study are adequately informed 
about the protocol, any amendments to the protocol, the study treatments, and their study related 
duties and functions. The Investigator must maintain a list of sub-investigators and other 
appropriately qualified persons to whom he or she has delegated significant study related duties. 
12.3. 
Patient Confidentiality 
Patient names will not be supplied to the Sponsor. If the patient name appears on any documents, 
it must be redacted before a copy of the document is supplied to the Sponsor. Study findings 
stored on a computer will be stored in accordance with local data protection laws. Patient blood 
and tissue samples, and radiographic images sent to outside laboratories and/or CROs are 
identified by study patient number only to ensure maintenance of confidentiality. The patient 
consent form will state publications resulting from this study will not refer to patient name or 
include any other information that might disclose the identity of the patient. The patients will be 
told that representatives of the Sponsor, a designated CRO, the IRB/IEC, or regulatory 
authorities may inspect their medical records to verify the information collected, and that all 
personal information made available for inspection will be handled in strictest confidence and in 
accordance with local data protection laws. The Investigator will maintain a personal patient 
identification list (patient numbers with the corresponding patient names) to enable records to be 
identified. 
12.4. 
Study Monitoring 
The Sponsor or its designee will monitor the conduct of the trial on a regular basis throughout 
the duration of the study, according to the monitoring plan and in compliance with ICH-GCP E6 
(R2). Monitoring of the study will serve to ensure: (a) The rights and well-being of human 
subjects are protected; (b) The reported trial data are accurate, complete, and verifiable from 
source documentation; and (c) The conduct of the trial is in compliance with the currently 
approved protocol/amendment(s), with GCP, and with applicable regulatory requirement(s). 
The study monitor will train site personnel on the conduct of the trial. The monitor will assess 
the trial site’s compliance with the protocol and will periodically review and verify a sample of 
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the patient data recorded on CRFs against source documentation. The study monitor will also 
review documents that provide evidence of the proper consent and eligibility of enrolled patients, 
the compliant conduct of study procedures, the administration and disposition of investigational 
product(s), the reporting of serious adverse events and adverse reactions, and the continued 
maintenance of trial records. 
The Investigator will allocate adequate time to support such monitoring activities. The 
Investigator will also ensure that the monitor is given reasonable remote and/or on-site access to 
study-related documents, source documents (regardless of media) and study-related facilities (eg, 
investigational pharmacy, etc.). Queries may be raised if any datum is unclear or contradictory. 
The Investigator and site personnel must address all queries in a timely manner. 
12.5. 
Study Committees 
12.5.1. 
Steering Committee 
A Steering Committee (SC) will be comprised of lead Investigators from North America and 
Europe. The purpose of the SC is to provide overall guidance regarding design of the study, 
conduct, and execution of the study. This includes (but is not limited to) safety, efficacy, 
enrollment, and contribution to scientific input for publications. Responsibilities of the SC and 
communication flow between ImmunoGen and the SC will be included in the SC charter 
document.  
12.5.2. 
Independent Data Monitoring Committee 
An IDMC will not be utilized in this study. Sponsor will monitor safety in accordance with ICH-
GCP E6 (R2) guidelines. 
12.6. 
Case Report Forms and Study Reports 
Electronic case report forms (eCRFs) are provided for each patient. All forms must be filled out 
by authorized study personnel. The Investigator is required to sign/e-sign the eCRF after all data 
have been captured for each patient. If corrections are made after review and signature by the 
Investigator, he or she must be made aware of the changes, and his or her awareness documented 
by re-signing the eCRF Critical Documents. 
Before ImmunoGen initiates the study at a given site, it is the responsibility of the Investigator to 
ensure that the following documents are made available to ImmunoGen or their designee: 
• Curricula vitae of Investigator and sub-Investigator(s) (current, dated and signed or 
supported by an official regulatory document) 
• Signed and dated agreement of the final protocol 
• Signed and dated agreement of any amendment(s), if applicable 
• Approval/favorable opinion from the IRB/IEC clearly identifying the document and 
document revision reviewed, including but not limited to, the protocol, any protocol 
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amendments, Investigator Brochure, Patient Information/ICF, and any other written 
information to be provided regarding patient recruitment procedures 
• Copy of IRB/IEC approved Patient Information/ICF/any other written 
information/advertisement 
• List of IRB/IEC Committee members/constitution or equivalent compliance statement 
• Study and Financial agreement(s) 
• Completed Form FDA 1572 or equivalent form 
• Completed Financial Disclosure Form 
Additional documents such as laboratory reference ranges and certifications will be collected 
during the study. Ongoing regulatory approvals and notifications, as required, must also be made 
available to ImmunoGen. 
12.7. 
Protocol Adherence 
Each Investigator must adhere to the protocol as detailed in this document and agree that any 
changes to the protocol must be approved by ImmunoGen’s authorized representative in writing 
before seeking approval, where necessary, from the IRB/IEC, Research Ethics Committee 
(REC), or Ethics Review Board (ERB). Each Investigator will be responsible for allowing only 
those patients who have met protocol eligibility criteria to be enrolled. 
Modifications to the protocol should not be made without agreement of the Investigators and 
ImmunoGen. Changes to the protocol will require written IRB/IEC, REC, or ERB 
approval/favorable opinion before implementation, except when the modification is needed to 
eliminate an immediate hazard(s) to patients. The IRB/IEC/REC/ERB may provide expedited 
review and approval/favorable opinion for minor change(s) in ongoing studies that have the 
approval/favorable opinion of the IRB/IEC/REC/ERB. ImmunoGen will submit all protocol 
modifications to the appropriate regulatory authorities in accordance with the governing 
regulations. 
When immediate deviation from the protocol is required to eliminate an immediate hazard(s) to 
patients, the Investigator will contact ImmunoGen, if circumstances permit, to discuss the 
planned course of action. Any departures from the protocol must be fully documented in the 
source documentation. 
Prospective waivers or exemptions are not permitted.  
12.8. 
End of Study 
EOS will occur 12 months after the primary analysis for ORR. If patients are still receiving 
clinical benefit from MIRV at EOS, either the study will be amended to allow those patients to 
continue to receive study drug with limited data collection (eg, SAEs, dosing information) until 
they are no longer benefiting or patients will be given the option to roll-over to a long-term 
extension study.  
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12.9. 
Study Termination 
If the Sponsor, an Investigator, or Clinical Study Monitor discovers conditions arising during the 
study that indicate that the clinical investigation should be halted due to an unacceptable patient 
risk, the study must be terminated after appropriate consultation between ImmunoGen and the 
Investigators. In addition, a decision on the part of ImmunoGen to suspend or discontinue 
development of the study drug may be made at any time.  
Within 15 days of premature closure, ImmunoGen must notify the competent authorities and 
IECs/IRBs of any member state where the study is being conducted, providing the reasons for 
study closure. 
12.10. 
Site Termination 
If ImmunoGen, an Investigator, or regulatory authorities discover conditions during the study 
that indicate that the study or related activities at a particular center should be terminated, this 
action may be taken after appropriate consultation between ImmunoGen and the Investigator. 
Conditions that may warrant study or center termination include but are not limited to: 
• Discovery of an unexpected, serious, and/or unacceptable risk to patients enrolled in 
the study 
• Decision on the part of ImmunoGen to suspend or discontinue testing, evaluation, or 
development of the clinical program 
• Unacceptable benefit-risk relationship of the investigational product 
• Recommendations of a regulatory body 
• Investigator failure to comply with applicable regulatory authority requirements or 
protocol requirements 
• Submission of knowingly false information from the center to ImmunoGen or 
regulatory authorities 
Study or center termination and follow-up will be performed in compliance with the conditions 
set forth in 21 CFR § 312 and in compliance with the principles set forth in International 
Conference on Harmonisation (ICH) Good Clinical Practices (GCP). 
12.11. 
Access to Source Documentation 
According to the ICH-GCP, the monitoring team must check the clinical trial database entries 
against the source documents. The ICF will include a statement by which the patient allows the 
Sponsor’s duly authorized personnel, the IRB/IEC, and the regulatory authorities to have direct 
access to original medical records which support the data in the clinical trial database (eg, 
patient's medical file, appointment books, original laboratory records, etc.). These personnel, 
bound by professional secrecy, must maintain the confidentiality of all personal identity or 
personal medical information (according to confidentiality and personal data protection rules). 
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12.12. 
Audits and Inspections 
Regulatory authorities, the IEC/IRB, or the Sponsor may request access to all source documents, 
CRFs, and other study documentation for on-site audit or on-site or remote inspection. Direct 
access to these documents must be guaranteed by the Investigator, who must provide support at 
all times for these activities. Monitoring and auditing procedures that comply with local 
regulations and current GCP guidelines will be followed. On-site or remote review of the clinical 
trial database for completeness and clarity, crosschecking with source documents, and 
clarification of administrative matters will be performed. 
12.13. 
Data Generation and Analysis 
The clinical trial database will be developed and maintained by a CRO or other vendors as 
designated by ImmunoGen. ImmunoGen or its designee will be responsible for performing study 
data management activities and analyses. 
12.14. 
Retention of Data 
Essential documents will be retained until the following requirements are met: 
• a minimum of 2 years (or longer, if required by local/regional regulation) has elapsed 
after an approval of a marketing application which was supported by this study, or 
• there are no pending or contemplated marketing applications, or 
• at least 2 years have elapsed since the formal discontinuation of clinical development 
of the investigational product, or  
• the record retention policies and guidelines for countries in which the study is being 
conducted are followed (whichever is longer) 
It is the responsibility of the Sponsor to inform the Investigator or institution as to when these 
documents no longer need to be retained. 
12.15. 
Financial Disclosure 
The Investigator must disclose any financial interests in the Sponsor as described in 21 CFR Part 
54 before beginning this study and for 12 months after the study has been completed. The 
appropriate form will be provided to the Investigator by the Sponsor, which will be signed and 
dated by the Investigator, before the start of the study. If financial interests change at any time 
during the study and for up to 12 months after the study has been completed, an updated 
financial disclosure form is required. 
All financial details relating to the Investigators’ participation in this study are provided in the 
separate contract between the institution and ImmunoGen. 
12.16. 
Insurance Compensation 
The Sponsor certifies that it has taken out a liability insurance policy covering all clinical trials 
under its sponsorship. This insurance policy is in accordance with local laws and requirements. 
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The insurance of the Sponsor does not relieve the Investigator and the collaborators from any 
obligation to maintain their own liability insurance policy. An insurance certificate will be 
provided to the IECs/IRBs or regulatory authorities in countries requiring this document. 
12.17. 
Publication and Disclosure Policy 
The information obtained during the conduct of this clinical study is confidential, and disclosure 
to third parties other than those noted below is prohibited. All information concerning the 
product as well as any matter concerning the operation of the Sponsor, such as clinical 
indications for the drug, its formula, methods of manufacture and other scientific data relating to 
it, that have been provided by the Sponsor and are unpublished, are confidential and must remain 
the sole property of the Sponsor. The Investigator will agree to use the information only for the 
purposes of carrying out this study and for no other purpose unless prior written permission from 
the Sponsor is obtained. 
Information obtained during the conduct of this study will be used by ImmunoGen in connection 
with the development of the study drug. The study Investigator is obliged to provide 
ImmunoGen with complete test results and all data developed in this study. The Sponsor has full 
ownership of the original case report forms completed as part of the study. This information may 
be disclosed to other physicians who are conducting similar studies and to the global health 
authorities as deemed necessary by the Sponsor. Patient-specific information may be provided to 
other appropriate medical personnel related to the care of that patient only with patient's prior 
consent.  
The Investigator and any other clinical personnel associated with this study will not publish the 
results of the study, in whole or in part, at any time, unless they have consulted with 
ImmunoGen, provided ImmunoGen a copy of the draft document intended for publication, and 
obtained ImmunoGen’s written consent for such publication. All information obtained during the 
conduct of this study will be regarded as confidential. ImmunoGen will use the information for 
registration purposes and for the general development of the drug. 
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13.
LIST OF REFERENCES
Ab O, Whiteman KR, Bartle LM, et al. IMGN853, a folate receptor-α (FRα)-targeting antibody-
drug conjugate, exhibits potent targeted antitumor activity against FRα-expressing tumors. Mol 
Cancer Ther. 2015;14(7):1605-13. 
Aghajanian C, Blank SV, Goff BA et al. OCEANS: a randomized, double-blind, placebo-
controlled phase III trial of chemotherapy with or without bevacizumab in patients with 
platinum-sensitive recurrent epithelial ovarian, primary peritoneal, or fallopian tube cancer. J 
Clin Oncol. 2012;30(17):2039-45. 
Allard JE, Risinger JI, Morrison C, et al. Overexpression of folate binding protein is associated 
with shortened progression-free survival in uterine adenocarcinomas. Gynecol Oncol. 
2007;107(1):52-7. 
Armstrong DK, Alvarez RD, Bakkum-Gamez JN, et al. NCCN guidelines insights: Ovarian 
Cancer, Version 1.2019. J Natl Compr Canc Netw. 2019;17(8):896-909. 
Avastin. Package Insert. Genentech, Inc. 2020 
Baldwin LA, Huang RW, Miller T, et al. Ten-year relative survival for epithelial ovarian cancer. 
Obstet Gynecol. 2012;120(3)612-8. 
Basal E, Eghbali-Fatourechi GZ, Kalli KR, et al. Functional folate receptor alpha is elevated in 
the blood of ovarian cancer patients. PLoS One. 2009;4(7):e6292. 
Bruchim I, Jarchowsky-Dolberg O, Fishman A. Advanced (>second) line chemotherapy in the 
treatment of patients with recurrent epithelial ovarian cancer. Eur J Obstet Gynecol Reprod Biol 
2013;166:94–8. 
Burger RA, Brady MF, Bookman MA, et al. Incorporation of bevacizumab in the primary 
treatment of ovarian cancer. N Engl J Med. 2011;365(26):2473–83. 
Cannistra SA. Cancer of the ovary. N Engl J Med. 2004;351(24):2519-29. 
Castells MC, Tennant NM, Sloane DE, et al. Hypersensitivity reactions to chemotherapy: 
outcomes and safety of rapid desensitization in 413 cases. J Allergy Clin Immunol. 
2008;122(3):574-580. doi:10.1016/j.jaci.2008.02.044 
CDER. Olaparib Medical Review of Application Number: 206162Orig1s000. Review date 
December 2, 2014. Accessed January 19, 2021. 
https://www.accessdata.fda.gov/drugsatfda_docs/nda/2014/206162Orig1s000MedR.pdf 
CDER. Rucaparib Multi-Discipline Review of Application Number: 2019115Orig1s000. Review 
date November 22, 2016. Accessed January 19, 2021. 
https://www.accessdata.fda.gov/drugsatfda_docs/nda/2016/209115Orig1s000MultiDisciplineR.p 
df 
Chen YL, Chang MC, Huang CY, et al. Serous ovarian carcinoma patients with high alpha-folate 
receptor had reducing survival and cytotoxic chemo-response. Mol Oncol. 2012;6(3):360-9.  
Confidential and Proprietary 
ImmunoGen, Inc. 
77 
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Cobb LP, Gaillard S, Wang Y, et al. Adenocarcinoma of mullerian origin: review of 
pathogenesis, molecular biology, and emerging treatment paradigms. Gynecol Oncol Res Pract. 
2015;2:1-16. 
Coleman RL, Brady MF, Herzog TJ, et al. Bevacizumab and paclitaxel-carboplatin 
chemotherapy and secondary cytoreduction in recurrent, platinum-sensitive ovarian cancer (NRG 
Oncology/Gynecologic Oncology Group study GOG-0213): a multicentre, open-label, 
randomised, phase 3 trial. Lancet Oncol. 2017 Jun;18(6):779-791. 
Crane LMA, Arts JG, van Oosten M, et al. The effect of chemotherapy on expression of folate 
receptor-alpha in ovarian cancer. Cellular Oncol (Dordr). 2012;35(1):9-18. 
Dainty LA, Risinger JI, Morrison C, et al. Overexpression of folate binding protein and 
mesothelin are associated with uterine serous carcinoma. Gynecol Oncol. 2007;105(3):563-70. 
Eisenhauer E, Therasse P, Bogaerts J, et al. New response criteria in solid tumors: revised 
RECIST guideline (version 1.1). Eur J Cancer. 2009;45(2):228-47. 
Elnakat H, Ratnam M. Distribution, functionality and gene regulation of folate receptor 
isoforms: implications for targeted therapy. Adv Drug Deliv Rev. 2004;56(8):1067-84. 
Erickson HK, Park PU, Widdison WC, et al. Antibody-maytansinoid conjugates are activated in 
targeted cancer cells by lysosomal degradation and linker-dependent intracellular processing. 
Cancer Res. 2006;66(8):4426-33. 
EUCAN. Cancer Fact Sheet: Ovary. https://gco.iarc.fr/today/data/factsheets/cancers/25-Ovary-
fact-sheet.pdf. Effective December 2020. Accessed August 2021. 
Fisher RE, Siegel BA, Edell SL, et al., Exploratory study of 99mTc-EC20 imaging for 
identifying patients with folate receptor-positive solid tumors. J Nucl Med. 2008;49(6):899-906. 
Flatiron Health, Inc. Ovarian Cancer Cohort, 2017-2020. Data available upon request 
Gaillard S, Ghamande SA, Pardo B, et al. Phase III trial of Lurbinectedin versus PLD or 
Topotecan in platinum-resistant ovarian cancer patients: Results of CORAIL trial. Ann Oncol. 
2018;29(suppl_8):viii332-viii358. 
Garcia A, Singh H. Bevacizumab and ovarian cancer. Ther Adv Med Oncol. 2013;5(2):133-41. 
Garin-Chesa P, Campbell I, Saigo PE, Lewis JL Jr, Old LJ, Rettig WJ. Trophoblast and ovarian 
cancer antigen LK26. Sensitivity and specificity in immunopathology and molecular 
identification as a folate-binding protein. Am J Pathol. 1993;142(2):557-67. 
Gladieff L, Ferrero A, De Rauglaudre G et al. Carboplatin and pegylated liposomal doxorrubicin 
versus carboplatin and paclitaxel in platinum-sensitive ovarian cancer patients: results from a 
subset analysis of the CALYPSO phase 3 trial. Annals of Oncology 2012; 23: 1185-1189. 
Gordon AN, Fleagle JT, Guthrie D, Parkin DE, Gore ME, Lacave AJ. Recurrent epithelial 
ovarian carcinoma: a randomized phase III study of pegylated liposomal doxorubicin versus 
topotecan. J Clin Oncol. 2001;19(14):3312-22. 
Confidential and Proprietary 
ImmunoGen, Inc. 
78 
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Gore M, ten Bokkel Huinink W, Carmichael J, et al. Clinical evidence for topotecan-paclitaxel 
non-cross-resistance in ovarian cancer. J Clin Oncol. 2001;19(7):1893-1900. 
Grant DJ, Moorman PG, Akushevich L, et al. Primary peritoneal and ovarian cancers: an 
epidemiological comparative analysis. Cancer Causes Control. 2010;21(7):991-998.  
Hanker LC, Loibl S, Burchardi N, et al. The impact of second and sixth line of therapy on 
survival of relapsed ovarian cancer after primary taxane/platinum-based therapy. Ann Oncol. 
2012;23(10):2605-12. 
Hoskins P, Eisenhauer E, Beare S, et al. Randomized phase II study of two schedules of 
topotecan in previously treated patients with ovarian cancer: a National Cancer Institute of 
Canada Clinical Trials Group study. J Clin Oncol. 1998;16(6):2233-7. 
Hough CD, Cho KR, Zonderman AB, Schwartz DR, Morin PJ. Coordinately up-regulated genes 
in ovarian cancer. Cancer Res. 2001;61(10):3869-76. 
International Collaborative Ovarian Neoplasm Group. Paclitaxel plus carboplatin versus standard 
chemotherapy with either single-agent carboplatin or cyclophosphamide, doxorubicin, and 
cisplatin in women with ovarian cancer: the ICON3 randomised trial. Lancet. 2002 Aug 
17;360(9332):505-15 
Jones MB, Neuper C, Clayton A, et al. Rationale for folate receptor alpha targeted therapy in 
“high risk” endometrial carcinomas. Int J Cancer. 2008;123(7):1699-703. 
Kalli KR, Oberg AL, Keeney GL, et al. Folate receptor alpha as a tumor target in epithelial 
ovarian cancer. Gynecol Oncol. 2008;108(3):619-26. 
Kelemen LE. The role of folate receptor alpha in cancer development, progression and treatment: 
cause, consequence or innocent bystander? Int J Cancer. 2006;119(2):243-50. 
Lin K, Harrell M, Oza A, et al. BRCA reversion mutations in circulating tumor DNA predict 
primary and acquired resistance to the PARP inhibitor rucaparib in high-grade ovarian carcinoma 
Cancer Discov. 2019; 9: 210-219 
Mantovani LT, Miotti S, Menard S, et al. Folate binding protein distribution in normal tissues 
and biological fluids from ovarian carcinoma patients as detected by the monoclonal antibodies 
MOv18 and MOv19. Eur J Cancer. 1994;30A(3):363-9. 
Markman M, Kennedy A, Webster K, et al. Clinical features of hypersensitivity reactions to 
carboplatin. J Clin Oncol. 1999;17(4):1141. doi:10.1200/JCO.1999.17.4.1141 
Naumann WR, Coleman RL. Management strategies for recurrent platinum-resistant ovarian 
cancer. Drugs. 2011;71(11):1397-1412.  
National Cancer Institute. Surveillance, Epidemiology, and End Results Program (SEER). 
Cancer Stat Facts: Ovarian. https://seer.cancer.gov/statfacts/html/ovary.html. Accessed 2021. 
Navo M, Kunthur A, Badell ML, et al. Evaluation of the incidence of carboplatin 
hypersensitivity reactions in cancer patients. Gynecol Oncol. 2006;103(2):608-613. 
doi:10.1016/j.ygyno.2006.04.002 
Confidential and Proprietary 
ImmunoGen, Inc. 
79 
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ImmunoGen, Inc. 
80 
NCCN Clinical Practice Guidelines in Oncology. Ovarian Cancer Including Fallopian Tube 
Cancer and Primary Peritoneal Cancer. Version 1.2021. 
https://www.nccn.org/professionals/physician_gls/pdf/ovarian.pdf. Published February 26, 2021. 
Accessed March 2021. 
Neff RT, Senter L, Salani R. BRCA mutation in ovarian cancer: testing, implications and 
treatment considerations. Ther. Adv. Med. Oncol. 2017. 9, 519–531. 
O'Malley DM, Vetter MH, Cohn DE, Khan A, Hays JL. Outpatient desensitization in selected 
patients with platinum hypersensitivity reactions. Gynecol Oncol. 2017;145(3):603-610. 
doi:10.1016/j.ygyno.2017.03.015 
O’Shannessy DJ, Jackson SM, Twine NC, et al. Gene expression analyses support fallopian tube 
epithelium as the cell of origin of epithelial ovarian cancer. Int J Mol Sci. 2013;14(7):13687-
13703. 
Rustin GJ, Quinn M, Thigpen T, et al. Re: New guidelines to evaluate the response to treatment 
in solid tumors (ovarian cancer). J Natl Cancer Inst. 2004;96(6):487-8. 
Sandercock J, Parmar MK, Torri V, Qian W. First-line treatment for advanced ovarian cancer: 
paclitaxel, platinum and the evidence. Br J Cancer. 2002 Oct 7;87(8):815-24. 
Scorer P, Lawson N, Quinn A. Scorer P, Lawson N, Quinn A. A Full Immunohistochemical 
Evaluation of a Novel Monoclonal Antibody to Folate Receptor – alpha (FR-a). Novocastra 
Journal of Histopathology, reAGENTS. 2010;3:8-12. 
Simon R. Optimal two-stage designs for phase II clinical trials. Control Clin Trials. 
1989;10(1):1-10. doi:10.1016/0197-2456(89)90015-9 
van Dam GM, Themelis G, Crane LM, et al. Intraoperative tumor-specific fluorescence imaging 
in ovarian cancer by folate receptor-α targeting: first in-human results. Nat Med. 
2011;17(10):1315-9. 
Wadler S, Benson A, Engelking C, et al. Recommended guidelines for the treatment of 
chemotherapy-induced diarrhea. J Clin Oncol. 1998;16(9):3169-78. 
Weitman SD, Lark RH, Coney LR et al. Distribution of the folate receptor GP38 in normal and 
malignant cell lines and tissues. Cancer Res. 1992;52(12):3396-401.  
Younes A, Kim S, Romaguera J, et al. Phase I multidose-escalation study of the anti-CD19 
maytansinoid immunoconjugate SAR3419 administered by intravenous infusion every 3 weeks 
to patients with relapsed/refractory B-cell lymphoma. J Clin Oncol. 2012;30(22):2776-82. 
Zejula (niraparib) [package insert]. Research Triangle Park, NC. GlaxoSmithKline. 2019. 
Zweizig S, Roman LD, Muderspach LI. Death from anaphylaxis to cisplatin: a case report. 
Gynecol Oncol. 1994;53(1):121-122. doi:10.1006/gyno.1994.1098 
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APPENDIX A. EASTERN COOPERATIVE ONCOLOGY GROUP 
PERFORMANCE STATUS SCALE 
GRADE 
SCALE  
0 
Fully active, able to carry out all pre-disease performance without restriction. 
(Karnofsky 90-100) 
1 
Restricted in physically strenuous activity but ambulatory and able to carry out work 
of a light or sedentary nature, eg, light housework, office work. (Karnofsky 70-80) 
2 
Ambulatory and capable of all self-care but unable to carry out work activities. Up 
and about more than 50% of waking hours. (Karnofsky 50-60) 
3 
Capable of only limited self-care, confined to bed or chair more than 50% of 
waking hours. (Karnofsky 30-40) 
4 
Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair. 
(Karnofsky 10-20) 
 
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APPENDIX B. RESPONSE DEFINITIONS (RECIST V1.1) 
(Eisenhauer 2009) 
DEFINITIONS 
Baseline: Baseline is defined as the most recent assessment performed before the first dose of 
study drug. Baseline assessments must be performed within the period defined in the protocol 
eligibility criteria. 
Measurable Lesions: Except for lymph nodes (described below), measurable lesions are defined 
as those that can be accurately measured in at least 1 dimension (longest diameter to be recorded) 
as ≥ 10 mm with CT scan (if CT scans have slice thickness greater than 5 mm, the minimum size 
of a measurable lesion is twice the slice thickness).  
• To be considered pathologically enlarged and measurable, a lymph node must be 
≥ 15 mm in short axis when assessed by CT scan (CT scan slice thickness 
recommended to be no greater than 5 mm). At baseline and in follow-up, only the 
short axis will be measured and recorded. 
• MRI may be substituted for contrast-enhanced CT for lesions at some anatomical 
sites, but not for lesions in the lungs. The minimum size for measurability is the same 
as for CT (10 mm) as long as the scans are performed with slice thickness of 5 mm 
and no gap. If MRI is performed with thicker slices, the size of a measurable lesion at 
baseline should be twice the slice thickness. In the event there are inter-slice gaps, 
this also needs to be considered in determining the size of measurable lesions at 
baseline. 
Non-measurable Lesion: all other lesions (or sites of disease) including small lesions (longest 
diameter < 10 mm or pathological lymph nodes with ≥ 10 to < 15 mm short axis), are considered 
non-measurable.  
• Lymph nodes that have a short axis < 10mm are considered non-pathological and are 
not to be recorded or followed.  
• Bone lesions, leptomeningeal disease, ascites, pleural/pericardial effusions, 
lymphangitis cutis/pneumonitis, inflammatory breast disease, and abdominal masses 
(not followed by CT or MRI), are considered as non-measurable. 
Target Lesions: All measurable lesions up to a maximum of 2 lesions per organ and 5 lesions in 
total, representative of all involved organs, are to be identified as target lesions and measured 
and recorded at baseline.  
• Target lesions are to be selected on the basis of their size (lesions with the longest 
diameter) to represent all involved organs, and to be those that lend themselves to 
reproducible repeated measurements.  
• It may be the case that on occasion, the largest lesion does not lend itself to 
reproducible measurement in which circumstance the next largest lesion which can be 
measured reproducibly should be selected. 
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• Target lesions will be measured at each assessment (longest axis for non-nodal 
lesions, shortest axis for measurable malignant nodal lesions). 
Non-target Lesions: All other lesions (or sites of disease) including all non-measurable lesions 
(including pathological lymph nodes with ≥ 10 to < 15 mm short axis) and all measurable lesions 
over and above the five target lesions are to be identified as non-target lesions and recorded at 
baseline.  
• Measurements of these lesions are not required, but the presence, absence, 
unequivocal progression of each is to be recorded throughout follow-up.  
• Lymph nodes that have a short axis < 10 mm are considered non-pathological and are 
not to be recorded or followed. 
Special Considerations 
Clinical Examination of Lesions: Superficial or visible lesions that cannot be assessed by CT 
scan or MRI will only be considered for response assessment if these lesions are biopsy-proven 
metastatic lesions and ≥ 10 mm in diameter. These lesions will be considered non-measurable 
and thus non-target for response assessment. 
Cystic Lesions: Cystic lesions thought to represent cystic metastases can be considered as 
measurable lesions if they meet the definition of measurability described above. However, if 
non-cystic lesions are present in the same patient, these are preferred for selection as target 
lesion.  
Bone Lesions: Bone scan, positron emission testing (PET) scan or plain films are not considered 
adequate imaging techniques to measure bone lesions. However, these techniques can be used to 
confirm the presence or disappearance of bone lesions. 
• Lytic bone lesions or mixed lytic-blastic lesions, with identifiable soft tissue 
components, that can be evaluated by cross-sectional imaging techniques such as CT 
or MRI can be considered as measurable lesions if the soft tissue component meets 
the definition of measurability described above. 
• Blastic bone lesions are non-measurable. 
Lesions with Prior Local Treatment: Lesions situated in a previously irradiated area, or in an 
area subjected to other locoregional therapy, are usually not considered measurable; however, if 
they meet the following criteria, they may be considered for study: 
• there has been prior documented progression in the lesion by at least 2 sequential CT 
or MRI scans performed after the completion of radiation, or  
• histopathological evidence of progression 
Additionally, if such lesions meet the criteria for measurability, they may be considered target 
lesions. 
 
 
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Imaging Methods 
The same method of assessment and the same technique used to characterize each identified and 
reported lesion at baseline should be used during each follow-up assessment. Imaging-based 
evaluation is preferred to evaluation by clinical examination unless the lesion(s) being followed 
cannot be imaged but are assessable by clinical exam (referring to biopsy-proven visible 
lesions(s) at the vaginal apex).  
Chest X-ray: Lesions that are identified on chest X-ray must be confirmed and followed by CT 
scan. If there is/are pre-existing chest lesion(s) before the baseline tumor assessment, a chest X-
ray is not necessary to assess those lesions. The pre-existing chest lesion(s) must be assessed at 
baseline and followed by CT scans. 
Conventional CT or MRI: This guideline has defined measurability of lesions on CT scan based 
on the assumption that CT slice thickness is 5 mm or less. If CT scans have slice thickness 
greater than 5 mm, the minimum size for a measurable lesion is twice the slice thickness. MRI is 
also acceptable in certain situations (eg, for body scan) except for lung.  
CA-125: Tumor marker CA-125 alone cannot be used to assess response or determine 
progression; however, it will be followed. CA-125 assessments will be performed as indicated in 
Table 2. Patients whose CA-125 is above the upper limit of normal (ULN) at baseline will need 
to have their values normalize to ≤ ULN, in addition to complete disappearance of measurable or 
evaluable disease, to be considered in complete response. 
Other methods of assessment, PET-CT, ultrasound, and FDG-PET should not be used for 
response assessment in this study. 
Time Point Assessments 
Radiologic tumor evaluation by CT or MRI of chest, abdomen, and pelvis will be performed 
within 28 days before first dose of study drug and every 6 weeks (±1 week) from C1D1 for the 
first 36 weeks on study and every 12 weeks (± 3 weeks) thereafter. 
At baseline, tumors and lymph nodes are classified and documented as target or non-target per 
the definitions provided above. It is possible to record multiple non-target lesions involving the 
same organ as a single item (eg, ‘multiple liver metastases’).  
At all post-baseline evaluations, the baseline classification (target, non-target) is to be maintained 
and lesions are to be documented and described in a consistent fashion over time (eg, recorded in 
the same order on source documents and CRFs). 
For target lesions, measurements should be taken and recorded in metric notation. All tumor 
measurements must be recorded in millimeters. 
At each assessment, a sum of the diameters (longest for non-nodal lesions, short axis for nodal 
lesions) for all target lesions will be calculated and reported. The baseline sum of the longest 
diameters (SLD) will be used as reference to further characterize any objective tumor regression 
in the measurable dimension of the disease. The lowest SLD (nadir) since, and including, the 
baseline value will be used as reference for evaluating progression. 
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After baseline, the actual size of the target lesion should be documented, if possible, even if the 
lesions become very small. If in the opinion of the radiologist, the lesion has likely disappeared, 
0 mm should be recorded. If the lesion is present but too small to measure, an indicator of “too 
small to measure” will be provided on the CRF (a default value of 5 mm will be imputed during 
analysis).  
Non-target lesions are to be assessed qualitatively (present, resolved, or unequivocal 
progression) and new lesions, if any, are to be documented separately. 
At each evaluation, a time point response is to be determined for target lesions, non-target 
lesions, new lesions, and overall. 
Time Point Response Criteria 
Target Lesion Time Point Response (TPR) 
Complete Response (CR) 
Disappearance of all target lesions. All pathological lymph nodes (whether target or 
non-target) must have reduction in short axis to < 10mm.  
Partial Response (PR) 
At least 30% decrease in the sum of diameters (SoD of target lesions, taking as 
reference the baseline SoD 
Progressive Disease (PD) 
At least a 20% increase in the SoD of target lesion, taken as reference the smallest 
(nadir) SoD since and including baseline. In addition to the relative increase of 
20%, the SoD must also demonstrate an absolute increase of at least 5 mm. 
Stable Disease (SD) 
Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for 
PD. 
Not Applicable (N/A) 
No target lesions identified at baseline 
Unable to Evaluate (UE) 
One or more target lesions are not imaged and the remainder of the SoD compared 
with the nadir SoD does not meet the criteria for PD 
If the target lesion for a patient meets the criteria for both PR and PD at a given time point, the target lesion 
response is PD. 
If the nadir SoD is 0 (ie, the patient had a prior target lesion CR), the re-appearance of any prior target lesions to 
any degree constitutes PD. 
Non-Target Lesion TPR 
Complete Response (CR) 
Disappearance of all non-target lesions and normalization of tumor marker level if 
tumor marker at baseline is above the upper limit of normal (ULN). All lymph 
nodes must be non-pathological in size (< 10 mm short axis).  
Non-CR/Non-PD 
Persistence of one or more non-target lesion(s) and/or maintenance of CA-125 
above the normal limits if CA-125 at baseline is above the ULN. 
Progressive Disease (PD) 
Unequivocal progression of non-target lesions. Unequivocal progression should not 
normally trump target lesion status. It must be representative of overall disease 
status change, not a single lesion increase. 
Not Applicable (N/A) 
No non-target lesions identified at baseline. 
Unable to Evaluate (UE) 
One or more non-target lesions are not imaged and the remaining non-target lesions 
do not meet the criteria for PD. 
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If the target lesion for a patient meets the criteria for both PR and PD at a given time point, the target lesion 
response is PD. 
If the nadir SoD is 0 (ie, the patient had a prior target lesion CR), the re-appearance of any prior target lesions to 
any degree constitutes PD. 
New Lesion TPR 
Yes 
Lesion present at follow-up visit either for the very first time or re-appearing (ie, 
lesion was present at baseline, disappeared at a follow-up visit and re-appeared 
later). 
No 
No new lesions present at follow-up 
Unable to Evaluate (UE) 
Patient non assessed or incompletely assessed for new lesion 
Determining Overall TPR 
Target Lesion TPR 
Non-Target TPR 
New Lesions TPR 
Overall TPR 
CR 
CR or NA 
No 
CR* 
CR 
Non-CR/non-PD 
No 
PR* 
CR 
UE 
No 
PR* 
PR 
Non-PD or NA or UE 
No 
PR* 
SD 
Non-PD or NA or UE 
No 
SD 
UE 
Non-PD 
No 
UE 
PD 
Any 
No or Yes or UE 
PD 
Any 
PD 
No or Yes or UE 
PD 
Any 
Any 
Yes 
PD 
NA 
CR 
No 
CR* 
NA 
Non-CR/non-PD 
No 
Non-CR/non-PD 
Non-PD 
Non-PD 
UE 
UE 
Any = CR, PR, SD, PD, NA, or UE; CR = complete response; NA = not applicable (no such lesions at 
Screening); PD = progressive disease; PR = partial response; SD = stable disease; TPR = time point response; UE 
= unable to evaluate. 
The overall response at a given time point does not depend upon the overall response assigned at any prior time 
point. 
*Patients with an overall response of CR or PR must have a repeat tumor assessment performed no less than 4 
weeks after the criteria for response are first met. 
Confirmation - The main goal of confirmation of objective response is to avoid overestimating 
the observed response rate. For patients with an overall response of PR or CR a given time point, 
changes in tumor measurements must be confirmed by repeat assessments that should be 
performed no less than 4 weeks after the criteria for response are first met. However, the 
presence or absence of confirmation is not considered when assigning a time point response. 
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Best Overall Response - Best overall response, incorporating confirmation requirements, will be 
derived during statistical analysis from the series of time point responses and need not be 
considered when assigning response at any time point. 
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APPENDIX C. GYNECOLOGIC CANCER INTERGROUP CRITERIA 
FOR EVALUATION OF CA-125 
(Rustin 2004) 
On the basis of the available data and extensive discussions among the cooperative groups within 
the GCIG, it is recommended that the following definition of response be used in ovarian cancer 
trials so that response can be measured by either RECIST or CA-125 criteria. If the response is 
evaluable by both criteria, then the date of response will be the date of the earlier of the 2 events. 
Definition of response: 
• ≥ 50% reduction in CA-125 levels from baseline 
• the response must be confirmed and maintained for at least 28 days 
• the pretreatment sample must be ≥ 2.0 times the ULN and within 2 weeks before 
starting treatment 
• the date of response corresponds to the date when the CA-125 level is first reduced by 
50%  
To calculate CA-125 responses accurately, the following rules apply:  
• Intervening samples and the 28-day confirmatory sample must be less than or equal to 
(within an assay variability of 10%) the previous sample 
• Variations within the normal range of CA-125 levels will not interfere with the 
response definition.  
Evaluation of Progression 
Progression or Recurrence based on serum CA-125 levels will be defined on the basis of a 
progressive serial elevation of serum CA-125, according to the following criteria:  
a. Patients with elevated CA-125 pretreatment and normalization of CA-125 must show 
evidence of CA-125 greater than, or equal to, 2 times the ULN on 2 occasions at least 
1 week apart, or  
b. Patients with elevated CA-125 pretreatment, which never normalizes must show 
evidence of CA-125 greater than, or equal to, 2 times the nadir value on 2 occasions 
at least 1 week apart, or  
c. Patients with CA-125 in the normal range pretreatment must show evidence of 
CA-125 greater than, or equal to, 2 times the ULN on 2 occasions at least 1 week 
apart.  
Elevated values must be confirmed by 2 separate measurements obtained at least 1 week apart. 
CA-125 progression will be assigned the date of the first measurement that meets the criteria as 
noted. Patients are not evaluable by CA-125 if they have received mouse antibodies (unless the 
assay used has been shown not to be influenced by HAMA [Taylor 2005 and Rustin 2005]) or if 
there has been medical and/or surgical interference with their peritoneum or pleura during the 
previous 28 days.  
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A patient may be declared to have progressive disease on the basis of either the objective 
RECIST criteria or the CA-125 criteria. The date of progression will be the date of the earlier of 
the 2 events if both are documented. 
Definition of progression after first-line therapy in ovarian cancer as proposed by the 
GCIG  
GCIG 
subcategorized 
group 
RECIST Measurable/non-measurable 
disease 
 
CA-125 
A 
Compared to baseline (or lowest sum 
while on study if less than baseline), a 
20% increase in sum of longest diameters 
(RECIST definition) 
or 
Any new lesions (measurable or non-
measurable) 
Date PD: date of documentation of 
increase or new lesions 
A
N
D 
/ 
O
R 
CA-125 ≥ 2 x ULN 
documented on 2 
occasions # 
Date of PD: first date of 
the CA-125 elevation to  
≥ 2x nadir value 
 
B 
As for A 
CA-125 ≥ 2 x nadir value 
on 2 occasions # 
Date of PD: first date of 
the CA-125 elevation to  
≥ 2x nadir value 
B 
As for A 
As for A 
GCIG groups A, B & C defined above.  
# Repeat CA-125 any time, but normally not less than 1 week after the first elevated CA-125 level. CA-125 levels 
sampled after patients received mouse antibodies (unless the assay used has been shown not to be influenced by 
HAMAa,b) or if there has been medical and/or surgical interference with their peritoneum or pleura during the 
previous 28 days, should not be taken into account. 
a Taylor PT, Haverstick D. J Natl Cancer Inst 2005, 97:151, Re: new guidelines to evaluate the response to 
treatment in solid tumors [ovarian cancer].  
b Rustin GJS. J Natl Cancer Inst 2005, 97:152, Re: new guidelines to evaluate the response to treatment in solid 
tumors [ovarian cancer]. 
 
Timing of CA-125 assessments: 
The GCIG recommends that CA-125 measurements be taken at specific time intervals.  
• The first sample would be collected within 2 weeks before treatment is started 
• CA-125 assessments will be performed as indicated in Table 2.  
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• For each patient, the same assay method must be used and the assay must be tested in 
a quality-control scheme. Patients are not evaluable by CA-125 if they have received 
mouse antibodies or if there has been medical and/or surgical interference with their 
peritoneum or pleura during the previous 28 days.  
This CA-125 response definition has been produced to evaluate relapse therapy. If assessing 
therapy that includes 2 treatment modalities for relapse (eg, surgery and chemotherapy), any 
CA-125 response results from both treatments. CA-125 cannot distinguish between the effects of 
each treatment. To calculate response rates in protocols, an ITT analysis should be used that 
includes all patients with an initial CA-125 level of at least twice the ULN as eligible and 
evaluable. In addition to calculating response rates in protocols, it is advisable to record those 
patients who have both a CA-125 response and whose CA-125 level falls to within the normal 
range.  
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APPENDIX D. ADJUSTED IDEAL BODY WEIGHT CALCULATION 
 
Adjusted Ideal Body Weight (AIBW) 
AIBW = IBW1 + 0.4 (Actual weight – IBW1) 
 
Ideal Body Weight (IBW) 
IBW1 (female) = 0.9H1-92 
 
(1H=height in cm; W=weight in kg) 
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SUMMARY OF CHANGES: 
A summary of the rationale for the changes within this protocol is provided in the table below, with reference to the pertinent sections. 
None of the proposed changes is believed to pose an increased risk to study patients. 
The primary reasons for this protocol amendment were as follows: 
• To clarify the translational and exploratory components of the protocol 
• To incorporate the newly determined name of the protocol 
• To update the ocular exam requirements for assessment 
The following sections have been modified as noted below: 
Description of Change 
Rationale 
Sections Affected 
The study title of IMGN853-0419 was revised to 
include the name PICCOLO. 
Naming of clinical trials improves 
communication across the globe. 
Title Page 
Protocol Synopsis (Title of Study) 
Protocol versions were updated to include 
Amendment 1. 
Revisions were made to clarify versioning. 
Title Page 
Headers 
Sponsor contact information was updated. 
Contact information updated to remain current 
and accurate. 
Title Page 
Sponsor Contact List 
Exploratory objectives and endpoints were 
updated to add gene mutation(s) in the correlation 
of homologous recombination status with tumor 
FRα levels and soluble FRα levels in blood. 
To allow exploratory analyses to determine 
soluble and tumor FRα correlations with MIRV 
safety and efficacy and to correlate tumor and 
soluble FRα levels with patient subsets 
(specifically homologous recombination 
deficiency status). 
Protocol Synopsis (Objectives and 
Endpoints) 
Section 2.1.4. 
Section 2.2.4. 
Section 6.3.3. 
Section 7.4. 
Prior anticancer therapy inclusion criteria were 
updated. 
Criteria were updated to reflect current 
treatment standards. 
Protocol Synopsis (Inclusion criteria) 
Section 3.1.1. 
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Description of Change 
Rationale 
Sections Affected 
Folate supplements added to prohibited 
concomitant medications mention within protocol 
synopsis. 
Concomitant medications updated for 
consistency with Section 5.8.3. 
Protocol Synopsis (Prohibited 
Concomitant Medications) 
Schedule of assessments was modified to include 
the following changes: 1) C1D8 and C3D8 
columns removed, 2) assessment collections 
added to C3/C5D1, 3) blood sample for 
biomarkers collection added to C2D1 and 
Survival follow-up with detailed footnote “i” 
added to provide more context to timing, 4) 
details for FRα sample requirements added to 
footnote “d,” 5) indirect fundoscopy removed as 
part of ophthalmologic examination, and 6) 
immunogenicity assessment collection timepoint 
revised. 
1) C1D8 and C3D8 were removed because 
there are no procedures performed on 
these days. 
2) FRα draw at C3D1 was added to the 
Schedule of Assessments. The FRα blood 
sample at C3D1 is different than C2D1+, 
which is why an additional visit in the 
schedule of assessments was created. 
3) Additional blood sample for biomarkers 
was added to Survival Follow-Up phase, 
and timing clarification was provided. 
4) Further detail on how tumor samples must 
be submitted to the analytical laboratory 
was provided. 
5) Indirect fundoscopy was removed due to 
absence of toxicity associated with 
treatment in past trials. 
6) Timepoint was updated for accuracy. 
Schedule of Assessments (Table 2) 
Section 6.1. 
Section 6.2. 
Section 7.9.2. 
Details for FRα sample requirements were added 
to specify options of archival tissue blocks or 
fresh cut slides from an available block. 
Language was modified to improve sample 
collection flexibility. 
Schedule of Assessments (Table 2) 
Section 6.2. 
Section 7.1. 
Section 7.4. 
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Description of Change 
Rationale 
Sections Affected 
Blood draw requirements for patients 
experiencing Grade 2+ IRRs post administration 
of MIRV were removed. 
IRRs are not common in prior IMGN853 
studies, ADA development is uncommon and 
not linked to either sensitivity or efficacy, and 
limited conclusions can be derived based on 
the results from the blood draws. Removing 2 
blood draws also reduces the burden on a 
patient who just experienced an IRR. 
Section 5.5.5. 
Blood biomarker language was updated to 
provide a deeper rationale as well as added 
content to specify that remaining sera will be 
preserved for future analysis of additional 
biomarkers. 
Clarification on rationale for increase blood 
biomarker sampling. 
Section 6.3.1. 
Indirect fundoscopy was removed as part of 
ophthalmologic examination. 
Indirect fundoscopy was removed due to the 
absence of toxicity associated with treatment in 
past trials. 
Schedule of Assessments (Table 2) 
Section 7.9.2. 
Pre-screening ICF uses were expanded to include 
multiple timepoints of soluble FRα levels and 
other FRα testing. 
Text was revised to ensure that patients 
understand that these blood draws will be used 
to support translational and exploratory 
endpoints. 
Section 12.1.2. 
“Remote” inspection and review option was 
added for audits and inspections. 
The option was added to increase flexibility 
and accurately depict the nature of these 
inspections. 
Section 12.12. 
Allowed window of time to update the financial 
disclosure form was expanded to include 1 year 
after study completion. 
Text was revised for clarity and consistency 
purposes. 
Section 12.15. 
Abbreviations: ADA = antidrug antibody; C = cycle; D = day; FRα = folate receptor alpha; ICF = informed consent form; IRR = infusion-related reaction; 
MIRV = mirvetuximab soravtansine. 
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