Study of Imprime PGG and Pembrolizumab in Advanced Melanoma and Triple Negative Breast Cancer

Study Overview
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Brief Summary
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Objective: To determine the Overall Response Rate (ORR) to Imprime PGG + pembrolizumab in subjects with advanced melanoma or metastatic TNBC Safety: To characterize the safety of Imprime PGG + pembrolizumab given in combination Hypothesis: Restore (for melanoma) or enhance (for TNBC) sensitivity to checkpoint inhibitors (CPI) by appropriate and effective stimulation of the subject's innate and adaptive immune systems in those subjects who have failed 1st line therapy The study will incorporate Simon's optimal 2-stage design with sample size fixed at 12 subjects each in Stage 1 for advanced melanoma and for Triple Negative Breast Cancer (TNBC) subjects. The safety criterion of ≤ 4 (or ≤ 33%) subjects with Grade 3/4 adverse events in Cycle 1 within either tumor type must be met in order to proceed to Stage 2. The starting dose is 4 mg/kg for Imprime PGG. In the event there are a total of > 4 (or > 33%) of subjects with Grade 3/4 adverse events in Cycle 1, the dose of Imprime PGG will be reduced to 2 mg/kg, and Stage 1 will be repeated at a dose of 2 mg/kg with an additional cohort of n=12 subjects. For the dose that meets the safety criterion in Stage 1, at least 1 response in melanoma subjects and 2 responses in TNBC subjects amongst the 12 subjects within each tumor type must be observed in order to proceed to Stage 2. Stage 2 will enroll an additional 17 subjects with melanoma, and 30 subjects with TNBC. For the dose that meets the Stage 1 safety criterion, success will be declared if at least 4 amongst the total of up to 29 subjects with melanoma, and 13 amongst the total of up to 42 subjects with TNBC achieve an objective response.

Official Title
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A Multicenter, Open-label, Phase 2 Study of Imprime PGG and Pembrolizumab in Subjects With Advanced Melanoma Failing Front-line Treatment With Checkpoint Inhibitors (CPI) or TNBC Failing Front-line Chemotherapy for Metastatic Disease

Conditions
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Advanced Melanoma, Triple-Negative Breast Cancer

Intervention / Treatment
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* Biological: Imprime PGG
* Drug: Pembrolizumab


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Have signed an informed document prior to any study-specific procedures or treatment Be ≥ 18 years of age at time of consent For Melanoma Subjects: Have histologically or cytologically confirmed diagnosis of unresectable Stage III or metastatic (Stage IV) melanoma not amenable to local therapy, and irrespective of PD-L1 status For TNBC Subjects: Have histologically or cytologically confirmed diagnosis of metastatic (Stage IV) TNBC, and irrespective of PD-L1 status. TNBC is defined as negative immunohistochemistry (IHC) assays for Estrogen Receptor (ER), and Progesterone Receptor (PR), and HER2 negative (IHC 0 or 1+, or 2+ by IHC confirmed negative by FISH) Have documented objective radiographic or clinical disease progression after PD-1/PD-L1 +/- anti-CTLA-4 inhibitor therapy (melanoma) or after at least 1 line of chemotherapy for metastatic disease (TNBC) Have resolution of all previous treatment-related toxicities to Grade 1 severity or lower, except for stable sensory neuropathy (less than or equal to Grade 2) or alopecia. If subject received major surgery or radiation therapy of > 30 Gy, must have recovered from the toxicity and/or complications from the intervention. Have at least one radiologically measurable lesion as per RECIST v1.1 defined as a lesion that is at least 10 mm in longest diameter or lymph node that is at least 15 mm in short axis imaged by CT scan or MRI and obtained by imaging within 28 days prior to start of study treatment. Tumor lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions. Have peripheral blood levels of IgG anti-β-glucan antibody (ABA) of ≥ 20 mcg/mL as determined by an ELISA test within 28 days prior to start of study treatment Be willing to consider providing fresh tissue for biomarker analysis, and, based on the adequacy of the tissue sample quality, for assessment of biomarker status. Repeat samples may be required if adequate tissue is not provided. Newly obtained biopsy specimens are preferred to archived samples and formalin-fixed, paraffin-embedded block specimens are preferred to slides. Note: Information on 1 tumor biopsy sample is mandatory and is as follows: (1) To determine eligibility, historical (diagnostic) tumor biopsy official pathology report +/- an archival sample. Additional biopsy samples, preferably obtained from the same localized region, are highly desirable when feasible at the following time points: (2) Sample before the first dose of study treatment, (3) Sample after completion of Cycle 2 but before the start of Cycle 3 dosing, and (4) Sample either at the time of response or at the End of Study Visit (if no response). Have Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 (see Appendix 14.3) Have life expectancy of 3 months or greater as determined by the treating physician Have adequate organ function (all screening labs should be performed within 15 days prior to treatment initiation): Total bilirubin ≤ 1.5 × upper limit of normal (ULN) OR direct bilirubin ≤ ULN for subjects with total bilirubin levels > 1.5 x ULN Aspartate aminotransferase (AST) ≤ 2.5 × ULN or ≤ 5 × ULN for subjects with known hepatic metastases Alanine aminotransferase (ALT) ≤ 2.5 × ULN or ≤ 5 × ULN for subjects with known hepatic metastases Have adequate renal function as defined by the following criteria: Creatinine ≤ 1.5 x ULN and CrCl ≥ 30 ml/min per Cockcroft Gault formula: Have adequate hematologic function, defined as meeting all of the following criteria: Hemoglobin ≥ 9 g/dL (uncorrected by RBC transfusion) Absolute neutrophil count (ANC) ≥ 1.5 × 109/L Platelet count ≥ 100 × 109/L Have adequate coagulation functioning within 15 days prior to start of study treatment, defined by either of the following criteria: INR < 1.5 × ULN OR for subjects receiving warfarin or low molecular weight heparin (LMWH), the subjects must, in the Investigator's opinion, be clinically stable with no evidence of active bleeding while receiving anticoagulant therapy. The INR for these subjects may exceed 1.5 × ULN if that is the goal of anticoagulant therapy. Activated Partial Thromboplastin Time (aPTT) < 1.5 × ULN unless subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants Female subjects of childbearing potential as defined in Section 5.7.2 must have a negative urine or serum pregnancy within 72 hours prior to receiving the first dose of study medication. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required. If of childbearing potential as defined in Section 5.7.2, must be willing to use an adequate method of contraception (see Section 5.7.2) from the first dose of study medication through 120 days after the last dose of study medication Be willing and have the ability to comply with scheduled visits (including geographical proximity), treatment plans, laboratory tests, and other study procedures Exclusion Criteria: Has disease that is suitable for local therapy administered with curative intent Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks of the first dose of treatment Has a diagnosis of immunodeficiency or receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of study treatment. The use of physiologic doses of corticosteroids may be approved after consultation with the Sponsor. Has known history of active tuberculosis Has known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies) Has known active Hepatitis B (eg, HBsAg reactive) or Hepatitis C (eg, HCV RNA [qualitative] is detected Has a history of clinically severe autoimmune disease, or history of organ transplant Has a history of ocular melanoma Has known hypersensitivity to baker's yeast Had previous exposure to Betafectin® or Imprime PGG Has hypersensitivity to pembrolizumab or any of its excipients Had a prior anti-cancer monoclonal antibody (except immune CPI in the case of melanoma subjects) within 30 days prior to start of study treatment, or failure to recover to CTCAE Grade 1 or better from the adverse events of prior therapies Had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to Study Day 1 or who has not recovered from adverse events due to a previously administered agent or major surgery Has received transfusion of blood products (including platelets or red blood cells) or administration of colony stimulating factors (including G-CSF, GM-CSF, or recombinant erythropoietin) within 4 weeks prior to Study Day 1 Has known additional malignancy that is progressing or requires active treatment. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer. Has known active central nervous system metastases and/or carcinomatous meningitis. Subjects with previously treated brain metastases may participate provided they are stable (without evidence of progression by imaging for at least 4 weeks prior to the first dose of trial treatment and any neurologic symptoms have returned to baseline), have no evidence of new or enlarging brain metastases, and are not using steroids for at least 7 days prior to trial treatment. This exception does not include carcinomatous meningitis, which is excluded regardless of clinical stability. Has active autoimmune disease requiring systemic treatment in the past 2 years (ie, with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (eg, thyroxine, insulin, or physiologic corticosteriod replacement therapy for adrenal or pituitary insufficiency) is not considered a form of systemic treatment. Has evidence of (non-infectious) pneumonitis that required steroids or current pneumonitis Has a history of interstitial lung disease Has an active infection requiring systemic therapy Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject's participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating Investigator Has a clinically significant cardiovascular disease such as unstable angina, myocardial infarction, or acute coronary syndrome within ≤180 days prior to start of study treatment, symptomatic or uncontrolled arrhythmia, congestive heart failure, or any Class 3 or 4 cardiac disease as defined by the New York Heart Association Functional Classification Has a known psychiatric or substance abuse disorder(s) that would interfere with informed consent or cooperation with the requirements of the trial Is pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the pre-screening or screening visit through 120 days after the last dose of trial treatment With TNBC has received prior therapy with an anti-PD-1, anti-PD-L1, anti-CTLA-4, or anti-PD-L2 agent Has received a live-virus vaccination within 30 days of planned treatment start. Seasonal flu vaccines that do not contain live virus are permitted

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Melanoma<br>Imprime PGG + Pembrolizumab | Biological: Imprime PGG<br>* Imprime PGG is a soluble, β-1,3/1,6 glucan isolated from the cell wall of a proprietary Saccharomyces cerevisiae yeast strain. Imprime PGG acts as a Pathogen-Associated Molecular Pattern (PAMP). Imprime will be administered at a dose of 4 mg/kg IV over a 2-hour infusion time on Days 1, 8 and 15 of each 3-week treatment cycle.<br>* Other names: Imprime;Drug: Pembrolizumab<br>* Pembrolizumab is a humanized monoclonal antibody against the programmed death receptor-1 protein. Pembrolizumab will be given at a fixed dose of 200 mg IV over 30 minutes on Day 1 of each 3-week treatment cycle after the Imprime infusion.<br>* Other names: Keytruda;|
| Experimental: Triple Negative Breast Cancer<br>Imprime PGG + Pembrolizumab | Biological: Imprime PGG<br>* Imprime PGG is a soluble, β-1,3/1,6 glucan isolated from the cell wall of a proprietary Saccharomyces cerevisiae yeast strain. Imprime PGG acts as a Pathogen-Associated Molecular Pattern (PAMP). Imprime will be administered at a dose of 4 mg/kg IV over a 2-hour infusion time on Days 1, 8 and 15 of each 3-week treatment cycle.<br>* Other names: Imprime;Drug: Pembrolizumab<br>* Pembrolizumab is a humanized monoclonal antibody against the programmed death receptor-1 protein. Pembrolizumab will be given at a fixed dose of 200 mg IV over 30 minutes on Day 1 of each 3-week treatment cycle after the Imprime infusion.<br>* Other names: Keytruda;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall Response Rate (ORR) to Imprime PGG + pembrolizumab using RECIST v1.1 criteria |  | Within 18 months of last patient enrolled | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to response (TTR) using RECIST v1.1 criteria |  | Within 24 months of last patient enrolled | 
| Complete response rate (CRR) using RECIST v1.1 criteria |  | Within 24 months of last patient enrolled | 
| Duration of overall response (DoR) using RECIST v1.1 criteria |  | Within 24 months of last patient enrolled | 
| Progression-Free Survival (PFS) and PFS rate at 6 months and 1 year using RECIST v1.1 criteria |  | Within 24 months of last patient enrolled | 
| Overall survival (OS) and OS rate at 1 year using RECIST v1.1 criteria |  | Within 24 months of last patient enrolled | 
| Pharmacokinetic (PK) data of Imprime PGG in combination with Pembrolizumab | Correlate serum Imprime PGG concentration/time relationship | Within 24 months of last patient enrolled |