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ClinicalTrials.gov ID: NCT03502330 Title: APX005M With Nivolumab and Cabiralizumab in Advanced Melanoma, Non-small Cell Lung Cancer or Renal Cell Carcinoma Document Type: Protocol and SAP
Date: 3/21/2022 A Phase I/Ib Study of APX005M in Combination with Nivolumab and Cabiralizumab in Patients with Advanced Melanoma, Non-small Cell Lung Cancer or Renal Cell Carcinoma Whose Disease Has Progressed on Anti-PD1/PD-L1 **Therapy**
BMS Protocol Number:
CA025-007  
| Institutional Protocol Number   | HIC #2000021757                                                            |
|---------------------------------|----------------------------------------------------------------------------|
| Investigational Products:       | APX005M, Cabiralizumab (FPA008), and Nivolumab                             |
| IND Number:                     | 139038                                                                     |
| Development Phase:              | Phase 1/1b                                                                 |
| Indications Studied:            | Melanoma, NSCLC, RCC                                                       |
| Protocol Version:               | 10                                                                         |
| Date of Protocol:               | 21 Mar-2022                                                                |
| Sponsor:                        | Yale Cancer Center                                                         |
| Industry Collaborators:         | Bristol-Myers Squibb, Apexigen, Inc.                                       |
| Principal Investigator:         | Harriet Kluger, MD Yale Cancer Center harriet.kluger@yale.edu 203-737-2572 |
| Co-Principal Investigators      | Scott Gettinger, MD                                                        |
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confidentiality statement

The information contained in this document is confidential and the proprietary property of Bristol-Myers Squibb and Apexigen. Any unauthorized use or disclosure of such information without the prior written authorization of Bristol-Myers Squibb and Apexigen is prohibited.
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study synopsis

| Title:                                 | A Phase 1/1b Study of APX005M in Combination with Nivolumab and Cabiralizumab in Patients with Advanced Melanoma, Non-small Cell Lung Cancer or Renal Cell Carcinoma Whose Disease Has Progressed on Anti-PD1/PD-L1 Therapy                                                                                                                                                                                                                                                                                                                                           |
|----------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Protocol Number:                       | CA025-007                                                                                                                                                                                                                                                                                                                                 |
| Clinical Phase:                        | 1/1b                                                                                                                                                                                                                                                                                                                                      |
| Sponsor:                               | Yale Cancer Center                                                                                                                                                                                                                                                                                                                        |
| Industry Collaborators:                | Bristol-Myers Squibb, Apexigen, Inc.                                                                                                                                                                                                                                                                                                      |
| Study Center:                          | Yale Cancer Center                                                                                                                                                                                                                                                                                                                        |
| Background:                            | New combinatorial therapeutic strategies are needed to overcome resistance to immune checkpoint inhibitors in a number of malignancies. We hypothesize that manipulation of the innate immune system by targeting macrophage activity will assist in reversing local immune suppression and overcome resistance to PD-1/PD-L1 inhibition. |
| Objectives: Phase 1 Objectives Primary | - To assess the safety and tolerability of APX005M in combination with cabiralizumab - To assess the safety and tolerability of APX005M in combination with cabiralizumab and nivolumab - To determine the recommended phase 2 dose (RP2D) of APX005M in combination with a fixed dose of cabiralizumab and nivolumab                     |
| Secondary                              | - To determine the adverse event (AE) profile of this combination                                                                                                                                                                                                                                                                         |
| Exploratory                            | - To characterize the pharmacokinetic (PK) profile of APX005M when administered in combination with cabiralizumab and nivolumab - To characterize the pharmacodynamic (PD) profile of APX005M when administered in combination with cabiralizumab and nivolumab - To further characterize the PD profile and immunogenicity of APX005M in combination with cabiralizumab and nivolumab by analyses of pretreatment and on-treatment tumor biopsies and blood collection                                                                                                                                                                                                                                                                                                                                           |  
Phase 1b Objectives  
| CA025-007       | Version 10                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | 21 Mar -2022   |
|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
| Primary         | - Determine the objective response rate (ORR) using RECIST v1.1 to APX005M in combination with cabiralizumab and nivolumab in patients with advanced melanoma, non-small cell lung cancer (NSCLC), and renal cell carcinoma (RCC) whose tumors are resistant to anti-PD-1/PD-L1 therapy - Evaluate the safety and tolerability of the RP2D of APX005M in combination with cabiralizumab and nivolumab                                                                                                                                                |                |
| Secondary       | - To determine the progression-free survival (PFS) of patients with melanoma, NSCLC or RCC treated with APX005M in combination with cabiralizumab and nivolumab whose tumors are resistant to anti-PD-1/PDL1 therapy. - To determine the overall survival (OS) of patients with melanoma, NSCLC or RCC treated with APX005M in combination with cabiralizumab and  nivolumab whose tumors are resistant to anti-PD-1/PD-L1 therapy. - To assess the association of selected biomarker measures and clinical efficacy measures using pre-treatment and on-treatment tumor biopsies                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                |
| Exploratory     | - To identify immune correlates that are associated with clinical response or resistance to the triple combination. Biomarker analyses will include study of pre-treatment and on-treatment biopsies as well as analyses of select serum and PBMC markers.                                                                                                                                                                                                                                                                                           |                |
| Investigational | - APX005M Solution for Intravenous Infusion                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                |
| Products        | - Cabiralizumab Solution for Intravenous Infusion - Nivolumab Solution for Intravenous Infusion This trial is a phase 1/1b study to evaluate the safety, efficacy, and tolerability                                                                                                                                                                                                                                                                                                                                                                  |                |
| Study Design    | of APX005M in combination with nivolumab and cabiralizumab. The phase 1  dose escalation portion will enroll patients with advanced solid tumors (melanoma, NSCLC, and RCC) to determine the RP2D of APX005M. The phase 1b dose expansion portion will study the triple drug combination in three disease cohorts. APX005M is a humanized IgG1 agonistic monoclonal antibody that binds CD40. Nivolumab is a humanized IgG4 monoclonal antibody directed against PD-1. Cabiralizumab is a humanized IgG4 monoclonal antibody directed against CSF1R. |                |  
Phase 1: Dose Escalation Patients with advanced solid tumors will be sequentially enrolled in 6 cohorts using a standard 3 + 3 dose escalation design to determine safety, characterize the AEs, and establish the RP2D of APX005M in combination with nivolumab and cabiralizumab. A minimum of 48 hours observation will be required after each patient is enrolled in cohorts 1-6, before a subsequent patient can be enrolled. Approximately 3 patients will be enrolled per cohort. Cohorts 1, 3, and 5 will include cabiralizumab at 4 mg/kg and dose escalation of APX005M.  
Cohorts 2, 4, and 6 will include nivolumab at 240 mg, cabiralizumab at 4 mg/kg, and dose escalation of APX005M. Each cycle will be 14 days with anticipated dosing as follows:  
| Phase 1 Dose Escalation Cohorts Cohort Nivolumab   | Cabiralizumab   | APX005M   |      |
|----------------------------------------------------|-----------------|-----------|------|
| (mg)                                               | (mg/kg)         | (mg/kg)   |      |
| 1                                                  | Not given       | 4         | 0.03 |
| 2                                                  | 240             | 4         | 0.03 |
| 3                                                  | Not given       | 4         | 0.1  |
| 4                                                  | 240             | 4         | 0.1  |
| 5                                                  | Not given       | 4         | 0.3  |
| 6                                                  | 240             | 4         | 0.3  |  
If none of the first 3 evaluable patients in a dose cohort experience a doselimiting toxicity (DLT) in the first two cycles, then the next 3 patients will be treated at the next higher dose cohort. If 1 of 3 patients within a cohort experiences a DLT in the first two cycles, then 3 additional patients will be added to that cohort. If a second patient experiences a DLT at that dose level in the first two cycles, the next cohort will not be initiated, and the dose of one or more drugs will be de-escalated. Patients at each dose level will be evaluated for at least 4 weeks from the start of treatment before additional patients can be treated at a higher dose level. If DLTs are observed in 2 or more patients within a cohort, the maximum tolerated dose (MTD) will have been exceeded and no further patients will be treated at that dose level. At 8 weeks, imaging studies will be performed to assess for response. Of note, 2 sets of cohorts will be conducted simultaneously: Cohorts 2 and 3, and Cohorts 4 and 5, as depicted below.  
  
Dose escalation will be based on the number of DLTs experienced during the DLT evaluation interval as determined by dose escalation meetings attended by the PIs and Industry Collaborators (see Section 3.1.2.1.1 for DLT criteria).  
The DLT evaluation interval begins on the first day of treatment and continues for 28 days.  
| Number of Patients with DLT at a Given Dose Level   | Dose Escalation Decision Rule                                                                          |
|-----------------------------------------------------|--------------------------------------------------------------------------------------------------------|
| 0/3                                                 | Escalation will occur into the next highest dose cohort                                                |
| 1/3                                                 | Enroll 3 additional patients at current dose level Stop enrolment. Enroll 3 more patients at the lower |
| >2/3                                                | dose level, if only 3 were previously entered, or at an intermediate dose level.                       |
| 1/6                                                 | Open next cohort                                                                                       |
| >2/6                                                | Stop enrolment. Enter 3 more patients at the lower dose level or at an intermediate dose level.        |  
Phase 1b Study Once a specific dose regimen is determined to be safe as determined by the Sponsors and Industry Collaborators, the phase 1b portion will follow and will enroll additional patients in three disease-specific cohorts, all of whom who have progressed on prior PD-1/PD-L1 therapy: advanced melanoma, NSCLC,
and RCC who have progressed on prior PD-1/PD-L1 therapy. Patients will be treated at the estimated APX005M RP2D in combination with nivolumab 240 mg IV and cabiralizumab 4 mg/kg on day 1 of each 14-day cycle.  
Number **of Patients** In the Phase 1 dose escalation portion, at least 3 patients with advanced solid tumors will be enrolled per cohort using a standard 3+3 design. There are a total of 6 cohorts. In the Phase 1b portion, a Simon's two-stage design will be used to study 3 disease cohorts: advanced melanoma, NSCLC, and RCC. The null hypothesis that the true response rate is 10% will be tested against a onesided alternative. In the first stage, 13 patients in each disease cohort will be accrued. If there are 1 or fewer responses in these 13 patients, the enrollement in that disease cohort will be stopped. Otherwise, 21 additional patients will be accrued for a total of 34 patients per disease cohort. The null hypothesis will be rejected if 6 or more responses are observed in 34 patients. This design yield a type I error rate of 0.1 and a power of 80% when the true response rate is 25%.
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study population

The phase 1 dose escalation portion will include patients with advanced melanoma, NSCLC, and RCC with the same criteria as listed below for the phase 1b portion.
The Phase 1b dose expansion portion of the trial studying APX005M at the RP2D in combination with cabiralizumab and nivolumab will consist of three solid tumor cohorts. All patients in all tumor types are required to have progressed while on anti-PD(L)-1 therapy without any intervening therapy.  
Additional descriptions are below:
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melanoma

- Unresectable stage III or stage IV melanoma, irrespective of *BRAF*
status, with histologic or cytologic confirmation RCC:
- Histologic or cytologically documented, locally advanced unresectable or metastatic RCC irrespective of histologic subtype  
NSCLC:
- Histologic or cytologically documented, locally advanced or metastatic (i.e. Stage IIIB not eligible for definitive chemoradiotherapy, stage IV, or recurrent) NSCLC.  
- Patients known to harbor an ALK rearrangement or EGFR mutation known to be sensitive to FDA-approved tyrosine kinase inhibitors (TKI), are only eligible after experiencing disease progression (during or after treatment) or intolerance to an FDA approved ALK TKI or EGFR TKI, respectively.  
- Patients with TKI-treated EGFR mutant NSCLC harboring the secondary EGFR T790M tumor must have received prior osimertinib.  
- Patients with crizotinib-treated ALK rearranged NSCLC must have received a next generation ALK inhibitor.
Inclusion Criteria  
1. Biopsy proven metastatic melanoma, NSCLC or RCC whose disease has progressed on a prior regimen containing a PD-1 or PD-L1 inhibitor, without intervening therapy. Progression will be determined by the investigator based on clinical and/or radiographic features.  
2. At least 1 site of disease must be accessible to provide repeat biopsies for tumor tissue. This site may be a target lesion as long as it will not be made unmeasurable by the biopsy procedure 3. Age ≥18, able to understand and sign the informed consent form 4. ECOG performance status < 2 5. Any number of previous treatments. Other prior systemic therapies must have been administered at least 4 weeks before administration of the study drugs; the exception to this is small molecule inhibitors, which must be
stopped at least 2 weeks or after five half-lives of the drug, whichever is shorter, prior to the start of the study drugs.  
6. Life expectancy of at least 6 months 7. A history of previously treated brain metastases is allowed, provided that they are stable for at least 4 weeks.  
8. Willingness to undergo mandatory tumor biopsy prior to initiation of therapy and before the fifth cycle.  
9. Willingnessto provide an archivalspecimen block, if available, for research.  
10. Patients must have normal organ and marrow function (as outlined in Section 3.2.2)
11. Female subject of childbearing potential should have a negative urine or serum pregnancy within 24 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.  
12. Female subjects of childbearing potential should be willing to use a highly effective contraception (hormonal or IUD) or be surgically sterile, or abstain from heterosexual activity for a period of at least 5 months after the last dose of study drug. Subjects of childbearing potential are those who have not been surgically sterilized or have not been free from menses for > 1 year.  
13. Male subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through at least 7 months after the last dose of study drug.  
14. Patients must have at least one measurable lesion at baseline by computed tomography (CT) or magnetic resonance imaging (MRI) as per RECIST v1.1 criteria.  
a. Tumor sites situated in a previously irradiated area, or in an area subjected to other loco-reginal therapy, are not considered measurable unless there has been demonstrated progression in the lesion.  
15. Prior focal radiotherapy is allowed. Radiation to brain, pulmonary or intestinal sites must be completed at least 4 weeks prior to study Day 1.  
There is no time restriction prior to study Day 1 for patients who have received radiation to bone, soft tissue or other sites. No radiopharmaceuticals (strontium, samarium) within 8 weeks before first dose of study drug administration.  
16. Major surgery must be completed at least 4 weeks prior to the first dose of study drug administration. Surgery requiring local/epidural anesthesia must
be completed at least 72 hours before first dose of study drug administration and patients should have recovered. Wounds must be healed.
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exclusion criteria 1. untreated brain

2. A patient who has had prior immune therapy or chemotherapy, within 4 weeks prior to study Day 1, or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to a previously administered agent will be excluded. The exception is targeted therapy that must have been completed at least 2 weeks or after 5 half-lives, which ever is shorter, prior to study Day 1. Patients who have had prior ipilimumab must have received their last dose no less than 4 weeks prior to study Day 1.  
a. Note: If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.  
b. Note: Toxicity that has not recovered to ≤ Grade 1 is allowed if it meets the inclusion requirements for laboratory parameters.  
3. Has had prior treatment with any other CSF1R inhibitor or CD40 agonist 4. Use of corticosteroids to control immune related adverse events at enrollment will not be allowed, and patients who previously required corticosteroids for symptom control must be off steroids for at least 2 weeks. Low-dose steroid use (≤10 mg of prednisone or equivalent) as corticosteroid replacement therapy for primary or secondary adrenal insufficiency is allowed.  
5. Has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to prior treatments with the exception of clinically insignificant adverse events such as alopecia, clinically insignificant laboratory abnormalities, clinically insignificant rash and Grade 2 neuropathy.  
6. History of grade 3-4 neurologic or cardiac toxicity or life-threatening liver toxicity poorly responsive to steroids with prior anti-PD-1/anti-PDL1 monotherapy.  
7. Presence of leptomeningeal disease.  
8. Has active autoimmune disease unrelated to use of immune checkpoint inhibitors that has required systemic treatment in the past year (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs).  
Replacement therapy (eg., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.  
9. Pregnancy or breast feeding. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with nivolumab, cabiralizumab or APX005M, breastfeeding must be discontinued if the mother is enrolled on this trial.  
10. Patients may not be receiving any other investigational agents and may not have participated in a study of an investigational agent or using an investigational device within 4 weeks of the first dose of treatment.  
11. Either a concurrent condition (including medical illness, such as active infection requiring treatment with intravenous antibiotics or the presence of laboratory abnormalities) or history of a prior condition that places the patient at unacceptable risk if he/she were treated with the study drug or a medical condition that confounds the ability to interpret data from the study.  
12. Concurrent, active malignancies in addition to those being studied.  
13. Active (non-infectious) pneumonitis.
14. Has a known Human Immunodeficiency Virus (HIV), Hepatitis B (HBV),
or Hepatitis C (HCV) acute or chronic infection.  
15. Has received a live vaccine within 30 days prior to the first dose of trial treatment.  
16. History of myocardial infarction or unstable angina within 3 months prior to Cycle 1, Day 1.
17. Prisoners, or subjects who are under compulsory detention  
18. Current or history of clinically significant muscle disorders (e.g., myositis),
recent unresolved muscle injury, or any condition known to elevate serum CK levels 19. History of anti-drug antibodies, severe allergic, anaphylactic, or other infusion-related reaction to a previous biologic agent 20. Concomitant use of statins while on study. However, a patient using statins for over 3 months prior to study drug administration and in stable status without CK rise may be permitted to enroll 21. Open wounds and active skin infections 22. Uveal melanoma in the Phase Ib dose expansion trial  
| All medications taken within 28 days before the administration of the first dose of any study drug and all concomitant therapy administered during the study until 100 (±7) days after last dose of any study drug (or use of subsequent anticancer therapy) will be collected. All subsequent anti-cancer therapy will be collected in the Long-Term Follow-up Period. Information on all prior treatments indicated for advanced cancer, including chemotherapy, biochemotherapy, immunotherapy, radiation, surgery, biologic, and experimental therapy will be collected. No concomitant medication information will be collected following patient discontinuation from the study except for concomitant medication use associated with study drug-related AEs or AEs that lead to discontinuation from the study. Patients must discontinue study drugs for any of the following reasons: - Withdrawal of informed consent (patient's decision to withdraw for any reason)   |
|---|  
Withdrawal Criteria  
Patients *must* discontinue study drugs for any of the following reasons:  
- Withdrawal of informed consent (patient's decision to withdraw for any  
reason)  
- Any clinically significant AE, abnormal laboratory test results, or  
intercurrent illness which, in the opinion of the Investigator, indicates that continued participation in the study is not in the best interest of the patient  
- Patients who are required to have prohibited concomitant medications  
- Pregnancy - Termination of the study by the Sponsor - Loss of ability to freely provide consent through imprisonment or  
involuntary incarceration for treatment of a psychiatric or physical (e.g.,  
infectious disease) illness  
- Documented disease progression or clinical deterioration while receiving active study therapy
- Non-compliance by the patient
list of key study personnel
exclusion criteria 1. untreated brain

| Sponsor:                    | Yale Cancer Center                                                               |
|-----------------------------|----------------------------------------------------------------------------------|
| Industry Collaborators:     | Bristol-Myers Squibb, Apexigen, Inc.                                             |
| Principal Investigator:     | Harriet Kluger, MD                                                               |
| Co-Principal Investigators: | Scott Gettinger, MD Anne Chiang, MD                                              |
| Co-Investigators:           | Sarah Goldberg, MD Roy Herbst, MD, PhD  Michael Hurwitz, MD, PhD Mario Sznol, MD |  
Serious Adverse Event **Reporting:** Bristol-Myers Squibb  
| Apexigen, Inc. FDA   |
|----------------------|
list of key study personnel
table of contents

Study Synopsis List of Key Study Personnel Table of Contents  
| List of Abbreviations and Definitions    |                                  |
|------------------------------------------|----------------------------------|
| 1.                                       | Introduction and Study Rationale |
| Introduction .                           |                                  |
| 1.1                                      |                                  |  
1.2 Rationale for Combination of APX005M with nivolumab and cabiralizumab..26 1.3  
| Target Receptor Background .                                                                                                         |                                                                                                                         |
|--------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------|
| 1.3.1                                                                                                                                | Tumor-Associated Macrophages and Colony Stimulating Factor 1 Receptor                                                   |
| ..................................................................................................................................30 |                                                                                                                         |
| 1.3.2                                                                                                                                | Programmed Cell Death-1 (PD-1; CD279).........................................................31                        |
| 1.3.3                                                                                                                                | CD40 .                                                                                                                  |
| 1.3.4                                                                                                                                | Product Development Background .                                                                                        |
| 1.3.4.1                                                                                                                              | Mechanism of Action                                                                                                     |
| 1.3.4.1.1                                                                                                                            | Cabiralizumab .......................................................................................................33 |
| 1.3.4.1.2                                                                                                                            | Nivolumab                                                                                                               |
| APX005M                                                                                                                              |                                                                                                                         |
| 1.3.4.1.3                                                                                                                            |                                                                                                                         |
| 1.3.5                                                                                                                                | Preclinical Summary                                                                                                     |
| 1.3.5.1                                                                                                                              | Cabiralizumab                                                                                                           |
| 1.3.5.2                                                                                                                              | Nivolumab                                                                                                               |
| 1.3.5.3                                                                                                                              | APX005M                                                                                                                 |
| 1.3.6                                                                                                                                | Clinical Summary .                                                                                                      |
| 1.3.6.1                                                                                                                              | Cabiralizumab                                                                                                           |
| Clinical Study Summary of Cabiralizumab .........................................39                                                  |                                                                                                                         |
| 1.3.6.1.1                                                                                                                            |                                                                                                                         |
| 1.3.6.1.2                                                                                                                            | Clinical Pharmacology Summary (Pharmacokinetics,                                                                        |
| Immunogenicity, and Pharmacodynamics) of Cabiralizumab .......39                                                                     |                                                                                                                         |
| 1.3.6.1.3                                                                                                                            | Clinical Safety Summary of Cabiralizumab ........................................39                                     |
| 1.3.6.2                                                                                                                              | Nivolumab                                                                                                               |
| Clinical Pharmacology Summary of Nivolumab                                                                                           |                                                                                                                         |
| 1.3.6.2.1                                                                                                                            |                                                                                                                         |
| 1.3.6.2.2                                                                                                                            | Safety Summary of Nivolumab                                                                                             |
| 1.3.6.3                                                                                                                              | APX005M                                                                                                                 |  
1.4  
| Clinical Pharmacology Summary of APX005M                                                        |                                                                                                            |
|-------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------|
| 1.3.6.3.1                                                                                       |                                                                                                            |
| 1.3.6.3.2                                                                                       | Pharmacokinetics of APX005M                                                                                |
| 1.3.6.3.3                                                                                       | Safety Summary of APX005M .................................................................44              |
| Clinical Experience Involving Serum Enzyme Elevations ...................................... 45 |                                                                                                            |
| 1.4.1                                                                                           | Serum Enzyme Elevations with Cabiralizumab .................................................... 45         |
| Serum Enzyme Elevations with Nivolumab                                                          |                                                                                                            |
| 1.4.2                                                                                           |                                                                                                            |
| 1.4.3                                                                                           | Serum Enzyme Elevations in APX005M .................................................................... 46 |
list of key study personnel
2.

Objectives  
| 2.1                                                                          | Phase 1a Objectives                                                                  |
|------------------------------------------------------------------------------|--------------------------------------------------------------------------------------|
| 2.1.1                                                                        | Primary .                                                                            |
| 2.1.2                                                                        | Secondary                                                                            |
| 2.1.3                                                                        | Exploratory                                                                          |
| 2.2                                                                          | Phase 1b Objectives                                                                  |
| 2.2.1                                                                        | Primary                                                                              |
| 2.2.2                                                                        | Secondary                                                                            |
| 2.2.3                                                                        | Exploratory                                                                          |
| Investigational Plan .                                                       |                                                                                      |
| 3.1                                                                          | Study Design and Duration.                                                           |
| Screening Period .                                                           |                                                                                      |
| 3.1.1                                                                        |                                                                                      |
| 3.1.2                                                                        | Treatment Period .                                                                   |
| Phase 1 Cohorts and Combination Dose Escalation Cohorts.................. 50 |                                                                                      |
| 3.1.2.1                                                                      | Dose Limiting Toxicity .                                                             |
| 3.1.2.1.1                                                                    |                                                                                      |
| 3.1.2.2                                                                      | Phase 1 Dose Escalation Extended Treatment Period ............................... 54 |
| 3.1.2.3                                                                      | Phase 1b Expansion Cohorts .                                                         |
| 3.1.3                                                                        | End-of-Treatment Follow-up Period                                                    |
| Long-Term Follow-up                                                          |                                                                                      |
| 3.1.4                                                                        |                                                                                      |
| 3.1.5                                                                        | Study Duration .                                                                     |
| 3.1.6                                                                        | S Stopping Rules .                                                                   |
| 3.1.6.1                                                                      | Stopping Rules for All Cohorts .                                                     |
| 3.1.6.2                                                                      | Treatment Beyond Progression .                                                       |  
3.  
| 3.2                                                                                                              | Study Population                     |
|------------------------------------------------------------------------------------------------------------------|--------------------------------------|
| 3.2.1                                                                                                            | Planned Number of Patients           |
| 3.2.2                                                                                                            | Inclusion Criteria for All Cohorts . |
| 3.2.3                                                                                                            | Exclusion Criteria for All Cohorts . |
| 3.2.4                                                                                                            | Women of Childbearing Potential      |
| 3.3                                                                                                              | Concomitant Medications              |
| Prohibited and/or Restricted Treatments ..................................................................... 61 |                                      |
| 3.3.1                                                                                                            |                                      |
| 3.3.2                                                                                                            | Permitted Therapy                    |
| 3.4                                                                                                              | Long-Term Follow-up                  |
| Study Drugs                                                                                                      |                                      |
| Investigational Products                                                                                         |                                      |
| 4.1                                                                                                              |                                      |
| 4.2                                                                                                              | Handling and Dispensing              |
| 4.2.1                                                                                                            | Cabiralizumab                        |
| 4.2.2                                                                                                            | Nivolumab                            |
| 4.2.3                                                                                                            | APX005M                              |  
4.  
4.3 4.4  
| Method of Assigning Patient Identification .   |                        |
|------------------------------------------------|------------------------|
| Study Drug Dosing and Dose Modification        |                        |
| 4.4.1                                          | DOSING .               |
| 4.4.1.1                                        | Nivolumab Dosing .     |
| 4.4.1.2                                        | Cabiralizumab Dosing . |
| 4.4.1.3                                        | APX005M Dosing         |  
4.5 Blinding/Unblinding 4.6 Dose Modifications, Delays or Discontinuation................................................................. 69 4.7 Criteria to Resume Treatment with APX005M, Cabiralizumab and Nivolumab
...............................................................................................................................................69 4.8 Management of Adverse Events and Supportive Care Guidelines...................... 70 4.9 Criteria for Holding, Discontinuing, or Modifying Study Drug........................... 74 4.10 Dose Reduction 4.11 Treatment Discontinuation Criteria ............................................................................................... 79 s.  
| 4.12 Infusion Delays and Missed Doses with Nivolumab, Cabiralizumab and                                |                                                                                                                                                   |
|--------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------|
| APX005M                                                                                                |                                                                                                                                                   |
| 4.13                                                                                                   | Treatment Beyond Progression .                                                                                                                    |
| 4.14                                                                                                   | T Treatment Compliance                                                                                                                            |
| 4.15 Destruction of Study Drug .                                                                       |                                                                                                                                                   |
| 4.16 Return of Study Drug.                                                                             |                                                                                                                                                   |
| Study Assessments and Procedures .                                                                     |                                                                                                                                                   |
| 5.1                                                                                                    | Schedule of Assessments.                                                                                                                          |
| 5.2                                                                                                    | Study Procedures by Visit.                                                                                                                        |
| 5.2.1                                                                                                  | Phase 1 Dose Escalation                                                                                                                           |
| 5.2.1.1                                                                                                | Screening Period (Day –28 to Day 0)                                                                                                               |
| 5.2.1.2                                                                                                | Cycle 1, Day 1 .                                                                                                                                  |
| 5.2.1.3                                                                                                | Cycle 1, Day 2                                                                                                                                    |
| 5.2.1.4                                                                                                | Cycle 1, Day 3                                                                                                                                    |
| 5.2.1.5                                                                                                | Cycle 1, Day 8                                                                                                                                    |
| 5.2.1.6                                                                                                | Cycle 2, Day 1 .                                                                                                                                  |
| 5.2.1.7                                                                                                | Cycle 2, Day 2                                                                                                                                    |
| 5.2.1.8                                                                                                | Cycle 2, Day 3 .                                                                                                                                  |
| 5.2.1.9                                                                                                | Cycle 2, Day 8 .                                                                                                                                  |
| 5.2.1.10                                                                                               | Subsequent Cycles, Day 1 ...................................................................................................... 88                |
| 5.2.1.11                                                                                               | End-of-Treatment Follow-up Period ................................................................... 89                                          |
| 5.2.2                                                                                                  | Phase 1b .                                                                                                                                        |
| 5.2.2.1                                                                                                | Screening Period (Day -28 to Day 0)                                                                                                               |
| 5.2.2.2                                                                                                | Cycle 1, Day 1 ........................................................................................................................ 91        |
| 5.2.2.3                                                                                                | Cycle 1, Day 2                                                                                                                                    |
| 5.2.2.4                                                                                                | Cycle 2, Day 1 ............................................................................................................................... 93 |
| 5.2.2.5                                                                                                | Cycle 2, Day 2                                                                                                                                    |
| 5.2.2.6                                                                                                | Phase 1b, Subsequent Cycles, Day 1 .................................................................... 94                                        |
| End of Treatment Follow-up Period ................................................................. 95 |                                                                                                                                                   |
| 5.2.2.7                                                                                                |                                                                                                                                                   |
| 5.2.3                                                                                                  | Long-Term Follow-up for All Patients ....................................................................... 95                                   |
| 5.3                                                                                                    | Study Assessments                                                                                                                                 |
| 5.3.1                                                                                                  | Se                                                                                                                                                |  
| 5.3.2                                                                                                                                                        | Efficacy Assessments ........................................................................................................................... 96             |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 5.3.2.1                                                                                                                                                      | Primary Efficacy Parameters .............................................................................. 96                                                   |
| 5.3.2.1.1                                                                                                                                                    | T Tumor Assessment ................................................................................................97                                           |
| 5.3.2.2                                                                                                                                                      | Additional Efficacy Parameters ......................................................................... 97                                                     |
| 5.3.2.3                                                                                                                                                      | Tumor Biopsy for Fresh Tumor Tissue Collection .................................... 97                                                                          |
| 5.3.3                                                                                                                                                        | Pharmacokinetic Assessments                                                                                                                                     |
| 5.3.4                                                                                                                                                        | Biomarker Assessments                                                                                                                                           |
| T Tumor Tissue Specimens ............................................................................................98                                      |                                                                                                                                                                 |
| 5.3.4.1                                                                                                                                                      |                                                                                                                                                                 |
| 5.3.4.2                                                                                                                                                      | Flow Cytometry                                                                                                                                                  |
| Adverse Events                                                                                                                                               |                                                                                                                                                                 |
| 6.1                                                                                                                                                          | Collection of Adverse Events ............................................................................................................ 100                   |
| 6.2                                                                                                                                                          | Serious Adverse Events .                                                                                                                                        |
| 6.2.1                                                                                                                                                        | Serious Adverse Event Reporting ............................................................................... 101                                             |
| Non-Serious Adverse Events.......................................................................................................... 105                     |                                                                                                                                                                 |
| 6.3                                                                                                                                                          | Non-serious Adverse Event Reporting                                                                                                                             |
| 6.3.1                                                                                                                                                        |                                                                                                                                                                 |
| 6.4                                                                                                                                                          | Laboratory Test Result Abnormalities ................................................................................ 105                                       |
| 6.5                                                                                                                                                          | Pregnancy                                                                                                                                                       |
| 6.6                                                                                                                                                          | Overdose                                                                                                                                                        |
| 6.7                                                                                                                                                          | Potential Drug Induced Liver Injury                                                                                                                             |
| Statistical Considerations                                                                                                                                   |                                                                                                                                                                 |
| 7.1                                                                                                                                                          | Sample Size Determination ................................................................................................................................. 108 |
| 7.2                                                                                                                                                          | Demographics and Baseline Characteristics ................................................................... 108                                               |
| Efficacy Analyses ...................................................................................................................................... 108 |                                                                                                                                                                 |
| 7.3                                                                                                                                                          |                                                                                                                                                                 |
| 7.4                                                                                                                                                          | Se                                                                                                                                                              |
| 7.5                                                                                                                                                          | Pharmacokinetic Analyses .                                                                                                                                      |
| Biomarker Analyses                                                                                                                                           |                                                                                                                                                                 |
| 7.6                                                                                                                                                          |                                                                                                                                                                 |
| Ethical Considerations .                                                                                                                                     |                                                                                                                                                                 |  
6.  
7. 8.  
8.1 Good Clinical Practice 8.2 Institutional Review Board/Independent Ethics Committee ................................ 111 9.  
| 8.3                                         | Informed Consent .                                                                                                                              |
|---------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------|
| Study Management .                          |                                                                                                                                                 |
| 9.1                                         | Compliance                                                                                                                                      |
| 9.1.1                                       | Compliance with the Protocol and Protocol Revisions .................................. 113                                                      |
| Yale Safety Reporting and Monitoring (DSMP) |                                                                                                                                                 |
| 9.1.2                                       | SOURCE DOCUMENTATION .                                                                                                                          |
| 9.1.2.1                                     |                                                                                                                                                 |
| 9.1.3                                       | Investigational Site Training ................................................................................................. 114             |
| 9.2                                         | Records                                                                                                                                         |
| 9.2.1                                       | Records Retention .......................................................................................................................... 15 |
| 9.2.2                                       | Study Drug Records .................................................................................................................... 15      |
| 9.2.2.1                                     | Case Report Forms                                                                                                                               |
| References .                                |                                                                                                                                                 |
| Appendices                                  |                                                                                                                                                 |  
10.  
1.  
| ACTH   | Adrenocorticotropichormone              |
|--------|-----------------------------------------|
| ADA    | Anti-drug antibody                      |
| AE     | Adverse event                           |
| ALT    | Alanine aminotransferase                |
| ANA    | Antinuclear antibody                    |
| ANC    | Absolute neutrophil count               |
| AST    | Aspartate aminotransferase              |
| AT     | Aminotransferase                        |
| AUC    | Area under the concentration-time curve |
| β-HCG  | Beta-human chorionic gonadotropin       |
| BID    | Bis in die; twice daily                 |
| BMI    | Body mass index                         |
| BMS    | Bristol-Myers Squibb                    |
| BOR    | Best overall response                   |
| BP     | Blood pressure                          |
| BTLA   | B- and T-lymphocyte attenuator          |
| BUN    | Blood urea nitrogen                     |
| ºC     | Degrees Celsius                         |
| CBC    | Complete blood count                    |
| CD     | Cluster of differentiation              |
| CEA    | Carcinoembryonic antigen                |
| CFR    | Code of Federal Regulations             |
| CHO    | Chinese hamster ovary                   |
| CI     | Confidence interval                     |
| CK     | Creatine kinase                         |
| CL     | Clearance                               |
| Cmax   | Maximum observed concentration          |
| Cmin   | Minimum observed concentration          |
| CMV    | Cytomegalovirus                         |
| CNS    | Central nervous system                  |
| CR     | Complete response                       |
list of key study personnel
list of abbreviations and definitions

| CRC         | Colorectal cancer                                           |
|-------------|-------------------------------------------------------------|
| CRF         | Case report form, may be paper or electronic                |
| CRO         | Contract research organization                              |
| CRP         | C-reactive protein                                          |
| CSF1        | Colony stimulating factor 1                                 |
| CSF1R       | Colony stimulating factor 1 receptor                        |
| CSR         | Clinical study report                                       |
| CT          | Computed tomography                                         |
| CTA         | Clinical trials agreement                                   |
| CTCAE v 5.0 | Common Terminology Criteria for Adverse Events, version 5.0 |
| CTLA-4      | Cytotoxic T lymphocyte antigen 4                            |
| CTX         | C-terminal collagen crosslink peptides                      |
| CV          | Coefficient of variation                                    |
| DC          | Dendritic cell                                              |
| DILI        | Drug-induced liver injury                                   |
| dL          | Deciliter                                                   |
| DLT         | Dose-limiting toxicity                                      |
| DMARD       | Disease-modifying anti-rheumatic drug                       |
| DNA         | Deoxyribonucleic acid                                       |
| DOR         | Duration of response                                        |
| dt-TGCT     | Diffuse-type tenosynovial giant-cell tumor                  |
| EC50        | Half-maximal effective concentration                        |
| ECG         | Electrocardiogram                                           |
| ECLA        | Electrochemiluminescence assay                              |
| ECM         | Extracellular matrix                                        |
| ECOG        | Eastern Cooperative Oncology Group                          |
| eCRF        | Electronic case report form                                 |
| EDC         | Electronic data capture                                     |
| EDTA        | Ethylene diamine tetraacetic acid                           |
| e.g.        | exempli gratia (for example)                                |
| ELISA       | Enzyme-linked immunosorbent assay                           |
| ePPND       | Enhanced pre- and post-natal development                    |  
| ESR       | Erythrocyte sedimentation rate            |
|-----------|-------------------------------------------|
| ºF        | Degrees Fahrenheit                        |
| FACS      | Fluorescent-activated cellsorter          |
| Fc        | Fragment crystallizable                   |
| FDA       | Food and Drug Administration              |
| FFPE      | Formalin-fixed,paraffin-embedded          |
| FISH      | Fluorescent in situ hybridization         |
| FivePrime | Five Prime Therapeutics, Inc.             |
| FOXP3+    | Forkhead box p3                           |
| FSH       | Follicle stimulating hormone              |
| g         | Gram                                      |
| GBM       | Malignant glioma                          |
| GCP       | Good Clinical Practice                    |
| GI        | Gastrointestinal                          |
| h         | Hour                                      |
| HBsAg     | Hepatitis B surface antigen               |
| HBV       | Hepatitis B virus                         |
| HCV       | Hepatitis C virus                         |
| HIV       | Human Immunodeficiency Virus              |
| HR        | Heart rate                                |
| HRT       | Hormone replacement therapy               |
| IB        | Investigator'sBrochure                    |
| IC50      | Half-maximal inhibitory concentration     |
| ICD       | Implantable cardioverter defibrillator    |
| ICF       | Informed consent form                     |
| ICH       | International Conference on Harmonization |
| ICOS      | Inducible co-stimulator                   |
| i.e.      | id est (that is)                          |
| IEC       | Independent ethics committee              |
| IFN       | Interferon                                |
| IgG       | Immunoglobulin G                          |
| IHC       | Immunohistochemistry                      |  
| IL    | Interleukin                                     |
|-------|-------------------------------------------------|
| IM    | Intramuscular                                   |
| IMP   | Investigational medicinal product               |
| IND   | Investigational new drug                        |
| INR   | International normalized ratio                  |
| I-O   | Immuno-oncology                                 |
| irAE  | Immune-related adverse event                    |
| IRB   | Institutional review board                      |
| ITIM  | Immunoreceptor tyrosine inhibitory motif        |
| ITSM  | Immunoreceptor tyrosine-based switch motif      |
| IU    | International unit                              |
| IV    | Intravenous                                     |
| IXRS  | Integrated voice and web response system        |
| kg    | Kilogram                                        |
| KM    | Kaplan-Meier                                    |
| LAG-3 | Lymphocyte-activate gene 3                      |
| LDH   | Lactate dehydrogenase                           |
| LFT   | Liver function test                             |
| LOQ   | Limit of quantitation                           |
| MABEL | Minimum anticipated biological effect level     |
| mCRPC | Metastatic castration-resistant prostate cancer |
| MDSC  | Myeloid-derived suppressor cell                 |
| mg    | Milligram                                       |
| min   | Minute                                          |
| µL    | Microliter                                      |
| mL    | Milliliter                                      |
| MLR   | Mixed lymphocyte reaction                       |
| µM    | Micrometer                                      |
| mM    | Millimolar                                      |
| mm3   | Cubic millimeters                               |
| mmHg  | Millimeters of mercury                          |
| MRI   | Magnetic resonance imaging                      |  
| MSD        | Meso Scale Discovery                                         |
|------------|--------------------------------------------------------------|
| MTD        | Maximum tolerated dose                                       |
| N          | Number of patients or observations                           |
| NCI        | National Cancer Institute                                    |
| ng         | Nanogram                                                     |
| NOAEL      | No-observable-adverse-effectlevel                            |
| NSCLC      | Non-small cell lung cancer                                   |
| NYHA       | New York Heart Association                                   |
| NSAID      | Non-steroidal, anti-inflammatory drug                        |
| ORR        | Objective response rate                                      |
| OS         | Overallsurvival                                              |
| PBMC       | Peripheral blood mononuclear cell                            |
| PD         | Pharmacodynamics                                             |
| PD-1       | Programmed cell death 1                                      |
| PDAC       | Pancreatic ductal adenocarcinoma                             |
| PD-L1      | Programmed death ligand 1                                    |
| PD-L2      | Programmed death ligand 2                                    |
| PFS        | Progression-free survival                                    |
| PK         | Pharmacokinetics                                             |
| PO         | Per os; by mouth                                             |
| PPK        | Population pharmacokinetics                                  |
| PR         | Partial response                                             |
| PT         | Prothrombin time                                             |
| PTT (aPTT) | Partial thromboplastin time                                  |
| PVC        | Polyvinyl chloride                                           |
| q2w        | Every two weeks                                              |
| PVNS       | Pigmented villonodular synovitis                             |
| qPCR       | Quantitative real-time polymerase chain reaction             |
| qRT-PCR    | Quantitative reverse-transcription polymerase chain reaction |
| QTcF       | Fridericia's correction formula for QT interval              |
| RA         | Rheumatoid arthritis                                         |
| RBC        | Red blood cell                                               |  
| RCC         | Renal cell carcinoma                                                              |
|-------------|-----------------------------------------------------------------------------------|
| RD          | Recommended Dose                                                                  |
| RECIST v1.1 | Response Evaluation Criteria in Solid Tumors, version 1.1                         |
| RNA         | Ribonucleic acid                                                                  |
| SAE         | Serious adverse event                                                             |
| SAP         | Statistical analysis plan                                                         |
| SCCHN       | Squamous-cell carcinoma of the head and neck                                      |
| SD          | Stable disease                                                                    |
| SkTnI       | Skeletal troponin                                                                 |
| SOP         | Standard operating procedure                                                      |
| Src         | Sarcoma homology protein                                                          |
| T3          | Triiodothyronine                                                                  |
| T4          | Thyroxine                                                                         |
| TAM         | Tumor-associatedmacrophage                                                        |
| TB          | Tuberculosis                                                                      |
| TCR         | T-cell receptor                                                                   |
| TIL         | Tumor-infiltrating lymphocyte                                                     |
| Tmax        | Time of maximum observed concentration                                            |
| TNF         | Tumor necrosis factor                                                             |
| Trap5b      | Tartrate resistant acid phosphatases 5b                                           |
| ULN         | Upper limit of normal                                                             |
| USP         | United States Pharmacopeia                                                        |
| Vss         | Volume of distribution at steady state                                            |
| Vz          | Volume of distribution of terminal phase (if IV and if multi-exponential decline) |
| WBC         | White blood cell                                                                  |
| WHO         | World Health Organization                                                         |
| WOCBP       | Women of childbearing potential                                                   |
list of key study personnel
1. introduction and study rationale

Immunotherapies including PD-1/PD-L1 inhibitors have become effective standard therapies in several advanced cancers. Objective response rates (ORR) for advanced melanoma patients treated with dual (ipilimumab and nivolumab) or single agent (nivolumab) immune checkpoint inhibitors have reached up to 57.6% and 43.7%, respectively [1-4]. However, not all patients respond and after 2 years of monotherapy, approximately half of the responders have progressed. Similarly, in advanced non-small cell lung cancer (NSCLC) patients with greater than 50% tumor PD-L1 positivity, pembrolizumab is used in the front-line setting with a 44.8% response rate [5]. Nivolumab and atezolizumab are also approved for NSCLC patients who have progressed on platinum-based chemotherapy and who are not candidates for EGFR or ALK inhibitors [6, 7]. Additionally, nivolumab is approved in second-line treatment of advanced renal cell carcinoma (RCC) with a 25% ORR [8]. In the absence of targetable driver mutations, limited treatment options exist for next-line therapy in patients who do not initially respond to or who develop acquired resistance to PD-1 inhibitors. New combinatorial therapeutic strategies are needed to overcome this resistance. Proposed mechanisms for resistance to anti-PD-1/PD-L1 therapy include lack of or inactivation of T cells, T cell exhaustion, loss of antigen presentation, or expression of other immunosuppressive molecules. Tumor-associated macrophages (TAMs) comprise up to 30% of innate immune cells in the tumor microenvironment [9] and can serve as both negative (M1) and positive (M2) regulators of tumor growth. M2 macrophages are anti-inflammatory and secrete immunosuppressive growth factors that negatively impact cytotoxic T-cell capabilities [10-13] and promote tumorigenesis, invasion, and metastasis [14, 15]. We hypothesize that manipulation of the innate immune system by targeting macrophage activity will assist in reversing local immune suppression and overcome resistance to PD-1/PD-L1 inhibition.
list of key study personnel
1.2 rationale for combination of

Immunotherapies including CSF1R inhibitors (CSF1Ri) and CD40 agonists (CD40α) target innate immune cells. Researchers including those at Yale have shown these agents to suppress poorly Tcell infiltrated melanomas in a T-cell independent fashion. Macrophage colony-stimulating factor 1 (CSF-1) is chemotactic signal that stimulates monocyte tumor infiltration and differentiation into M2 macrophages [10, 16] and elevated expression of CSF-1 and CSF1R is associated with poor prognosis [17]. For example, in a melanoma mouse model, CSF1Ri improved efficacy of adoptive cell therapy by increasing T-cell tumor infiltration and decreasing immunosuppressive macrophage infiltration [18]. CD40 is similarly expressed on macrophages and other antigen presenting cells, and interacts with its ligand, CD40L, on T cells. CD40α have also been shown to increase tumoricidal activity of macrophages and stimulate maturation of antigen presenting cells.  
In a pancreatic mouse model, combination PD-1 blockade and CD40α improved anti-tumor immunity compared to either agent alone [19]. Clinical trials of CD40α have shown activity in melanoma, including durable responses [20].  
Pre-clinical studies at Yale in the Kaech and Bosenberg laboratories have supported the notion that TAMs may confer resistance to PD-1/PD-L1 inhibition [21]. Using the BrafV600E/Pten-/-
genetically engineered mouse melanoma model (GEMM), we have generated a series of cell lines
(YUMM for Yale University Mouse Melanoma) and irradiated derivatives (YUMMER for Yale  
 University Mouse Melanoma Exposed to UVB Radiation). These models are unique in that they are driven by mutations relevant to human melanomas and can be studied in immune competent mice. YUMM tumors tend to be resistant to PD-1/PD-L1 inhibitors, while the YUMMER tumors are less resistant, but do develop resistance over time, mimicking primary and acquired resistance seen in humans. We have found that the predominant immune population present in tumors with poor cytotoxic T cell infiltration are TAMs. TAMs are particularly in abundance relative to CD8+ T cells in YUMM tumors, with the inverse being observed in YUMMER tumors (Figure 1).  
Figure 1. Content of immune infiltrating cells in the BrafV600E/Pten-/- genetically engineered mouse melanoma models (GEMM), a cell line model derived from these GEMM tumors, YUMM 1.7, and a model generated by exposure to UVB
radiation (YUMMER1.7), which is more sensitive to PD-1/PD-L1 inhibitors, but develops resistance over time. TAM content is abundant in the former, whereas more CD8 cells are infiltrating the latter.  
Tumor infiltrating neutrophils (TINs) and CD4 T cells are present as well, but mostly at the tumor  
 margin. Tumor growth in this model is not responsive to anti-PD-1/PD-L1 treatment alone, but combination therapy with CSF1Ri slows tumor growth significantly compared to the control (data not shown). Treatment with combined CSF1Ri/CD4α slows tumor growth more than either agent alone (Figure 2 upper panel). The combination therapy also resulted in increased tumor infiltrating immune cells, clearly impacting the TAM population (Figure 2 lower panel).  
  
Figure 2. Upper panel: Groups of 12 mice were treated with control vehicle, CD40 agonist alone, CSF1R inhibitor alone, or the combination 30 days after tumor induction. The combination resulted in significant inhibition of tumor growth compared with either drug alone. Lower Panel: Treatment of mice with CD40 agonists, CSF1R inhibitors or the combination thereof impacted tumor infiltrating immune cells, particularly tumor associated macrophages (TAM) and neutrophils (TAN).  
Additional detailed mechanistic studies have been conducted supporting the combination of CD40α and CSF1Ri in these animal models and their role in activating the innate immune system (Perry CJ et al, submitted). Combined treatment with CD40α and CSF1Ri alters the composition of TAMs, increases Type I inflammation and chemokine expression, and enhances CD8 T-cell infiltration and PD-1 expression.  
As shown in the flow plots in Figure 3 for example, the expression TNF-α on TAMs significantly  
  
Figure 3. Treatment with CSF1Ri and CD40α in combination alters the macrophage content to a greater degree than either drug alone.  
Inflammatory cytokines including TNFα and IFNγ appear to be necessary for anti-tumor immunity provided by combined CSF1Ri and CD4α therapy.  As shown in the Kaplan-Meier curves (Figure 4 upper panel) and the associated log-rank p values (Mantel-Cox) (Figure 4 lower panel), TNFα and IFNy blocking therapy actually interferes with tumor growth suppression from combined CSF1Ri and CD40α therapy. Data are from one experiment (n=3-6), representative of three independent experiments (total n=6-15).  
  
| Two-way comparison   | Log-rank P value        |        |
|----------------------|-------------------------|--------|
| Control              | CD40+CSF1Ri             | 00011  |
| Control              | CD40+CSF1Ri +αTNFα/IFNγ | 0.0068 |
| Control              | CD40+CSF1Ri +αTNFα      | 0.0285 |
| Control              | CD40+CSF1Ri +αlFNγ      | 0.0189 |
| CD40+CSF1Ri          | CD40+CSF1Ri +αTNFα/IFNγ | 0.0177 |
| CD40+CSF1Ri +αTNFα   | CD40+CSF1Ri +αTNFα/IFNγ | 0.010  |
| CD40+CSF1Ri +αlFNγ   | CD40+CSF1Ri +αTNFα/IFNγ | 0.010  |  
Figure 4. Kaplan Meier survival curves (upper panel) and associated statistical comparisons (lower panel) show that TNFα and IFN γ are necessary for anti-tumor immunity provided by combined CSF1Ri and CD40α therapy, as blocking them interferes with the inhibition of tumor growth by these drugs.  
In pilot experiments, we have shown that mice (n=11) treated with the triple combination of anti-
PD-1/CSF1Ri/CD40α had superior survival compared to treatment with anti-PD-1/CSF1Ri or anti-PD-1/CD40α (Figure 5).  
  
Figure 5. YUMM 1.7 bearing mice were treated with control vehicle, CD40 agonistic antibodies (CD40α),
CSF1R inhibitors (CSF1Ri) or anti-PD-1/L1. These tumors are resistant to any of the three monotherapies, and survival was clearly superior with triplet therapy compared with doublets of CSF1Ri or CD40α and PD-1 axis inhibitors.  
Thus, based on the above pre-clinical data, we hypothesize that addition of CSF1Ri/CD40α to PD1 blockade may further disengage T cell suppression and potentiate the anti-tumor immune response. We therefore propose a phase I/Ib clinical trial of the CD40α APX005M in combination with cabiralizumab (CSF1Ri) and nivolumab in advanced solid tumors including melanoma, NSCLC, and RCC. Our preliminary data from immune profiling of murine tumors treated with CSF1Ri and CD40α indicate that biomarkers of response include TNFα, IL-6, CCL3,4,5 and CD8+ T cell/neutrophil recruitment. We aim to identify immune correlates that are associated with clinical response to the triple combination and to develop biomarkers of response using mandatory pre-treatment and on-treatment biopsies. Seeing that APX005M and cabiralizumab have not been used in combination, and both drugs activate macrophages, we propose an initial cohort of the APX005M and cabiralizumab. This cohort will be followed by the addition of fixed dose nivolumab. APX005M will then be slowly dose escalated in combination with cabiralizumab, with and without nivolumab, to establish safety and to establish the RP2D of APX005M in combination with nivolumab and cabiralizumab.
list of key study personnel
1.3 target receptor background 1.3.1

Macrophages are myeloid-derived cells that carry out a variety of functions in the human body. They can colonize tissues and tumors through two distinct mechanisms: hematogenous seeding from circulating monocytes or local self-renewal in the form of tissue-resident macrophages [22]. Recent studies have shown that macrophages exert their physiological effect within, and play roles unique to, the tissues in which they are active [23]. Macrophage regulation is complex as these cells actively secrete and respond to multiple cytokine and chemokine gradients within their local environment.  
Macrophages are among the most abundant immune cell types in the tumor microenvironment. Based on their opposing functions, macrophages can be classified into two major phenotypes, M1 and M2. M1 macrophages are immunostimulatory and tumor suppressive, while M2 macrophages are immunosuppressive and tumor promoting. Substantial evidence suggests that tumor-associated macrophages (TAMs) are polarized towards an anti-inflammatory M2 phenotype [24]. Consistent with this, increased levels of TAMs are associated with a poor prognosis in the majority of cancers [25]. Based on their tumor-promoting phenotype TAMs have become an attractive therapeutic target. Colony stimulating factor 1 receptor (CSF1R) signaling plays a fundamental role in the differentiation, maintenance, and function of macrophages [26]. There are two ligands for CSF1R: CSF1 and IL34. These agonists bind to overlapping regions of CSF1R with similar affinity (reviewed in Masteller and Wong [27]). Mice lacking CSF1R, CSF1, or IL34 have deficiencies in macrophages, underscoring the essential role of the CSF1R pathway in the biology of this cell type [27, 28]. Pharmacologic treatments that block CSF1R in cancer settings are expected to reduce or reprogram M2 TAMs and reduce immune suppression. Following treatment with anti-CSF1R agents, the remaining macrophage compartment may be repolarized from an M2 immunosuppressive state to an M1 anti-tumor state, which would support T-cell responses. This conversion associated with concurrent treatment modalities, such as anti-PD-1 treatment, could have an increased effect on reduction of tumor growth [29]. Support for targeting CSF1R in cancer comes from animal studies in which antibody or small molecule inhibition of CSF1R decreases M2 TAMs resulting in decreased immune suppression and a more robust cytotoxic T-cell response [30-32]. Cabiralizumab is a recombinant, humanized immunoglobulin G4 (IgG4) monoclonal antibody that binds to human CSF1R. The interaction of cabiralizumab and CSF1R antagonizes the binding of both CSF1 and IL34 to CSF1R, thereby preventing receptor activation. In *vitro*, cabiralizumab inhibits CSF1 and IL34-induced proliferation and survival of peripheral blood monocytes. In *vivo,* cabiralizumab inhibits the survival of subsets of monocytes and macrophages. Taken together, these and other emerging data suggest that blocking CSF1R with cabiralizumab treatment may reduce immunosuppression in the tumor environment generated by TAMs and enhance the efficacy of immune-based anti-cancer therapies.
list of key study personnel
1.3.2 programmed cell death-1 (pd-1

PD-1 is a cell surface signaling receptor that delivers inhibitory signals to regulate the balance between T-cell activation and tolerance by interacting with its ligands, PD-L1 (CD274; B7-H1) and PD-L2 (B7-DC/CD273). It is a 55 kDa type I transmembrane protein that is a member of the CD28 family of T-cell costimulatory receptors, which also includes inducible co-stimulator (ICOS), cytotoxic T lymphocyte antigen-4 (CTLA-4), and B- and T-lymphocyte attenuator (BTLA) [33]. PD-1 contains an intracellular membrane proximal immunoreceptor tyrosine inhibitory motif (ITIM) and a membrane distal immunoreceptor tyrosine-based switch motif (ITSM). PD-1 is primarily expressed on activated T cells, B cells, and myeloid cells [34]. Its ligands, PD-L1 and PD-L2, have been shown to down-regulate T-cell activation upon binding to PD-1 in both murine and human systems [35, 36]. PD-1 delivers a negative signal by the recruitment of Src homology region 2 domain-containing phosphatase-2 (SHP-2) to the phosphorylated tyrosine residue in the ITSM in its cytoplasmic region [37, 38]. Evidence for a negative regulatory role of PD-1 comes from studies of PD-1-deficient mice, which develop various autoimmune phenotypes, including dilated cardiomyopathy and a lupuslike syndrome with arthritis and nephritis [39-41]. The emergence of these autoimmune phenotypes is dependent on the genetic background of the mouse strain; many of these phenotypes emerge at different times and show variable penetrance. In addition to the phenotypes of null mutations, PD-1 inhibition by antibody-mediated blockade in several murine models has been found to play a role in the development of autoimmune diseases such as encephalomyelitis, graft-versus-host disease, and type I diabetes [42-44]. Taken together, these results suggest that PD-1 blockade has the potential to activate anti-self T-cell responses, but these responses are variable and dependent upon various host genetic factors. Thus, PD-1 deficiency or inhibition is not accompanied by a universal loss of tolerance to self-antigens. The PD-1 targeting agent, nivolumab has been investigated clinically in several tumor types including non-small cell lung cancer (NSCLC), melanoma, and renal cell carcinoma (RCC), Classical Hodgkin lymphoma, squamous cell carcinoma of the head and neck, and urothelial carcinoma as a single agent or in combination with other treatments. A selection of efficacy data is described in the Nivolumab Investigator's Brochure).. As a single agent, nivolumab shows remarkably durable efficacy in responding patients. Nivolumab is currently approved in the US for the following indications [45]:
- BRAF V600 wild-type unresectable or metastatic melanoma, as a single agent.  
- BRAF V600 mutation-positive unresectable or metastatic melanoma, as a single agent.  
- Unresectable or metastatic melanoma, in combination with ipilimumab.  
- Metastatic non-small cell lung cancer and progression on or after platinum-based chemotherapy. Patients with EGFR or ALK genomic tumor aberrations should have disease progression on FDA-approved therapy for these aberrations.  
- Advanced renal cell carcinoma for patients who have received prior anti-angiogenic therapy.  
- Classical Hodgkin lymphoma (cHL) that has relapsed or progressed after autologous hematopoietic stem cell transplantation (HSCT) and post-transplantation brentuximab vedotin or 3 or more lines of therapy that includes autologous HSCT.  
- Recurrent or metastatic squamous cell carcinoma of the head and neck with disease progression on or after a platinum-based therapy.  
- Locally advanced or metastatic urothelial carcinoma who:
- have disease progression during or following platinum-containing chemotherapy
- have disease progression within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.
list of key study personnel
1.3.3 cd40

Apexigen has developed the mAb APX005M, which binds and activates CD40, a costimulatory molecule expressed by antigen presenting cells (APC). As such, APX005M is a CD40 agonistic antibody. The cell surface molecule CD40, a member of the tumor necrosis factor receptor (TNFR) superfamily, plays an important role in induction of tumor apoptosis and regulation of immune activation, especially in crosstalk between T cells and APCs [46]. CD40 is expressed by dendritic cells (DC), B cells, monocytes, and some non-lymphoid cells [47]. The natural ligand
(CD40L) for CD40 is CD154, which is expressed on activated T cells and provides a major component of T cell "help" for immune response. Agonistic CD40 antibodies can substitute for the function of CD154 on T cells to boost immunity. Signaling through CD40 on APCs, including dendritic cells (DCs), monocytes, and B cells, can, in turn, enhance the T cell response via improvement in antigen processing and presentation and through the release of cytokines from activated APCs [48, 49]. Therefore, an agonistic CD40 antibody can activate and stimulate both innate and adaptive immunity. CD40 is also expressed on many tumor cells and can mediate a direct cytotoxic effect. In addition to B cell lymphoma, CD40 expression has been reported in 30−70% of primary human solid tumor samples including melanoma and carcinomas [50]. Activation of CD40 on tumor cells results in tumor cell apoptosis and inhibition of tumor growth [12]. Due to its action on both immune and tumor cells, CD40 has been studied as a target for novel cancer immunotherapy; agonistic anti-CD40 antibodies have been demonstrated to be potent stimulators of tumor immune responses in both animal models and cancer subjects [50-53].  
The potential mechanisms of action for an agonistic anti-CD40 antibody, depending on its isotype, include stimulation of immune response by activating antigen processing and presentation, recruitment of immune effectors such as natural killer (NK) cells and macrophages, and direct cytotoxic effects on tumor cells. Thus, the desired therapeutic CD40 agonist antibody should have these functionalities.
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1.3.4 product development background 1.3.4.1

Cabiralizumab is a recombinant, humanized IgG4 monoclonal antibody that binds to human CSF1R. Cabiralizumab contains a single amino acid substitution in the hinge region to prevent hemi-dimer exchange. Binding of cabiralizumab to CSF1R antagonizes its natural ligands, CSF1 and IL34, thereby preventing activation of CSF1R. Cabiralizumab inhibits both CSF1 and IL34-induced CSF1R phosphorylation in a cell line engineered to overexpress CSF1R (CHO-CSF1R), demonstrating that cabiralizumab blocks the activation of ligand-induced CSF1R signaling pathways. Cabiralizumab also inhibits CSF1 and IL34-induced proliferation and survival of peripheral blood monocytes *in vitro*, demonstrating that cabiralizumab inhibits not only the initiation of CSF1 and IL34 signaling pathways, but also the subsequent physiologic responses of primary human monocytes to these ligands. CSF1R is expressed on cells of the monocyte/macrophage lineage and signaling through CSF1R via its ligands, CSF1 and IL34, supports differentiation, maintenance, and function of monocytes, macrophages, and osteoclasts. TAMs are among the most abundant immune cell types in the tumor microenvironment. Substantial evidence suggests that TAMs are polarized towards an anti-inflammatory phenotype (M2 TAMs) and through both cell surface inhibitors and soluble factors, such as immunosuppressive cytokines, play a major role in inhibiting antitumor immune responses [24]. CSF1 is a major survival factor for TAMs and targeting CSF1R
through cabiralizumab should reduce TAM-mediated immune suppression resulting in strengthening the anti-tumor response to immunotherapy. Therefore, a drug that inhibits CSF1R should limit the immune-suppressive influence of TAMs on the tumor microenvironment and could be complementary and augment current cancer therapies.
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1.3.4.1.2 nivolumab

Cancer immunotherapy rests on the premise that tumors can be recognized as foreign rather than as self and can be effectively attacked by an activated immune system. An effective immune response in this setting is thought to rely on immune surveillance of tumor antigens expressed on cancer cells that ultimately results in an adaptive immune response and cancer cell death.  
Meanwhile, tumor progression may depend upon acquisition of traits that allow cancer cells to evade immuno-surveillance and escape effective innate and adaptive immune responses [54-57]. Current immunotherapy efforts attempt to break the apparent tolerance of the immune system to tumor cells and antigens by either introducing cancer antigens by therapeutic vaccination or by modulating regulatory checkpoints of the immune system. T-cell stimulation is a complex process involving the integration of numerous positive as well as negative co-stimulatory signals in addition to antigen recognition by the T-cell receptor (TCR)
[58]. Collectively, these signals govern the balance between T-cell activation and tolerance. PD1 signaling has been shown to inhibit CD28-mediated upregulation of IL2, IL10, IL13, interferon-γ (IFN-γ) and Bcl-xL. PD-1 signaling has also been noted to inhibit T-cell activation, and expansion of previously activated cells. Evidence for a negative regulatory role of PD-1 comes from studies of PD-1 deficient mice, which develop a variety of autoimmune phenotypes [59]. These results suggest that PD-1 blockade has the potential to promote anti-self T-cell responses, but these responses are variable and dependent upon various host genetic factors. Thus, PD-1 deficiency or inhibition is not accompanied by a universal loss of tolerance to self antigens.  
In *vitro*, nivolumab binds to PD-1 with high affinity (EC50 0.39-2.62 nM), and inhibits the binding of PD-1 to its ligands, PD-L1 and PD-L2 (IC50 ± 1 nM). Nivolumab binds specifically to PD-1 and not to related members of the CD28 family such as CD28, ICOS, CTLA-4 and BTLA. Blockade of the PD-1 pathway by nivolumab results in a reproducible enhancement of both proliferation and IFN-γ release in a mixed lymphocyte reaction (MLR). Using a cytomegalovirus (CMV) re-stimulation assay with human peripheral blood mononuclear cells (PBMCs), the effect of nivolumab on antigen-specific recall response is indicative of nivolumab-augmented IFN-γ secretion from CMV-specific memory T cells in a dose-dependent manner versus an isotypematched control. In *vivo* blockade of PD-1 by a murine analog of nivolumab enhances the antitumor immune response and results in tumor rejection in several immunocompetent mouse tumor models (MC38, SA1/N, and PAN02) [60].
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1.3.4.1.3 apx005m

The agonistic CD40 mAb, APX005M, a humanized IgG1 mAb with a mutation in the Fc portion, is engineered to enhance interaction with Fc receptors to mediate antibody crosslinking. APX005M has demonstrated biological activity in human subjects and a favorable toxicity profile when given IV at doses up to 1 mg/kg body weight.  
Recently, Zippelius and co-authors [61] showed in preclinical models that CD40 engagement with an agonistic mAb leads to a T cell and IFN-γ dependent upregulation of PD-L1 on tumor infiltrating monocytes and macrophages, thereby feeding into a negative feedback loop, which hampers CD40 induced T-cell responses. This resistance mechanism was successfully circumvented by coadministration of PD-1/PD-L1 blocking antibodies.  
Similarly, other groups showed in preclinical models of pancreatic cancer that CD40 activation drove T-cell immunity and reversed the complete resistance of pancreatic tumors to checkpoint blockade.  
Combining a CD40 agonistic antibody with PD-1/PD-L1 blockade enhanced anti-tumor immunity and improved overall survival versus either monotherapy [19, 62, 63]. Studies elucidating the mechanism of APX005M action showed that it activates the CD40 signaling pathway, leading to APC activation, as seen in increased CD80, CD83, and CD86 expression and release of cytokines from human lymphocytes and monocytes. In particular, APX005M induced interleukin (IL)-12 p(70), TNF-α and IL-6 secretion from DCs. The CD40-agonistic activity of APX005M can be further enhanced by a toll-like receptor (TLR) 4 agonist. In comparison with 3 other CD40-agonistic antibody analogs (CP-870,893, SGN-40, and ADC-1013), APX005M is the most potent CD40 agonist. APX005M's CD40-agonistic activity depends on its ability to bind FcγRs. In in vitro cultures with T cells and DCs, APX005M was able to enhance antigen-specific Tcell proliferation and promote IFN-γ secretion. In combination with an antibody against programmed cell death ligand-1 (PD-L1), APX005M synergistically enhances antigen-specific T-cell responses.  
Upon binding to CD40-expressing tumor cells, APX005M was capable of inducing ADCP and tumor cell apoptosis. APX005M did not appear to have a substantive effect on normal human DC and Tcell counts, but could partially reduce B-cell counts in vitro [64].
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1.3.5 preclinical summary 1.3.5.1 cabiralizumab

The PK profile of cabiralizumab is complex and characterized by nonlinear clearance that is likely mediated by binding to CSF1R on cells. As monocyte and macrophage cells are dependent on CSF1R for viability, these target-bearing cells are reduced in number following cabiralizumab treatment, resulting in a decrease of target-mediated clearance. As target-mediated clearance becomes saturated at high or repeat doses, cabiralizumab clearance is similar to other human IgG antibodies. Three PD biomarkers correlate with cabiralizumab exposure in nonclinical studies: CSF1 serum levels, circulating CD16-positive peripheral blood monocytes (CD16+ monocytes), and serum markers of bone resorption (Trap5b and CTX). CSF1 serum levels rapidly rise and CD16+
monocyte levels rapidly fall in a dose-dependent manner that correlates closely with cabiralizumab plasma concentration. Saturation of the PD response is achieved at a low dose of cabiralizumab (3 mg/kg weekly) in cynomolgus monkeys. The half-maximal response (IC50) for reduction of CD16+ monocytes occurs at a serum concentration of approximately 3 µg/mL and the maximal response occurs at approximately 10 µg/mL. The level of CD16-negative (CD16–)
monocytes does not change with exposure to cabiralizumab.  
In the in *vivo* toxicology studies in cynomolgus monkeys, cabiralizumab was generally well tolerated. The most prominent clinical observation was reversible periorbital edema, seen after prolonged exposure to cabiralizumab. The onset of the edema did not show a clear relationship to exposure levels, but edema resolved after systemic clearance of the drug. Periorbital edema is a known side effect of drugs affecting the CSF1 pathway [31, 65]. The main hematologic change was a reversible decrease in circulating CD16+ monocytes, which was considered a PD effect.  
Cabiralizumab-related clinical chemistry effects included reversibly increased ALT, AST, CK, and LDH serum levels. These laboratory abnormalities were not associated with any histopathological evidence of liver, cardiac, or muscle tissue injury. Additionally, cardiac troponin, skeletal troponin (SkTnI), myoglobin, and aldolase did not show any changes further confirming the lack of any liver or muscle injury. The increased serum levels are attributed to diminished clearance of ALT, AST, CK, and LDH molecules from serum due to a reduced number of liver Kupffer cells. Kupffer cells are the normal clearance mechanism for these serum enzymes so a loss of macrophages leads to an elevation of these serum enzymes [66]. Accordingly, ALT, AST, CK, and LDH elevations are considered non-toxic and an indirect PD effect of cabiralizumab exposure. One histopathological finding was the reversible expansion of the submucosal collagen fibers by clear space and varying amounts of a blue, granular extracellular matrix (ECM) in a variety of tissues. This change was neither associated with inflammatory cells nor with any sign of degeneration or other alteration of the collagen fibers, fibroblasts, or the smooth muscle cells within the area of expansion. Because it was not associated with clinical signs and was reversible, it was deemed to be a non-adverse event. A similar observation was also seen in op/op mice that lack functional CSF1. The reduction of tissue macrophages is the likely cause of the observed accumulation of ECM due to a decreased clearance of glycosaminoglycans, especially hyaluronic acid, that are prominent in connective tissue and are normally catabolized by macrophages [67]. This change is also considered to be an indirect PD effect of cabiralizumab. The no-observable-adverse-effect level (NOAEL) for cabiralizumab was determined to be 100 mg/kg when administered for 13 weekly doses to cynomolgus monkeys, which provides a 32-fold safety factor based on body surface area calculation for the starting dose of 1 mg/kg in humans. For more detailed information or background on cabiralizumab, please refer to the Cabiralizumab Investigator's Brochure.
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1.3.5.2 nivolumab

Nivolumab has been shown to bind specifically to the human PD-1 receptor and not to related members of the CD28 family, such as ICOS, CTLA-4, and BTLA(Nivolumab Investigator's Brochure) . Nivolumab inhibits the interaction of PD-1 with its ligands, PD-L1 and PD-L2, resulting in enhanced T-cell proliferation and IFN-γ release *in vitro*[68] (Nivolumab Investigator's Brochure). Fluorescent-activated cell sorter (FACS) analysis confirmed that nivolumab binds to transfected Chinese hamster ovary (CHO) with human or cynomolgus monkey PD-1, but not to rat or rabbit PD-1 molecules. Nivolumab has also been shown to bind to PD-1 on activated human T cells expressing cell surface PD-1 or on virus-specific CD8+ T
cells from chronically infected hepatitis C virus patients [69, 70]. PD-1 inhibition in an MLR resulted in a reproducible concentration-dependent enhancement of IFN-γ release in the MLR up to 50 µg/mL. No effect was observed with a human IgG4 isotype control or CD4+ T cells and dendritic cell (DC) controls [71].  
In intravenous repeat-dose toxicology studies in cynomolgus monkeys, nivolumab was well tolerated at doses up to 50 mg/kg, administered weekly for 5 weeks, and at doses up to 50 mg/kg, administered twice weekly for 27 doses. Nivolumab-related findings were limited to a reversible decrease of 28% in triiodothyronine (T3) among the females administered 27 doses of 50 mg/kg nivolumab. No corresponding changes in the level of thyroxine (T4), thyroid-stimulating hormone (TSH), or histologic changes in the thyroid were observed. While nivolumab alone was well tolerated in cynomolgus monkeys, combination studies have highlighted the potential for enhanced toxicity when combined with other immunostimulatory agents[45]. Ipilimumab (BMS-734016), an anti-CTLA-4 monoclonal antibody that blocks the downregulation of T-cell activation, was used in combination with nivolumab to investigate the effects of concurrent inhibition of the PD-1 and CTLA-4 receptors in nonhuman primates[68]. Although gastrointestinal (GI) toxicity has not been observed in cynomolgus monkeys treated with nivolumab alone, dose-dependent GI toxicity was evident in cynomolgus monkeys treated weekly for 4 weeks with a combination of nivolumab and ipilimumab at combinations of 10 mg/kg and 3 mg/kg and 50 mg/kg and 10 mg/kg, respectively. GI effects have also been observed at a low incidence after ipilimumab administration [68].  
In addition, an enhanced pre- and post-natal development (ePPND) study in pregnant cynomolgus monkeys with nivolumab was conducted [68]. Administration of nivolumab at up to 50 mg/kg every 2 weeks was well tolerated by pregnant monkeys; however, nivolumab was determined to be a selective developmental toxicant when administered from the period of organogenesis to parturition at ≥ 10 mg/kg (area under the concentration-time curve [AUC] from time zero to 168 hours [AUC(0-168 h)] 117,000 µg•h/mL). Specifically, increased developmental mortality (including late gestational fetal losses and extreme prematurity with associated neonatal mortality) was noted in the absence of overt maternal toxicity. There were no nivolumab-related changes in surviving infants tested throughout the 6-month postnatal period. Although the cause of these pregnancy failures was undetermined, nivolumab-related effects on pregnancy maintenance are consistent with the established role of PD-L1 in maintaining fetomaternal tolerance in mice [72]. For more detailed information or background on nivolumab, please refer to the Nivolumab Investigator's Brochure.
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1.3.5.3 apx005m

Preclinical experiments with APX005M showed that it activates the CD40 signaling pathway, leading to APC activation, as demonstrated by an increased expression of CD80, CD83, and CD86 and by expression and release of cytokines from human DCs and lymphocytes. As a result of APC activation, APX005M enhances T-cell proliferation to alloantigen, triggers production of IFN-γ in response to viral antigens, and enhances T-cell response to tumor antigens. APX005M
combined with a TLR 4 agonist or an antibody against programmed death ligand 1 (PD-L1) synergistically enhances T-cell responses.  
In comparison with other CD40-agonistic antibodies, such as CP-870,893, SGN-40, and ADC1013 analogs, APX005M is the most potent CD40 agonist. APX005M did not appear to have a substantive effect on normal human DC and T-cell counts, but could partially reduce B cell counts in vitro. The potential for APX005M to induce expression of cytokines was evaluated with peripheral blood mononuclear cells (PBMC) obtained from normal humans and treatment naïve cynomolgus monkeys, including anti CD3 antibody as a positive control. Cytokine secretion differed significantly between species with much less secretion from monkey PBMCs compared with human PBMCs. These data suggest that APX005M is a strong CD40-agonistic antibody that can activate APCs (DCs, B cells, and monocytes) and in turn stimulate T-cell response. For more detailed information or background on APX005M, please refer to the APX005M Investigator's Brochure.
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1.3.6 clinical summary 1.3.6.1 cabiralizumab

The clinical summary is based on three clinical studies:  
1. Study FPA008-001 evaluated the safety of cabiralizumab as single or dual escalating doses in 48 healthy volunteers (36 cabiralizumab and 12 placebo). This study also evaluated the safety and efficacy of cabiralizumab administered as two or three doses, 14 days apart, in 18 rheumatoid arthritis patients. This study has been completed.  
2. Study FPA008-002 is evaluating the safety and efficacy of cabiralizumab monotherapy for six months in approximately 40 patients with pigmented villonodular synovitis (PVNS).  
3. Study FPA008-003 is evaluating the safety and efficacy of cabiralizumab as monotherapy and in combination with nivolumab in approximately 295 patients with advanced cancers.
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1.3.6.1.2 clinical pharmacology summary (pharmacokinetics

The available PK, ADA, and nonclassical CD16+ monocyte status following cabiralizumab treatment with either monotherapy or in combination with nivolumab were characterized in three trials: FPA008 001, FPA008-002, and FPA008-003. The PK, ADA, and nonclassical CD16+ monocyte data from Study FPA008-003 are summarized below; data from Studies FPA008 001 and FPA008-002 are presented in the cabiralizumab IB. The PK profile of cabiralizumab is characterized by linear and nonlinear clearance pathways, with the latter likely mediated by binding to CSF1R on cells. As monocyte and macrophage cells are dependent on CSF1R for viability, these target-bearing cells are reduced in number following cabiralizumab treatment, resulting in a decrease of target-mediated clearance. Once target mediated clearance is saturated at high or repeat doses, cabiralizumab clearance is similar to other human IgG antibodies.
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1.3.6.1.3 clinical safety summary of

Thirty six healthy volunteers and 18 RA subjects received cabiralizumab in Study FPA008 001. No dose-limiting toxicities (DLTs) were reported and no unexpected treatment related adverse events (AEs) have been reported from RA subjects treated with three doses up to 6 mg/kg.
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1.3.6.1.3.2 study fpa008-002 - pigmented

Study FPA008-002 is currently ongoing and is evaluating cabiralizumab as monotherapy in subjects with PVNS. Details relating to safety are included in the latest version of the cabiralizumab IB (FivePrime, 2017).
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1.3.6.1.3.3 study fpa008-003 - advanced

As of August 1, 2017, cabiralizumab-related AEs were reported in 169 of 195 subjects (87%) treated Q2W in Phase 1b of Study FPA008-003. The AEs reported in more than 10% of the subjects included: CK increased (77 subjects, 40%); periorbital edema (73 subjects, 73%); AST increased (65 subjects, 33%); fatigue (61 subjects, 31%); ALT increased and pruritus (32 subjects each, 16%); amylase increase and rash (30 subjects each, 15%); lipase increase (29 subjects, 15%); nausea (27 subjects, 14%); and LDH increased (20 subject, 10%). Cabiralizumab-related Grade 3 AEs in Phase 1b were predominantly enzyme elevations of CK (14 Grade 3 and 14 Grade 4 events), LDH (one Grade 3 and one Grade 4 event), Alkaline phosphate ([ALP] two Grade 3 events), ALT (two Grade 3 events), and AST (10 Grade 3 events). Other related AEs that were Grade 3 and reported in 2 or subjects included 13 events of amylase increased (12 Grade 3 and one Grade 4), 15 events of Grade 3 lipase increased (14 Grade 3 and one Grade 4), 11 events of Grade 3 Fatigue, and three events of Grade 3 hypertension. Twenty-six of 195 subjects (13%) experienced a cabiralizumab-related SAE in Phase 1b. The SAEs reported in two or more subjects included: CK increased (three subjects, 3%), brain edema, pneumonitis, hyponatremia (two subjects each, 1%). Also SAEs included one event of Grade 4 CK increased (related to cabiralizumab and nivolumab), one event of Grade 3 autoimmune colitis (related to nivolumab), and one event of Grade 3 hypopituitarism (related to cabiralizumab and nivolumab). Two Grade 5 SAEs prior to study treatment discontinuation have occurred in Phase 1a of Study FPA008-003: one subject had a Grade 5 pulmonary embolus (not related) and a Grade 5 pneumonitis (related to both drugs; refer to Appendix 7 for management recommendations in cases of pneumonitis) and the other subject had a Grade 5 hypoxic respiratory failure secondary to pneumonia (not related). Six Grade 5 SAEs prior to study treatment discontinuation were reported in Phase 1b of this study. These included 1 sudden cardiac death (unrelated), 1 death due to tumor thrombus blocking a major blood vessel (unrelated), 2 patients with respiratory failure (unrelated), 1 patient with acute respiratory distress (related), and 1 patient with acute respiratory failure (related). Data from the Phase 1 dose escalation study of cabiralizumab +/- nivolumab in advanced solid tumors was presented at the Society for Immunotherapy of Cancer's 2017 Annual Meeting. Cabiralizumab administered at 4 mg/kg every 2 weeks depleted circulating non-classical monocytes and had a tolerable safety profile when administered with or without nivolumab. The most common treatment-related adverse events attributed to cabiralizumab were elevations in LDH, CK, and serum transaminases without elevation of bilirubin. Grade 3-4 serum enzyme elevations occurred in 9/24 (38%) patients on the cabiralizumab monotherapy arm and in 40/205
(20%) patients on the cabiralizumab plus nivolumab arm. All cases of periorbital edema except for one was grade 1-2, occurring in 5/24 (21%) patients on the cabiralizumab monotherapy arm and in 84/205 (41%) patients on the cabiralizumab plus nivolumab arm. In heavily pre-treated patients with pancreatic cancer, durable clinical benefit was observed in 5/31 (16%) patients with a confirmed ORR of 13%. All confirmed responses occurred in patients with MSS disease who historically have not received benefit from anti-PD-1/PD-L1 agents and a study of cabiralizumab plus nivolumab with or without chemotherapy in pancreatic cancer (NCT03336216) is planned.
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1.3.6.2 nivolumab 1.3.6.2.1 clinical pharmacology

The pharmacokinetics (PK) of nivolumab was studied in subjects over a dose range of 0.1 to 20 mg/kg administered as a single dose or as multiple doses of nivolumab every 2 or 3 weeks. Based on a population pharmacokinetic (PPK) analysis using data from patients with various tumor types, including melanoma, NSCLC, and RCC and a time varying CL model, nivolumab clearance was shown to decrease over time, with a median maximal reduction from baseline values of approximately 25% resulting in a geometric mean steady state clearance (CLss) (% coefficient of variation [CV%]) of 8.2 mL/h [53.9%]. The decrease in CLss is not considered to be clinically relevant. The geometric mean [CV%] volume of distribution at steady state (Vss) is 6.8 L (27.3%), and elimination half-life (t1/2) is 25 days (77.5%). Steady-state concentrations of nivolumab were reached by approximately 12 weeks when administered at 3 mg/kg every 2 weeks, and systemic accumulation was approximately 3.7-fold. The exposure to nivolumab increased dose proportionally over the dose range of 0.1 to 10 mg/kg administered every 2 weeks. The clearance of nivolumab increased with increasing body weight. The PPK analysis suggested that the following factors had no clinically important effect on the CL of nivolumab: age (29 to 87 years), gender, race, baseline LDH, PD-L1 status, solid tumor type, baseline tumor size, and hepatic impairment. The effect of renal impairment on the CL of nivolumab was evaluated in subjects with mild
(GFR < 90 and ≥ 60 mL/min/1.73 m2; n=379), moderate (GFR < 60 and ≥ 30 mL/min/1.73 m2; n=179), or severe (GFR <30 and ≥ 15 mL/min/1.73 m2; n=2) renal impairment compared to subjects with normal renal function (GFR ≥ 90 mL/min/1.73 m2; n=342) in the PPK analysis. No clinically important differences in the CL of nivolumab were found between subjects with mild or moderate renal impairment and subjects with normal renal function. Data from subjects with severe renal impairment are too limited to draw conclusions on this population [45].
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1.3.6.2.2 safety summary of nivolumab

Overall, the safety profile of nivolumab monotherapy as well as combination therapy is manageable and generally consistent across completed and ongoing clinical trials with no maximum tolerated dose (MTD) reached at any dose tested up to 10 mg/kg. There was no pattern in the incidence, severity, or causality of AEs to the nivolumab dose level. Most AEs were lowgrade (Grade 1 to 2) with relatively few related high-grade (Grade 3 to 4) AEs. Most high-grade events were manageable with the use of corticosteroids or hormone replacement therapy (endocrinopathies) as instructed in the management algorithms provided in the Nivolumab Investigator's Brochure. A total of 39 and 306 patients with selected recurrent or treatment-refractory malignancies have been treated in a completed Phase 1 single-dose study (CA209001) and an ongoing Phase 1 multi-dose study (CA209003), respectively. As the safety profile from CA209003 to date is consistent with that observed for CA209001, only data from the larger and more recent study, CA209003, are presented below. In CA209003 (n=306, including 129 patients with NSCLC), as of the 05-Mar-2013 database lock, drug-related AEs of any grade occurred in 75% of patients. The most frequent drug-related AEs occurring in at least 5% of patients included fatigue (28%), rash (15%), diarrhea (13%), pruritus (11%), nausea (9%), decreased appetite (9%), decreased hemoglobin (6%), and pyrexia (6%). The majority of events were low grade, with Grade 3/4 drug-related AEs observed in 17% of patients. The most common Grade 3/4 drug-related AEs occurring in at least 1% of patients were fatigue (2%), pneumonitis (1%), diarrhea (1%), abdominal pain (1%), hypophosphatemia (1%), and lymphopenia (1%). Drug-related SAEs occurred in 14% of patients; 8% were Grade 3/4 including pneumonitis (1%) and diarrhea (1%). The spectrum, frequency, and severity of drug-related AEs were generally similar across the dose levels tested. A review of the safety data by tumor type (RCC, NSCLC, metastatic castration-resistant prostate cancer [mCRPC], colorectal cancer [CRC], and melanoma) also did not show any clinically meaningful differences in the proportion of patients with AEs noted across tumor type. Select AEs with potential immune-related causality, previously termed "immune-related adverse events" or "adverse events of special interest" were also analyzed taking into account multiple events, with rates adjusted for treatment duration. Most events occurred within the first 6 months of therapy; cumulative or novel toxicities were not observed with prolonged drug exposure. Nineteen of 306 patients (6%) experienced Grade 3/4 treatment-related select AEs. Fifty-two of 230 patients (23%) with drug-related AEs required management with systemic glucocorticoids and/or other immunosuppressive agents. Twenty-one of 52 (40%) resumed nivolumab therapy after toxicity resolved, while the others discontinued therapy. Although tumor progression was the most common cause of mortality, there were 3 drug-related deaths associated with Grade 3/4 pneumonitis. Pneumonitis (any grade) occurred in 12 of 306 patients (4%), and Grade 3/4 pneumonitis occurred in 4 patients (1%), with clinical presentations ranging from asymptomatic radiographic abnormalities to progressive, diffuse pulmonary infiltrates associated with cough, fever, and/or dyspnea. No clear relationship between the occurrence of pneumonitis and tumor type, dose level, or treatment duration was noted. In 9 of 12 patients, pneumonitis was reversible after treatment discontinuation and/or with immunosuppressive therapy (glucocorticoids, infliximab, or mycophenolate).  
Additional details on the safety profile of nivolumab, including results from other clinical studies, are also available in the nivolumab IB and Opdivo® package insert [45].
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1.3.6.3 apx005m 1.3.6.3.1 clinical pharmacology

APX005M is an IgG1 humanized mAb with the S267E mutation at the Fc region. APX005M binds with high affinity to human CD40 (Kd = 1.2 × 10-10 M) and monkey CD40 (Kd = 3.5 × 10−10 M), but does not cross-react with mouse or rat CD40. APX005M blocks the binding of CD40 to CD40L. The APX005M binding epitope has been mapped to 2 specific regions on CD40. These are 92TSEACESCVLHRSCSP107 and 125PCPVGFFSNVSSAFEKCHPW144. The region 92TSEACESCVLHRSCSP107 is known as a CD40L binding domain. It has been shown that CD40L-blocking antibodies tend to have more potent CD40 agonistic activities than CD40L-non-blocking antibodies [73]. The direct cytotoxicity effect and the antibody effector functions such as Antibody-dependent cellular phagocytosis (ADCP) of APX005M were determined in CD40 positive human lymphoma xenograft models in mice. In human lymphoma Ramos models, APX005M was capable of inhibiting tumor growth in a dose-dependent manner, and eradicated established tumors at 3 mg/kg and 10 mg/kg. A significant anti-tumor effect was also observed in the rituximab-resistant Namalwa model [64]. These data suggest that APX005M, as a single agent, can induce potent growth inhibition of CD40-expressing human tumors. Preliminary human data shows that APX005M induces a dose-dependent activation of APCs (as demonstrated by increases in expression of activation markers such as CD54, CD70, CD80, CD86, HLA-DR), T cell activation and increases in circulating levels of IL12, INF-γ, TNF-α and IL6.
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1.3.6.3.2 pharmacokinetics of apx005m

Nonclinical pharmacokinetics (PK) of APX005M were determined in a Good Laboratory Practice (GLP) repeat-dose toxicology study using cynomolgus monkeys. Weekly intravenous
(IV) administration of 5 doses of APX005M was well tolerated at 0.3, 3, and 30 mg/kg. The PK properties of APX005M are typical of other mAbs and comprise low clearance (average range of 0.401–7.27 mL/h/kg), small volume of distribution (average range of 57–80.1 mL/kg), and long terminal half-life (average >66 hours at 3 mg/kg and 30 mg/kg). Positive anti-drug antibodies
(ADA) titers were observed in all animals in the low-dose group (0.3 mg/kg) but not in the highdose group (30 mg/kg) [16]. Based on these results, the no observed adverse effect level
(NOAEL) was considered 30 mg/kg. There are limited human PK data with APX005M at this time. Exposures to APX005M at dose levels of 0.03 mg/kg or less were for the most part below the limit of quantitation (BLOQ). IV administration of APX005M at doses between 0.1 and 1 mg/kg lead to rapid increase in serum concentrations, reaching a maximum just after the end of the infusion. Levels declined rapidly thereafter and were for the most part BLOQ between 24 and 168 hours after the start of dosing.  
Increases in the dose of APX005M (0.1 mg/kg to 1 mg/kg) led to approximately doseproportional increases in maximum serum concentration (Cmax) and area under the curve at the last measurable time point (AUC0–t). No accumulation of APX005M was observed with every 21 days dosing.
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1.3.6.3.3 safety summary of apx005m

Study APX005M-001 is a first in human phase 1 dose escalation study of APX005M with 8 preplanned dose levels. APX005M was administered to study subjects at doses up to 1 mg/kg. At the 1 mg/kg dose level, 1 out of 6 dose limiting toxicity (DLT)-evaluable subjects experienced a DLT (grade 4 cytokine release syndrome). Two additional subjects at the 1mg/kg dose level experienced serious adverse events (SAE) in later cycles (Grade 3 cytokine release syndrome and Grade 4 thrombocytopenia). On May 2, 2016 Apexigen decided to discontinue dose escalation and enroll up to 6 subjects in dose level 0.6 mg/kg (originally designed as an intermediate de-escalation dose level) and an additional 3 subjects at the previously completed dose level 0.3 mg/kg to better characterize the safety and pharmacodynamics (PDn) of APX005M and to help establish the single agent recommended phase 2 dose (RP2D). The RP2D for APX005M as a single agent every 21 days is 0.3 mg/kg body weight.  
As of the data cutoff date of 14 April 2017, 432 AEs have been reported in the 30 subjects enrolled in Study APX005M-001. The majority of AEs (371/432 [85.9%]) were mild or moderate (≤ Grade 2) in severity, 44 events (10.2%) were reported as Grade 3, and 8 events (1.9%) were reported as Grade 4. No Grade 5 events have been reported.  
As of 14 August 2017, 17 SAEs had been reported in 6 subjects. With the exception of cytokine release syndrome and thrombocytopenia, all SAEs were considered unrelated to APX005M. Cytokine release syndrome is an expected on-target side effect of CD40 agonists. No thromboembolic or bleeding events have been reported to date for APX005M.  
APX005M demonstrated a dose-dependent activation of APCs (as demonstrated by increases in expression of activation markers such as CD54, CD70, CD80, CD86, HLA-DR), T cell activation and increases in circulating levels of IL12, INF-γ, TNF-α and IL6.  
For further details on the APX005M-001 study please refer to latest version of the APX005M Investigator's Brochure [64]. Symptoms associated with cytokine release syndrome (including but not limited to flushing, itchiness, chills, fever, rash, tachycardia, hypotension, hypertension, rigor, and myalgia) after administration of APX005M are possible and have been observed in some of the subjects receiving APX005M. Guidance for monitoring and management of cytokine release syndrome are included in this protocol and in the APX005M Investigator's Brochure. Transient transaminase elevations (≤ Grade 2) have been observed in several subjects with liver metastases, which were not associated with a particular dose of APX005M. Six subjects with liver metastases enrolled in the study experienced a transient increase in total bilirubin. Liver function test abnormalities tend to resolve to baseline within 7 days from APX005M administration.  
Transient decreases in peripheral blood lymphocyte count in general and B-cell count in particular have been observed for APX005M as well as for other CD40-agonistic mAbs and are believed to be a PDn effect. Transient decreases in platelet counts were observed for some of the subjects receiving higher doses of APX005M but were not associated with bleeding or other clinical manifestations. Other symptoms might also occur, including allergic reactions, which could be severe, pulmonary edema, and rarely, thromboembolic events, myocardial infarction and/or death. In the ongoing Phase 1 study APX005M-001, APX005M demonstrated a dose-dependent activation of APCs, T cell activation and increases in circulating levels of cytokines. The biological effects and the overall tolerability of APX005M up to 1mg/kg body weight suggest a best in class profile for APX005M and the possibility of a safe and tolerable combination with other immunomodulatory antibodies such as nivolumab.
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1.4 clinical experience involving serum

The safety and preliminary efficacy of cabiralizumab is currently being evaluated in 3 clinical trials. A common feature observed across the clinical trials is an elevation of AST, CK, and LDH after the administration of cabiralizumab. These alterations are the consequence of the direct effect of anti-CSF1R antibodies on the Kupffer cell in the liver that results in a depletion of these cells. Depletion of Kupffer cells allows the enzymes, which are released following normally occurring liver cell turnover, to enter circulation (where they are measured by routine laboratory assessment) rather than being absorbed by the Kupffer cells. Elevated liver enzymes, thus, represent a PD marker rather than a safety signal. The observed elevations were asymptomatic not permanent and not associated with clinical sequelae. Similar effects have been observed across other CSF1R targeted agents (see cabiralizumab IB for additional details). There is a significant body of evidence from the cabiralizumab preclinical and clinical experience as well as from others in the field that suggest elevations of serum enzymes caused by inhibition of the CSF1R pathway are reversible and are not associated with clinical sequelae [66, 74-78].
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1.4.1 serum enzyme elevations with

In Study FPA008-003, 34 subjects have been dosed as part of Phase 1a dose escalation (24 in cabiralizumab monotherapy and 10 in cabiralizumab + nivolumab combination therapy) and 195 subjects have been dosed as part of Phase 1b dose expansion as of 1 August 2017. In Phase 1a, CK was elevated in 11 of 34 subjects (32%), and 3 events (1%) were Grade 3 or higher. AST was elevated in 16 of 34 subjects (47%), and 10 events (29%) were Grade 3 or higher. ALT was elevated in 4 of 34 subjects (17%), and none of these were Grade 3 or higher. In Phase 1b, CK was elevated in 82 of 195 subjects (42%), and 29 events (15%) were Grade 3 or higher. AST was elevated in 76 of 195 subjects (39%), and 14 events (7%) were Grade 3 or higher. ALT was elevated in 39 of 195 subjects (20%), and five events (3%) were Grade 3 or higher.  
The serum enzyme elevations for Studies FPA008-001 and FPA008-002 follow a similar pattern. Please refer to the cabiralizumab IB for more detailed information about these serum enzyme elevations.
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1.4.2 serum enzyme elevations with

The hepatic enzyme changes caused by cabiralizumab and nivolumab are due to different mechanisms that should not be additive. For cabiralizumab, the elevations are hypothesized to be due to the on-target effect of Kupffer cell reduction and not to liver cell toxicity. Hepatic AEs, including possible drug induced liver injury (DILI) cases, have been managemable using an established management algorithm and thus do not meaningfully alter the benefit/risk of nivolumab in the advanced malignancy populations. Guidelines for management and safety assessments focused on the liver can be found in Section 4.8 and Section 4.9.
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1.4.3 serum enzyme elevations in

Transient transaminase elevations (≤ Grade 2) with APX005M administration have been observed in several subjects with liver metastases, which were not associated with a particular dose of APX005M. Six subjects with liver metastases enrolled in the study experienced a transient increase in total bilirubin. Liver function test abnormalities tend to resolve to baseline within 7 days from APX005M administration. Elevations of ALT, AST, CK, and LDH were not associated with signs or symptoms of hepatic or muscle injury as demonstrated by concurrent normal total bilirubin, INR, aldolase, and troponin levels. Please refer to the APX005M Investigator's Brochure for more detailed information about serum liver ezyme elevations and their management, as outlined in Section 4.8 and Section 4.9. Additional laboratory abnormality management algorithms are included to help manage elevations of CK in Section 4.8 and Section 4.9.
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2. objectives 2.1 phase 1a

- To assess the safety and tolerability of APX005M in combination with cabiralizumab - To assess the safety and tolerability of APX005M in combination with cabiralizumab and nivolumab
- To determine the recommended RP2D of APX005M in combination with a fixed dose of cabiralizumab and nivolumab in advanced melanoma, NSCLC, and RCC
2.1.2 **Secondary**
- To determine the AE profile of this combination
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2.1.3 exploratory

- To characterize the pharmacokinetic (PK) profile of APX005M when administered in combination with cabiralizumab and nivolumab
- To characterize the pharmacodynamic (PD) profile of APX005M when administered in combination with cabiralizumab and nivolumab
- To further characterize the PD profile and immunogenicity of APX005M in combination with cabiralizumab and nivolumab by analyses of pre-treatment and on-treatment tumor biopsies and blood collection
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2.2 phase 1b objectives 2.2.1

- To determine the objective response rate (ORR) using RECIST v1.1 to APX005M in combination with cabiralizumab and nivolumab in 3 separate patient cohorts: advanced melanoma, NSCLC, and RCC whose tumors are resistant to anti-PD-1/PD-L1 therapy
- To evaluate the safety and tolerability of the RP2D of APX005M in combination with cabiralizumab and nivolumab
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2.2.2 secondary

- To determine the PFS of patients with melanoma, NSCLC or RCC treated with APX005M in combination with cabiralizumab and nivolumab whose tumors are resistant to anti-PD-1/PD-L1 therapy.  
- To determine the OS of patients with melanoma, NSCLC or RCC treated with APX005M in combination with cabiralizumab and nivolumab whose tumors are resistant to anti-PD-1/PD-L1 therapy.  
- To assess the association of selected biomarker measures and clinical efficacy measures using pre-treatment and on-treatment tumor biopsies and blood collection
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2.2.3 exploratory

- To identify immune correlates that are associated with clinical response or resistance to the triple combination. Biomarker analyses will include study of pre-treatment and ontreatment biopsies as well as analyses of select serum and PBMC markers.
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3. investigational plan 3.1 study

This study is a Phase 1/1b, open-label, single institution, dose escalation and dose expansion study to evaluate the efficacy, safety, and tolerability of APX005M in combination with nivolumab and cabiralizumab in patients with advanced melanoma, NSCLC, and RCC. Nivolumab is a fully human monoclonal antibody directed against PD-1. Cabiralizumab is a humanized monoclonal antibody directed against CSF1R. APX005M is a humanized IgG1 agonistic monoclonal antibody that binds CD40. Patients will be sequentially enrolled in the phase 1 dose escalation portion in 6 cohorts using a standard 3 + 3 design to determine safety, characterize the adverse events, and establish the MTD of APX005M in combination with cabiralizumab and nivolumab. A minimum of 48 hours observation will be required after each patient is enrolled in cohorts 1-6, before a subsequent patient can be enrolled. Approximately 3 patients will be enrolled into each cohort. Cohorts 1, 3, and 5 will include cabiralizumab at the fixed RP2D of 4 mg/kg and dose escalation of APX005M. Cohorts 2, 4, and 6 will include nivolumab at 240 mg, cabiralizumab at 4 mg/kg, and dose escalation of APX005M.  
All study drugs will will be given on Day 1 of each 14-day treatment cycle. Pre-medications will be given before nivolumab. Nivolumab will be administered as an IV infusion over 30 minutes first followed by a 30-minute break and then cabiralizumab will be administered as an IV infusion over 30 minutes. After another 30-minute break, APX005M will be administered as an IV infusion over 60 minutes. Patients must remain near the vicinity of a hospital with rapid access to an intensive care unit setting during the initial 48 hour period after treatment for the first two treatment cycles. Dose escalation will be based on the number of DLTs experienced during the DLT evaluation interval as determined by the PI and Industry Collaborators (see Section 3.1.2.1.1 for DLT criteria). The DLT evaluation interval begins on the first day of treatment and continues for 28 days. The phase 1b portion will enroll patients in three cohorts (advanced melanoma, NSCLC, and RCC) to study the RP2D of APX005M in combination with nivolumab and cabiralizumab.
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3.1.1 screening period

All screening evaluations must be completed and reviewed by the Investigator for the enrollment process to confirm that patients meet all eligibility criteria before the first infusion of study drug. Written informed consent for participation in the study must be obtained before performing any study specific screening tests or procedures. Screening assessments will be performed within 28 days prior to the first dose of study drug unless otherwise specified.  
The Investigator may repeat qualifying lab tests and vitals/ECGs prior to enrollment if a nonqualifying finding is considered an error or an acute finding is likely to meet eligibility criteria upon repeat testing. Study procedure-related AEs that occur after signing of the ICF and before administration of the first study drug dose will be collected during this period.
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3.1.2 treatment period 3.1.2.1 phase

Phase 1 consists of three dose escalation cohorts of APX005M in combination with cabiralizumab alone, and three dose-escalation cohorts of APX005M in combination with nivolumab and cabiralizumab. A minimum of 3 patients will be enrolled in each cohort. The planned dose levels and schedules for the Phase 1 dose escalation cohorts are as follows in Table 2:
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table 2

| Cohort   | Nivolumab   | Cabiralizumab   | APX005M   |
|----------|-------------|-----------------|-----------|
| (mg)     | (mg/kg)     | (mg/kg)         |           |
| 1        | Not given   | 4               | 0.03      |
| 2        | 240         | 4               | 0.03      |
| 3        | Not given   | 4               | 0.1       |
| 4        | 240         | 4               | 0.1       |
| 5        | Not given   | 4               | 0.3       |
| 6        | 240         | 4               | 0.3       |  
A minimum of 48 hours observation will be required after each patient is enrolled in cohorts 1-6, before a subsequent patient can be enrolled. As depicted in Figure 6, accrual to cohorts 2 and 3 will only start after the last patient in cohort 1 has been observed for toxicity for at least two 14day cycles (28 days in total); accrual to cohort 4 will commence when the last patients on cohorts 2 and 3 have been observed for at least two 14-day cycles, accrual to cohort 5 will commence only after the last patient on cohort 3 has been observed for at least two 14 day cycles, and accrual to cohort 6 will accrue once the last patients on cohorts 4 and 5 have been observed for at least two 14-day cycles. Doses will be de-escalated as determined by toxicities.  
Figure 6  
 All dose escalation decisions will be based on assessment of toxicity, overall safety, and tolerability. Dose escalation decisions will be agreed upon by the PIs and study collaborators. Prior to initiating each new dose level or expanding an existing dose level, a safety teleconference will be held wherein the PIs and study collaborators will review patient data, including but not limited to the available demographics, dosing, concomitant medications, hematology, serum chemistry, and AEs; and confer and document agreement that dose escalation or expanding an existing dose level is considered appropriate. If the PIs collectively agree, following review of safety, PK, and PD data (if available), that a different dose escalation scheme should be used than the one outlined, this will be permitted. Review of safety, PK, and PD profiles may inform decisions to add cohorts with alternative dose levels or dose regimens (e.g., less frequent dosing) in order to reach an optimal target exposure. For the purpose of dose escalation, we will require a 28 day observation period from the time the last patient in a given cohort was treated. For the purpose of calculating the MTD, we will require a minimum of 28 days of observation for each **patient.** Dose escalation in Phase 1 will proceed as follows:
If none of the first 3 evaluable patients in a dose cohort experience a DLT in the first two cycles, then the next 3 patients will be treated at the next higher dose cohort. If 1 of 3 patients within a cohort experiences a DLT in the first two cycles, then 3 additional patients will be added to that cohort. If a second patient experiences a DLT at that dose level in the first two cycles, the next cohort will not be initiated, and the dose of one or more drugs will be de-escalated. Patients at each dose level will be evaluated for at least 28 days from the start of treatment before additional patients can be treated at a higher dose level. If DLTs are observed in 2 or more patients within a cohort, the maximum tolerated dose (MTD) will have been exceeded and no further patients will be treated at that dose level. DLT evaluation and enrollment decisions will follow the guidance in Table 3.  
| Number of Patients with DLT at a Given Dose Level   | Dose Escalation Decision Rule                                                                           |
|-----------------------------------------------------|---------------------------------------------------------------------------------------------------------|
| 0/3                                                 | Escalation will occur into the next highest dose cohort                                                 |
| 1/3                                                 | Enroll 3 additional patients at current dose level Stop enrollment. Enroll 3 more patients at the lower |
| >2/3                                                | dose level, if only 3 were previously entered, or at an intermediate dose level.                        |
| 1/6                                                 | Open next cohort                                                                                        |
| >2/6                                                | Stop enrollment. Enter 3 more patients at the lower dose level at an intermediate dose level.           |  
Dose escalation will continue until either the MTD or maximum planned dose of APX005M is reached, with a minimum of 3 patients enrolled in each cohort.  
The MTD is defined as the highest dose associated with DLTs in less than or equal to 33% of patients receiving APX005M in combination with cabiralizumab or with cabiralizumab and nivolumab, administered during the DLT period. This will normally be the dose recommended for further study; however, based on review of safety, PK, and PD (if available) data, the RP2D could be lower than the MTD. If the MTD is not reached, and the highest evaluated APX005M dose in combination with cabiralizumab and nivolumab is well tolerated, the data will be reviewed to assess whether further dose escalations of APX005M are warranted.  
In order to calculate the **MTD and RP2D**, every patient included in this calculation must have received at least 2 doses of study drugs and have been monitored for at least 2 full cycles (28 days). If a patient does not receive 2 doses of study drugs and does not complete safety assessments (e.g., safety lab and/or AE reporting) in the first 28 days for reasons other than drugrelated AEs (e.g., disease progression or withdrawal of consent), then an additional patient will be enrolled into the cohort so that the cohort has at least 3 patients evaluable for 28 days. All such discussions and decisions will be documented as part of the dose escalation decisionmaking process.
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3.1.2.1.1 dose limiting toxicity

A DLT is defined as any of the following AE (graded using National Cancer Institute [NCI] Common Terminology Criteria for Adverse Events [CTCAE] v5.0), which occurs during the first 28-days of cabiralizumab/APX005M or nivolumab/cabiralizumab/APX005M administration that is not clearly due to a cause other than the study medication (e.g., disease under study, car accident).  
1. Grade 4 neutropenia or grade 4 thrombocytopenia lasting ≥ 7 days 2. Neutropenic fever of any duration 3. Grade > 3 thrombocytopenia if associated with:  
a. Clinically significant bleeding or requirement for platelet transfusion, or b. A life-threatening bleeding event which results in urgent intervention and admission to an Intensive Care Unit
4. Any grade ≥3 non-hematologic toxicity (not laboratory) **with the exception of**:
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5. any grade >= 3

a. Immune suppression other than corticosteroids is required to treat the subject, or  
b. The abnormality itself soley leads to hospitalization, or
c. The abnormality persists for >1 week. For AST/ALT > 12x ULN, DLT is defined as not improving after >7 days or the value increases by more than 5X ULN over 72 hours; Page 54 of 135
- Grade 3 tumor flare (defined as local pain, irritation, or rash localized at sites of known or suspected tumor)
- Grade 3 joint pain - Grade 3 fatigue lasting less than 1 week
- Serum elevations of CK > 15X ULN and < 20X ULN that last for < 7 days - Grade 3 or Grade 4 electrolyte abnormalities that are not complicated by associated clinical adverse experiences, last less than 72 hours and either resolve spontaneously or respond to conventional medical intervention
- Grade 3 nausea, vomiting, or diarrhea lasting less than 72 hours, and either resolves spontaneously or responds to conventional medical intervention including adequate anti-emetics or other supportive care
- Grade 3 or grade 4 elevation of amylase or lipase not associated with clinical or radiographic evidence of pancreatitis
- Grade 3 fever not associated with hemodynamic compromise (eg, hypotension, clinical or laboratory evidence of impaired end-organ perfusion)
- Grade 3 endocrinopathy that is well controlled by hormone replacement
- Grade 3 infusion reaction that returns to Grade 1 in < 6 hours e.g. if an AST of 300 rises to 500 in 72 hours, where AST 36 is ULN, a rise of 200 is greater than 5X ULN (180) and would be considered a DLT  
6. Any Grade ≥ 3 AST/ALT elevation combined with total bilirubin >2x ULN (for patients with Gilbert's syndrome, use bilirubin > 2X baseline) or INR > 1.5 not on warfarin 7. Failure to recover from a treatment-related AE to baseline or ≤ Grade 1 within 12 weeks of last dose of investigational product (except Grade 2 alopecia and Grade 2 fatigue)
8. Any death not clearly due to the underlying malignancy or extraneous causes (e.g. car accident)
9. Recurrence of Grade 4 rash, or other Grade 3 immune-related AE (irAE), or Grade 4 infusionrelated AE. Recurrent grade 3 infusion reactions should be discussed with the study PI.  
10. Any toxicity requiring dose reduction of APX005M or permanent discontinuation of any of the study drugs.
irAE is defined as a clinically significant AE that is associated with study drug exposure, with the exception of AEs related to cytokine release, attributable to APX005M, and is consistent with an immune-mediated mechanism. Certain toxicities, even if already resolved, will make it unacceptable to advance to subsequent cohorts as planned, including but not limited to:  
- Grade 4 myocarditis; Grade 3 myocarditis will need to be discussed with the study PI - Grade 3 neurotoxicity with the exception of peripheral neuropathy - Grade 4 pneumonitis
- Bone marrow aplasia
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3.1.2.2 phase 1 dose escalation

Patients from the Phase 1 dose escalation combination cohorts are allowed to continue to receive APX005M in combination with nivolumab and/or cabiralizumab at the same dose levels until disease progression, unacceptable toxicity, or other reason for treatment discontinuation.  
If a complete response (CR) is achieved, patients will be allowed to continue on therapy until disease progression, unacceptable toxicity, or other reason for treatment discontinuation.
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3.1.2.3 phase 1b expansion cohorts

To further characterize safety and efficacy of APX005M in combination with nivolumab and cabiralizumab, Phase 1b will enroll patients of 3 advanced cancer types: melanoma, NSCLC, and RCC. Enrollment in Phase 1b will begin when an RP2D for APX005M has been identified based on overall safety, tolerability, PK, and PD (if available) data. During enrollment of any expansion cohort, if the observed number of responses makes it unlikely to achieve a target response rate for that indication, then further recruitment to that cohort may be suspended or terminated.
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3.1.3 end-of-treatment follow-up period

All patients should return to the clinic 28 (±7) days and 100 (±7) days from their last dose of study drug to complete the End-of-Treatment Follow-up Period, irrespective of whether a patient is discontinued from the study drug at a planned visit or mid-cycle. AEs will be assessed until resolution, return to baseline, or are stabilized per treating Investigator's assessment. Adverse event reporting will continue until 100 (±7) days after the last dose of study drug or until initiation of subsequent anti-cancer therapy.
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3.1.4 long-term follow-up

Patients should continue onto Long-Term Follow-up after completing the End-of-Treatment Follow-up Period. Patients will be followed every 12 weeks for survival, or more frequently as needed. Patients who discontinue treatment while showing clinical benefit (CR, partial response [PR], or stable disease [SD]) should have tumor assessments during these visits for duration of response. Long-term Follow-up for survival may be conducted by telephone, rather than by an in-person visit, once tumor progression is determined or use of subsequent anti-cancer therapy has been initiated. During the Long-Term Follow-up Period, if the patient undergoes local therapy (e.g., resection, radiation) or new systemic therapy is initiated, this should be documented.
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3.1.5 study duration

Patients who receive study drug(s) may continue as long as they experience clinical benefit in the opinion of the Investigator or until unacceptable toxicity or symptomatic deterioration attributed to disease progression as determined by the Investigator after an integrated assessment of radiographic data, biopsy results (if available), and clinical status, or withdrawal of consent. The maximum time allowed time on study treatment will be up to 2 years unless the study is terminated sooner by the Sponsor.
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3.1.6 stopping rules 3.1.6.1 stopping

Management of drug-related toxicities and laboratory abnormalities will follow the guidelines outlined in Section 4.8 and Section 4.9. The Sponsor will discuss such cases with the Industry Collaborators as appropriate to determine further enrollment. IRBs may be notified by the Sponsor of all cases and decisions regarding continued enrollment, according to applicable regulatory requirements or institution procedures.
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3.1.6.2 treatment beyond progression

Accumulating clinical evidence indicates that the emergence of objective responses to agents that activate anti-tumor immune responses may follow delayed kinetics of weeks or months, and can be preceded by initial apparent progression of disease with the appearance of new lesions or some enlarging of lesions while certain index lesions are regressing ("mixed response"). Therefore, it is reasonable to allow patients who experience apparent progression to continue to receive treatment until progression is confirmed at the next imaging assessment. These considerations should be balanced by clinical judgment as to whether the patient is clinically deteriorating and unlikely to receive any benefit from continued treatment. Such deterioration will be assessed to have occurred after a clinical event that, in the Investigator's opinion, is attributable to disease progression and is unlikely to reverse with continued study treatment and therefore indicates that the patient is not benefiting from study treatment and cannot be managed by the addition of supportive care. The decision to continue treatment should be discussed with the PI.
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3.2 study population 3.2.1 planned

In the Phase 1 dose escalation portion of the trial, we will enroll at least 3 patients per cohort. There are a total of 6 cohorts. In the Phase 1b portion, a Simon two stage design will be used. At least 13 patients per each disease cohort (advanced melanoma, NSCLC, and RCC) will be enrolled in the first phase and in the second phase, an additional 21 patients per disease cohort, for a maximum of 34 patients per disease cohort, are expected to be enrolled, for a total of 102 subjects.
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3.2.2 inclusion criteria for all

1. Biopsy proven metastatic melanoma, NSCLC or RCC whose disease has progressed on anti-PD(L)-1 therapy without any intervening therapy. Progression will be determined by the investigator based on clinical and/or radiographic features. Additional requirements as below:
Melanoma:
- Unresectable stage III or stage IV melanoma, irrespective of *BRAF* status, with histologic or cytologic confirmation RCC:
- Histologic or cytologically documented, locally advanced unresectable or metastatic RCC irrespective of histologic subtype NSCLC:
- Histologic or cytologically documented, locally advanced or metastatic (i.e.  
Stage IIIB not eligible for definitive chemoradiotherapy, stage IV, or recurrent) NSCLC.  
- Patients known to harbor an ALK rearrangement or EGFR mutation known to be sensitive to FDA-approved tyrosine kinase inhibitors (TKI), are only eligible after experiencing disease progression (during or after treatment) or intolerance to an FDA approved ALK TKI or EGFR TKI, respectively.  
- Patients with TKI-treated EGFR mutant NSLC harboring the secondary EGFR T790M tumor must have received prior osimertinib.  
- Patients with crizotinib-treated ALK rearranged NSCLC must have received a next generation ALK inhibitor.
2. At least 1 site of disease must be accessible to provide repeat biopsies for tumor tissue.  
This site may be a target lesion as long as it will not be made unmeasurable by the biopsy procedure. Subjects may forgo the pretreatment biopsy if 1) an entire archival FFPE tumor block is available that was taken after the last systemic therapy was administered or 2) if the Investigator deems that the subject does not have tumor in a site that is amenable to biopsy.  
3. Age ≥18, able to understand and sign the informed consent form
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4. ecog performance status <

5. Any number of previous treatments. Other prior systemic therapies must have been administered at least 4 weeks before administration of the study drugs; the exception to this is molecular targeted therapies which must have been administered at least 2 weeks prior to the start of the study drugs or after 5 half-lives have occurred, whichever is shorter.  
6. Life expectancy of at least 6 months 7. A history of previously treated brain metastases is allowed, provided that they are stable for at least 4 weeks.  
8. Willingness to undergo mandatory tumor biopsy prior to initiation of therapy and before the fifth cycle.  
9. Willingness to provide an archival specimen block, if available, for research.
10. Patients must have normal organ and marrow function as defined below:  
| System                                                                                                   | Laboratory Value                                                                                               |
|----------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------|
| Hematological Absolute neutrophil count (ANC)                                                            | ≥1,500 /mcL                                                                                                    |
| Platelets                                                                                                | ≥100,000 / mcL                                                                                                 |
| Hemoglobin                                                                                               | ≥9 g/dL or ≥5.6 mmol/L without transfusion or EPO dependency (within 7 days of assessment)                     |
| Renal Serum creatinine OR Measured or calculateda creatinine clearance (GFR can also be used in place of | ≤1.5 X upper limit of normal (ULN) OR ≥50 mL/min for subject with creatinine levels > 1.5 X  institutional ULN |  
| creatinine or CrCl) Hepatic Serum total bilirubin                                                                    | ≤ 1.5 X ULN OR Direct bilirubin ≤ ULN for subjects with total bilirubin levels > 1.5 ULN                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| AST (SGOT) and ALT (SGPT)                                                                                            | ≤ 2.5 X ULN                                                                                                                                                                                                                                                                                     |
| Albumin                                                                                                              | >2.5 mg/dL                                                                                                                                                                                                                                                                                      |
| Coagulation International Normalized Ratio (INR) or Prothrombin Time (PT)                                            | ≤1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants ≤1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants |
| a Creatinine clearance should be calculated per institutional standard. Activated Partial Thromboplastin Time (aPTT) |                                                                                                                                                                                                                                                                                                 |  
11. Female subject of childbearing potential should have a negative urine or serum pregnancy within 24 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.  
12. Female subjects of childbearing potential should be willing to use a highly effective contraception
(hormonal or IUD) or be surgically sterile, or abstain from heterosexual activity for a period of at least 5 months after the last dose of study drug. Subjects of childbearing potential are those who have not been surgically sterilized or have not been free from menses for > 1 year.  
13. Male subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through at least 7 months after the last dose of study drug.
14. Patients must have at least one measurable lesion at baseline by computed tomography
(CT) or magnetic resonance imaging (MRI) as per RECIST v1.1 criteria.  
a. Tumor sites situated in a previously irradiated area, or in an area subjected to other loco-reginal therapy, are not considered measurable unless there has been demonstrated progression in the lesion.  
15. Prior focal radiotherapy must be completed before first dose of study drug administration, although palliative radiation may be allowed on treatment (see permitted concomitant therapies below). Radiation to pulmonary or intestinal sites must be completed at least 4 weeks prior to study Day 1. There is no time restriction prior to study Day 1 for patients who have received radiation to bone, soft tissue sites or other sites. No radiopharmaceuticals (strontium, samarium) within 8 weeks before first dose of study drug administration.
16. Major surgery must be completed at least 4 weeks before first dose of study drug administration. Surgery requiring local/epidural anesthesia must be completed at least 72 hours before first dose of study drug administration and patients should have recovered. Surgical wounds must be healed.
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3.2.3 exclusion criteria for all

Patients who meet ANY of the following criteria will be excluded from study entry.
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1. untreated brain metastases.

2. A patient who has had prior immune therapy or chemotherapy within 4 weeks prior to study Day 1, or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to a previously administered agent will be excluded. Patients who have had prior molecular targeted therapy using small molecule inhibitors must have received their last dose no less than 2 weeks prior to or no less than five half-lives from study Day 1.  
a. Note: If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.  
b. Note: Toxicity that has not recovered to ≤ Grade 1 is allowed if it meets the inclusion requirements for laboratory parameters.  
3. Has had prior treatment with any other CSF1R inhibitor or CD40 agonist.  
4. Use of corticosteroids to control immune related adverse events at enrollment will not be allowed, and patients who previously required corticosteroids for symptom control must be off steroids for at least 2 weeks. Low-dose steroid use (≤10 mg of prednisone or equivalent) as corticosteroid replacement therapy for primary or secondary adrenal insufficiency is allowed.  
5. Has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to prior treatments with the exception of clinically insignificant adverse events such as alopecia, clinically insignificant laboratory abnormalities, clinically insignificant rash and Grade 2 neuropathy.  
6. History of grade 3-4 neurologic or cardiac toxicity or life-threatening liver toxicity poorly responsive to steroids with prior anti-PD-1/anti-PDL1 monotherapy.  
7. Presence of leptomeningeal disease. 8. Has active autoimmune disease unrelated to immune checkpoint inhibitors that has required systemic treatment in the past year (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (eg., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.  
9. Pregnancy or breast feeding. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with nivolumab, cabiralizumab or APX005M, breastfeeding must be discontinued if the mother is enrolled on this trial.
10. Patients may not be receiving any other investigational agents and may not have participated in a study of an investigational agent or using an investigational device within 4 weeks of the first dose of treatment.  
11. Patients with either a concurrent medical condition (including medical illness, such as active infection requiring treatment with intravenous antibiotics or the presence of laboratory
abnormalities) or history of a prior condition that places the patient at unacceptable risk if he/she were treated with the study drug or a medical condition that confounds the ability to interpret data from the study.  
12. Concurrent, active malignancies in addition to those being studied (other than cutaneous squamous cell carcinoma or basal cell carcinoma)
13. Active (non-infectious) pneumonitis.  
14. Has a known Human Immunodeficiency Virus (HIV), Hepatitis B (HBV), or Hepatitis C
(HCV) acute or chronic infection.
15. Has received a live vaccine within 30 days prior to the first dose of trial treatment. 16. History of myocardial infarction or unstable angina within 3 months prior to Cycle 1, Day 1 17. Prisoners, or subjects who are under compulsory detention  
18. Current or history of clinically significant muscle disorders (e.g., myositis), recent unresolved muscle injury, or any condition known to elevate serum CK levels 19. History of anti-drug antibodies, severe allergic, anaphylactic, or other infusion-related reaction to a previous biologic agent
20. Concomitant use of statins on study. However, a patient using statins for over 3 months prior to study drug administration and in stable status without CK rise may be permitted to enroll 21. Open wounds and active skin infections 22. Uveal melanoma in the Phase Ib dose expansion trial
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3.2.4 women of childbearing potential

Women of childbearing potential (WOCBP) include any females who have experienced menarche and who have not undergone surgical sterilization (hysterectomy, bilateral tubal ligation, or bilateral oophorectomy), and who are not post-menopausal. Post-menopause is defined as:  
- Amenorrhea ≥12 consecutive months without another cause, and a documented serum follicle stimulating hormone (FSH) level >35 mIU/mL, or
- Women with irregular menstrual periods and a documented serum FSH level
>35 mIU/mL (*Note*: FSH level testing is not required for women ≥62 years old with amenorrhea of ≥1 year), or
- Women on hormone replacement therapy (HRT).
Women who are using oral or other hormonal contraceptives, such as vaginal products, skin patches, or implanted or injectable products, or mechanical products, such as an intrauterine Page 61 of 135 device or barrier methods (diaphragm, condoms, spermicides) to prevent pregnancy or who are practicing abstinence or who have a sterile (e.g., vasectomy) partner should be considered to be of childbearing potential [79, 80].
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3.3 concomitant medications

All medications taken within 28 days before the administration of the first dose of any study drug and all concomitant therapy administered during the study until 100 (±7) days after last dose of any study drug (or until initiation of subsequent anti-cancer therapy) will be collected. All subsequent anti-cancer therapy will be collected in the Long-Term Follow-up Period. Information on all prior treatments indicated for advanced cancer, including chemotherapy, biochemotherapy, immunotherapy, radiation, surgery, biologic, and experimental therapy will be collected. No concomitant medication information will be collected following patient discontinuation from the study except for concomitant medication use associated with study drug-related AEs or AEs that lead to discontinuation from the study.
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3.3.1 prohibited and/or restricted treatments

The following medications are prohibited during the study (unless utilized to treat a drug-related AE or specified in the eligibility section):  
- Immunosuppressive agents - Immunosuppressive doses of systemic corticosteroids - Vaccines except as noted in Section 3.3.2
- Statins for treatment of hypercholesterolemia. Statins will be allowed only if the patient is on a stable dose for over 3 months prior to the study and has a stable status without any CK elevations
- Other therapies including biologic, immunotherapy, extensive non-palliative radiation therapy, standard treatments, or investigational agents or devices
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3.3.2 permitted therapy

Patients are permitted to use of topical, ocular, intra-articular, intranasal, and inhaled corticosteroids (with minimal systemic absorption). Adrenal replacement steroid doses >10 mg daily prednisone are permitted. A brief (less than 3 weeks) course of corticosteroids for prophylaxis (e.g., contrast dye allergy) or for treatment of non-autoimmune conditions (e.g., delayed-type hypersensitivity reaction caused by a contact allergen) and also for the treatment of tumor-related AE is permitted. Concomitant palliative and supportive care for disease-related symptoms (including bisphosphonates and RANK-L inhibitors) is allowed. Transfusions are permitted as needed.  
The inactivated seasonal influenza vaccine can be given to patients while on therapy without restriction. Influenza vaccines containing live virus or other clinically indicated vaccinations for infectious diseases (i.e., pneumovax, varicella, etc.) must be discussed with the Investigators and Industry Collaborators. In general, live vaccines are prohibited within 30 days prior to start of study drugs and within the first 12 cycles on study. Palliative radiation or metastasectomy is allowed; these lesions will are not subsequently be included for tumor measurements. Concomitant use of statins will be allowed only if the patient is on a stable dose for over 3 months prior to the study and is in stable status without any CK elevations.
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3.4 long-term follow-up

Patients who discontinue treatment while still receiving clinical benefit (i.e., CR, PR or SD) should get follow-up tumor scans every 12 (±2) weeks until disease progression or use of subsequent anti-cancer therapy to determine the duration of response, unless consent is withdrawn. Long-Term Follow-up for survival may be conducted by telephone, rather than by an in-person visit, once tumor progression is determined or use of subsequent anti-cancer therapy has been initiated.
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4. study drugs

In this study, APX005M, cabiralizumab and nivolumab, are considered Investigational Medicinal Products (IMP).
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4.1 investigational products

An investigational product, also known as investigational medicinal product in some regions, is defined as a pharmaceutical form of an active substance or placebo being tested or used as a reference in a clinical study, including products already having a marketing authorization but used or assembled (formulated or packaged) differently than the authorized form, or used for an unauthorized indication, or when used to gain further information about the authorized form. In this protocol, the investigational products are APX005M, cabiralizumab and nivolumab.  
| Table 4                                           | Study treatments       |            |                        |                                 |
|---------------------------------------------------|------------------------|------------|------------------------|---------------------------------|
| Product Description / Class and Dosage Form       | Potency/Route of       | Blinded or | Packaging /            | Storage                         |
| Administration                                    | Open Label             | Appearance | Conditions (Per Label) |                                 |
| Nivolumab (BMS-936558-01) Solution for Injection  | 100 mg                 | Open label | Vial                   | Refer to the label on container |
| (10 mg/mL)                                        | and/or pharmacy manual |            |                        |                                 |
| Nivolumab (BMS-936558-01) Solution for Injection  | 40 mg                  | Open label | Vial                   | Refer to the label              |
| (10 mg/mL)                                        | on container           |            |                        |                                 |
| and/or pharmacy manual                            |                        |            |                        |                                 |
| Cabiralizumab (BMS-986227) Solution for Injection | 140 mg                 | Open label | Vial                   | Refer to the label              |
| (20 mg/mL)                                        | on container           |            |                        |                                 |
| and/or pharmacy manual                            |                        |            |                        |                                 |
| APX005M Solution for Injection                    | 200 mg                 | Open label | Vial                   | Refer to the label              |
| (10 mg/mL)                                        | on container           |            |                        |                                 |
| and/or pharmacy manual                            |                        |            |                        |                                 |  
Please refer to the Pharmacy Manual and/or Investigator's brochures for more specific information on each drug product.
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4.2 handling and dispensing

The investigational product should be stored in a secure area according to local regulations. It is the responsibility of the Investigator to ensure that investigational product is only dispensed to Patients. The investigational product must be dispensed only from official study sites by authorized personnel according to local regulations.  
The applicable site personnel should ensure that the study drugs are stored in accordance with the environmental conditions (temperature, light, and humidity) determined by the Sponsor. If concerns regarding the quality or appearance of the study drugs arise, do not dispense the study drugs and contact the Sponsor or designee immediately.  
Study drug documentation including all processes required to ensure drug is accurately administered must be maintained. This includes documentation of drug storage and administration and, as applicable, storage temperatures, reconstitution, and use of required processes (e.g. required diluents, administration sets). Please refer to the current version of the Investigator Brochures and/or pharmacy manual for complete preparation, storage, and handling information.
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4.2.1 cabiralizumab

The investigational supply of cabiralizumab will be provided to the study centers by BristolMyers Squibb and will be administered to patients in the clinical study by a trained healthcare professional.  
Cabiralizumab drug product is supplied for IV administration as a sterile, aqueous, colorless to pale yellow liquid, clear to slightly opalescent pyrogen-free solution in 7 mL glass vials stoppered with coated stoppers, and equipped with aluminum seals. Light (few) particulates (consistent in appearance to proteinaceous particles) may be present. Each vial contains a minimum of 7 mL of a 20 mg/mL solution of cabiralizumab (approximately 140 mg per vial). Storage Conditions: 2–8°C (36–46°F). The vials will be provided in a carton. Both vials and cartons will be labeled per local regulations. Refer to Cabiralizumab Investigator's Brochure for more specific information on the drug product.
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4.2.2 nivolumab

The investigational supply of nivolumab will be provided to the study centers by the BristolMyers Squibb.  
Nivolumab Injection, 100 mg/10 mL (10 mg/mL) is a clear to opalescent, colorless to pale yellow liquid, which may contain light (few) particulates. The drug product is a sterile, nonpyrogenic, single-use, isotonic aqueous solution formulated at 10 mg/mL in sodium citrate, sodium chloride, mannitol, diethylenetriaminepentacetic acid (pentetic acid), and polysorbate 80 (Tween 80), pH 6.0 and includes an overfill to account for vial, needle, and syringe holdup. It is supplied in 10-cc Type I flint glass vials, stoppered with butyl rubber stoppers and sealed with aluminum seals. Nivolumab injection is to be administered as an IV infusion through a 0.2-micron to 1.2-micron pore size, low-protein binding (polyethersulfone membrane) in-line filter at the protocol specified doses and infusion times. It is not to be administered as an IV push or bolus injection.  
Nivolumab injection can be infused undiluted (10 mg/mL) or diluted with 0.9% Sodium Chloride Injection, USP or 5% Dextrose Injection, USP to protein concentrations as low as 0.35 mg/mL.  
During drug product preparation and handling, vigorous mixing or shaking is to be avoided. Care must be taken to assure sterility of the prepared solution as the product does not contain any antimicrobial preservative or bacteriostatic agent. Nivolumab infusions are compatible with polyvinyl chloride (PVC) or polyolefin containers and infusion sets, and glass bottles. Vials of nivolumab injection must be stored at 2 degrees C to 8 degrees C (36°F to 46°F) and protected from light and freezing. The administration of nivolumab infusion must be completed within 24 hours of preparation. If not used immediately, the infusion solution may be stored under refrigeration conditions (2°C to 8°C, 36°F to 46°F) for up to 24 hours, and a maximum of 8 hours of the total 24 hours can be at room temperature (20°C to 25°C, 68°F to 77°F) and room light. The maximum 8-hour period under room temperature and room light conditions includes the product administration period. Refer to the Nivolumab Investigator's Brochure for for more specific information on the drug product.
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4.2.3 apx005m

The investigational supply of APX005M will be provided to the study centers by Apexigen.  
APX005M is supplied in 20 mL Type 1 clear glass vials for IV administration. Each vial contains 10 mg APX005M/mL in a sterile, clear to slightly opalescent, colorless to slightly yellow, preservativefree solution (pH 5.5) containing 25 mM sodium acetate, 248 mM trehalose, and 0.02% polysorbate 20 in water for injection (WFI). The 20 mL vials are intended for single use.  
APX005M is intended for IV infusion. For use, APX005M is diluted in normal saline and infused via IV infusion or syringe pump.  
Refer to the APX005M Investigator's Brochure for more specific information on the drug product.
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4.3 method of assigning patient

Patients must be able to provide written informed consent and meet all eligibility criteria. No waivers of inclusion or exclusion criteria will be granted by Sponsor or its designee for any patient enrolled in the study. Before enrolling a patient, all eligibility criteria must be satisfied. See Section 4.4.1 and Figure 6 for dosing schema. Patients who qualify for Phase 1 dose esclation of the study will be enrolled as follows:
- Cohort 1 will be enrolled first and these patients will be followed one 14-day cycle.  
- Once the DLT follow-up period of 28 days is cleared for Cohort 1, simultaneous enrollment to Cohort 2 and Cohort 3 will occur. Patients in these cohorts will be treated for a total of one 14-day cycle.  
- Simultaneous enrollment into Cohort 4 and Cohort 5 will proceed once the 14-day DLT
period for dose escalation is cleared in the preceeding Cohorts 2 and 3.  
- Once the DLT period of 28 days for dose escalation is cleared Cohorts 4 and 5, enrollment to the final Cohort 6 will occur.  
- The MTD will be calculated for patients who have received at least 2 cycles (at least 28 days) of study drug.  
- Dose escalation into sequential dose levels of APX005M in combination with cabiralizumab and nivolumab may proceed until DLTs are observed either in the cabiralizumab/APX005M doublet therapy cohorts 1, 3, and 5 or in the nivolumab/cabiralizumab/APX005M triplet therapy cohorts after discussion and agreement between the PIs and Industry Collaborators.
In Phase 1b, a maximum of 34 patients will be enrolled per disease-specific cohort (advanced melanoma, NSCLC, or RCC). Enrollment will be open for all cohorts in parallel and will continue until the enrollment target is reached. Once a disease cohort is filled, further enrollment will be restricted to the cohort(s) that have not been filled. A total of approximately 102 patients will be enrolled in the Phase 1b arm of the study.
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4.4 study drug dosing and

Dosing calculations should be based on the body weight assessed at Cycle 1 Day 1 prior to the first dose of study drug administration. It is not necessary to recalculate subsequent doses if the patient's weight is within 10% of the weight used to calculate the previous dose. All doses should be rounded to the nearest milligram. Patients should be carefully monitored for infusion reactions during study drug administration. If an acute infusion reaction is noted, patients should be managed according to the guidelines in Section 4.8 and Section 4.9. Patients must remain near the vicinity of a hospital with rapid access to an intensive care unit setting during the initial 48 hour period after treatment for the first two treatment cycles. All vials are for single use only. Further instructions on study drug preparation and administration are provided in the Pharmacy Manual. Please refer to the study schema for dosing as follows:
- Phase 1 Dose Escalation (Dosing on Day 1 of each 14-day cycle):  
o Cohort 1: Cabiralizumab 4 mg/kg + APX005M 0.03 mg/kg o Cohort 2: Nivolumab 240 mg + Cabiralizumab 4 mg/kg + APX005M 0.03 mg/kg o Cohort 3: Cabiralizumab 4 mg/kg + APX005M 0.1 mg/kg o Cohort 4: Nivolumab 240 mg + Cabiralizumab 4 mg/kg + APX005M 0.1 mg/kg o Cohort 5: Cabiralizumab 4 mg/kg + APX005M 0.3 mg/kg o Cohort 6: Nivolumab 240 mg + Cabiralizumab 4 mg/kg + APX005M 0.3 mg/kg
- Phase 1b (Dosing on Day 1 of each 14-day cycle):  
o ALL patients: Nivolumab 240 mg + Cabiralizumab 4 mg/kg + APX005M at the RP2D
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4.4.1.1 nivolumab dosing

The following patients on the trial will receive nivolumab as follows:
- Phase 1:
o Cohorts 1, 3, and 5: will NOT receive nivolumab o Cohorts 2, 4, and 6: nivolumab 240 mg IV
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- phase 1b

o All patients will receive nivolumab 240 mg IV as the first drug in sequence Nivolumab will be dosed as a 30-minute IV infusion on Day 1 of each 14-day treatment cycle as above. Routine premedication administered 30 minutes prior to nivolumab should include:  
- H1 antagonist (e.g. Benadryl 25 mg PO)
- Oral or IV H2 antagonist (e.g., ranitidine 150−300 mg, cimetidine 300−800 mg, nizatidine 150−300 mg, and famotidine 20−40 mg)
- Oral nonsteroidal anti-inflammatory drug (may comprise ibuprofen 400 mg or equivalent)
- Acetaminophen 650 mg
If a grade 1-2 infusion reaction is observed during the proposed infusion rate of nivolumab 240 mg over 30 minutes, the infusion rate will be extended to 60 minutes. Nivolumab should be held for a grade 3 infusion reaction and retreatment should be discussed with study PI. Nivolumab should be discontinued for a grade 4 infusion reaction. There will be no dose escalations or reductions of nivolumab allowed. Refer to the Pharmacy Manual for nivolumab preparation instructions.
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4.4.1.2 cabiralizumab dosing

All patients in all cohorts of the trial will receive cabiralizumab. Cabiralizumab will be administered as a fixed dose of 4 mg/kg given over 30 minutes by IV infusion. In phase 1 dose escalation cohorts 1, 3, and 5, cabiralizumab will be given first followed by APX005M. In this case, premedications outlined in Section 4.4.1.1 should be given 30 minutes prior to cabiralizumab on Day 1 of each 14-day treatment cycle.  
In phase 1 dose escalation Cohorts 2, 4, and 6, and in all patients on the phase 1b portion of the trial, cabiralizumab will be administered 30 minutes after the end of the nivolumab infusion, on Day 1 of each 14-day treatment cycle.  
If any Grade 3 or higher infusion reaction is observed during the proposed infusion rate of cabiralizumab 4 mg/kg over 30 minutes, cabiralizumab should be discontinued permanently. For further management of infusion reactions, please see Section 4.8 and Section 4.9. A research pharmacist (or other responsible personnel) will prepare the solution for administration. After calculating the number of vials, based on the patient's weight, the study drug product will be diluted with 0.9% Sodium Chloride Injection, USP. Prepared cabiralizumab should be administered within 6 hours after preparation (ambient temperature). The IV administration setup for cabiralizumab infusion must contain a 0.2 or 0.22 µm in-line filter or a 0.2 or 0.22 µm syringe filter. Cabiralizumab will be administered under medical supervision as a 30 minute (± 5 minutes) IV infusion via a peripheral vein or central venous catheter. No incompatibilities between cabiralizumab infusion and polyvinyl chloride (PVC), ethylene/propylene IV components, or glass bottles have been observed.
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4.4.1.3 apx005m dosing

All patients in all cohorts of the trial will receive APX005M as follows:
- Phase 1:
o Cohorts 1 and 2: APX005M 0.03 mg/kg o Cohorts 3 and 4: APX005M 0.1 mg/kg o Cohorts 5 and 6: APX005M 0.3 mg/kg
- Phase 1b:
o At the determined RP2D
APX005M is administered on Day 1 of each 14-day treatment cycle approximately 30 minutes following cabiralizumab using a 60 minute IV infusion. A window between -5 minutes and +10 minutes is permitted (i.e., infusion time is 55 minutes to 70 minutes). Premedication should have already been administered 30 minutes prior to first dose of study drug, as described in Section 4.4.1.1. When the time between premedication and scheduled APX005M administration exceeds 4 hours, patients may receive an additional course of premedication prior to APX005M administration. The APX005M infusion can be interrupted in the case of a grade 1-2 infusion reaction (see Section 4.8 and Section 4.9). Once symptoms resolve, infusion should be restarted at 50% of the initial infusion rate (e.g., from 50 mL/hr to 25 mL/hr). For a grade 3 infusion reaction, APX005M should be held and the investigator should dose reduce with the next cycle. Grade 4 infusion The Pharmacy Manual contains specific instructions for the preparation of the APX005M infusion and administration of infusion solution.
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4.5 blinding/unblinding

This is an open-label study and there will be no blinding or unblinding of patients during this study.
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4.6 dose modifications delays or

Doses of study drugs may be interrupted, delayed, or discontinued depending on how the patient tolerates the treatment. Dose reductions for nivolumab and cabiralizumab are not permitted. Dose reduction for APX005M is permitted as per Section 4.8 and Section 4.9. If there is an infusion reaction or other unforeseen delay that makes dosing of APX005M impractical on the same day as nivolumab and cabiralizumab, the patient may be infused with APX005M the following day at the discretion of the Investigator.  
Administration of nivolumab, cabiralizumab and/or APX005M combination therapy should be skipped for the following reasons:  
- The treating physician determines that the patient would benefit from a break in treatment due to non-life threatening grade 1-2 toxicities such as fatigue, arthralgias or edema.  
- Any drug-related laboratory abnormalities would not require a dose delay unless clinically indicated or specified in the protocol or abnormal laboratory management guidelines (see Section 4.8 and Section 4.9). Please discuss with the PI as needed.  
- For dose delays or modifications for all other AEs please refer to the AE management guidelines in Section 4.8 and Section 4.9.
If the causality of the AE requiring a dose delay is confirmed to be due to one of three study drugs, then the non-offending drug may be continued per protocol taking into account the safety and clinical benefit to the patient.
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4.7 criteria to resume treatment

Patients may resume treatment with APX005M, cabiralizumab and/or nivolumab when the drugrelated AE resolves as noted in Section 4.8 and Section 4.9.  
A new treatment cycle should be initiated only if all toxicities are ≤ Grade 1 except:
- Grade 2 neuropathy lasting shorter than 28 days (hold nivolumab only)
- Grade 2 alopecia - Grade 2 rash or other skin toxicity - Grade 2 hypophysitis/endocrinopathies - Grade 2 fatigue - Grade 2-3 neutropenia/lymphopenia
- CK increase up to 15x ULN
If a subject fails to meet these retreatment criteria then the treatment cycle should be skipped. The PI can be contacted at any time if further clarification is needed.