Safety Study of Enoblituzumab (MGA271) in Combination With Ipilimumab in Refractory Cancer

This study is a Phase 1 open-label, dose escalation, and cohort expansion study of
enoblituzumab administered intravenously (IV) on a weekly schedule for up to 51 doses in
combination with IV ipilimumab administered on an every-3-week schedule for 4 doses.

The dose escalation phase is designed to characterize the safety and tolerability of the
combination of enoblituzumab and ipilimumab and to define the maximum tolerated or
administered dose (MTD/MAD) in patients with B7-H3 expressing mesothelioma, urothelial
cancer, NSCLC, SCCHN, Clear cell renal cell carcinoma (ccRCC), ovarian cancer, melanoma,
thyroid cancer, Triple negative breast cancer (TNBC), pancreatic cancer, colon cancer, soft
tissue sarcoma, or prostate cancer.

The cohort expansion phase, 2 cohorts of 16 patients each will be enrolled to further
evaluate the safety and potential efficacy of the combination administered at the MTD/MAD
dose in patients with melanoma and NSCLC.

All tumor evaluations will be carried out by both Response Evaluation Criteria in Solid
Tumors (RECIST) and immune-related response criteria (irRC).

Inclusion Criteria - Cohort Expansion Phase:

- Histologically-proven, unresectable, locally advanced or metastatic melanoma or NSCLC

- Melanoma: Advanced or metastatic melanoma patients may be systemic therapy naïve
or may have received systemic treatment for unresectable locally advanced or
metastatic disease. A patient who previously received systemic therapy must have
had progression on a checkpoint inhibitor (e.g., anti-PD-L1, anti-PD-1,
anti-CTLA-4) as the most recent prior therapy.

- NSCLC: NSCLC that has progressed during or following 1 or more prior systemic
therapies for unresectable locally advanced or metastatic disease. Patients who
are intolerant of, or have refused treatment with standard first line cancer
therapy, will be allowed to enroll. Patients must not have had more than 5 prior
systemic regimens (excluding experimental therapies) for unresectable locally
advanced or metastatic disease.

- B7-H3 expression is not required for eligibility in this study; however, tumor
expression of B7-H3 will be evaluated for all patients.

- Measurable disease per RECIST 1.1 criteria

- ECOG performance status 0 or 1

- Acceptable laboratory parameters and adequate organ reserve.

Exclusion Criteria - Cohort Expansion Phase:

- Patients with a history of symptomatic central nervous system metastases, unless
treated and asymptomatic

- Patients with history of autoimmune disease with certain exceptions

- History of allogeneic bone marrow, stem cell, or solid organ transplant

- Treatment with systemic cancer therapy or investigational therapy within 4 weeks;
radiation within 2 weeks; trauma or major surgery within 4 weeks

- History of clinically-significant cardiovascular disease; gastrointestinal
perforation; gastrointestinal bleeding, acute pancreatitis or diverticulitis within 4
weeks;

- Active viral, bacterial, or systemic fungal infection requiring parenteral treatment
within 7 days; positive for human immunodeficiency virus or AIDS, hepatitis B or C.

- Known hypersensitivity to recombinant proteins, polysorbate 80, or any excipient
contained in the drug or vehicle formulation for MGA271 or ipilimumab.