A Phase 1/2 Study of REGN4018 (A MUC16×CD3 Bispecific Antibody) Administered Alone or in Combination with Cemiplimab in Patients with Recurrent Ovarian Cancer or Other Recurrent MUC16+ Cancers

The main purpose of this study is to:

- Learn about the safety of REGN4018 and to find out what dose of REGN4018 can be given
alone or with cemiplimab to patients with ovarian cancer or cancer of the uterus

- The study will also look at the levels of REGN4018 and/or cemiplimab in your body and
measure how well your body can remove the study drug(s). This is called pharmacokinetics

- The study will also look at any signs that REGN4018 alone or with cemiplimab can treat
recurrent advanced ovarian cancer or cancer of the uterus

- To find out how safe and tolerable the sarilumab pretreatment is, in combination with
REGN4018 and cemiplimab

Key Inclusion Criteria:

1. Ovarian Cancer Cohorts Only: Patients with histologically or cytologically confirmed
diagnosis of advanced, epithelial ovarian cancer (except carcinosarcoma), primary
peritoneal, or fallopian tube cancer who have all of the following:

1. serum CA-125 level ≥2 x upper limit of normal (ULN) (in screening)

2. has received at least 1 line of platinum-containing therapy or must be
platinum-intolerant (applicable for dose escalation and non-randomized dose
expansion cohorts)

3. documented relapse or progression on or after the most recent line of therapy

4. no standard therapy options likely to convey clinical benefit

2. Adequate organ and bone marrow function as defined in the protocol

3. Life expectancy of at least 3 months

4. Randomized phase 2 expansion cohort (Ovarian Cancer only): Platinum-resistant ovarian
cancer patients who have had 1 to 3 lines of platinum-based therapy as defined in the
protocol.

5. Endometrial Cancer Cohorts Only: histologically confirmed endometrial cancer that has
progressed or recurrent after prior anti-Programmed Cell Death Ligand 1 (PD-1) therapy
and platinum-based chemotherapy:

1. MUC16 positivity of tumor cells ≥25% by immunohistochemistry (IHC)

2. 1-2 prior lines of systemic therapy

Key Exclusion Criteria:

1. Prior treatment with anti-Programmed Cell Death (PD-1)/PD-L1 therapy, as described in
the protocol

2. Ovarian Cancer Expansion cohorts only: More than 4 prior lines of cytotoxic
chemotherapy

3. Prior treatment with a MUC16 - targeted therapy

4. Untreated or active primary brain tumor, central nervous system (CNS) metastases, or
spinal cord compression, as described in the protocol

5. History and/or current cardiac findings as defined in the protocol

6. Severe and/or uncontrolled hypertension at screening. Patients taking
anti-hypertensive medication must be on a stable anti-hypertensive regimen

Note: Other protocol Inclusion/Exclusion Criteria apply