A Phase 1/2 Study of REGN4018 (A MUC16xCD3 Bispecific Antibody) Administered Alone or in Combination with Cemiplimab in Patients with Recurrent Ovarian Cancer

Primary Objectives

In the Dose Escalation Phase:

• To assess the safety and pharmacokinetics (PK) in order to determine a maximally tolerated
dose (MTD) or recommended phase 2 dose (RP2D) of REGN4018 as monotherapy and in combination
with cemiplimab.

In the Dose Expansion Phase:

• To assess the preliminary efficacy of REGN4018 as monotherapy and in combination with
cemiplimab, (separately by cohort) as determined by the objective response rate (ORR) by
Response Evaluation Criteria in Solid Tumors (RECIST) 1.1

Secondary Objectives

In the Dose Escalation Phase:

• To assess the preliminary efficacy of REGN4018 as monotherapy and in combination with
cemiplimab (separately by cohort) as determined by ORR by RECIST 1.1

In the Dose Expansion Phase:

- To characterize the safety profile in each expansion cohort

- To characterize the PK of REGN4018 as monotherapy and in combination with cemiplimab.

- To assess the effects of REGN4018 as monotherapy and in combination with cemiplimab on
patient-reported outcomes (PROs), including health-related quality of life (HRQoL),
functioning, and symptoms

In both the Dose Escalation and Dose Expansion Phases:

- To assess preliminary efficacy of REGN4018 as monotherapy and in combination with
cemiplimab (separately by cohort) as measured by ORR based on iRECIST, best overall
response (BOR), duration of response (DOR), disease control rate, complete response (CR)
rate and progression-free survival (PFS) based on RECIST 1.1 and iRECIST

- To assess efficacy of REGN4018 as monotherapy and in combination with cemiplimab as
measured by CA-125 level.

- Immunogenicity of REGN4018 and cemiplimab

Key Inclusion Criteria:

1. 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 ≥2x 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

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 cohorts only: Platinum resistant ovarian cancer patients
who have had 1 to 4 lines of platinum-based therapy and prior treatment with a poly
ADP-ribose polymerase (PARP) inhibitor or bevacizumab as defined in the protocol.

Key Exclusion Criteria:

1. Recent treatment with anti-Programmed Cell Death (PD-1)/PD-L1 therapy

2. Expansion cohort only: More than 4 prior lines of cytotoxic chemotherapy

3. Prior treatment with a Mucin 16 (MUC16)-targeted therapy

4. Untreated or active primary brain tumor, central nervous system (CNS) metastases, or
spinal cord compression

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