This study is researching an investigational drug called REGN5668 :
* alone or, * combined with cemiplimab (also known as REGN2810) or, * combined with both cemiplimab and fianlimab (also known as REGN3767), or * combined with ubamatamab (also known as REGN4018), with or without sarilumab.
The main purposes of this study are to:
* Learn about the safety and profile of any side effects from the study drugs and to determine the highest, safe dose that can be given to participants with ovarian cancer or cancer of the uterus * Look for signs that the study drugs can treat ovarian cancer or cancer of the uterus
This study has 2 parts. The purpose of Part 1 (Escalation) is to find the highest, safe dose of the study drug(s). The purpose of Part 2 (Expansion) is to use the doses chosen in Part 1. Participants with cancer of the uterus will only participate in Part 2.
The study is looking at several other research questions, including:
* Side effects that may be experienced by participants taking REGN5668 alone and/or in combination with cemiplimab, cemiplimab and fianlimab, or ubamatamab * How REGN5668 works in the body either alone and/or in combination with cemiplimab, cemiplimab and fianlimab, or ubamatamab * How much of the study drugs (REGN5668, cemiplimab, fianlimab, ubamatamab) are in the blood * To see if REGN5668 in combination with cemiplimab, cemiplimab and fianlimab, or ubamatamab works to treat cancer
Ovarian Cancer Cohorts Only: Has histologically or cytologically confirmed diagnosis of advanced epithelial ovarian cancer (except carcinosarcoma), primary peritoneal, or fallopian tube cancer that has received at least 1 line of platinum-based systemic therapy as defined in the protocol
Expansion cohorts only: Has at least 1 lesion that is measurable by RECIST 1.1 as described in the protocol.
Has a serum CA-125 level ≥2x ULN (in screening, not applicable to endometrial cohorts)
Has adequate organ and bone marrow function as defined in the protocol
Current or recent (as defined in the protocol) treatment with an investigational agent, systemic biologic therapy, or anti-cancer immunotherapy
Has had another malignancy within the last 5 years that is progressing, requires active treatment, or has a high likelihood of recurrence as defined in the protocol
Prior treatment with a Mucin 16 (MUC16)-targeted therapy
Ovarian Expansion cohorts only: More than 5 prior lines of systemic therapy