Phase Ib/II Study of Carboplatin + M6620 + Avelumab in PARPi-resistant Ovarian Cancer

Inclusion Criteria:

* Female participants with recurrent epithelial ovarian cancer who have disease progression following maintenance treatment with a PARPi as defined below:

  1. Participant must have histologically diagnosed epithelial ovarian, primary peritoneal, or fallopian tube cancer, with nonmucinous histology
  2. Participants must have completed at least 2 previous courses of platinum containing therapy (for example, carboplatin or cisplatin) and had documented response (complete response \[CR\] or partial response \[PR\]) to the last platinum-based treatment prior to treatment with a PARPi
  3. Participant has received the last dose of platinum-containing treatment at least 6 months prior to study enrollment
  4. Participant has documented disease progression (radiological) after at least 4 months of maintenance treatment with PARPi following a response to platinum-based chemotherapy.
* Confirmed breast cancer gene (BRCA) 1/2 mutation status or agree to its testing on samples collected in the study.
* Available formalin-fixed, paraffin-embedded (FFPE) tumor biopsies.
* Part A: Optional 2 paired on-treatment biopsies on Day 2 of Cycle 1 (first biopsy) and Day 2 of Cycle 1 or Cycle 2 (second biopsy) respectively, before and after M6620 administration, if assessed as feasible at low risk by the interventional radiologist.
* Part B: Histological tissue specimen (tissue block or 8 to 10 unstained slides) must be available. An archival tumor biopsy is acceptable if obtained after the last progression on PARPi treatment and is less than 4 months old. Otherwise, participants must be willing to undergo mandatory biopsy during the Screening Period to obtain sufficient tissue for histological assessment. Participants need to have an attempted biopsy. However, participants who have measurable disease documented by a radiologist as not feasible or safe to be biopsied are eligible to enter the study
* Measurable disease according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1).
* Other protocol defined inclusion criteria could apply

Exclusion Criteria:

* Treatment with a nonpermitted drug/intervention as listed below:

  1. Concurrent anticancer treatment (e.g., cytoreductive therapy, radiotherapy, immune therapy, cytokine therapy, monoclonal antibody, or targeted small molecule therapy) or any study intervention within 4 weeks prior to start of study intervention, or not recovered from AEs related to such therapies
  2. History of prior dose reductions or dose interruptions while receiving cisplatin or carboplatin due to toxicity from the platinum or intolerance to either agent, unless discussed with and approved by the Sponsor Medical Monitor
  3. Prior treatment with a PD-1/PD-L1 targeting agent
* Current use of the following medications at the time of enrollment:

  1. Immunotherapy or immunosuppressive drugs at the time of enrollment (for example (e.g.,) chemotherapy or systemic corticosteroids) EXCEPT for (a) intranasal, inhaled, topical steroids, or local steroid injection (e.g., intra articular injection), (b) systemic corticosteroids at physiologic doses less than or equals to (≤) 10 milligram per day (mg/day) of prednisone or equivalent, (c) steroids as premedication for hypersensitivity reactions (e.g., computed tomography \[CT\] scan premedication)
  2. Growth factors EXCEPT where indicated for treatment of study intervention related myelosuppression and for prophylaxis of repeat myelosuppression after initial occurrence
  3. Herbal remedies with immunostimulating properties (e.g., mistletoe extract) or known to potentially interfere with major organ function (e.g., hypericin)
  4. Other DNA damage repair inhibitors (except PARPi) (e.g., inhibitors of ATR, ataxia telangiectasia mutated \[ATM\] kinase, DNA-dependent protein kinase \[DNA-PK\], or Wee kinases).
* Other protocol defined exclusion criteria could apply