Study of Tuvusertib (M1774) in Combination With DNA Damage Response Inhibitor or Immune Checkpoint Inhibitor (DDRiver Solid Tumors 320)

Inclusion Criteria:

• Parts A1, A1.1, A1.2, A2, A3, and A2/3: Participants with metastatic or locallyadvanced unresectable solid tumors refractory to standard therapy or for which nostandard therapy is judged appropriate by the Investigator, which may conveyclinical benefit, or who cannot tolerate standard of care treatment

• Parts A1.1 and A1.2: Triple negative breast cancer, epithelial ovarian cancer,castrate resistant prostate cancer, urothelial cancer, endometrial cancer, andcolorectal cancer independent of mutation status.

• Part A2: Participants with advanced prostate cancer whose tumor carries a geneticloss of function (LoF) mutation(s) in the gene ataxia telangiectasia mutated (ATM).No more than 3 prior lines of therapy for castrate resistant disease. Prior therapymust have included a taxane and a novel antiandrogen (example [e.g.] enzalutamide).

• Part A3: Participants with advanced endometrial cancer whose tumor carries a geneticLoF mutation(s) in the gene AT-rich interaction domain 1A (ARID1A). Prior therapymust have included a platinum agent. Prior therapy must also have included acheckpoint inhibitor if the participant has mismatch repair (MMR)-deficientendometrial cancer. Note for Parts A2/A3: Participants with ATM LoF mutated prostatecancer and ARID1A LoF mutated endometrial cancer should be prioritized to therespective expansion arms instead of being enrolled in Part A1.1. The presence ofATM and ARID1A LoF mutations will be determined according to historic data collectedprior to prescreening, generated by an assay with appropriate regulatory status, ineither tumor or liquid biopsy. The Sponsor will confirm that mutations certified byhistoric data fulfil this definition.

• Participants with eastern Cooperative Oncology Group (ECOG) performance status 0 or 1, with estimated life expectancy of at least 3 months

• Adequate hematological, hepatic, and renal function as defined in the protocol

• Other protocol defined inclusion criteria could apply

Exclusion Criteria:

• Participants with any condition, including any uncontrolled disease state other thanwith metastatic or locally advanced unresectable solid tumors, that in theInvestigator's opinion constitutes an inappropriate risk or a contraindication forparticipation in the study or that could interfere with the study objectives,conduct, or evaluation

• Participants with a known additional malignancy that is progressing and/or requiresactive treatment

• Participants with carcinomatous meningitis are excluded regardless of clinicalstability

• Participants with serious gastrointestinal bleeding within 3 months, refractorynausea and vomiting, uncontrolled diarrhea, known malabsorption, significant smallbowel resection or gastric bypass surgery, use of feeding tubes, other chronicgastrointestinal disease, and/or other situations that may preclude adequateabsorption of oral medications

• Participants with organ transplantation, including allogeneic stem cell transplant

• Other protocol defined exclusion criteria could apply