• Phase 1 Dose Escalation cohorts, Phase 1 Backfill cohorts, and Phase 2 Tumor Type-Specific cohort(s): must meet one of the following criteria:

• HER2- metastatic breast cancer:

‣ Hormone refractory hormone receptor positive metastatic breast cancer with progression on or after treatment with CDK4/6 inhibitor plus at least one line of systemic chemotherapy in the advanced setting

⁃ Triple negative metastatic breast cancer with progression after at one line of systemic chemotherapy in the advanced setting.

• Patients with advanced solid tumors that progressed on or following treatment with Enhertu and/or Trodelvy per label

• mCRPC: Histologically confirmed, metastatic castration resistant adenocarcinoma of the prostate

‣ May have received up to 2 prior chemotherapies in mCRPC setting

⁃ Prior therapy with PARP (poly-ADP ribose polymerase) inhibitor, PLUVICTO, Radium-223, or Provenge is allowed

• Pancreatic cancer: PDAC (pancreatic ductal adenocarcinoma) with progression on or after treatment with at least one line of systemic chemotherapy in the advanced setting.

• PROC: Histologically or cytologically confirmed platinum-resistant high-grade serous ovarian, fallopian, or primary peritoneal cancer;

• Phase 1 Dose Escalation cohorts, Phase 1 Backfill cohorts, and Phase 2 Tumor Type-Specific cohorts (except mCRPC; see inclusion criterion 2 above): must have measurable disease per RECIST 1.1

• Phase 2 All Comers cohort: Patients with advanced solid tumors that have progressed during or after treatment with approved therapies or for whom there is no standard effective therapy available.

• Adequate bone marrow and organ function.

• Provide informed consent, which includes compliance with protocol-specified requirements and restrictions