Study of OP-3136 in Advanced or Metastatic Solid Tumors

Eligibility Criteria

Key Inclusion Criteria:

* Participants with advanced or metastatic ER+HER2- breast cancer, mCRPC, or NSCLC (Part 1) or advanced or metastatic ER+HER2- BC or mCRPC (Part 2).
* Part 1 (Dose escalation): Participants must have a tumor that is unresectable or metastatic and for which life prolonging measures do not exist or available therapies are intolerable or no longer effective.
* Part 2 (Dose Expansion in ER+ HER2- mBC): Participants must have received up to 3 prior lines of endocrine therapy (one of which must be in combination with CDK4/6 inhibitor) and up to 1 prior line of chemotherapy or an antibody-drug conjugate.
* Part 2 (Dose Expansion in mCRPC): Participants must have received up to 4 lines of prior systemic therapy for prostate cancer. Prior therapy must include treatment with an androgen receptor pathway inhibitor(s).

Key Exclusion Criteria:

* Prior therapy with KAT6A/B inhibitor in any treatment setting.
* Participants with advanced/metastatic, symptomatic, visceral spread, that are at risk of life-threatening complications in the short term.
* Known active or symptomatic central nervous system (CNS) metastases, carcinomatous meningitis, leptomeningeal disease, or a spinal cord compression that require CNS-specific treatment, or participants who did not demonstrate clinical and radiologic stability during the last 2 months prior to the first dose of study treatment or require or are currently on steroid therapy for CNS metastases.
* History of cerebral vascular disease, including transient ischemic attack, within 6 months prior to the first dose of study treatment.
* History of or ongoing impaired cardiac function or clinically significant cardiac disease within 6 months prior to the first dose of study treatment.

Note: Additional inclusion/exclusion criteria may apply.