Phase 1 Study of OP-3136 in Advanced or Metastatic Solid Tumors

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 1A (Dose escalation for OP-3136 monotherapy): 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 1B (Dose escalation for OP-3136 in combination with fulvestrant): Participants with advanced or metastatic ER+ HER2- breast cancer that have progressed on or after at least 1 prior line of treatment that included endocrine therapy and CDK 4/6 inhibitor in advanced or metastatic setting and must have received no more than 2 prior lines of endocrine therapy (one of which must be in combination with CDK4/6 inhibitor) and no more than 1 prior line of chemotherapy or an antibody-drug conjugate in the advanced or metastatic setting. * Part 1C (Dose escalation for OP-3136 in combination with palazestrant): Participants with advanced or metastatic ER+ HER2- breast cancer that have progressed on or after at least 1 prior line of treatment that included endocrine therapy and CDK 4/6 inhibitor in advanced or metastatic setting and must have received no more than 2 prior lines of endocrine therapy (one of which must be in combination with CDK4/6 inhibitor) and no more than 1 prior line of chemotherapy or an antibody-drug conjugate in the advanced or metastatic setting. * Part 2A (…