A Study of PRT3789 in Participants With Select Advanced or Metastatic Solid Tumors With a SMARCA4 Mutation

This is a Phase 1 dose-escalation study of PRT3789, a SMARCA2 degrader, in participants with advanced or metastatic solid tumors with loss of SMARCA4 due to truncating mutation and/or deletion. The purpose of this study is to evaluate the safety, tolerability, pharmacokinetic (PK), and pharmacodynamic (PD) of PRT3789, describe any dose limiting toxicities (DLTs), define the dosing schedule, and to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) to be used in subsequent development of PRT3789.

Inclusion Criteria:Willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations (including contraception requirements), and other study proceduresHistologically confirmed advanced, recurrent, or metastatic solid tumor malignancy with loss of SMARCA4 due to truncating mutation and/or deletion by local testing that have either progress on or ineligible for standard of care therapyMust have measurable or non-measureable (but evaluable) diseaseEastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1Willing to provide either archival or fresh tumor tissue sampleAdequate organ function (hematology, renal, and hepatic)Exclusion Criteria:Participants with solid tumors with known concomitant SMARCA2 mutation or loss of protein expressionClinically significant or uncontrolled cardiac disease, uncontrolled electrolyte disorders, uncontrolled or symptomatic central nervous system (CNS) metastases or leptomeningeal diseaseHistory of another malignancy within 3 years except for adequately treated basal cell or squamous cell skin cancer, superficial bladder cancer, prostate intraepithelial neoplasm, carcinoma in situ of the cervix, or other noninvasive or indolent malignancies, or malignancies previously treated with curative intent and not on active therapy or expected to require treatment or recurrence during the studyConcurrent treatment with strong or moderate CYP3A4 inhibitor or inducer