A Study of TAS0612 in Participants With Advanced or Metastatic Solid Tumor Cancer

Inclusion Criteria

• Inclusion Criteria: Dose Escalation: Have histologically confirmed, locally advanced, and unresectable cancer, or metastatic cancer and have progressed on or were intolerant to standard treatments or refused standard of care (SOC). Dose Expansion: Have documented histologically or cytologically confirmed adenocarcinoma of the prostate with documented PTEN loss or loss of function mutation, who have metastatic castration-resistant disease and have: - Disease progression per the Prostate Cancer Clinical Trials Working Group 3 (PCWG3)/modified RECIST 1.1 after the most recent regimen. - Received androgen receptor directed therapy previously with or without chemotherapy consisting of no more than 2 prior taxane-based regimens. - Been receiving androgen deprivation therapy with serum testosterone <50 ng/dL (<2.0 nM). Note: previously documented PTEN loss or loss of function mutation from archived tissue sample testing or cfDNA sample testing is acceptable if done in a CLIA certified lab or a locally certified lab. Have an ECOG score of 0 or 1 Dose Escalation (Part 1): Have no measurable or measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Dose Expansion (Part 2): Have measurable or no measurable disease per PCWG3/modified RECIST 1.1 • No more than 30 patients with no measurable disease will be enrolled in Dose Expansion (Part 2). Exclusion Criteria: - Participating in medical research not compatible with this study - Have not discontinued or recovered from previous treatments for cancer - Have a significant cardiac condition - Have untreated brain metastases - Have a primary brain tumor - Have a serious concomitant disorder - Unable to swallow or digest pills - Poorly controlled diabetes - Concomitant medications or substances that are strong inhibitors/inducers of CYP3A.Study