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

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