PK and Dose Escalation and Expansion Study of DST-2970

Inclusion Criteria:

1. Male patients who have histologically or cytologically confirmed adenocarcinoma of the prostate (castrate sensitive or castrate resistant);

   1. During the dose escalation phase:

      Patients taking abiraterone acetate or enzalutamide as a single agent or in combination with Androgen Deprivation Therapy (ADT)
   2. During the expansion phase:

   Patients taking abiraterone acetate as a single agent or in combination with Androgen Deprivation Therapy (ADT).
2. Patients who have prostate-specific antigen (PSA) progression;

   1. During the dose escalation phase: Increasing PSA confirmed by 3 rising values (1.0 ng/mL minimum starting value) with or without radiographic progression
   2. During the dose expansion phase: Increasing PSA confirmed by sequence of rising values at a minimum of 1-week intervals (1.0 ng/mL minimum starting value) with or without radiographic progression
3. For the Expansion Cohorts

   1. Expansion Cohort 1: History of achieved an "initial PSA response to abiraterone" as defined in Section 3.1.
   2. Expansion Cohort 2: History of not having achieved an "initial PSA response to abiraterone as defined in Section 3.1.
4. Age ≥ 18 years.
5. ECOG Performance Status 0 or 1.
6. Patients must have the following laboratory values:
7. ANC \> 1500/µL
8. Platelet count \>100,000/µL
9. Hemoglobin \> 9 g/dL
10. Bilirubin \< 1.5 x upper limits of normal
11. ALT and AST \< 2.5x upper limits of normal
12. Have acceptable renal function: calculated creatinine clearance ≥60 mL/min
13. Albumin \> 2.8 g/dL.
14. Patient consent has been obtained according to local Institutional Review Board for acquisition of research specimens.
15. Patient is accessible and compliant for follow-up.
16. Patients with female partners of childbearing potential must agree to use barrier contraception (male condom) during the treatment period and for at least 30 days after the last dose.
17. Patient has a life expectancy of greater than 12 weeks.
18. Patient to be able to swallow the required tablets.

Exclusion Criteria:

1. For the Expansion Cohorts:

   1. Previous treatment with chemotherapy in the castrate resistant setting
   2. Positive for the ARV7 variant
2. History of failure after previous treatment with any androgen receptor blockers at any time (e.g., enzalutamide, apalutamide, darolutamide)

   a. Escalation Cohort: enzalutamide not excluded
3. Patients who had received previous therapy with ketoconazole for prostate cancer, lasting more than 7 days.
4. Have a corrected QT interval (using Fridericia's correction formula) (QTcF) of \>450 msec in men
5. Have not recovered from adverse events (must be Grade ≤1) due to agents administered more than 4 weeks earlier.
6. Known hypersensitivity to any study drug component, or experienced grade 3 toxicity or higher with abiraterone acetate.
7. Concomitant use of strong CYP3A4 inducers unless these can be discontinued before enrollment into the study.
8. Concomitant use of sensitive CYP2D6 and CYP2C8 substrates unless these can be discontinued during the study (see Appendix 5)
9. Any concomitant condition that in the opinion of the investigator could compromise the objectives of this study and the patient's compliance.
10. Current malignancies of another type, with the exception of adequately treated in situ basal cell skin cancer or other malignancies with no evidence of disease for 2 years or more.
11. Known active HIV, HBV or HCV infection. Patients with a history of hepatitis B or C are allowed if HBV DNA or Hep C RNA are undetectable.
12. Documented or known serious bleeding disorder.
13. Clinically evident CNS metastases or leptomeningeal disease not controlled by prior surgery or radiotherapy; history of seizure disorder not controlled by anti-seizure medication at the time of enrollment. Patients with primary CNS malignancies are excluded.
14. Patients with a significant cardiovascular disease or condition, including:

    1. Myocardial infarction within 6 months of study entry
    2. NYHA Class III or IV heart failure, or known LVEF \<50% (See Appendix 2)
    3. Uncontrolled dysrhythmias or poorly controlled angina.
    4. History of serious ventricular arrhythmia (VT or VF, ≥ 3 beats in a row) and/or risk factors (e.g., heart failure, hypokalemia, family history of Long QT Syndrome)
    5. Hypertension Grade 3 or higher. Patients with adequately treated hypertension are allowed.