Inclusion Criteria:

          1. At least 18 years of age

          2. Ability to understand the purposes and risks of the study and has signed a written
             informed consent form approved by the investigator's Institutional Review Board
             (IRB)/Independent Ethics Committee (IEC)

          3. Recovered from toxicities of prior therapy to Grade 0 or 1

          4. Measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST version
             1.1) criteria or for rising prostate specific antigen (PSA) according to the Prostate
             Cancer Working Group 3 (PCWG3) criteria for subjects with CRPC

          5. Available tissue (including archival tissue) for retrospective AKR1C3 expression
             analysis (except for subjects with CRPC where this is not a requirement for
             inclusion). Patients must agree to a fresh tumor biopsy in case an archival sample is
             not available.

          6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

          7. Cardiac QTcF interval ≤ 450msec for males and ≤470 msec for females

          8. Acceptable liver function:

               1. Bilirubin ≤1.5 × institutional ULN

               2. AST and ALT ≤3.0 × ULN, or ≤5.0 × ULN for subjects with liver involvement

          9. Acceptable renal function:

             a. Creatinine clearance >30 mL/min according to the Cockcroft-Gault formula

         10. Acceptable hematologic status (without hematologic support, other than red blood cell
             transfusion):

               1. ANC ≥1500 cells/μL

               2. Platelet count ≥100,000/μL

               3. Hemoglobin ≥9.0 g/dL

         11. Females of childbearing potential must not have had unprotected sexual intercourse
             within 30 days before study entry and must agree to use a highly effective method of
             contraception (e.g., total abstinence, an intrauterine device, a double-barrier method
             [such as condom plus diaphragm with spermicide], a contraceptive implant, an oral
             contraceptive, or have a vasectomized partner with confirmed azoospermia) throughout
             the entire study period and for 30 days after study drug discontinuation.

             Dose Escalation Phase Subjects Only (Inclusion Criteria):

         12. Histologically or cytologically confirmed solid malignancy that is metastatic or
             unresectable and for which standard curative or palliative measures do not exist or
             are no longer effective

         13. Tumor progression after most recent therapy

             Expansion Phase- CRPC Cohort Only (Inclusion Criteria):

         14. Histologically confirmed diagnosis of adenocarcinoma of the prostate

         15. Documented evidence of metastatic CRPC

         16. Progressive disease according to the PCWG3 criteria for rising PSA or according to
             RECIST version 1.1 for measurable soft tissue disease

         17. Receipt of two or more lines of systemic standard of care treatment

         18. Castrate due to prior bilateral orchiectomy or ongoing LHRH analog therapy (with or
             without an androgen synthesis inhibitor). Subject must be able to remain on androgen
             deprivation therapy during study treatment (if no prior orchiectomy)

         19. Serum testosterone concentration of 50 ng/dL or less

             Expansion Phase - CRPC Cohort Only (Inclusion Criteria):

         20. Histologically confirmed advanced HCC not amenable to curative surgery or local
             treatment

         21. Prior treatment with an FDA-approved systemic therapy, including but not limited to
             sorafenib, lenvatinib, regorafenib, and/or nivolumab. Subjects may have progressed on,
             been intolerant of, or refused treatment with these agents

         22. Child-Pugh Classification with score ≤6 points within 7 days of the first study dose

         23. No history of hepatic encephalopathy

         24. No prior or current clinically significant ascites as measured by physical examination
             and that requires active paracentesis for control (subjects who have ascites only on
             radiographic imaging are eligible)

         25. No concomitant anticoagulation treatment

         26. No active alcohol abuse

         27. Adequate organ function for this HCC cohort is the same as for the Dose Escalation
             Cohort except as specified here (and if safety data from Dose Escalation allows):

               1. Platelet count ≥60,000/μL (HCC subjects with platelet counts ≥60,000/μL to
                  <99,000/μL must not have had hemorrhage within 6 months prior to study entry or,
                  if esophageal varices are present, the subject must have been treated prior to
                  study entry)

               2. ANC ≥1000 cells/μL

               3. Serum bilirubin ≤3 mg/dL

               4. AST/ALT ≤5 × ULN,

               5. International normalized ratio (INR) ≤2.3 or prothrombin time ≤6 seconds above
                  control

               6. Albumin ≥2.8 g/dL

        Exclusion Criteria:

          1. Prior radiotherapy to more than 25% of the bone marrow

          2. Symptomatic brain metastases, unless previously treated and well controlled for at
             least 4 weeks after central nervous system (CNS)-directed treatment as ascertained by
             clinical examination and brain imaging (magnetic resonance imaging [MRI] or computed
             tomography [CT]) during the Screening Period. Patients with known leptomeningeal
             disease are excluded.

          3. Previously treated malignancies, except for adequately treated non-melanoma skin
             cancer, in situ cancer, or other cancers whose natural history or treatment does not
             have the potential to interfere with the safety or efficacy assessment of the current
             study

          4. Major surgery, other than diagnostic surgery, within 4 weeks prior to Day 1, without
             complete recovery

          5. Active, uncontrolled bacterial, viral, or fungal infections, requiring systemic
             therapy

          6. Treatment with radiation therapy, surgery, chemotherapy, targeted therapies or
             hormones within 3 weeks prior to study entry (6 weeks for nitrosoureas or mitomycin C)

          7. Concomitant use of strong CYP3A4 inhibitors/inducers

          8. Subjects who participated in an investigational drug or device study within 28 days
             prior to study entry

          9. Subjects with known HIV infection, unless CD4 ≥500 cells/μL and HIV RNA below the
             limit of detection on stable doses of antiretroviral therapy

         10. Subjects with chronic HBV infection, unless Screening viral load <100 IU/mL on stable
             doses of antiviral therapy. Note: Subjects with chronic HCV infection are allowed to
             enroll in the study but do not have a defined maximum viral load requirement for study
             entry.

         11. Females who are pregnant or breast-feeding

         12. Concomitant disease or condition that could interfere with the conduct of the study,
             or that would, in the opinion of the investigator, pose an unacceptable risk to the
             subject in this study

         13. Unwillingness or inability to comply with the study protocol for any reason