A Study Evaluating the Safety and Pharmacokinetics of Orally Administered SM08502 in Subjects With Advanced Solid Tumors

Key Inclusion Criteria: 1. Subjects with advanced solid tumors (as defined below): 1. Part 1A - Subjects with advanced solid tumors who are refractory to or intolerant of established therapy known to provide clinical benefit for their condition (i.e., subjects must not be candidates for regimens known to provide clinical benefit) and for which histologic or cytologic confirmation of malignancy was obtained at diagnosis, with the exception of hepatocellular carcinoma if it meets appropriate imaging-only diagnostic criteria (per the National Comprehensive Cancer Network \[NCCN\], Liver Imaging Reporting and Data System \[LI-RADS\], American Association for the Study of Liver Diseases \[AASLD\], Asian Pacific Association for the Study of the Liver \[APASL\], or European Association for the Study of the Liver - European Organisation for Research and Treatment of Cancer \[EASL-EORTC\]). 2. Part 1B - Subjects with advanced and/or metastatic solid tumors who are refractory to or intolerant of established therapy known to provide clinical benefit for their condition (i.e., subjects must not be candidates for regimens known to provide clinical benefit in the Investigator's judgment). Histologic or cytologic confirmation of malignancy must have been obtained at diagnosis. The tumor types include: i. NSCLC (adenocarcinoma subtype) ii. TNBC iii. CRPC iv. CRC v. Endometrial cancer (endometrioid subtype) vi. Ovarian cancer (serous, mucinous, and endometrioid subtypes). 3. Part 2 - Subjects with advanced and/or metastatic solid tumors who are refractory to or intolerant of established therapy known to provide clinical benefit for their condition. Histologic or cytologic confirmation of malignancy must have been obtained at diagnosis. Subjects must have received no more than 2 prior lines of myelosuppressive chemotherapy. Additionally, CRPC subjects must have received no more than 4 total lines of treatment (including any hormonal therapies) in any setting. The tumor types include: i. NSCLC (adenocarcinoma subtype) ii. CRPC in two biomarker selected cohorts. 2. Measurable or evaluable disease per RECIST 1.1 (Part 1A). For Parts 1B and 2, at least 1 measurable lesion per RECIST 1.1 that has not been previously irradiated. In CRPC subjects (Parts 1B and 2) without measurable disease per RECIST 1.1, a PSA that is concordant with clinical disease progression (rising) is eligible. A PSA value of 2 ng/ml or greater is required for study entry. 3. Subjects must have archived tumor specimens available for analysis (as specified in Section 7.2.2). Otherwise, a fresh tumor biopsy will be required at study entry. At the discretion of the Sponsor's Medical Monitor, a fresh tumor biopsy may not be required for eligibility if there are extenuating circumstances (e.g., inaccessible sites of disease or lack of subject suitability to undergo a fresh biopsy, or molecular profiling of archived tissue already performed). 4. Subjects must have recovered (i.e., Grade 1 \[or better\] based on CTCAE v5.0) from all toxicity associated with previous chemotherapy, targeted therapy, experimental therapy, biological therapy, immuno-oncology therapy, surgery, radiotherapy, or other locoregional therapy (Exceptions include subjects with: continuing alopecia regardless of any CTCAE grade, Grade 2 or lower neuropathy, and well-controlled hypothyroidism and/or adrenal insufficiency on chronic hormone replacement. All subjects with these exceptions are eligible). 5. Eastern Cooperative Oncology Group (ECOG) performance status ≤ 1. Key Exclusion Criteria: 1. Women who are pregnant or lactating 2. Women of childbearing potential (WOCBP) who do not agree to follow the contraceptive guidelines as outlined in the study protocol 3. Men of reproductive potential who do not agree to follow the contraceptive guidelines as outlined in the study protocol 4. Subjects with a corrected QT interval (QTc) using Fridericia's formula (QTcF) \> CTCAE v5.0 Grade 1 (\>480 msec) based on the mean of triplicate evaluation at Screening. 5. Subjects with clinically significant ventricular tachycardia (VT), atrial fibrillation (AF), ventricular fibrillation (VF), second or third degree heart block 6. Subjects with myocardial infarction (MI) within 1 year, Class II-IV congestive heart failure (CHF) per New York Heart Association (NYHA) classification, or clinically significant coronary artery disease (CAD) 7. Subjects with active infection requiring parenteral antibiotic therapy. 8. Organ transplant recipients. 9. Subjects with known osteoporosis. 10. Subjects with a second malignancy unless adequately treated with no recurrence for 3 years. Subjects with history of previous or recent adequately treated skin basal cell carcinoma, squamous cell carcinoma of the skin, or carcinoma in situ of any source are eligible. 11. Subjects with active gastrointestinal (GI) disease or other condition that will interfere significantly with the absorption, distribution, metabolism, or excretion of SM08502 per Investigator's opinion 12. Subjects with known active human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV) infection 13. Subjects with chronic liver disease or dysfunction and a Child-Pugh score of B or C 14. Subjects with untreated, progressing, or known symptomatic brain metastasis 15. Subjects with retinal abnormalities, specifically diabetic retinopathy, macular degeneration, other forms of retinal degenerative disease, or other retinal findings that may place the subject at risk