This Phase 1, multi-center, open-label, first-in-human study evaluates multiple ascending daily oral doses of STC-15 in Q3W treatment cycles in a 3+3 cohort design with dose levels determined by a modified Fibonacci algorithm. The study is designed to systematically assess safety and tolerability, pharmacokinetics, pharmacodynamics and clinical activity of STC-15 in adult subjects with advanced malignancies. Dose levels for further evaluation in expansion cohorts will be selected based on all available PK, pharmacodynamic, target engagement, efficacy, safety, and tolerability data including long-term safety data beyond dose limiting toxicities (DLTs). The study may be amended to evaluate STC-15 in combination with a Food and Drug Administration-approved standard of care treatment regimen, which could encompass targeted/chemotherapy, radiation therapy and/or immunotherapy with immune checkpoint blockers.

Key Inclusion Criteria:

• > 18 years of age
• Histologic or cytologic confirmation of advanced malignancy that has failed standard of care (SOC) therapy and no further SOC therapy is available or the subject has declined additional SOC therapy
• Adequate organ and marrow function
• ECOG PS of 0 or 1

Key Exclusion Criteria:

• Treatment with any local or systemic antineoplastic therapy within 3 weeks prior to first dose of STC-15
• Major surgery or radiation within the 3 weeks
• Immune-related AEs from immunotherapy that required permanent discontinuation
• Central nervous system (CNS) disease involvement, or prior history of Grade ≥3 drug-related CNS toxicity.
• Active autoimmune disease that has required systemic treatment in the 2 years prior to Screening