An Open-Label, Phase 1 Study to Evaluate Safety, Tolerability and Pharmacokinetics of the CTPS1 Inhibitor STP938 in Adult Subjects With Advanced Solid Tumors, With a Safety Expansion in Advanced CTPS2 Null Ovarian Cancer

Main Inclusion Criteria: * Signed and dated informed consent, and able to comply with the study procedures and any locally required authorization. * Male or female aged ≥ 18 years. * Advanced disease not curable by available therapies and requires systemic therapy. * Histologically confirmed diagnosis of eligible cancer type. * Must have tumor tissue available for biomarker testing. * Measurable disease (Part 1) and measurable disease per RECIST (Part2) * Eastern Cooperative Oncology Group (ECOG) performance status ≤2. * Life expectancy \> 3 months as assessed by the Investigator. * Adequate organ function (bone marrow, hepatic, renal function and coagulation). * All toxicities (except alopecia) from prior cancer treatments or procedures must have resolved to ≤Grade 1 or returned to baseline levels prior to enrollment. Main Exclusion Criteria: * Pregnant or breastfeeding females and women of childbearing potential or males unwilling to comply with contraception requirements. * Known active or symptomatic CNS metastases, carcinomatous meningitis, leptomeningeal disease or a history of spinal cord compression * Active malignancy within 2 years of study enrollment * Prior radiation within 2 weeks of start of therapy. * Systemic cancer treatments, monoclonal antibody-directed therapies, other investigational agents within 4 weeks before enrollment, or \<5 half-lives since completion of previous investigational therapy, whichever is shorter. * Uncontrolled intercurrent illness. * Immunocompromised subjects with increased risk of opportunistic infections or history of opportunistic infection in the last 12 months. * Known active or chronic hepatitis B or active hepatitis C virus (HCV) infection. * Subjects with corrected QT interval \>470 msec based on averaged triplicate electrocardiogram (ECG) readings at the Screening Visit using the QT interval corrected for heart rate using Fridericia's method (QTcF).