A Study of Sovilnesib in Subjects With Ovarian Cancer

Key Inclusion Criteria: * All Parts: Age ≥ 18 years, ECOG Performance Status ≤ 1, at least 1 site of measurable disease evaluable by CT scan or MRI per RECIST 1.1, able to take oral medication without alteration * Histologically confirmed locally advanced, inoperable, or metastatic tumor. * High Grade Serous Ovarian Cancer, Fallopian Tube or Primary Peritoneal Cancer - histologically confirmed; locally advanced, inoperable or metastatic; p16 positive (Part 2 only); platinum resistant (defined as radiographic progression/recurrence \<180 days after last dose of ≥ 4 cycles of platinum containing therapy) or refractory; prior bevacizumab treatment, unless ineligible or intolerant; if germline and/or somatic BRCA1/2 mutation, previously treated with PARP-inhibitor (unless ineligible or intolerant). Key Exclusion Criteria: * Part 1 only: MSI-H, dMMR, POLE gene hotspot mutated, or known hypermutator phenotype * Endometrioid, clear cell, mucinous, sarcomatoid, low-grade/borderline ovarian tumor or mixed tumors containing any of the above histologies * Previously received KIF18A inhibitor * Leptomeningeal disease, or new or progressive CNS metastases or spinal cord compression * Cardiac parameters: MI, PE, CABG, severe/unstable angina or stroke ≤ 6 months, NYHA Class ≥ II, LVEF \< 50% * Any gastrointestinal condition (e.g. malabsorption syndrome, surgical anastomosis, short bowel syndrome) that might affect the absorption of oral medications including the study drug