Part 1b MTD Dose Expansion: Histologically or cytologically confirmed platinum-resistant or platinum-refractory high grade serous ovarian cancer. Platinum-resistant disease is defined by progression <6 months following the last administered platinum-based regimen, and platinum-refractory is defined by lack of at least a partial response while on platinum-containing regimens. Platinum sensitive disease (recurrent after 6 months) must have been treated with additional platinum containing regimens or PARPi if tBRCAm+ or other HRD+