Inclusion Criteria:  Women ≥ 18 years of age  Is not a woman of childbearing potential:  Surgically sterile (i.e., had a bilateral tubal ligation, hysterectomy, salpingectomy, or bilateral oophorectomy at least 6 months prior to Day 1 of the study) or; Postmenopausal for at least 1 year prior to Day 1 of the study, and have follicle stimulating hormone levels in the postmenopausal range for the study site. Signed written informed consent Histologically confirmed high grade serous or endometrioid carcinoma of the ovary, fallopian tube, or primary peritoneal cancer 1 to 3 prior systemic treatment lines. Prior maintenance therapy with bevacizumab or PARP inhibitors is permitted. Platinum-sensitive carcinoma, defined as disease progression after ≥ 6 months following the most recent platinum-based therapy of the disease Measurable disease on CT/MRI scan according to RECIST 1.1 ECOG Performance status 0 to 1 Life expectancy of at least 6 months  Meet the following laboratory requirements:  Hemoglobin (HGB) ≥ 100 × 109/L Absolute neutrophil count (ANC) ≥ 1.5 × 109/L Platelet count ≥ 100 × 109/L aPTT/PT ≤ 1.5 x ULN Total bilirubin level ≤ 1.5 × ULN AST and ALT ≤ 2.5 × ULN (≤ 5 × ULN if liver metastasis present) Creatinine Clearance > 60 mL/min, as calculated by Cockcroft-Gault formula, or serum creatinine ≤ 1.5 × ULN.  Exclusion Criteria:  Have received an anti-cancer/investigational drug within 4 weeks prior to study drug administration Have received a vaccine for COVID-19 within 14 days prior to the first dose of ATX-101 or are scheduled/intend to have a COVID-19 vaccine on Day 1 or during the DLT period (i.e. C1D2 [Day 2] through to C2D2 [Day 30]) of the study Have not recovered from AEs (≥ CTCAE Grade 2 other than alopecia) due to agent(s) administered more than 4 weeks earlier Radiotherapy within 4 weeks prior to study drug administration Major surgery or significant trauma within 28 days (4 weeks) of Screening Anticipated requirement for surgery or initiation of anti-cancer therapy, other than described in this study protocol, during the study period Known hypersensitivity to any of the combination partners of ATX-101 Any malignancy over the last 5 years, other than ovarian/fallopian tube/primary peritoneal cancer, with exception of basal cell carcinoma or squamous cell carcinoma of the skin or carcinoma in situ of the cervix that is considered cured by excision Cardiac failure NYHA III/IV. LVEF < 50% (ECHO or MUGA must not be older than 12 weeks) QTcF > 470 msec Any organ dysfunction or current acute or chronic disease, other than the study indication, that would significantly increase the expected risk in participants participating in the study, in the judgment of the Investigator Pregnant or breast-feeding women Unwilling or unable to follow protocol requirements A past positive status of HIV and/or positive for HIV at Screening Active Hepatitis B or C. In participants with a history of Hepatitis B or Hepatitis C infection, HBsAg and HCV RNA tests have to be negative.