• Patients with platinum-sensitive recurrent ovarian, fallopian or primary peritoneal cancer (defined as recurrent disease \> 6 months after completing last platinum- based chemotherapy) that are eligible to receive platinum-based chemotherapy).

• Documented disease recurrence/progression based on GCIG-RECIST

• Must have had at least 1 prior line of platinum-based therapy, prior bevacizumab or PARPi use are allowed. Women with germline BRCA mutations should be considered for PARPi maintenance as standard of care treatment prior to consideration of clinical trial enrollment

• Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2 with life expectancy of ≥ 3months

• Adequate organ function

‣ Serum creatinine ≤1.5mg/dL or 24-hour clearance ≥50mL/min

⁃ AST/ALT \<2.5x ULN (or \<5x ULN if liver metastasis are present)

⁃ Total bilirubin ≤ ULN or total bilirubin ≤3.0 x ULN or direct bilirubin ≤1.5 x ULN in patients with well-documented Gilbert's Syndrome

⁃ Hemoglobin ≥9 gm/dl, Platelets ≥100,000/μl ANC ≥1500/μl

⁃ INR ≤1.5

⁃ Potassium, total calcium (corrected for serum albumin), magnesium, and sodium within normal limits for the institution or corrected to within normal limits with supplements before first dose of study medication

• Must be able to swallow CPI-0209 tablet/oral suspension

• Able to provide informed consent and comply with all study protocol

• Treated CNS metastasis allowed if treatment is completed ≥8 weeks prior to enrollment. Patients must be asymptomatic off systemic corticosteroids for at least 4 weeks after completion of radiation therapy. CNS disease must be stable or regressed on repeat imaging performed at least 4 weeks after completion of therapy.

• Women of child-bearing potential (those who have had a menstrual cycle within the last year and have not had a tubal ligation or surgical removal of both ovaries and/or hysterectomy) must agree to abstain from vaginal intercourse or use and continue highly effective methods of contraception for at least 183 days after discontinuation of study treatment.

‣ Total abstinence when this is in line with the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception.

⁃ Female sterilization (have had surgical bilateral oophorectomy with or without hysterectomy), total hysterectomy, or tubal ligation at least six weeks before taking study treatment. In case of oophorectomy alone, only when the reproductive status of the woman has been confirmed by follow-up hormone level assessment.

⁃ Male sterilization (at least 6 months prior to screening). The vasectomized male partner should be the sole partner for that patient.

⁃ Use of oral, injected or implanted hormonal methods of contraception or placement of an intrauterine device (IUD) or intrauterine system (IUS), or other forms of hormonal contraception that have comparable efficacy (failure rate \<1%), for example hormone vaginal ring or transdermal hormone contraception.

⁃ In case of use of oral contraception, women should have been stable on the same pill for a minimum of 3 months before taking study treatment.