Inclusion Criteria:

• Be willing and able to provide written informed consent/assent for the trial.
• Be ≥ 18 years of age on day of signing informed consent.
• Have received 1-5 prior chemotherapy lines for treating epithelial ROC (i.e., 2-6 total prior lines counting the front line).
• Have measurable disease based on RECIST 1.1.
  • Note: Tumor lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions.
• Have a performance status of 0 or 1 on the ECOG Performance Scale.
• Have histologically diagnosed recurrent epithelial ovarian, fallopian or primary peritoneal ovarian cancer.
• Have provided a tumor tissue sample from an archival tissue specimen collected from the primary ovarian tumor at the time of the initial debulking surgery. If primary ovarian cancer tissue is not available alternatively non lymph node tissue from a later biopsy may be used instead.
• Have received a tumor tissue test result of NanoString gene expression profiling that is indicative of the immunoreactive molecular subtype.
• Demonstrate adequate organ function as defined in Table 1, all screening labs should be performed within 28 days of treatment initiation.
• Adequate Organ Function Laboratory Values:
• Hematological
  • Absolute neutrophil count (ANC) ≥ 1,500 /mcL;
  • Platelets ≥ 100,000 / mcL;
  • Hemoglobin ≥ 9 g/dL or ≥ 5.6 mmol/L without transfusion or EPO dependency (within 7 days of assessment).
• Renal
  • Serum creatinine OR Measured or calculated* creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤ 1.5 X upper limit of normal (ULN) OR ≥ 45 mL/min for subject with creatinine levels > 1.5 X institutional ULN.
• Hepatic
  • Serum total bilirubin ≤ 1.5 X ULN OR Direct bilirubin ≤ ULN for subjects with total bilirubin levels > 1.5 ULN
  • AST (SGOT) and ALT (SGPT) ≤ 2.5 X ULN OR ≤ 5 X ULN for subjects with liver metastases
  • * Creatinine clearance should be calculated per institutional standard.
• Female subject of childbearing potential should have a negative urine or serum pregnancy within 72 hours prior to receiving the first dose of study medication. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required.
• Have received front line platinum-based chemotherapy (preoperative chemotherapy is allowed).
• Female subjects of childbearing potential must be willing to use an adequate method of contraception.  Contraception, for the course of the study through 120 days after the last dose of study medication.
  • Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the subject.

Exclusion Criteria: 

• Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 2 weeks of the first dose of treatment.
• Has had progression on or within 4 weeks of completing frontline platinum-based chemotherapy (primary platinum refractory).
• Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of trial treatment.
• Has a known history of active TB (Bacillus Tuberculosis).
• Hypersensitivity to pembrolizumab or any of its excipients.
• Has had a prior anti-cancer monoclonal antibody (mAb) within 4 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to agents administered more than 4 weeks earlier.
• Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to a previously administered agent.
  • Note: Subjects with ≤ Grade 2 neuropathy are an exception to this criterion and may qualify for the study.
  • Note: If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.
• Has a known additional malignancy that is progressing or requires active treatment. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer.
• Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis. Subjects with previously treated brain metastases may participate provided they are stable (without evidence of progression by imaging for at least four weeks prior to the first dose of trial treatment and any neurologic symptoms have returned to baseline), have no evidence of new or enlarging brain metastases, and are not using steroids for at least 7 days prior to trial treatment. This exception does not include carcinomatous meningitis which is excluded regardless of clinical stability.
• Has active autoimmune disease that has required systemic treatment in the past 2 years (i.e., with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.
• Has a history of (non-infectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease.
• Has an active infection requiring systemic therapy.
• Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject’s participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating investigator.
• Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial.
• Is pregnant or breastfeeding, or expecting to conceive children within the projected duration of the trial, starting with the pre-screening or screening visit through 120 days after the last dose of trial treatment. 16. Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent.
• Has a known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies).
• Has a known history of Hepatitis B (defined as Hepatitis B surface antigen [HBsAg] reactive) or known active Hepatitis C virus (defined as HCV RNA [qualitative] is detected) infection.
• Has received a live vaccine or live-attenuated vaccine within 30 days of planned start of study therapy. Administration of killed vaccines is allowed.
  • Note: Seasonal influenza vaccines for injection are generally inactivated flu vaccines and are allowed; however intranasal influenza vaccines (e.g., Flu-Mist®) are live attenuated vaccines, and are not allowed.

Eligibility last updated 8/31/21. Questions regarding updates should be directed to the study team contact.