Pembrolizumab and Olaparib Treatment for Relapsed or Refractory Peripheral T-Cell Lymphoma

Inclusion Criteria: 1. Male/female participants who are at least 21 years of age on the day of signing informed consent with histologically or cytologically-confirmed diagnosis of peripheral T-cell lymphoma (PTCL), including angioimmunoblastic T-cell lymphoma (AITL), peripheral T-cell lymphoma of T-follicular helper cell derivation (PTCL-TFH), anaplastic large cell lymphoma (ALCL), NK/T-cell lymphoma (NKTCL), gamma-delta T cell lymphoma (GDTL), enteropathy associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), subcutaneous panniculitis like T-cell lymphoma, and PTCL, not otherwise specified (PTCL-NOS) will be enrolled in this study. 2. Male participants: A male participant must agree to use a contraception as detailed in Appendix 3 of this protocol during the treatment period and for at least the time needed to eliminate the study intervention (180 days for Olaparib; no requirement for pembrolizumab) after the last dose of study treatment and refrain from donating sperm during this period. 3. A female participant is eligible to participate if she is not pregnant (see Appendix 3), not breastfeeding, and at least one of the following conditions applies: a. Not a woman of childbearing potential (WOCBP) as defined in Appendix 3 OR b. A WOCBP who agrees to follow the contraceptive guidance in Appendix 3 during the treatment period and for at least the time needed to eliminate the study intervention (180 days for Olaparib; 120 days for pembrolizumab) after the last dose of study treatment. 4. Participants must have progressed on treatment with at least one prior systemic anti-cancer therapy including investigational agents. These may include an anti-PD-1/L1 mAb administered either as monotherapy or in combination with other checkpoint inhibitors or other therapies. PD-1 treatment progression is defined by meeting all of the following criteria: 1. Has received at least 2 doses of an approved anti-PD-1/L1 mAb. 2. Has demonstrated disease progression after anti-PD-1/L1 as defined by Cheson response criteria. The initial evidence of PD is to be confirmed by a second assessment no less than 4 weeks from the date of the first documented disease progression, in the absence of rapid clinical progression (as defined in 4.c). 3. Progressive disease has been documented within 12 weeks from the last dose of anti-PD-1/L1 mAb. * Progressive disease is determined according to Cheson response criteria. * This determination is made by the investigator. Once disease progression is confirmed, the initial date of disease progression documentation will be considered the date of disease progression. Progression on other systemic anti-cancer therapy including investigational agents is defined by radiographic disease progression based on Cheson response criteria. 5. The participant (or legally acceptable representative if applicable) provides written informed consent for the trial. 6. Have measurable disease based on Cheson criteria. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions. 7. Archival tumor tissue sample or newly obtained \[core, incisional or excisional\] biopsy of a tumor lesion not previously irradiated has been provided. Formalin-fixed, paraffin embedded (FFPE) tissue blocks are preferred to slides. Newly obtained biopsies are preferred to archived tissue. 8. Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1. Evaluation of ECOG is to be performed within 7 days prior to the first dose of study intervention. 9. Have adequate organ function as defined in the following. Specimens must be collected within 10 days prior to the start of study intervention. * Absolute neutrophil count (ANC)≥500/μL * Platelets ≥25 000/μL * Hemoglobin ≥8 g/dL * Creatinine OR Measured or calculated creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤1.5 × ULN OR ≥30 mL/min for participant with creatinine levels \>1.5 × institutional ULN * Total bilirubin ≤1.5 ×ULN OR direct bilirubin ≤ULN for participants with total bilirubin levels \>1.5 × ULN * AST (SGOT) and ALT (SGPT) ≤2.5 × ULN (≤5 × ULN for participants with liver metastases) * International normalized ratio (INR) OR prothrombin time (PT) ≤1.5 × ULN unless participant is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants * Activated partial thromboplastin time (aPTT) ≤1.5 × ULN unless participant is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants 10. Hepatitis B and C screening tests are required: * Hepatitis B positive subjects * Participants who are HBsAg positive are eligible if they have received HBV antiviral therapy for at least 4 weeks and have undetectable HBV viral load prior to enrolment. * Participants should remain on anti-viral therapy throughout study intervention and follow local guidelines for HBV anti-viral therapy post completion of study intervention. * Participants with history of HCV infection are eligible if HCV viral load is undetectable at screening. * Participants must have completed curative anti-viral therapy at least 4 weeks prior to enrolment. 11. Participant has a life expectancy of at least 3 months Exclusion Criteria: 1. A WOCBP who has a positive urine pregnancy test within 72 hours prior to treatment (see Appendix 3). If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required. 2. Has received prior systemic investigational agents within 4 weeks (or shorter interval for kinase inhibitors or other short half-life drugs, per investigator discretion) or has used an investigational device within 4 weeks prior to treatment. 3. Has received prior radiotherapy within 2 weeks of start of study intervention or radiati