Pembrolizumab and Trifluridine/Tipiracil With Previously Treated Advanced Gastric Cancer

Prior treatment

• Has received prior therapy with TAS-102.
• Has any unresolved ≥Grade 2 toxicity (per CTCAE v5.0) attributed to any prior therapies at the time of enrollment.
• Has had major surgery within 2 weeks prior to first dose of study interventions.
• Has received radiotherapy for gastric cancer treatment within 2 weeks prior to the first dose of study drugs.
• Has received a live vaccine or live-attenuated vaccine within 30 days prior to the first dose of study drug.
• Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of study drug.
• Has participated has used an investigational device within 4 weeks prior to the first dose of study intervention.
• Has had an allogenic tissue/solid organ transplant.

Other illness

• Has other concurrently active malignancies.
• Is contraindicated for pembrolizumab and/or TAS-102, or have severe hypersensitivity to any of those drugs and/or their excipients.
• Has a history of uncontrollable or significant cardiovascular disease.
• Has active (significant or uncontrolled) gastrointestinal bleeding.
• Has active autoimmune disease that has required systemic treatment in the past 2 years.
• Has a history of (non-infectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease.
• Has an active, unresolved infection requiring systemic therapy.
• Has a known history of Human Immunodeficiency Virus (HIV) infection.
• Has a known history of Hepatitis B (defined as Hepatitis B surface antigen \[HBsAg\] reactive) or known active Hepatitis C virus infection.
• Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial.

Lab values

• Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study.

Other

• Has known active central nervous system (CNS) metastases.

• Has provided written informed consent fo the trial.
• Is male or female at least 18 years of age.
• Has a histologically or cytologically confirmed diagnosis of advanced or metastatic gastric/gastroesophageal junction (GEJ) adenocarcinoma.
• Has previously received at least 2 prior regiments.
• Has a life expectancy of at least 3 months.
• Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Have 1 or more measurable disease as determined by RECIST 1.1.
• Is able to take medications orally.
• Has adequate organ function as defined by the following criteria.
• Is willing to follow and follow research procedures.
• A male participant must agree to use a contraception of this protocol during the treatment period and for at least 120 days post TAS-102.
• A female participant is eligible to participate if she is not pregnant or breastfeeding.