Pembrolizumab in Treating Patients With Metastatic or Unresectable Gastroesophageal Adenocarcinoma

Inclusion Criteria

• •The subject (or legally acceptable representative if applicable) provides written informed consent for the trial. The subject may also provide consent for future biomedical research. However the subject may participate in the main trial without participating in future biomedical research.
• •Be willing and able to provide written informed consent/assent for the trial.
• •Histologically and cytologically documented diagnosis as gastroesophageal adenocarcinoma.
• •Have a documented advanced (metastatic and/or unresectable) gastroesophageal adenocarcinoma that is incurable and for which prior first-line or later-line standard of care (SOC) treatments have failed. There is no limit to the number of prior treatment regimens. Prior neoadjuvant or adjuvant therapy included in initial treatment may not be considered first- or later-line SOC treatment unless such treatments were completed less than 12 months prior to the current tumor recurrence.
• •Have submitted an evaluable tissue sample for biomarker analysis from a newly obtained endoscopic, core, incisional, or excisional biopsy of a tumor lesion not previously irradiated. The tumor tissue submitted for analysis must be from a single tumor tissue specimen and of sufficient quantity and quality to allow biomarker study. A newly obtained tumor specimen, defined as a specimen obtained up to 6 weeks (42 days) prior to initiation of treatment on day 1, for biomarker characterization will be required for enrollment of all subjects. Tissue from tumor progressing at a site of prior radiation may be allowed for biomarker characterization upon agreement from Merck. Subjects for whom newly-obtained samples cannot be provided (e.g. inaccessible or subject safety concern) may submit an archived specimen only upon agreement from the Merck.
• •Have measurable disease based on RECIST 1.1 as assessed by the investigator. 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 Eastern Cooperative Oncology Group (ECOG) performance scale.
• •Life expectancy of greater than 3 months per the judgment of the investigators.
• •Absolute neutrophil count (ANC) \>= 1,500 /mcL (within 5 days prior to the start of study treatment).
• •Platelets \>= 100,000/mcL (within 5 days prior to the start of study treatment).
• •Hemoglobin \>= 9 g/dL or \>= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (within 5 days prior to the start of study treatment).
• •Serum creatinine OR measured or calculated creatinine clearance (glomerular filtration rate \[GFR\] can also be used in place of creatinine or creatinine clearance \[CrCl\]) =\< 1.5 X upper limit of normal (ULN) OR \>= 60 mL/min for subject with creatinine levels \> 1.5 X institutional upper limit of normal (ULN) (within 5 days prior to the start of study treatment). Creatinine clearance should be calculated per institutional standard.
• •Serum total bilirubin =\< 1.5 X ULN OR direct bilirubin =\< ULN for subjects with total bilirubin levels \> 1.5 ULN (within 5 days prior to the start of study treatment).
• •Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\]) and alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\< 2.5 X ULN OR =\< 5 X ULN for subjects with liver metastases (within 5 days prior to the start of study treatment).
• •Albumin: \>= 2.5 mg/dL (within 5 days prior to the start of study treatment).
• •International normalized ratio (INR) or prothrombin time (PT) =\< 1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or partial thromboplastin time (PTT) is within therapeutic range of intended use of anticoagulants (within 5 days prior to the start of study treatment).
• •Activated partial thromboplastin time (aPTT) =\< 1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants (within 5 days prior to the start of study treatment).
• •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.
• •Male and female subjects of childbearing potential must be willing to use an adequate method of 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.