CD8+ T Cell Therapy and Pembrolizumab in Treating Patients With Metastatic Gastrointestinal Tumors

Inclusion: 1. Histopathologic documentation of pancreatic adenocarcinoma, colorectal adenocarcinoma, cholangiocarcinoma, esophageal cancer and gastric cancer with radiographic evidence of metastatic disease. 2. Male or female subjects greater than or equal to 18 years of age. 3. ECOG/ Zubrod performance status of 0 or 1. 4. Women of childbearing potential (WOCBP) must be using an adequate method of contraception to avoid pregnancy throughout the study in such a manner that the risk of pregnancy is minimized. Suggested precautions should be used to minimize the risk or pregnancy for at least 1 month before start of therapy, and while women are on study for at least 8 weeks after pembrolizumab is stopped. WOCBP include any female who has experienced menarche and who has not undergone successful surgical sterilization (hysterectomy, bilateral tubal ligation or bilateral oophorectomy) or is not postmenopausal. Acceptable forms of birth control include condom, diaphragm, hormonal, IUD, or sponge plus spermacide. Abstinence is also an acceptable form of birth control. 5. Men must be willing and able to use an acceptable method of birth control, during and for at least 3 months after completion of the study, if their sexual partners are WOCBP. 6. Willing and able to give informed consent. 7. Adequate vein access: consider PICC or other central line. 8. Patients must have adequate tissue (fresh or frozen) available or planned removal of adequate tissue for analysis. At least 250mg of tumor are needed for peptide elution. There is no specific time limit on how long the tissue can remain frozen prior to use. The tissue will be collected and analyzed under Lab protocol PA15-0176. 9. Patients can have any lines (including zero) of prior therapy to sign consent prior to tissue harvest. 10. Toxicity related to prior therapy must either have returned to \</= grade 1, baseline, or been deemed irreversible. 11. ELIGIBILITY FOR TREATMENT: ECOG/Zubrod performance status of 0 to 2. 12. Bi-dimensionally measurable disease by radiographic imaging (CT scan) that represents at least one measurable lesion per RECIST v1.1. 13. At least 4 Weeks must have elapsed since the last chemotherapy, radiotherapy or major surgery. 14. Toxicity related to prior therapy must either have returned to less than or equal to grade 1, baseline, or been deemed irreversible. 15. Subjects must have received at least one line of chemotherapy prior to receiving adoptive T cell therapy and should have exhausted standard of care systemic therapy options. The decision to implement the T cell therapy will be at the discretion of the treating physician. The timing and total exposure to chemotherapy will depend on the tumor type in question (more systemic options for breast cancer; fewer for gastric cancer, for example). Due to the heterogeneity of tumors being treated in this protocol, the discretion of the treating physician in terms of timing of immunotherapy will be critical. Exclusion: 1. EXCLUSION FOR ENROLLMENT: Any other malignancy from which the patient has been disease-free for less than 5 years, with the exception of adequately treated and cured basal or squamous cell skin cancer, superficial bladder cancer, and carcinoma in situ of the cervix. 2. Pregnant women, nursing mothers, men or women of reproductive ability who are unwilling to use effective contraception. Women of childbearing potential with a positive pregnancy test within 3 days prior to entry. 3. Significant cardiovascular abnormalities as defined by any one of the following: 1. Congestive heart failure NYHA classes II-IV. Patients with asymptomatic class I CHF may participate in conjunction with a Cardiology consultation. 2. Clinically significant hypotension. 3. Symptoms of coronary artery disease. 4. Presence of arrhythmias in EKG requiring drug therapy. 4. Active and untreated central nervous system (CNS) metastases (including metastasis identified during screening MRI or contrast CT). Patients with asymptomatic, treated metastases may be eligible if their lesion(s) have demonstrated stability over 2 months. 5. Autoimmune disease: Patients with a history of Inflammatory Bowel Disease are excluded from this study, as are patients with a history of autoimmune disease (e.g. Systemic Lupus Erythematosus, vasculitis, infiltrating lung disease) whose possible progression during treatment would be considered by the Investigator to be unacceptable. 6. Any underlying medical or psychiatric condition, which in the opinion of the Investigator, will make the administration of study drug hazardous or obscure the interpretation of adverse events, such as a condition associated with frequent diarrhea. 7. Inadequate organ function at enrollment defined by: WBC less than or equal to 2000/uL. Hct less than or equal to 24% or Hgb less than or equal to 8 g/dL. ANC less than or equal to 1000. Platelets less than or equal to 75,000. Creatinine greater than or equal to 1.5 x ULN OR creatinine clearance \>50 ml/min/1.73m2 for patients with creatinine levels above institutional normal limits. AST/ALT greater than or equal to 2.5 x ULN. Bilirubin greater than or equal to 2.0 x ULN 8. Positive screening tests for HIV, Hep B, and Hep C. If positive results are not indicative of true active or chronic infection, the patient can be treated 9. EXCLUSION CRITERIA FOR TREATMENT: WBC less than or equal to 2000/uL. Hct less than or equal to 24% or Hgb less than or equal to 8 g/dL. ANC less than or equal to 1000. Platelets less than or equal to 75,000. Creatinine greater than or equal to 1.5 x ULN OR creatinine clearance \>50 ml/min/1.73m2 for patients with creatinine levels above institutional normal limits. AST/ALT greater than or equal to 2.5 x ULN. Bilirubin greater than or equal to 2.0 x ULN 10. Pregnant women, nursing mothers, men or women of reproductive ability who are unwilling to use effective contraception. Women of childbearing potential with a positive pregnancy test within 3 days prior to entry. 11. Steroids are not permitted 3 days prior to T cell infusion and concurrently during therapy. 12. Uncontrolled concurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. 13. Any non-oncology vaccine therapy used for the prevention of infectious disease within 1 month before or after any anti-PD-1 dose. 14. After the T cell infusion, patients may not be on any other treatments for their cancer aside from those included in the treatment section of the protocol. 15. Coagulation ≤1.5 x ULN unless participant is receiving anticoagulant therapy as long as PT or a PTT is within therapeutic range of intended use of anticoagulants.