Inclusion Criteria:

• Patients with histologically confirmed metastatic colorectal cancer (CRC) who are planned for, or have received <30 days of first-line treatment in the metastatic setting with FOLFOX/bev, CAPEOX/bev, FOLFOXIRI/bev, or CAPOXIRI/bev per SOC
• Measurable and unresectable metastatic disease according to RECIST v1.1
• Availability of formalin-fixed paraffin-embedded (FFPE) tumor specimens.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Patient has adequate organ function per defined criteria
• If women of childbearing potential (WCBP), must be willing to undergo pregnancy testing and agrees to the use at least 1 highly effective contraceptive method during the study treatment period and for 150 days after last investigational study treatment.

Exclusion Criteria:

• Patients with deficient mismatch repair (dMMR) or microsatellite instability (MSI-H) phenotype
• Patient has a known tumor mutation burden <1 non-synonymous mutations/megabase
• Known DNA Polymerase Epsilon mutations
• Patients with known BRAFV600E mutations
• Bleeding disorder or history of significant bruising or bleeding following IM injections or blood draws
• Immunosuppression anticipated at time of study treatment
• History of allogeneic tissue/solid organ transplant
• Active or history of autoimmune disease or immune deficiency
• Patient with symptomatic or actively progressing central nervous system (CNS) metastases, carcinomatous meningitis, or has been treated with whole brain radiation
• History of other cancer within 2 years with the exception of neoplasm that has undergone potentially curative therapy
• Any severe concurrent non-cancer disease that, in the judgment of the Investigator, would make the patient inappropriate for the current study
• Active tuberculosis or recent (<2 weeks) clinically significant infection, evidence of active hepatitis B or hepatitis C, or known history of positive test for HIV
• History of pneumonitis requiring systemic steroids for treatment (with the exception of prior resolved in-field radiation pneumonitis)
• Myocardial infarction within previous 3 months, unstable angina, serious uncontrolled cardiac arrhythmia, history of myocarditis, or congestive heart failure (Class III or IV).
• Pregnant, planning to become pregnant, or nursing.

• HIV antibody negative
• Hepatitis B antigen negative
• Hepatitis C antibody negative or HCV RNC negative (i.e., no current HCV infection) 13. More than four weeks must have elapsed since any prior systemic therapy or radiotherapy at the time the patient receives the KK-LC-1 TCR T cells. Adverse events from prior therapy must have resolved to≤ grade 1 according to CTCAE Version 5 or have demonstrated clinical stability and meet the eligibility criteria for the protocol. 14. Oxygen saturation ≥ 92% on room air. 15. Left ventricular ejection fraction ≥45% by echocardiogram or MUGA for patients 50 years of age or older.

Inclusion Criteria:

Subject must meet all of the following applicable inclusion criteria to participate in this study:
• Written informed consent and HIPAA authorization for release of personal health information must be obtained either from the subject or their representative. See protocol. NOTE: HIPAA authorization may be included in the informed consent or obtained separately.
• Age ≥ 18 years at the time of consent.
• ECOG Performance Status of 0-1.
• Locally advanced, metastatic, or unresectable hepatocellular carcinoma that has not received prior systemic therapy. Note: if no prior histologic diagnosis exists, prefer fresh biopsy if it is both safe and feasible. If fresh biopsy is not safe and feasible, imaging criteria may be used for diagnosis as per AASLD criteria in cirrhotic patients (please see www.aasld.org for up to date guidelines).
• Child Pugh Class B7 or B8 liver dysfunction or cirrhosis with the following limitations:
• Bilirubin ≤ 3 mg/dL
• Albumin ≥ 2.8 g/dL
• INR ≤ 1.7
• Absent to slight [CP=1 to 2] (no moderate [CP=3]) ascites (Also see exclusion criteria).
• No clinically significant encephalopathy (Also see exclusion criteria).
• At least 1 untreated measurable lesion according to RECIST 1.1.
• Willingness to undergo fresh tumor biopsy at baseline if safe and feasible. Note: archival tissue may be used at baseline provided histologic diagnosis was made and sufficient tissue is available for NGS analysis.
• NGS analysis must be requested from archival tissue or fresh biopsy (if applicable) as per standard of care. Foundation One CDX is the preferred platform. Prior NGS sequencing results (including from another platform) will be accepted if NGS sequencing was previously obtained (please see protocol).
• Demonstrate adequate bone marrow and organ function as defined below:
• Hematologic
• Absolute neutrophil count (ANC) ≥ 1,000/mcL
• Lymphocyte count ≥ 0.5 x 10^9/L (500uL)
• Hemoglobin ≥ 90 g/L (9 g/dL)
• Platelet count ≥ 70,000/mcL
• Renal
• Serum creatinine OR calculated* serum creatinine clearance (GFR can be used in place of creatinine or creatinine clearance) ≤ 1.5 x ULN OR ≥ 30 mL/min for participants with creatinine levels > 1.5 x institutional ULN *calculate serum creatinine clearance using the standard Coccroft-Gault formula
• Urine protein: Urine dipstick for proteinuria < 2+ within 7 days prior to start of study treatment *Patients with with ≥ 2+ proteinuria on dipstick analysis at baseline should undergo a 24-hour urine collection which must demonstrate < 1g of protein in 24 hours.
• Hepatic
• AST (SGOT) and ALT (SGPT) ≤ 8 x ULN
• Alkaline phosphastase (ALP) ≤ 8 x ULN
• For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods with a failure rate of < 1% per year during the treatment period and for at least 5 months after the last dose of atezolizumab, or 6 months after the last dose of bevacizumab. See also the protocol for definition of childbearing potential.
• For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use effective contraceptive measures. Men with female partners of childbearing potential must remain abstinent or use a condom plus an additional contraceptive method that together result in a failure rate of < 1% per year during the treatment period and for 6 months after the last dose of bevacizumab. With pregnant female partners, men must remain abstinent or use a condom during the treatment period and for 6 months after the last dose of bevacizumab to avoid exposing the embryo. See also the protocol for additional information.
• As determined by the enrolling physician or protocol designee, ability of the subject to understand a written informed consent document, and ability and willingness to comply with study procedures for the entire length of the study. Patients with impaired decision-making capacity (IDMC) who have a close caregiver or legally authorized representative (LAR) and/or family member available are also eligible.

Exclusion Criteria:

Subjects meeting any of the criteria below may not participate in the study:
• Histologic diagnosis of fibrolamellar or sarcomatoid HCC or mixed cholangiocarcinoma-HCC.
• Patients who have had chemotherapy, definitive radiation, biological cancer therapy, or investigational agent/device within 21 days of first planned dose of study therapy (within 14 days for palliative radiation). Patients who have had major surgery within 4 weeks of start of study therapy or anticipation of need for a major surgical procedure during the study.
• Patients who have not recovered from adverse events due to prior anti-cancer therapy (i.e., have residual toxicities > CTCAE Grade 1) with the exception of alopecia or neuropathy.
• Patients who have received prior systemic therapy for HCC.
• Patients who have received prior immunotherapy.
• Patients with clinically meaningful ascites, defined as ascites requiring non-pharmacologic intervention (e.g. paracentesis) to maintain symptomatic control within 3 months prior to the first dose of study treatment. Note: Patients with ascites meeting eligibility criteria who require pharmacologic intervention (e.g. diuretics) to maintain symptomatic control and who have been on stable doses of diuretics for 2 months prior to the first dose of study treatment are eligible.
• Patients with clinically meaningful encephalopathy, defined as a history of hepatic encephalopathy within 6 months prior to first dose of study treatment or requirement for medications to prevent or control encephalopathy (e.g. lactulose, rifaximin).
• Any of the following additional high-risk features:
• Patients with untreated or incompletely treated esophageal and/or gastric varices with bleeding or high risk for bleeding. Note: Patients must undergo an esophagogastroduodenoscopy (EGD), and all size of varices (small to large) must be assessed and treated per local standard of care prior to enrollment. Patients who have undergone an EGD with appropriate management of varices (if applicable) within 6 months of prior to initiation of study treatment do not need to repeat the procedure.
• History of esophageal and/or gastric hemorrhage within 3 months prior to study treatment.
• History of hemoptysis (< 2.5 mL of bright red blood per episode) within 1 month prior to study treatment.
• History of intracranial hemorrhage within 1 month prior to study treatment.
• History of abdominal or tracheoesophageal fistula, gastrointestinal (GI) perforation, or intra-abdominal abscess within 6 months prior to initiation of study treatment. Evidence of abdominal free air that is not explained by paracentesis or recent surgical procedure.
• Serious, non-healing or dehiscing wound, active ulcer, or untreated bone fracture within 30 days prior to start of study treatment.
• Metastatic disease that involves major airways or blood vessels. Patients with vascular invasion of the portal or hepatic veins may be enrolled.
• Significant vascular disease (e.g. aortic aneurysm requiring surgical repair) or vasculitis within 6 months prior to initiation of study treatment.
• History of arterial thrombotic event (e.g. myocardial infarction, unstable angina, cerebrovascular accident, or transient ischemic attack) within 6 months prior to initiation of study treatment.
• Chronic or recent (within 10 days of first dose of study treatment) use of aspirin > 325 mg/day, dipyramidaole, ticlopidine, clopidogrel, or dilostazol. Note: Use of aspirin < 325 mg/day is allowed.
• History of venous thromboembolic event (e.g. deep vein thrombosis, pulmonary embolism, portal vein thrombosis, or any other significant thromboembolism) must be on a stable dose of anticoagulation for 1 month prior to initiation of study treatment and must have completely treated varices.
• Use of Coumadin-like products or full dose oral or parenteral anticoagulants. Use of prophylactic low dose anticoagulation, unfractionated heparin or LMWH is allowed.
• Evidence of bleeding diathesis or significant coagulopathy (in the absence of therapeutic anticoagulation).
• Core biopsy or other minor surgical procedure within 3 days prior to the first dose of bevacizumab.
• History of intestinal obstruction. Note: Patients with previous intestinal obstruction may be enrolled if they have received definitive treatment for symptom resolution.
• History of inflammatory process within 6 months prior to start of study treatment including but not limited to active peptic ulcer disease, diverticulitis or colitis.
• Significant traumatic injury within 4 weeks prior to start of study treatment.
• Uncontrolled pleural effusion or pericardial effusion requiring frequent drainage procedures (> once monthly). Patients with indwelling catheters (e.g. PleurX®) are allowed.
• History of nephrotic or nephritic syndrome.
• Uncontrolled hypertension defined as systolic pressure ≥ 150/90 in spite of maximum anti-hypertensive therapy.
• Patients with untreated/uncontrolled CNS/leptomeningeal disease. Note: Patients with asymptomatic, treated CNS disease are eligible if the treating physician determines that immediate CNS specific treatment is not required and is unlikely to be required during the first cycle of therapy and the following criteria are met:
• No evidence of interim progression between the completion of CNS-directed therapy and the start of study enrollment.
• No stereotactic radiation or whole-brain radiation within 28 days prior to randomization.
• No evidence of intracranial hemorrhage or spinal cord hemorrhage.
• Patients with active autoimmune disease requiring systemic corticosteroids greater than the equivalent of prednisone 10 mg daily or other systemic immunosuppressive medications including but not limited to: systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, colitis, vascular thrombosis associated with antiphospholipid syndrome, Wegener's granulomatosis, Sjögren's syndrome, Bell's palsy, Guillain-Barré syndrome, multiple sclerosis, autoimmune thyroid disease, vasculitis, or glomerulonephritis, with the following exceptions:
• Patients with a history of autoimmune hypothyroidism on thyroid replacement hormone are eligible.
• Patients with Type 1 diabetes mellitus on an insulin regimen are eligible.
• Patients with eczema, psoriasis, lichen simplex chronicus of vitiligo with dermatologic manifestations only are eligible provided: 1) rash covers < 10% of body surface area (BSA), 2) disease is well controlled at baseline and requires only low potency topical steroids (e.g., hydrocortisone 2.5%, hydrocortisone butyrate 0.1%, flucinolone 0.01%, desonide 0.05%, aclometasone dipropionate 0.05%).
• See protocol for a more comprehensive list of autoimmune diseases and immune deficiencies.
• Patients receiving treatment with systemic immunosuppressive medications (including, but not limited to, prednisone, cyclophosphamide, azathioprine, methotrexate, thalidomide, and anti-tumor necrosis factor [TNF] agents) within 6 weeks must discontinue these medications prior to starting protocol therapy, with the exception of:
• Patients with active autoimmune disease managed with systemic corticosteroids less than the equivalent of prednisone 10 mg daily.
• Patients who have received acute, low dose, systemic immunosuppressant medications (e.g., a one-time dose of dexamethasone for nausea).
• The use of inhaled corticosteroids and mineralocorticoids (e.g., fludrocortisone) for patients with orthostatic hypotension and adrenocortical insufficiency.
• History of idiopathic pulmonary fibrosis, organizing pneumonia (e.g., bronchiolitis obliterans), drug-induced pneumonitis, or idiopathic pneumonitis, or evidence of active pneumonitis on screening chest computed tomography (CT) scan. Note: History of radiation pneumonitis in the radiation field (fibrosis) is permitted.
• Patients who have undergone prior solid organ or bone marrow transplant with the exception of patients with prior renal transplant for whom dialysis may be employed in the event of graft rejection.
• Patients with serious active infection within 2 weeks prior to enrollment (e.g. requiring hospitalization and/or intravenous [IV] antibiotics) infection within 2 weeks prior to enrollment, or currently receiving oral or IV antibiotics for the treatment of infection. Patients receiving prophylactic antibiotics are eligible.
• Patients must have documented hepatitis virology status.
• Patients with active hepatitis B virus (HBV) infection must have a viral load < 500 IU/mL within 28 days prior to start of study treatment and be on suppressive therapy (per local standard of care) for a minimum of 14 days prior to start of study treatment and for the length of the study.
• Patients with co-infection with HBV and hepatitis C virus (HCV) are excluded. Patients with a history of HCV infection but with negative HCV RNA by PCR are considered non-infected with HCV.
• Patients with known human immunodeficiency virus (HIV) are allowed on study provided they have:
• A stable regimen of highly active anti-retroviral therapy (HAART)
• No requirement for concurrent concurrent antibiotics or antifungal agents for the prevention of opportunistic infection
• A CD4 count above 250 cells/mcL
• An undetectable HIV viral load on standard PCR-based testing
• Patients with uncontrolled intercurrent illness (e.g., including but not limited to uncontrolled HTN [systolic BP ≥ 150, diastolic BP ≥ 100 despite optimal medical management or history of hypertensive crisis or hypertensive encephalopathy], symptomatic congestive heart failure [CHF], uncontrolled cardiac arrhythmia, or other within 3 months prior to start of study treatment or psychiatric illness/social situations or other conditions that would limit compliance with study requirements or substantially increase risk of incurring AEs in the opinion of the treating investigator.
• Patients with known concurrent malignancy that is expected to require active treatment within two years or may interfere with the interpretation of the efficacy and safety outcomes of this study in the opinion of the treating investigator. Note: Superficial bladder cancer, nonmelanoma skin cancers, and low-grade prostate cancer not requiring cytotoxic therapy should not exclude participation in this trial. Patients with CLL may be enrolled if they do not require active chemotherapy and their hematologic, renal and hepatic function meets criteria previously mentioned.
• Any other disease, metabolic dysfunction, physical examination finding, or clinical laboratory finding that contraindicates the use of an investigational drug, may affect the interpretation of the results, or may render the patient at high risk from treatment complications in the opinion of the treating investigator.
• Treatment with a live, attenuated vaccine within 4 weeks prior to initiation of study treatment.
• History of severe allergic anaphylactic reactions to chimeric or humanized antibodies or fusion proteins or know hypersensitivity to Chinese hamster ovary cell products or to any component of the atezolizumab or bevacizumab infusion.
• Uncontrolled tumor-related pain. NOTE: Patients requiring pain medication must be on a stable regimen at study entry. Symptomatic lesions (e.g., bone metastases or metastases causing nerve impingement) amenable to palliative radiotherapy should be treated prior to enrollment. Patients should be recovered from the effects of radiation. There is no required minimum recovery period.
• Uncontrolled or symptomatic hypercalcemia (ionized calcium > 1.5 mmol/L, calcium > 12 mg/dL or corrected serum calcium > ULN)
• Active tuberculosis
• Prior treatment with CD137 agonists or immune checkpoint blockade therapies, including anti-CTLA-4, anti-PD-1, and anti-PD-L1 therapeutic antibodies

Inclusion Criteria:

• Age >= 18 years.
• HCC diagnosis confirmed by histology/cytology or clinically by American Association for Study of Liver Diseases (AASLD) criteria in cirrhotic patients.
• Measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) version (v)1.1
• Locally advanced, metastatic, or unresectable disease.
• Child Pugh class A.
• Barcelona clinic liver cancer (BCLC) stage B (not amenable to liver directed therapy) or stage C.
• Prior treatment with atezolizumab and bevacizumab combination with radiographic progression that necessitates change in treatment per treating physician. Patients with rapid progression on atezolizumab and bevacizumab (defined as patients who progressed radiographically in the first restaging scan that necessitates change in treatment) are excluded.
• Washout period >= 4 weeks prior to registration is required since last atezolizumab and bevacizumab dose.
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1. (Form is available on the Academic and Community Cancer Research United [ACCRU] website).
• Absolute neutrophil count (ANC) >= 1000/mm ^ 3 (obtained =< 28 days prior to registration).
• Platelet count >= 60,000/mm^3 (obtained =< 28 days prior to registration).
• Hemoglobin >= 8.5 g/dL (obtained =< 28 days prior to registration).
• Total bilirubin =< 3 x upper limit of normal (ULN) (obtained =< 28 days prior to registration).
• Alanine aminotransferase (ALT) and aspartate transaminase (AST) =< 5 x ULN (obtained =< 28 days prior to registration).
• International normalized ratio (INR) =< 2.3 or Prothrombin time (PT) =< 6 seconds above control OR if patient is receiving anticoagulant therapy and INR is within target range of therapy creatinine =< 1.5x ULN (obtained =< 28 days prior to registration).
• Negative pregnancy test done =< 7 days prior to registration, for women of childbearing potential only.
• Note: If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required.
• Provide informed written consent =< 28 days prior to registration.
• Willing to return to enrolling institution for follow-up (during the active monitoring phase of the study).
• Note: During the active monitoring phase of a study (i.e., active treatment), participants must be willing to return to the consenting institution for follow-up.
• Willing to provide mandatory tissue specimens and blood specimens for correlative research purposes.

Exclusion Criteria:

• Any of the following because this study involves an investigational agent whose genotoxic, mutagenic and teratogenic effects on the developing fetus and newborn are unknown
• Pregnant persons
• Nursing persons
• Persons of childbearing potential who are unwilling to employ adequate contraception.
• Major surgery =< 4 weeks prior to registration.
• Liver directed therapy (transarterial chemoembolization [TACE], Y-90, liver directed radiation) =< 28 days prior to registration. Prior liver directed therapy > 28 days prior to registration is allowed as long as patient has at least one measurable untreated lesion by RECIST v1.1.
• Patients with rapid progression on atezolizumab and bevacizumab (who progressed radiographically in the first restaging scan that necessitates change in treatment) are excluded.
• Prior treatment =< 4 weeks prior to registration with anti-CTLA-4 antibody for HCC.
• Comorbid systemic illnesses or other severe concurrent disease which, in the judgment of the investigator, would make the patient inappropriate for entry into this study or interfere significantly with the proper assessment of safety and toxicity of the prescribed regimens.
• Immunocompromised patients and patients known to be human immunodeficiency virus (HIV) positive and currently receiving antiretroviral therapy.
• Note: Patients known to be HIV positive, but without clinical evidence of an immunocompromised state, are eligible for this trial.
• Uncontrolled intercurrent illness including, but not limited to:
• Ongoing or active infection excluding hepatitis C virus (HCV)
• Symptomatic congestive heart failure
• Unstable angina pectoris
• Unstable cardiac arrhythmia
• Psychiatric illness/social situations that would limit compliance with study requirements.
• Active infection including tuberculosis (clinical evaluation that includes clinical history, physical examination and radiographic findings, and tuberculosis [TB] testing in line with local practice), hepatitis B (known positive hepatitis B virus [HBV] surface antigen [HBsAg] result). Patients with a past or resolved HBV infection (defined as the presence of hepatitis B core antibody [anti-HBc] and absence of HBsAg) are eligible. Patients with chronic HBV infection as evidenced by detectable HBV surface antigen or HBV deoxyribonucleic acid (DNA) are eligible if on antiviral therapy and have HBV DNA < 100 IU/mL. Patients with active or resolved hepatitis C (HCV) infection as evidenced by detectable HCV ribonucleic acid (RNA) or antibody are eligible.
• Receiving any other investigational agent which would be considered as a treatment for the primary neoplasm =< 4 weeks prior to registration.
• Other active malignancy =< 2 years prior to registration. Exceptions: Non-melanotic skin cancer or carcinoma-in-situ of the cervix.
• History of myocardial infarction =< 6 months, or congestive heart failure requiring use of ongoing maintenance therapy for life-threatening ventricular arrhythmias.
• History of allogenic organ transplantation.
• Active or prior documented autoimmune or inflammatory disorders (including inflammatory bowel disease [e.g., colitis or Crohn's disease], diverticulitis [with the exception of diverticulosis], systemic lupus erythematosus, sarcoidosis syndrome, or Wegener syndrome [granulomatosis with polyangiitis, graves' disease, rheumatoid arthritis, hypophysitis, uveitis, etc]). The following are exceptions to this criterion:
• Patients with vitiligo or alopecia
• Patients with hypothyroidism (e.g., following Hashimoto syndrome) stable on hormone replacement
• Any chronic skin condition that does not require systemic therapy
• Patients without active disease in the last 5 years may be included but only after consultation with the study physician
• Patients with celiac disease controlled by diet alone
• History of leptomeningeal carcinomatosis.
• Known allergy or hypersensitivity to any of the study drugs or any of the study drug excipients.
• Current or prior use of immunosuppressive medication =< 14 days prior to registration. The following are exceptions to this criterion:
• Intranasal, inhaled, topical steroids, or local steroid injections (e.g., intra articular injection)
• Systemic corticosteroids at physiologic doses not to exceed 10 mg/day of prednisone or its equivalent
• Steroids as premedication for hypersensitivity reactions (e.g., computed tomography [CT] scan premedication).
• Receipt of live attenuated vaccine =< 30 days prior to registration; Note: Patients, if enrolled, should not receive live vaccine whilst on study treatment and up to 30 days after the last dose of study treatment.
• Any unresolved toxicity National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) v5.0 grade >= 2 from previous anticancer therapy with the exception of alopecia, vitiligo, and the laboratory values defined in the inclusion criteria.
• History of grade 3 or 4 immunotherapy related toxicity NCI CTCAE v5.0 due to prior regimen attributed to atezolizumab.

Inclusion Criteria:

• Written informed consent for the trial
• Must have operable gastric adenocarcinoma, T2-T4a, N0-N3, M0
• Staging evaluation within 42 days of enrollment consisting of staging laparoscopy, computed tomography (CT) scan of the abdomen and pelvis, and positron emission tomography (PET) scan will be acquired; also endoscopic ultrasound (EUS) tumor and nodal staging will be required
• Mismatch repair deficiency as identified by immunohistochemistry or other institutional standard, or Epstein-Barr virus positivity as determined by in situ hybridization or other institutional standard
• Be willing to provide tissue from a newly obtained core or excisional biopsy of a tumor lesion; newly-obtained is defined as a specimen obtained up to 10 weeks (70 days) prior to initiation of treatment on day 1; subjects for whom newly-obtained samples cannot be provided (e.g. inaccessible or subject safety concern) may submit an archived specimen (if available from prior biopsy) only upon agreement from the sponsor
• Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) performance scale
• Absolute neutrophil count (ANC) >= 1,500 /mcL
• Platelets >= 100,000 / mcL
• Hemoglobin >= 7 g/dL or >= 5.6 mmol/L with transfusion or erythropoietin (EPO) dependency
• Serum creatinine =< 1.5 X upper limit of normal (ULN) OR measured or calculated creatinine clearance (glomerular filtration rate [GFR] can also be used in place of creatinine or creatinine clearance [CrCl]) >= 60 mL/min for subject with creatinine levels > 1.5 X institutional ULN
• Serum total bilirubin =< 1.5 X ULN OR direct bilirubin =< ULN for subjects with total bilirubin levels > 1.5 ULN
• Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase [SGOT]) and alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 2.5 X ULN
• Albumin >= 2.5 mg/dL
• 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
• 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
• Female subject of childbearing potential should have a negative urine or serum pregnancy within 7 days of enrollment; if the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required
• 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
• Male subjects of childbearing potential must agree to use an adequate method of contraception starting with the first dose of study therapy through 120 days after the last dose of study therapy; Note: abstinence is acceptable if this is the usual lifestyle and preferred contraception for the subject

Exclusion Criteria:

• Presence of metastatic disease is not allowed; subjects must be evaluated with imaging consisting of CT scan and PET scan prior to enrollment for protocol therapy to exclude metastatic disease
• Prior chemotherapy, adjuvant therapy, or radiotherapy for gastric cancer
• Prior radiotherapy that overlaps with planned radiotherapy portal
• 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 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 (eg., 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 that required steroids or current pneumonitis
• Evidence of 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 or father 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
• 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 known active hepatitis B (e.g., hepatitis B surface antigen [HBsAg] reactive) or hepatitis C (e.g., hepatitis C virus (HCV) RNA [qualitative] is detected)
• Has received a live vaccine within 30 days of planned start of study therapy; 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

Inclusion Criteria:

• Histologically and/or cytologically confirmed metastatic or unresectable adenocarcinoma of esophageal, gastroesophageal junction or gastric origin
• Tumor is HER2 negative by standard local testing methodology
• Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 - 2
• Measurable disease by response evaluation criteria in solid tumors (RECIST) v1.1
• No prior systemic therapy for the present cancer given in the metastatic setting and > 6 months from administration of peri-operative chemotherapy, if applicable o Note: up to two prior cycles of mFOLFOX6 for the present illness is permitted if patients otherwise qualify for the study with adequate baseline imaging
• At least 18 years of age
• Adequate bone marrow and organ functions as defined by:
• Absolute neutrophil count ≥ 1500 cells/ μL
• Hemoglobin ≥ 8 g/ dL
• Platelets > 100,000 / μL
• Creatinine ≤ 1.5 x upper limit of normal (ULN) OR creatinine clearance ≥ 30 mL/min by Cockroft-Gault
• Total bilirubin ≤ ULN
• Aspartate aminotransferase (AST)/ Alanine aminotransferase (ALT) < 2.5 x ULN, unless with liver metastases and then must be <5 x ULN of normal
• Women and men of childbearing potential must agree to use adequate contraception (hormonal or barrier method of birth control or abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect pregnancy on study, she must notify her treating physician immediately.
• Ability to understand the nature of this study protocol and give written informed consent.
• Willingness and ability to comply with scheduled visits, treatment plans laboratory tests and other study procedures.

Exclusion Criteria:

• Receipt of any investigational agents at the time of registration
• Known, untreated brain metastases
• Grade two or greater peripheral neuropathy
• Presence of any additional active malignancy within the past three years where the malignancy is at least reasonably likely to later the course of therapy, require systemic therapy or interfere with imaging assessments
• For those patients who are going to receive nivolumab
• No active use of systemic corticosteroids at the time of enrollment, at a dose equivalent of 10 mg/day or prednisone
• Clinically significant autoimmune disease which is active or has required systemic immunosuppression within the last two years
• Prior organ transplant or bone marrow transplant
• History of interstitial lung disease or pneumonitis
• Uncontrolled intercurrent illness, including significant active infection, symptomatic congestive heart failure, unstable angina or active arrhythmia
• Major surgery within the four weeks prior to initiation of study treatment
• A history of allergy or hypersensitivity to any of the study drugs
• Any additional significant medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from fully participating in the study