Personalized Therapy for Esophagogastric Cancer Using Thymidylate Synthase Genetic Markers

Inclusion Criteria:

Pre-Registration Inclusion Criteria

* Histologically or cytologically confirmed unresectable or metastatic esophagogastric adenocarcinoma.
* Measurable disease defined as lesions that can be accurately measured in at least one dimension (longest diameter to be recorded) as \>10 mm with CT scan, as \>20 mm by chest x-ray, or \>10 mm with calipers by clinical exam. PET/CT scan is acceptable as a substitute for a CT scan if the CT portion of the PET/CT is of identical diagnostic quality to a diagnostic CT scan.
* At least 18 years of age.
* ECOG performance status \< 2
* Able to understand and willing to sign an IRB approved written informed consent document (or that of legally authorized representative, if applicable).

Registration Inclusion Criteria

* TSER genotype \*2/\*2
* ECOG performance status \< 2
* Normal bone marrow and organ function as defined below:

  * Absolute neutrophil count ≥ 1,500 cells/mm3
  * Platelets ≥ 100,000 cells/mm3
  * Total bilirubin \< 1.5 x IULN
  * AST(SGOT)/ALT(SGPT) \< 3.0 x IULN
  * Creatinine within normal institutional limits OR Creatinine clearance ≥ 45 mL/min/1.73 m2 for patients with creatinine levels above institutional normal
* Women of childbearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control, abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must inform her treating physician immediately.

Exclusion Criteria:

Pre-Registration Exclusion Criteria

* Prior therapy for this cancer.
* A history of other malignancy ≤ 5 years previous with the exception of basal cell or squamous cell carcinoma of the skin which were treated with local resection only or carcinoma in situ of the cervix.
* Uncontrolled intercurrent 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.
* Known HIV-positivity on combination antiretroviral therapy because of the potential for pharmacokinetic interactions with pemetrexed and/or oxaliplatin. In addition, these patients are at increased risk of lethal infections when treated with marrow-suppressive therapy. Appropriate studies will be undertaken in patients receiving combination antiretroviral therapy when indicated.

Registration Exclusion Criteria

* Currently receiving any other investigational agents.
* Known brain metastases. Patients with known brain metastases must be excluded from this clinical trial because of their poor prognosis and because they often develop progressive neurologic dysfunction that would confound the evaluation of neurologic and other adverse events.
* A history of allergic reactions attributed to compounds of similar chemical or biologic composition to pemetrexed, 5-FU, leucovorin or oxaliplatin, or other agents used for premedication in the study.
* Pregnant and/or breastfeeding. Patient must have a negative pregnancy test within 14 days of study entry.