This is a phase 1b prospective, single arm, open-label trial determining the efficacy and feasibility of using a response-guided approach to help guide neoadjuvant chemotherapy in subjects with Stage IB, II or Stage III adenocarcinoma of the stomach or gastroesophageal junction (GEA).

Inclusion Criteria:

• Patients must have histologically or cytologically confirmed adenocarcinoma of the stomach or gastroesophageal junction (GEA). Other GE histologies which are treated per NCCN guidelines for neoadjuvant treatment are eligible.

• Must have Stage IB, II or Stage III GEA eligible for (neo)adjuvant doublet or triplet chemotherapy for up to 6 months.

• Age ≥ 18 years Because the safety or efficacy of neoadjuvant chemotherapy for LGEA has not been tested or established for patients <18 years of age, children are excluded from this study but will be eligible for future pediatric trials, if applicable.

• Performance status: ECOG performance status ≤2

• Life expectancy of greater than 6 months

• Adequate organ and marrow function as defined below:

  1. hemoglobin ≥ 7g/dL
  2. absolute neutrophil count ≥ 1,500/mcL
  3. platelets ≥ 80,000/mcl
  4. total bilirubin within normal institutional limits
  5. AST(SGOT)/ALT(SPGT) ≤ 5 X institutional upper limit of normal
  6. creatinine <2 X ULN

• Docetaxel can cause fetal harm and irinotecan is known to be teratogenic. Since these compounds are part of the treatment regimens, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.

  1. A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:

  1. Has not undergone a hysterectomy or bilateral oophorectomy; or
  2. Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).

• Ability to understand and the willingness to sign a written informed consent. 1. Both men and women and members of all races and ethnic groups are eligible for this trial. Non-English speaking, deaf, hard of hearing and illiterate individuals are eligible for this trial.

Exclusion Criteria:

• Patients may not be receiving any other investigational agents.
• Patients with known distant metastases from GEA.
• History of allergic reactions attributed to agents used in study.
• 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.
• History of another primary cancer which requires active treatment or is expected to require treatment within 12 months after enrollment.
• Inability to comply with study and follow-up procedures as judged by the Investigator.
• Patients who are pregnant or nursing due to the potential for congenital abnormalities and the potential of this regimen to harm nursing infants.
• Patients with prior organ/bone marrow/non-autologous stem cell transplants