5-FU Based Maintenance Therapy in RAS Wild Type Metastatic Colorectal Cancer After Induction With FOLFOX Plus Panitumumab

PRIMARY OBJECTIVES: I. To compare the duration of progression free survival 1 (PFS1) in patients with RAS wild type who have received induction leucovorin calcium, fluorouracil, and oxaliplatin (FOLFOX) + panitumumab and not progressed at 6 cycles and randomized to maintenance therapy with fluorouracil (5FU) based therapy with or without panitumumab. SECONDARY OBJECTIVES: I. To compare the response rate (RR) in patients with RAS wild type who are randomized to maintenance therapy with 5FU based therapy to those randomized to 5FU based therapy with panitumumab. TERTIARY OBJECTIVES: I. Progress free survival 2 (PFS2). II. To assess the adverse event (AE) profile and safety of the proposed treatment in this population. III. To assess and compare the overall survival (OS) between the two treatment groups. IV. To compare the quality of life (QOL) as measured by health state index (HIS) between patients who achieve partial response (PR) versus (vs.) those who progress and those who have stable disease during the induction phase. V. To compare the QOL as measured by HSI between the two groups randomized to maintenance therapy. VI. To assess the evolution of RAS mutation under treatment during induction phase as well as maintenance. VII. To explore relationship between genomic and proteomic alterations of the tumor with response and PFS to panitumumab. OUTLINE: INDUCTION: Patients receive panitumumab intravenously (IV) over 30-60 minutes, oxaliplatin IV over 2 hours, leucovorin calcium IV, and fluorouracil over 46-48 hours on day 1. Treatment repeats every 14 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. MAINTENANCE: Patients who are not candidates for surgery, have no disease progression, or do not have complete response after Induction are randomized to 1 of 2 arms. ARM I: Patients receive panitumumab IV over 30 minutes, leucovorin calcium IV, and fluorouracil over 46-48 hours on day 1. Courses repeat every 14 days in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive capecitabine orally (PO) twice daily (BID) on days 1-21. Courses repeat every 21 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months.