Phase III study of irinotecan/5FU/LV (FOLFIRI) or oxaliplatin/5FU/LV (FOLFOX) ± cetuximab for patients (pts) with untreated metastatic adenocarcinoma of the colon or rectum (MCRC): CALGB 80203 preliminary results.

3509 Background: FOLFIRI or FOLFOX are 1st-line treatments (Rx) for MCRC. Cetuximab is an IgG1 Mab that targets the epidermal growth factor receptor (EGFR) and is approved as monotherapy or in combination with irinotecan in irinotecan-refractory, EGFR + pts with MCRC. CALGB 80203 randomized untreated MCRC pts to FOLFOX or FOLFIRI ± cetuximab (independent of EGFR status.) Methods: Pts with performance status 0-1 with tumor blocks available for EGFR analysis received either irinotecan 180 mg/m(2) over 1.5 hours (h) or oxaliplatin 85 mg/m(2) over 2h combined with LV 400 mg/m(2) over 2h and 5FU 400 mg/m(2) bolus, then 46-48h CI 5FU 2400 mg/m(2) q o w. Cetuximab dose: 400 mg/m(2) loading dose, then 250 mg/m(2) qw. Rx continued until progression or toxicity; subsequent Rx was not mandated although information was collected on such rx. Accrual goal was 2200 pts with intended 1° endpt of overall survival (OS). 80203 closed administratively in 1/05 (due to slow accrual) with 238 pts accrued. 2° endpts of response rate (RR), progression free survival (PFS), duration of R and toxicity are now able to be analyzed. RESULTS: Accrual: FOLFIRI (A) - 61; FOLFIRI + cetuximab (B) - 59: FOLFOX (C) - 60; FOLFOX + cetuximab (D) - 58; approx median follow-up (f/u) is 12 months. RR (CR + PR, not all yet confirmed): A - 34%; B - 42%; C - 32%; D - 55%. RR was similar in the FOLFIRI or FOLFOX arms (A+B v. C+D; 38% v. 43%, p=0.44; chi-square) while C225 containing arms (B+D) v. non-C225 arms (A+C) had a superior RR (49% v. 33%; p=0.014, chi-square) It is too early to tell if there are differences in PFS, duration of response or OS. No significant differences in gr III diarrhea or any gr IV toxicities were seen. CONCLUSIONS: These results suggest that FOLFIRI and FOLFOX are similar in efficacy for pts with untreated MCRC and that adding cetuximab to either in1st-line Rx appears to increase response rates. PFS and duration of response do not appear different at this analysis. Further f/u and an analysis of prospective companion correlative studies may help to further clarify these results. [Table: see text].

Duke Scholars

Author Donna Niedzwiecki Biostatistics & Bioinformatics, Division of Biostatistics