Pharmacogenetic study in metastatic colorectal cancer (CRC) patients receiving third-line panitumumab-irinotecan: A GERCOR ancillary study.

2537^ Background: Test the predictive value of gene polymorphisms potentially linked to panitumumab and irinotecan pharmacodynamics. Methods: 45 patients with metastatic CRC refractory to standard therapy were enrolled in this ancillary pharmacogenetic study as part of a phase II trial that included 63 patients. Inclusion required wild-type KRAS tumor status (codons 12-13, analyses performed in each center). After inclusion, central KRAS re-assessment was performed (codons 12-13-59-61) and 9 patients over 45 were found to carry a KRAS mutation. Patients received panitumumab (6 mg/kg, day 1) associated with irinotecan (180 mg/m2, day 1), Q2W until disease progression or unacceptable toxicity. Analyzed polymorphisms on blood DNA were : EGFR (CA repeats in intron 1, -216G>T, -191C>A), EGF (61A>G), CCND1 (870A>G), UGT1A1 (*28). Results: Cutaneous toxicity imputable to panitumumab i.e. folliculitis and paronychia was not linked to EGFR, EGF or CCND1 polymorphisms. Diarrhea (12 grade 1, 13 grade 2, 8 grade 3) w...