Analysis of KRAS/NRAS Mutations in a Phase III Study of Panitumumab with FOLFIRI Compared with FOLFIRI Alone as Second-line Treatment for Metastatic Colorectal Cancer

Marc Peeters, Kelly S. Oliner, Timothy J. Price, Andrés Cervantes, Alberto F. Sobrero, Michel Ducreux, Yevhen Hotko, Thierry André, Emily Chan, Florian Lordick, Cornelis J A Punt, Andrew H. Strickland, Gregory Wilson, Tudor E. Ciuleanu, Laslo Roman, Eric Van Cutsem, Pei He, Hua Yu, Reija Koukakis, Jan Henrik TerweyAndre S. Jung, Roger Sidhu, Scott D. Patterson

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: We evaluated the influence of RAS mutation status on the treatment effect of panitumumab in a prospective retrospective analysis of a randomized, multicenter phase III study of panitumumab plus fluorouracil, leucovorin, and irinotecan (FOLFIRI) versus FOLFIRI alone as second-line therapy in patients with metastatic colorectal cancer (mCRC; ClinicalTrials.gov, NCT0039183). Experimental Design: Outcomes were from the study's primary analysis. RAS mutations beyond KRAS exon 2 (KRAS exons 3, 4; NRAS exons 2, 3, 4; BRAF exon 15) were detected by bidirectional Sanger sequencing in wild-type KRAS exon 2 tumor specimens. Progression-free survival (PFS) and overall survival (OS) were coprimary endpoints. Results: The RAS ascertainment rate was 85%;18%of wild-type KRAS exon 2 tumors harbored other RAS mutations. For PFS and OS, the hazard ratio (HR) for panitumumab plus FOLFIRI versus FOLFIRI alone more strongly favored panitumumab in the wildtype RAS population than in the wild-type KRAS exon 2 population [PFS HR, 0.70 (95% confidence interval [CI], 0.54 0.91); P = 0.007 vs. 0.73 (95% CI, 0.59 0.90); P = 0.004; OS HR, 0.81 (95% CI, 0.63 1.03); P = 0.08 vs. 0.85 (95% CI, 0.70 1.04); P = 0.12]. Patients with RAS mutations were unlikely to benefit from panitumumab. Among RAS wild-type patients, the objective response rate was 41% in the panitumumab FOLFIRI group versus 10% in the FOLFIRI group. Conclusions: Patients with RAS mutations were unlikely to benefit from panitumumab FOLFIRI and the benefit risk of panitumumab FOLFIRI was improved in the wild-type RAS population compared with the wild-type KRAS exon 2 population. These findings support RAS testing for patients with mCRC.

Original languageEnglish
Pages (from-to)5469-5479
Number of pages11
JournalClinical Cancer Research
Volume21
Issue number24
DOIs
Publication statusPublished - Dec 15 2015

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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