Adding cetuximab to standard first-line FOLFIRI chemotherapy is beneficial for patients with RAS wild-type metastatic colorectal cancers but not for such tumors with other RAS mutations, according to a report published online Jan. 19 in Journal of Clinical Oncology.
When added to infusional fluorouracil, leucovorin, and irinotecan (FOLFIRI) combination chemotherapy, cetuximab improved survival outcomes in the phase III randomized CRYSTAL trial among patients who had KRAS codon 12 and 13 wild-type metastatic colorectal cancer. The researchers now presented the results of their post hoc analysis of a subset of 430 CRYSTAL participants, assessing the treatment’s effect in patients whose tumors carried mutations at RAS loci other than KRAS 12 or 13, said Dr. Eric Van Cutsem of University Hospitals Leuven (Belgium), and his associates.
Dr. Eric Van Cutsem
They found “a clear and significant benefit” in overall survival, progression-free survival, and the rate of objective tumor response when cetuximab was added to FOLFIRI among the 367 patients who had RAS wild-type tumors. In contrast, there was no clear benefit from the addition of cetuximab in the 63 patients who had tumors with other RAS mutations; it neither improved nor worsened outcomes, the investigators said (J. Clin. Oncol. 2015 January 19 [doi:10.1200/JCO.2014.59.4812]).
These findings indicate that molecular testing for all KRAS mutations is essential before considering anti-EGFR therapy for patients with metastatic colorectal cancer, to reserve the addition of cetuximab for those with RAS wild-type tumors, they added.