Panitumumab significantly improved overall survival in patients with KRAS wild-type exon 2 metastatic colorectal cancer (mCRC).1

Although no overall survival benefit has been observed with panitumumab monotherapy in wild-type KRAS exon 2 patients with mCRC, retrospective analyses have indicated that other KRAS and NRAS mutations are predictive of anti-epidermal growth factor receptor treatment effects.

Therefore, researchers sought to evaluate the overall survival benefit of panitumumab monotherapy in patients with wild-type KRAS and NRAS exons 2, 3, and 4 mCRC in a phase 3 trial.

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For the study, researchers enrolled 377 patients wild-type KRAS exon 2 mCRC. Participants were randomly assigned 1:1 to receive panitumumab 6 mg/kg every 2 weeks plus best supportive care or best supportive care alone.

Results showed that median overall survival was 10.0 months (95% CI, 8.7 – 11.4) with panitumumab vs 7.4 months (95% CI, 5.8 – 9.3) without (HR, 0.73; 95% CI, 0.57 – 0.93; P = .0096). Median progression-free-survival was 3.6 months (95% CI, 3.4 – 5.3) and 1.7 months (95% CI, 1.6 – 1.9), respectively (HR, 0.51; 95% CI, 0.41 – 0.64; P < .0001).

In patients with wild-type RAS disease, median overall survival was 10.0 months (95% CI, 8.7 – 11.6) with the immunotherapy (HR, 0.70; 95% CI, 0.53 – 0.93; P = .0135) and median progression-free survival was 5.2 months (95% CI, 3.5 – 5.3) vs 1.7 months (95% CI, 1.6 – 2.2), respectively (HR, 0.46; 95% CI, 0.35 – 0.59; P < .0001).

In contrast, researchers found no survival benefit from panitumumab treatment in patients with mutant RAS mCRC (HR, 0.99; 95% CI, 0.49 – 2.00).

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“The treatment effects in OS and PFS were more pronounced in those with wild-type RAS mCRC, further substantiating the importance of RAS testing at diagnosis to best inform the use of panitumumab to treat mCRC,” the authors concluded.

Reference

  1. Kim TW, Elme A, Kusic Z, et al. An open label, randomized phase III trial evaluating the treatment (tx) effects of panitumumab (pmab) + best supportive care (BSC) versus BSC in chemorefractory wild-type (WT) KRAS exon 2 metastatic colorectal cancer (mCRC) and in WT RAS mCRC [abstract]. J Clin Oncol. 2016;34(suppl 4S; abstr 642).

Topics:

Colorectal Cancer Gastrointestinal Cancer