Panitumumab Improves Overall Survival in Refractory KRAS Wild-type Exon 2 mCRC
Panitumumab significantly improved overall survival in patients with KRAS wild-type exon 2 metastatic colorectal cancer.
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.
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.
- 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).