Abstract
To investigate whether EGF receptor (EGFR) pathway mutations predicted response to monotherapy with panitumumab, an anti-EGFR monoclonal antibody, in a randomized phase III study of metastatic colorectal cancer. Using massively parallel multigene sequencing, we analyzed 320 samples for 9 genes, with multigene sequence data from 288 (90%) samples. Mutation rates were: KRAS (45%), NRAS (5%), BRAF (7%), PIK3CA (9%), PTEN (6%), TP53 (60%), EGFR (1%), AKT1 (<1%), and CTNNB1 (2%). In the randomized study and open-label extension, 22 of 138 (16%) wild-type KRAS (codons 12/13/61) patients versus 0 of 103 mutant KRAS (codons 12/13) patients had objective responses. Of 6 mutant KRAS (codon 61) patients, 1 with a Q61H mutation achieved partial response during the extension. Among wild-type KRAS (codons 12/13/61) patients, 0 of 9 patients with NRAS mutations, 0 of 13 with BRAF mutations, 2 of 10 with PIK3CA mutations, 1 of 9 with PTEN mutations, and 1 of 2 with CTNNB1 mutations responded to panitumumab. No patients responded to best supportive care alone. Panitumumab treatment was associated with longer progression-free survival (PFS) among wild-type KRAS (codons 12/13/61) patients [HR, 0.39; 95% confidence interval (CI), 0.28-0.56]. Among wild-type KRAS patients, a treatment effect for PFS favoring panitumumab occurred in patients with wild-type NRAS (HR, 0.39; 95% CI, 0.27-0.56) and wild-type BRAF (HR, 0.37; 95% CI, 0.24-0.55) but not mutant NRAS (HR, 1.94; 95% CI, 0.44-8.44). These results show the feasibility and potential clinical use of next-generation sequencing for evaluating predictive biomarkers.
Highlights
Improvements in progression-free survival (PFS) or objective response rate (ORR) following treatment with the Authors' Affiliations: 1Department of Oncology, Antwerp University Hospital, Edegem; 2University Hospital Gasthuisberg, Leuven; 3Centre du Cancer de I'Universite Catholique de Louvain; 4Erasme University Hospital, Brussels, Belgium; 5Amgen Inc., Thousand Oaks; 6Amgen Inc., South San Francisco, California; 7Amgen Inc., Cambridge, Massachusetts; 8Ospedale Niguarda Ca Granda, Milan, Italy; and 9Ho^pital Saint Antoine and Universite Pierre et Marie Curie, Paris, FranceNote: Supplementary data for this article are available at Clinical Cancer Research Online.M
Among wild-type KRAS patients, 0 of 9 patients with NRAS mutations, 0 of 13 with BRAF mutations, 2 of 10 with PIK3CA mutations, 1 of 9 with PTEN mutations, and 1 of 2 with CTNNB1 mutations responded to panitumumab
Panitumumab treatment was associated with longer progression-free survival (PFS) among wild-type KRAS patients [HR, 0.39; 95% confidence interval (CI), 0.28–0.56]
Summary
Improvements in progression-free survival (PFS) or objective response rate (ORR) following treatment with the Authors' Affiliations: 1Department of Oncology, Antwerp University Hospital, Edegem; 2University Hospital Gasthuisberg, Leuven; 3Centre du Cancer de I'Universite Catholique de Louvain; 4Erasme University Hospital, Brussels, Belgium; 5Amgen Inc., Thousand Oaks; 6Amgen Inc., South San Francisco, California; 7Amgen Inc., Cambridge, Massachusetts; 8Ospedale Niguarda Ca Granda, Milan, Italy; and 9Ho^pital Saint Antoine and Universite Pierre et Marie Curie, Paris, France. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/).
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