Vectibix: biomarker-specific benefits in mCRC

US biotechnology major Amgen says the results of a biomarker analysis indicate that, in metastatic colorectal cancer patients who have failed all other chemotherapeutic regimens, the efficacy of Vectibix (panitumumab) is confined to patients with non-mutated KRAS tumors. Specifically, in subjects with these tumors, the agent significantly increased progression-free survival and had an impact on quality of life and disease-related symptoms, compared to best supportive care alone.

These findings, which were generated from a biomarker analysis of a Phase III, randomized, controlled clinical trial that investigated the treatment effect of Vectibix monotherapy plus BSC versus BSC alone in patients with mCRC, were revealed at a press briefing during the 2008 American Society of Clinical Oncology Gastrointestinal Cancers Symposium in Orlando Florida.

Roger Perlmutter, executive vice president of R&D at Amgen, said: "we are hopeful that the use of biomarkers like KRAS will enable improved treatment outcomes for colorectal cancer patients." The data showed the relative effect of Vectibix vs BSC was significantly greater in patients with non-mutated vs mutated KRAS (HR = 0.45 vs HR = 0.99). Median PFS in patients without the mutation treated with Vectibix plus BSC was 12.3 weeks vs 7.3 weeks, respectively. When the analysis standardized the time-to-tumor-assessment, the median PFS was 16 weeks vs 8 weeks, respectively (HR= 0.49 vs 1.07).