Among the 71 patients with melanoma who had not previously received a BRAF inhibitor, the rate of unconfirmed objective response (complete or partial response) ranged from 50% to 77%, depending on the dose combination. Five patients had complete responses. For comparison, the response rate in BRAF-mutated melanoma has been 63% with the BRAF inhibitor alone and 40% with the MEK inhibitor alone.
Additionally, the rate of disease control (complete response, partial response, or stable disease) ranged from 95% to 100%, Dr. Infante reported. And the large majority of patients (83%) are still receiving combination therapy.
Analyses among the 24 patients with melanoma who had previously received a BRAF inhibitor showed that about half had a reduction in tumor size. There was no clear difference according to the duration of the earlier BRAF inhibitor therapy.
The investigators are now conducting a phase II trial in which 150 patients with V600E- or V600K-mutant melanoma are being randomly assigned to therapy with the BRAF inhibitor alone or in combination with the MEK inhibitor at two dose levels.
Dr. Dummer, the discussant, noted that obtaining biopsies is "very crucial" to understanding how such novel antimelanoma therapies are working. "Our patients, when you explain this to them, they will agree to sequential biopsies," he commented. "And I encourage all of you to participate in trials with a very strong translational research" component.
Dr. Infante reported that he is an unpaid consultant to GlaxoSmithKline, and that several coauthors are GSK employees. Dr. Dummer reported that he is a consultant to Bristol-Myers Squibb, Merck, Novartis, and Roche, and receives honoraria from Bristol-Myers Squibb.