Patients with an advanced form of melanoma have been shown to survive nearly twice as long, from about 9 months to almost 16 months, after treatment with the kinase inhibitor vemurafenib (Zelboraf), a pill taken two times a day.
“We knew this drug would make the melanomas shrink in a large proportion of patients and that it worked better than chemotherapy,” commented Antoni Ribas, MD, PhD, in a statement issued by University of California–Los Angeles (UCLA) Health Sciences. Study senior author Ribas is a professor of hematology/oncology and a researcher at UCLA’s Jonsson Cancer Center, one of 13 sites across the United States and Australia involved in the investigation. “This study shows that Zelboraf changes the natural history of this disease.”
The FDA approved Zelboraf in August 2011 for use in patients with metastatic or unresectable melanoma whose tumors express a gene mutation known as BRAF V600E. Approximately 50% of melanomas harbor this mutation. Before the drug became available, no more than 10% of persons with this advanced form of melanoma responded to conventional treatments.
At the time the FDA approved vemurafenib, the initial clinical trials had not followed patients long enough to determine overall survival. In the current study, funded by Zelboraf maker Hoffmann-LaRoche, Ribas and the rest of the international team followed 132 patients with previously treated BRAF V600-mutant metastatic melanoma who were undergoing vemurafenib therapy. The participants were followed for 0.6 to 20.1 months (median 12.9 months).
As the researchers reported in The New England Journal of Medicine (2012;366:707-714), tumors shrank by more than 30% in 53% of the group. An additional 30% of patients experienced tumor responses of a lesser magnitude. Only 14% did not respond to vemurafenib.
Median overall survival was 15.9 months, significantly exceeding the typical survival period of 6 to 10 months for most patients with metastatic melanoma.
“These results tell us that this drug is having a very big impact, and this changes the way we treat metastatic melanoma,” explained Ribas.
The most common adverse events to occur among the study participants were grade 1 or 2 arthralgia, rash, photosensitivity, fatigue, and alopecia. Cutaneous squamous-cell carcinoma (the majority, keratoacanthoma type) was diagnosed in 26% of patients.