At the three-month mark, patients taking vemurafenib were 63 percent less likely to die and 74 percent less likely to die or see their cancer return, compared to patients taking dacarbazine alone.
Few patients had side effects in the vemurafenib group, although some did develop squamous cell carcinoma, a less dangerous form of skin cancer.
This is the first drug that has been proven superior to chemotherapy in this group of hard-to-treat patients, the researchers said.
"There was such a substantial benefit that we recommended that patients cross over," Chapman said at a Sunday news briefing. "It's unprecedented to report a trial this early. The median follow-up time was three months." Yet the differences between the two groups became evident almost immediately.
Dr. Lynn Schuchter, co-moderator of the briefing and division chief of hematology-oncology at Abramson Cancer Center of the University of Pennsylvania in Philadelphia, said symptoms subsided in some patients almost immediately, enabling them to cut back on pain medication in just 72 hours.
"The median time to progression with dacarbazine was 1.6 months versus 5.3 months with vemurafenib, which is a huge difference," said Chapman.
In the second study, about 500 patients were randomly picked to receive Yervoy plus dacarbazine or dacarbazine alone.
Those taking both drugs lived a median of 11.2 months compared to 9.1 months for those taking dacarbazine alone. Time to recurrence of disease was about the same for both groups: 2.8 months and 2.6 months, respectively.
Almost half of those taking the combination therapy were alive after one year, compared to 36.3 percent in the other group. After two years, the rates were 28.5 percent and 17.9 percent, respectively.
By three years out, 20.8 percent of those in the combinatio
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