(Corrects paragraph 9 to show that 18 percent of patients developed low-grade skin cancer, not 25 percent)
* Improves survival, tumor response
* Regulatory approval decision expected by year-end
By Deena Beasley
CHICAGO, June 5 Advanced melanoma patients treated with an experimental pill developed by Roche ROG.VX and Daiichi Sankyo (4568.T) were 63 percent less likely to die than patients given chemotherapy, according to a new trial.
The drug, vemurafenib, is designed for use in patients with tumors that have a mutation in a gene known as BRAF. About half of all melanomas -- the deadliest form of skin cancer -- have the genetic aberration.
The trial results were "better than we expected," said Dr. Paul Chapman of Memorial Sloan-Kettering Cancer Center in New York and the study's lead investigator, noting that the testing plan was changed after it became clear that patients were faring better on the targeted drug.
The study, which was presented on Sunday at a meeting of the American Society of Clinical Oncology, included 675 patients with previously untreated, inoperable late-stage metastatic melanoma with the BRAF mutation.
After a median three months of treatment, patients receiving vemurafenib had a 63 percent reduction in the risk of death compared to patients given the chemotherapy drug dacarbazine.
"This is a huge difference," said Dr. Antoni Ribas, an oncologist at the University of California, Los Angeles, who has studied vemurafenib. "Even if it diminishes over time, who cares?"
Vemurafenib patients also had a 74 percent reduction in the risk of cancer progression compared to dacarbazine.
Nearly half of patients treated with the Roche drug had tumor shrinkage, compared to 5.5 percent of the chemotherapy group.
The most common side effects were skin rashes, photosensitivity and joint pain. About 18 percent of patients developed a low-grade skin cancer.
Analysts, on average, have forecast annual vemurafenib sales of $452 million by 2015, according to Thomson Pharma.
MORE HELP FOR MELANOMA PATIENTS
Roche expects U.S. and European regulators to decide on approval of the drug before the end of the year, according to Sandra Horning, head of global development for oncology at the Swiss company's Genentech unit.
It is the second new drug shown to improve survival in melanoma patients. The first, Bristol Myers Squibb's (BMY.N) Yervoy, or ipilimumab or ipi, was approved in March for patients with inoperable or metastatic melanoma.
New trial results unveiled at ASCO show that Yervoy, in combination with dacarbazine, improved survival in newly diagnosed metastatic melanoma patients.
"For patients who are stable with slow-growing tumors, I would start them on ipi," said Dr. Chapman. "That is a drug that can take a while to work, so if the person has time I would rather give him essentially two shots on goal rather than one."
If, however, a patient's melanoma "is quite advanced and maybe doesn't have time to get the benefit of ipi, it might be that starting them on vemurafenib is a better strategy," he said.
Ipilimumab is an antibody designed to activate the body's immune system to seek and destroy melanoma cells.
"To get an immune stimulant to work you are better off with less aggressive, less bulky disease," said Dr. Ribas. "If a patient has a very aggressive melanoma with a lot of symptoms, with vemurafenib you have immediate benefit and ipi is unlikely to work in that situation."
He expects vemurafenib will be used as an initial treatment for eligible patients, followed by ipilimumab once they relapse.
Bristol-Myers and Roche announced earlier this week a collaboration to evaluate the combination of Yervoy and vemurafenib as a therapy for metastatic melanoma.
More than 70,000 people in the United States and 160,000 worldwide are diagnosed with melanoma each year, according to the American Cancer Society. The five-year survival rate for the aggressive cancer is just 15 percent.
(Editing by Bill Trott)