Pharma

Could GSK’s melanoma therapy work better than Roche’s Zelboraf?

GlaxoSmithKline‘s (NYSE:GSK) phase 3 clinical trial on a combination melanoma treatment is just starting, but […]

GlaxoSmithKline‘s (NYSE:GSK) phase 3 clinical trial on a combination melanoma treatment is just starting, but the pharma giant already has reason to be excited. Midstage results showed that in some patients, the drug works better than Roche‘s (OTC:RHHBY) Zelboraf — a drug that set the cancer care community abuzz even before it was approved last year.

Dr. Jeffrey Webber, an oncologist who led a clinical study on the GSK combination drug, said that progression-free survival, or PFS, in patients on the drug was 10.8 months. In Zelboraf, also known as vemurafaib, PFS was about 7.4 months. Webber, speaking during a media briefing presenting research highlights that will be presented at the upcoming annual meeting of the American Society of Clinical Oncology,  cautioned that this difference of greater than three months came only with a group of 24 patients. But he called the results “extremely encouraging.”

“If it holds up, it will clearly look superior to the figure we’ve seen with vemurafenib,” said Webber, an oncologist at the H. Lee Moffitt Cancer Center in Tampa, Florida.

Zelboraf works on patients who express mutations on the BRAF gene. The drug is a BRAF inhibitor. Zelboraf received priority review and was considered a breakthrough cancer treatment when the U.S. Food and Drug Administration approved it last August. GSK is studying its own BRAF inhibitor, dabrafenib, in combination with another cancer drug, trametinib.

Emmy Wang, a spokeswoman for Roche subsidiary Genentech, said that a comparison with Zelboraf is not appropriate because the GSK trial did not evaluate the GSK combination therapy against Zelboraf. She said the median overall survival with Zelboraf is 13.2 months. Patients treated with dacarbazine chemotherapy show median overall survival of 9.6 months. Updated overall survival data will be presented at ASCO next month.

Webber studied 77 patients who had not previously been treated with any BRAF inhibitor. He said that the combination of the two GSK compounds showed “dramatic and significant” reduction in side effects. With the combination of the two drugs, just 3 percent of patients developed squamous cell carcinoma, or SCC, a form of skin cell cancer. In patients treated with a BRAF inhibitor alone, 15 percent to 25 percent of them would develop SCC. Just 5 percent of patients on the GSK combination treatment developed lesions called actinic keratosis. With a BRAF inhibitor alone, 20 percent to 40 percent of patients would develop that condition.

In the total group of patients, the GSK combination therapy showed disease control in 95 percent of patients. Webber noted that at the recommended phase 2 dose of 150 milligrams of dabrafenib and 2 milligrams of trametinib, disease control was 100 percent.

Dr. Sandra Swain, president-elect of ASCO, said that the GSK trial results are an example of how combining drugs will become a more important approach to treating cancer because of the ability to hit multiple targets at once. She called the GSK therapy an innovative approach because the combination actually decreases the side effects of the BRAF inhibitor.

[Photo from wikipedia]

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