(Reuters) - A combination of experimental drugs from Array BioPharma Inc kept patients with advanced melanoma associated with a common gene mutation alive for nearly three years and twice as long as a rival Roche Holding AG medicine, according to data from a late stage study released on Tuesday.

Array shares rose as much as 13 percent in early trading before giving back some of those gains.

The oral drugs, encorafenib and binimetinib, are awaiting a U.S. approval decision by June 30 based on promising data on their ability to stall disease worsening, or progression-free survival (PFS). European regulators are also reviewing the treatment.

However, overall survival is seen as the gold standard for cancer treatments and the new data is likely to significantly enhance approval and eventual sales prospects.

The Array combination - 450 milligrams of encorafenib once daily and 45 mg of binimetinib twice a day - led to median overall survival of 33.6 months in patients with advanced melanoma with a BRAF mutation, meaning half the patients were still alive nearly three years after treatment.

That compared with median overall survival of 16.9 months for patients in the Phase III study who received Roche’s Zelboraf, known chemically as vemurafenib.

Advanced melanoma is the deadliest form of skin cancer. About half of the estimated 200,000 new melanoma cases diagnosed worldwide each year carry BRAF mutations.

“There remains a substantial need for well-tolerated treatments that delay disease progression and improve overall survival,” Dr. Keith Flaherty, a lead investigator of the study from Massachusetts General Hospital Cancer Center in Boston, said in a statement.

“This data suggests that the combination of encorafenib and binimetinib may have the potential to become a meaningful new therapy for patients with advanced BRAF-mutant melanoma,” Flaherty added.

In a pivotal trial of a similar already approved combination from Novartis, nearly 30 percent of patients were still alive five years after being treated with Tafinolar and Mekinist.

PFS and safety data from the Array trial were previously announced.

The Array medicines are being co-developed by privately-held French pharmaceuticals group Pierre Fabre.

Array also reported a narrower-than-expected quarterly loss and nominal revenue of $42.2 million that also exceeded Wall Street estimates.

Array BioPharma shares were up $1.15, or 8 percent at $15.24 after climbing as high as $15.96 earlier.