ZURICH/MADRID (Reuters) - Swiss drugmaker Novartis notched a trial win for its drug cocktail against skin cancer on Monday, while a rival treatment from Roche with slipping sales failed in a separate study with a similar patient group.

FILE PHOTO - A Novartis logo is pictured on its headquarters building in Mumbai April 1, 2013. REUTERS/Vivek Prakash/File Photo

All the medicines were tested in melanoma patients who had undergone surgery to cut out tumors and had a genetic mutation called BRAF, making them likely to respond to the targeted cancer pills. Patients with BRAF mutations constitute around half of the melanoma population.

Novartis’s mix of Tafinlar and Mekinist slashed the risk of melanoma returning or death by 53 percent versus placebo in patients with stage III disease, according to data released at the European Society for Medical Oncology congress in Madrid.

“These are the best results ever shown for an adjuvant (post-surgery) treatment in stage III melanomas,” said Axel Hauschild of the University of Kiel, Germany, one of the main researchers on the Novartis trial. “These are practice-changing results.”

The findings by Hauschild and colleagues were also published online in the New England Journal of Medicine.

Novartis senior vice-president Jeff Legos said the company hoped to submit the combination for regulatory approval in the new adjuvant setting by the end of the year.

Roche’s Zelboraf, however, did not improve the primary endpoint of disease-free survival in patients with similar disease, although it appeared to be effective in those with earlier-stage melanoma.

The findings suggest Novartis is gaining the upper hand in expanding its combination therapy’s use against advanced, high-risk skin cancer for which there is a distinct risk of the potentially deadly tumors emerging elsewhere on the body.

Giving the powerful targeted medicines can have side effects and around a quarter of patients on the Novartis combination had to stop treatment due to adverse events.

Novartis is not alone with successful results in adjuvant melanoma. Bristol-Myers Squibb also reported positive data with its immunotherapy drug Opdivo, which is not restricted to use in patients with BRAF mutant tumors.

Revenue from Novartis’s anti-melanoma “Taf-Mek” combination already outpaces Roche’s offering.

Tafinlar and Mekinist have been on an upward trajectory, reaping $672 million in sales in 2016, compared to $453 million the previous year.

By contrast, Roche’s Zelboraf sales slipped to 213 million Swiss francs ($224 million) in 2016, down around a fifth from their 2014 levels.

While Roche in 2015 began pairing Zelboraf with Cotellic against mutant melanoma to counter combinations like Novartis’s that have become standard of care, their revenue combined remains less than half of Novartis’s drugs.

Tafinlar and Mekinist were originally developed by GlaxoSmithKline but were acquired by Novartis as part of a complex asset swap between the two companies.

Roche, which began its trial of Zelboraf in patients who had undergone surgery before it had Cotellic approval, said it was disappointed, but said the news was not exclusively dour.

For instance, its trial’s separate cohort of patients with less serious stage IIC to IIIB melanoma saw their risk of disease returning cut by 46 percent.

“To our surprise, it was less effective in the higher-risk cohort - it’s something we thought would happen the other way around - and it’s much more effective in the patients with lower risk,” Thomas Buechele, Roche’s head of global medical affairs for oncology, said in an interview.

“This is a bit sad, as a clinician, because there is certainly a clinical benefit here.”

Buechele said he would discuss the mixed data with regulators. The company does not plan any more studies in the adjuvant setting with Zelboraf and Cotellic.