By Ben Hirschler and Bill Berkrot
LONDON/NEW YORK, May 30 (Reuters) - U.S. health regulators have approved two new GlaxoSmithKline drugs for treating advanced melanoma, in the latest sign that companies are having more success getting novel medicines to market.
The Food and Drug Administration (FDA) gave the green light to Tafinlar and Mekinist late on Wednesday, bringing the tally of new drugs approved by the U.S. agency so far this year to 13, compared with 11 at the same stage in 2012.
After 39 FDA approvals last year - a record only beaten in 1996 - the continuing healthy run-rate for so-called new molecular entities is fuelling investor hopes the industry may finally be pulling out of a long period of poor productivity.
The FDA approved the two GSK drugs to be used as single agents against melanoma - the deadliest form of skin cancer - and not in combination after the medicines delayed tumour growth in separate clinical trials.
GSK, however, hopes further trials now underway will prove there is an additional benefit from combining the treatments, potentially giving it an edge over Roche's rival melanoma medicine Zelboraf.
After decades with virtually no progress in the fight against advanced melanoma and little to offer patients facing a virtual death sentence, Tafinlar and Mekinist mark the third and fourth new drugs approved by the FDA for metastatic melanoma in the past two years.
The drugs are a further step forward in targeted cancer care and will be used in patients with a specific genetic profile - an approach that will limit the number of people who get them.
As a result, sales expectations for the two medicines are relatively modest and analysts, on average, predict annual global revenue of $371 million for Tafinlar by 2017, with Mekinist expected to sell $425 million by the same time, according to forecasts compiled by Thomson Reuters Pharma.
Tafinlar, known chemically as dabrafenib, belongs to a class of cancer drugs called as BRAF inhibitors. Mekinist, or trametinib, inhibits a protein associated with cancerous tumours known as MEK.
Tafinlar was approved to treat patients with melanoma whose tumours express the BRAF V600E gene mutation, while Mekinist is for patients with either the BRAF V600E or V600K gene mutations. About half of skin melanomas have a BRAF mutation.
The FDA also approved the THxID BRAF test, made by France's Biomerieux, which will be used to determine if a patient's melanoma cells have the V600E or V600K mutation in the BRAF gene.
GSK also got further boost from another cancer drug late on Wednesday as its already marketed drug Arzerra, developed with Denmark's Genmab, proved successful in a late-stage study as a first-line treatment for chronic lymphocytic leukaemia (CLL).
Alongside the melanoma drug approvals, Deutsche Bank analyst Mark Clark said the Arzerra results represented "a triple dose of good news" for Britain's biggest drugmaker.
So far, Arzerra has only be used in a subset of hard-to-treat CLL patients and analysts' annual sales forecasts for the drug stand at $297 million by 2017, according to Thomson Reuters Pharma.
Deutsche Bank said this number was likely to rise as the medicine becomes a more viable competitor to Roche's Rituxan, which is also known as MabThera.
Shares in Genmab, whose fortunes are closely tied to sales of Arzerra, jumped more than 7 percent in early trading on Thursday, while GSK was little changed in a broadly flat London stock market. (Editing by John Wallace and David Holmes)