Swiss regulators have given the all clear to GlaxoSmithKline’s new breast cancer pill Tyverb, marking the drug’s first approval in Europe.

Specifically, Tyverb (lapatinib) has been given the nod for use in combination with capecitabine to treat patients with advanced breast cancer, and in women with HER-2 positive breast cancer who are unresponsive to therapy with Roche’s Herceptin (trastuzumab).

Swiss approval was based a pivotal Phase III trial in women with breast cancer which found that a combination of Tyverb and capecitabine was significantly better at keeping the disease at bay than the latter alone (27.1 weeks to progression versus 18.6 weeks, respectively).

The drug, which works within cells by blocking two enzymes – called kinases – thought to promote cancer, has certainly been a jewel in GSK's R&D crown, and is currently also being assessed in a number of indications, including squamous cell carcinoma of the head and neck and brain and kidney cancer.

Battle with Herceptin

Tyverb, which is already sold as Tykerb on the US market by Genentech, is currently being assessed by the European Medicines Agency, and a spokesperon for GSK told PharmaTimes UK News that if its application is successful, the drug will be launched in the region in the second half of this year.

Tyverb looks set to face a tough battle for market share with Herceptin, although some analysts expect that it will eventually overtake its rival and generate peak annual sales well in excess of $1 billion. This view is due, in part, to the fact that GSK's drug has the advantage of being orally-active, while Herceptin is dosed by injection.

But despite the news of the drug’s latest approval, the groups’ stock failed to recover after a report in the New England Journal of Medicine which threw a shadow of doubt over the safety profile of GSK’s diabetes drug Avandia (rosiglitazone), denting investor confidence.

The study found that patients taking the drug were 64% more likely to die from cardiovascular causes and 43% more likely to suffer a heart attack, but GSK says it “strongly disagrees with the conclusions reached in the NEJM article, which are based on incomplete evidence and a methodology that the author admits has significant limitations.”