The US FDA has approved two personalised medicines for advanced melanoma developed by GlaxoSmithKline (GSK), along with a new companion diagnostic developed by bioMerieux to guide their use.
The regulator gave a green light to GSK’s BRAF inhibitor Tafinlar (dabrafenib) and MEK inhibitor Mekinist (trametinib) as monotherapies to treat advanced or unresectable melanoma patients who have mutations in the BRAF gene.
Tafinlar is approved to treat patients with melanoma whose tumours express the BRAF V600E gene mutation, while Mekinist will be used in patients whose tumours express the BRAF V600E or V600K mutations, said the FDA. Patients suitable for treatment with the new drugs will be selected using bioMerieux’s THxID BRAF test.
The two drugs are the third and fourth new drugs for melanoma to be approved in the last couple of years, after Daiichi Sankyo/ Roche’s Zelboraf (vemurafenib) – which also targets BRAF-positive tumours – and Bristol-Myers Squibb’s anti-CTLA4 immunotherapy Yervoy (ipilimumab). Both drugs were given the nod in 2011.
Mutations in the BRAF gene are involved in around 50 per cent of malignant melanomas, according to the Institute of Cancer Research (ICR), so it is expected that Yervoy will lead the market in future as it can be used to treat any melanoma patient, regardless of their genetic profile.
Yervoy has already got off to a fantastic start in the marketplace, bringing in $706m in sales last year, and is expected to reach up to $2bn at peak, with Zelboraf following behind with Roche reporting CHF 234m ($244m) in sales last year. Zelboraf has been tipped to reach $1bn at peak, with GSK’s two products managing a little less ($350m-$500m) apiece.
GSK is also carrying out a trial of Tafinlar and Mekinist in combination, and some analysts believe the double-whammy of BRAF and MEK inhibition – which seems to alleviate some of the side effects of BRAF inhibition whilst reducing the risk of tumour resistance – could be help GSK’s drugs leapfrog Zelboraf and claim the number two spot in melanoma therapy in the coming years.
Roche is not sitting still, however, and said recently it has started a phase III study of Zelboraf alongside Exelixis’ MEK inhibitor GDC-0973.
GSK said it will be making Tafinlar and Mekinist available for prescription in the US “no later than in the early third quarter of 2013”.