Tafinlar: Deadly melanoma has a new foe

Project name: dabrafenib
Disease: Melanoma
Peak sales estimate: $350 million
Approved: May 23
Company: GlaxoSmithKline

The Scoop:
Melanoma has emerged as a highly competitive field in drug R&D, and GlaxoSmithKline ($GSK) is trying to position itself as a leader in that field with its two melanoma treatments, Tafinlar and Mekinist, approved together in May. Both are single-agent oral medications meant to treat the most lethal forms of skin cancer, melanomas that are advanced, or metastatic, or those that cannot be removed by surgery, known as unresectable melanoma. Tafinlar is not indicated for the treatment of patients with wild-type BRAF melanoma.

Though the drugs were approved as single products, London-based Glaxo is hopeful that the two could eventually be used as a combination therapy to thwart cancer reappearance in high-risk patients. In July, Glaxo filed an application with the FDA to sell a combination of dabrafenib and trametinib for melanoma based on Phase I/II data rather than late-stage results. The move is indicative of growing confidence among drugmakers that relatively small studies of very targeted cancer drugs can demonstrate enough of a basis for an FDA blessing.

"Advancements in our understanding of the biological pathways of a disease have allowed for the development of Tafinlar and Mekinist, the third and fourth drugs the FDA has approved for treating metastatic melanoma in the past two years," Dr. Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, said in a previous statement.

Tafinlar is a BRAF inhibitor that's approved to treat patients with melanoma whose tumors express the BRAF V600E gene mutation. About half of melanomas arising in the skin have a BRAF gene mutation, an abnormal change in a gene that can enable some melanoma tumors to grow and spread. The BRAF V600E mutation accounts for about 85% of all BRAF V600 mutations in metastatic melanoma.

In a study of 250 patients with BRAF V600E gene mutation-positive metastatic or unresectable melanoma, patients were randomly assigned to receive either Tafinlar or a standard chemotherapy drug, dacarbazine. Tumor growth was 2.4 months later in those who took Tafinlar than in those receiving dacarbazine.

In the United States, the wholesale acquisition cost of Tafinlar is $7,600 for a 30-day supply.

CEO Andrew Witty promised that 2013 would be a turning point for Glaxo, and it certainly proved to be. In November, a Morningstar top pharma analyst ranked Glaxo's pipeline of new medications No. 1 in the industry, noting its foray into oncology and respiratory diseases.

Glaxo beat out Roche's ($RHHBY) Genentech for approval of its new melanoma therapies. Genentech was wrapping up late-stage studies of a rival dual drug therapy, containing the experimental MEK inhibitor GDC-0973 from its partner Exelixis ($EXEL) and its marketed skin-cancer drug Zelboraf in certain melanoma patients. -- Emily Mullin (email | Twitter)

For more:
GlaxoSmithKline nabs key FDA approvals for two melanoma drugs
GlaxoSmithKline shoots for combo attack against melanoma in surgery patients
Genentech launches PhIII for melanoma combo with GSK in hot pursuit
GSK races to regulators for approvals of new skin cancer drugs

Tafinlar: Deadly melanoma has a new foe

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