FDA panel backs Pfizer's tofacitinib for arthritis

Pfizer won the endorsement of a US Food and Drug Administration (FDA) advisory committee for its rheumatoid arthritis drug tofacitinib yesterday, putting the first-in-class JAK inhibitor on track for approval by the agency's August deadline.

If the FDA follows the advice of the panel, tofacitinib would be the first oral disease-modifying anti-rheumatic drug (DMARD) to reach the market in more than a decade.

Analysts have predicted that it could become a major earner for Pfizer, with sales upwards of $2bn a year at peak.

Tofacitinib's potential lies in the fact that the convenience of oral administration would allow it to make inroads into the huge market for biologic rheumatoid arthritis drugs which are given by injection.

These include the multibillion dollar TNF inhibitor category currently led by Abbott Laboratories' $8bn-a-year Humira (adalimumab). TNF inhibitors are used to treat around a third of all patients with the disease.

The FDA panel voted 8 to 2 in favour of tofacitinib's approval as a treatment for adult patients with moderately to severely active rheumatoid arthritis, who have failed to respond to one or more other DMARDs.

Ahead of the meeting there had been discussion about the drug's tendency to affect blood cholesterol and liver enzyme levels, but the committee voted 7 to 2, with one abstention, that its safety profile supported approval.

There was considerable debate at the panel meeting over the best dosing of tofacitinib, with some experts arguing that in trials, a lower 5mg dose seemed to show superior safety and equivalent efficacy to the higher 10mg dose.

Some members of the panel called for additional, long-term safety data on the drug, given that the 10mg dose seemed to cause greater immunosuppression.

Pfizer is also studying oral tofacitinib in psoriasis, inflammatory bowel disease and renal transplant, and a topical formulation of the drug in both psoriasis and dry eye disease.

Meanwhile, other companies developing JAK inhibitors include Novartis, whose Jakavi (ruxolitinib) candidate was recently recommended for approval in Europe as a treatment for myelofibrosis. Vertex Pharmaceuticals' VX-509 (in phase IIb) and Galapagos/Abbott Laboratories' GLPG0634 (phase II).