Pfizer's novel rheumatoid arthritis (RA) treatment tofacitinib outperformed methotrexate in a phase III trial, but is facing a delay in the US following a Food and Drug Administration (FDA) request for more data.
The company published top-line data from the ongoing ORAL Start trial of the JAK inhibitor, indicating that it was significantly superior to methotrexate on both the signs and symptoms of RA and inhibiting structural damage in joints, with safety data in line with earlier testing.
The study was conducted in methotrexate-naïve moderate-to-severe RA patients and evaluated the use of tofacitinib at doses of 5mg or 10mg twice-daily, given as a monotherapy, compared to methotrexate.
Tofacitinib was recommended for approval by an FDA advisory committee in May based on the results of earlier phase III trials, and Pfizer chief executive Ian Read confirmed on a conference call that the agency has since requested "additional analysis of the existing data in our New Drug Application".
Read said that the nature of the request may mean that the FDA will require additional time beyond the August 23, 2012, deadline laid out under the Prescription Drug User Fee Act (PDUFA) commitments to complete its review of the dossier.
Pfizer stressed that it the request was for a "routine analysis" of data from the NDA, which included five phase III trials. Such requests are not uncommon, it added.
The new ORAL Start study will not have a bearing on the FDA's review because it was completed too late for inclusion in the NDA, but Read said Pfizer is "exploring the most appropriate method and timing to submit this information".
The FDA advisory committee said at its March meeting that it would have liked to have seen structural data for tofacitinib, so the new data is a positive development for the drug's prospects.
Tofacitinib is a critical project for Pfizer at the moment in the wake of late-stage pipeline disappointments as it tries to ride out the financial effects of losing patent protection for blockbuster cholesterol drug Lipitor (atorvastatin).
Analysts have predicted that it could become a major earner for Pfizer, with sales upwards of $2bn a year at peak, and its importance to the firm has only grown since it revealed disappointing phase III data for Alzheimer's candidate bapineuzumab.
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.