FDA harps on risks of Pfizer's tofacitinib as panel looms

FDA staffers drew attention to safety risks associated with Pfizer's blockbuster contender tofacitinib in briefing documents. The agency's concerns come days before a panel of non-FDA experts delves into Pfizer's application for approval of the oral med for rheumatoid arthritis.

Tofacitinib--which Pfizer hopes to establish as a rival to a host of multibillion-dollar RA treatments--offers the first oral drug of its kind to combat RA. But FDA staffers raised concerns about increased risks of malignant cancers--particularly lymphomas--and infections tied to the drug. As is common to such reviews, the agency staff questioned whether the benefits of the treatment outweighed the risks to patients, Reuters reported, and they critiqued the X-ray methodology that Pfizer used to measure efficacy.

Pfizer ($PFE) has high hopes for tofacitinib, which the U.S. drug giant has highlighted as one of the hottest prospects to come from its much-maligned R&D organization. Its initial plan is to gain approval of the JAK inhibitor for RA patients who have previously failed on drugs against the autoimmune disease such as methotrexate and blockbuster anti-TNF meds such as Abbott's ($ABT) Humira and Amgen's ($AMGN) Enbrel.

Yet with a slate of effective RA drugs on the market, the FDA appears to be in a position to keep the safety bar quite high in its review of tofacitinib. "Because it's not as much of an unmet medical need as it was a few years ago, the requirements have gone up," said Mark Schoenebaum, an analyst with ISI Group in New York, as quoted in a BusinessWeek article.

Rheumatoid arthritis affects more than 1 million patients in the U.S. and causes the immune system to mount attacks around the joints, causing pain and long-term disability. Pfizer believes there's a significant number of RA patients who aren't served by existing drugs, with 30% to 40% of patients failing to respond to the meds, BusinessWeek reported.

The FDA advisory committee is scheduled to meet on Wednesday to decide whether to back tofacitinib for approval.

- get the FDA briefing docs here
- see BusinessWeek's article
- and Reuters' report

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