Pfizer's arthritis hope Xeljanz gets US approval

Pfizer was celebrating yesterday after securing US approval for Xeljanz, an orally-active drug for rheumatoid arthritis (RA) that could mount a major challenge to biologic drugs for the disease.

Xeljanz (tofacitinib) is the first compound in the new class of Janus kinase (JAK) inhibitors to be cleared for marketing, getting a green light from the FDA yesterday to treat the 30 to 40 per cent of adults with moderately- to severely-active RA who do not respond to or cannot tolerate methotrexate.

The FDA has approved a 5mg dose of the twice-daily drug, but has said it still requires additional information on a higher 10mg formulation.

The drug enters a market currently dominated by injectable tumour necrosis factor (TNF) blockers, such as Abbott's huge-selling Humira (adalimumab) brand, and Ono/Bristol-Myers Squibb's T-cell (T-lymphocyte) inhibitor Orencia (abatacept). 

The TNF class alone currently accounts for nearly three quarters of rheumatoid arthritis sales in major world markets, which were valued at $11bn in 2011 according to Decision Resources data.

Analysts have predicted that as an oral alternative Xeljanz could become a major earner for Pfizer, with sales of $2bn a year or more in RA, rising even higher if trials in other indications such as psoriasis, inflammatory bowel disease and renal transplant are positive.

Pfizer needs a new blockbuster to help it recover from the loss of patent protection for big-sellers such as cholesterol-lowerer Lipitor (atorvastatin). 2012 is Pfizer's peak year for patent losses, with around $8bn of revenues at risk of being wiped off its top-line.

The safety and effectiveness of Xeljanz were evaluated in seven clinical trials, with patients treated with the drug experiencing significant improvements in clinical response and physical functioning compared to patients treated with placebo.

The use of Xeljanz is however associated with an increased risk of opportunistic infections, tuberculosis, cancers and lymphoma, notes the FDA, so labelling for the drug includes a boxed warning of these safety risks. Approval also comes with a Risk Evaluation and Mitigation Strategy (REMS) to help patients and physicians manage the possible side effects of therapy.