On March 6, 2016, interim safety data from a long-term extension study (OPAL Balance) on Pfizer’s Xeljanz (tofacitinib) in patients with psoriatic arthritis were presented at the 75th Annual American Academy of Dermatology (AAD) meeting. Xeljanz is an oral, small-molecule inhibitor of janus kinase 3 (JAK3), which affects the signaling of multiple cytokines that are involved in a broad spectrum of inflammatory diseases. OPAL Balance is an open-label, long-term extension study of two randomized Phase III trials, OPAL Broaden and OPAL Beyond, evaluating Xeljanz in psoriatic arthritis patients with an inadequate response to conventional synthetic disease modifying antirheumatic drugs (csDMARDs) and tumor necrosis factor inhibitors, respectively. Although Xeljanz is an oral formulation and will be a first-in-class drug for psoriatic arthritis, the FDA and EMA have previously expressed concern over Xeljanz’s safety profile in rheumatoid arthritis, emphasizing the importance of safety data from the OPAL Balance trial.
The OPAL Balance study enrolled 685 patients to receive 5mg of Xeljanz twice-daily for one month, after which time the dose could be increased to 10mg due to efficacy reasons. Patients were also allowed to receive concomitant treatment with a single csDMARD, oral corticosteroids, COX-2 inhibitors, or non-steroidal anti-inflammatory drugs. At Month 24, the most common adverse events included urinary tract infection (3.5%), nasopharyngitis (6.8%), and upper respiratory tract infection (6.2%). Further, 6.0% of patients experienced serious adverse events and three deaths were reported, although none were attributed to treatment with Xeljanz.
That being said, Xeljanz did not demonstrate any new safety concerns in psoriatic arthritis patients in comparison with other patient populations. Given rheumatologists familiarity with Xeljanz in rheumatoid arthritis, potential delays in initial uptake due to safety concerns may be dampened, with the potential to surpass $220 million in sales in 2025 across the seven major pharmaceutical markets (US, France, Germany, Italy, Spain, UK, Japan).