First JAK Inhibitor OK’d for Ankylosing Spondylitis

The FDA approved tofacitinib (Xeljanz, Xeljanz XR) for treating active ankylosing spondylitis in adults, Pfizer announced on Tuesday.

Tofacitinib is the first Janus kinase (JAK) inhibitor approved for ankylosing spondylitis, the drugmaker said, and is indicated specifically for individuals who cannot tolerate or fail to adequately respond to tumor necrosis factor (TNF) inhibitors.

Support for the approval came from a phase III study involving 269 adults with ankylosing spondylitis, presented at last year’s American College of Rheumatology annual meeting.

The multicenter, double-blind trial showed a 20% improvement on Assessment of SpondyloArthritis International Society (ASAS20) response criteria for 56.4% of patients randomized to a 5-mg twice-daily dose of tofacitinib at week 16, as compared with 29.4% of those assigned to the placebo arm (P<0.0001), meeting its primary endpoint.

In addition, a 40% improvement (ASAS40) was seen in 40.6% of patients on tofacitinib versus just 12.5% of those on placebo (P<0.0001).

“Ankylosing spondylitis, a type of arthritis that causes inflammation in certain parts of the spine, affects more than 350,000 people in the U.S. This disease often occurs in early adulthood and causes pain, swelling, and possibly restricted mobility,” said Steven Taylor, of the Arthritis Foundation in Atlanta, in a statement. “With this approval, physicians and patients now have an additional oral treatment option that can help address this chronic and often progressive disease.”

In the phase III trial, severe adverse events were reported in two patients on the tofacitinib arm and none of those on the placebo arm.

Due to the class-wide restrictions for JAK inhibitors from the FDA, tofacitinib is likely to only remain an option for patients who fail on anti-TNF drugs, and the labeling for the drug includes warnings related to the higher risk for major adverse cardiac events, mortality, cancers, and thrombosis. Patients treated with tofacitinib are also at increased risk for infections.

Use of tofacitinib in combination with biologic disease-modifying antirheumatic drugs “or potent immunosuppressants such as azathioprine and cyclosporine is not recommended,” according to Pfizer’s release.