The U.S. FDA (Food and Drug Administration) approved Xeljanz (tofacitinib) and Xeljanz XR for the treatment of psoriatic arthritis in December 2017. The medication, manufactured by Pfizer, is indicated for use in adults with active psoriatic arthritis who are intolerant to or have not responded to DMARDs (disease-modifying antirheumatic agents). The approved dosage is 5 mg two times a day for Xeljanz, and 11 mg one time a day for Xeljanz XR (also referred to as Xeljanz extended release).
How Xeljanz (tofacitinib) works
These medications are Janus kinase (JAK) inhibitors, meaning that they inhibit one or more enzymes in the JAK family. By interfering with these enzymes, major metabolic pathways within the body can be affected, including parts of the body’s immune system. This property is what allows Xeljanz and Xeljanz XR to alter the body’s immune function, and potentially reduce symptoms of psoriatic arthritis, including joint pain due to immune system-related inflammation. Xeljanz and Xeljanz XR are the first JAK inhibitors approved for the treatment of psoriatic arthritis as well as the treatment of moderate to severe rheumatoid arthritis. Xeljanz is typically taken in combination with nonbiologic DMARDs. It is not recommended for use with other immunosuppressant medications or biologic DMARDs.
Research behind Xeljanz (tofacitinib)
The FDA approved Xeljanz and Xeljanz XR based on the results of a Phase 3 clinical trial program called OPAL (Oral Psoriatic Arthritis Trial). The OPAL trial program included results from two major studies, OPAL Beyond and OPAL Broaden. The OPAL program also currently has an extension trial, OPAL Balance, going on currently, and preliminary results from this trial were used to inform the FDA’s decision as well. Results from OPAL Beyond and OPAL Broaden were published in the New England Journal of Medicine this year.
The OPAL Beyond and Broaden studies involved individuals who had active psoriatic arthritis for at least 6 months that was not responding to nonbiologic DMARDs. From there, these individuals were separated based on those who had tried and didn’t respond to tumor necrosis factor inhibiting medications (OPAL Beyond) and those who had never tried tumor necrosis factor inhibitors (OPAL Broaden). Those in the control group of each trial (meaning those who did not receive Xeljanz), received 40 mg of adalimumab every two weeks via a subcutaneous (under the skin) injection. Both studies met their primary efficacy endpoints, including having a statistically significant proportion of those taking Xeljanz achieve a 20 percent reduction in a composite measure of disease activity when compared to their placebo-receiving counterparts. This measurement is called an ACR20 and is defined by the American College of Rheumatology (ACR).
Possible side effects
The most common side effects experienced in those taking Xeljanz were headache, diarrhea, upper respiratory infections, and the common cold. However, the safety profile of Xeljanz when used for psoriatic arthritis was found to be consistent with the safety profiled when used for rheumatoid arthritis. As is the case with many immune system-affecting medications, individuals taking Xeljanz must be monitored for signs of serious infection while taking the medication.1