Newly released safety trial results have revealed heart and cancer risks associated with Xeljanz, a common treatment for rheumatoid arthritis (RA) and ulcerative colitis. The long-term study, a condition of the medication’s initial approval, was recently completed.

What is Xeljanz?

“XELJANZ is a Janus kinase (JAK) inhibitor that helps disrupt JAK pathways from inside the cells, which are believed to play a role in inflammation,” according to Pfizer, the drug’s manufacturer. Xeljanz’s anti-inflammatory effect has made it the go-to treatment for several different conditions. Pfizer touts it as the “#1 most prescribed JAK inhibitor” based on the calculations using IQVIA data.

Originally approved in 2012 as a treatment for RA, Xeljanz, also called tofacitinib, is available as a twice-a-day pill, or in its daily XR formula. In 2017, Xeljanz was given approval for active psoriatic arthritis. The following year it was granted approval for adults with moderate to severe ulcerative colitis. Late last year, the Food and Drug Administration approved its use for polyarticular juvenile idiopathic arthritis.

The trial

When Xeljanz was first approved by the FDA, the agency ordered an ongoing clinical trial to evaluate the chances of heart problems, cancer, infections, and other issues over time. For the trial, patients taking Xeljanz for RA were compared to ones receiving an alternate type of medication called tumor necrosis factor (TNF) inhibitors. According to a release from Pfizer , there were 4,362 participants in the trial-- 2,911 were given tofacitinib and 1,451 took TNFi. 1,455 of participants taking tofacitinib were given the standard 5mg dose, while 1456 were given a 10mg double dose.

Interim long-term study results released in 2019 showed a risk of blood clots and potential deaths. That prompted the FDA to issue a boxed warning -- a message printed on packaging and prescription paperwork that warns of potential serious side effects.

With the clinical trial concluded, the FDA announced that “initial results show a higher occurrence of serious heart-related events and cancer in RA patients treated with both doses of tofacitinib compared to patients treated with a TNF inhibitor.”

According to Pfizer’s data, 135 major cardiovascular events were recorded and 164 participants developed malignant cancers during the risk period. Of the cardiovascular issues, 98 subjects were taking Xeljanz and 37 were given TNFI. Among the cancer patients, 122 were taking Xeljanz, while only 42 in the group received TNFi.

The FDA will continue evaluating trial data as it becomes available. Pfizer has indicated that additional information will include effectiveness information as well as more data on outcomes, such as death and pulmonary embolism.

What should I do if I take Xeljanz?

The FDA urges patients to consult with their doctor before stopping any medication. Abruptly discontinuing the use of Xeljanz could potentially worsen your condition. Your doctor will help you weigh the benefits and risks of the medicine using guidance from the NIH’s prescribing information.

Sean Marsala is a health writer based in Philadelphia, Pa. Passionate about technology, he can usually be found reading, browsing the internet and exploring virtual worlds.

Article medically reviewed by Yvonne Stolworthy, MSN, RN