NEW YORK (Reuters Health)—The oral Janus kinase inhibitor tofacitinib (Xeljanz, Pfizer) does not increase the risk of malignancies, according to pooled data from more than 5000 rheumatoid arthritis (RA) patients.
In an April 22 online paper in Annals of the Rheumatic Diseases, Dr. Lisy Wang of Pfizer, Groton, Connecticut, and colleagues noted that in RA patients regardless of treatment regimens, some malignancies “occur more frequently than in the general population.”
In addition, they wrote, “In the development of immunomodulatory agents with new mechanisms of action such as tofacitinib, there is a particular need for close monitoring of safety events.”
The team examined pooled malignancy data from a total of 12 phase 2 and 3 studies and two long-term extension studies involving tofacitinib. Median tofacitinib exposure was for 2.35 years.
Of the 5671 tofacitinib-treated patients, after exclusion of 62 patients with non-melanoma skin cancers, 107 developed malignancies. Among the most common were lung cancer in 24 patients, breast cancer in 19 and lymphoma in 10. Twenty of the lung cancer patients were current or former smokers.
The types of malignancies observed as well as the overall incidence rates remained stable over time with increasing tofacitinib exposure. And the standardized incidence ratio as compared with the U.S. National Cancer Institute Surveillance, Epidemiology, and End Results database were within the range expected for patients with moderate to severe RA.
The results appear reassuring, but the researchers point out that “due to the presumed extended latency periods of some malignancies,” continued observation is required, and “the relationship between greater cumulative duration of tofacitinib use and malignancy warrants further study.”
Commenting on the findings by email, rheumatologist Dr. Joel Kremer told Reuters Health, “The overall incidence of new malignancies on tofacitinib does not appear to be different from what would be expected in a large population of individuals of this age.”
Dr. Kremer, Pfaff Family Professor of Medicine at Albany Medical College, New York, concluded, “Real-world registry data on patients receiving the drug outside of the context of industry trials will add to our confidence about these observations.”
Dr. Wang did not respond to requests for comment.
The study was funded by Pfizer and a number of the authors are employed by or have other ties to the company.