JAK Inhibitors' Warning Belies Durability in Registry Studies

Ted Bosworth

February 09, 2022

Several relatively large real-world analyses of Janus kinase inhibitors (JAKi) in patients with rheumatoid arthritis appear to show that the oral small-molecule drugs are discontinued and retained at rates similar to or better than biologic disease-modifying antirheumatic drugs (bDMARDs), including tumor necrosis factor inhibitors (TNFi), according to studies presented at the annual meeting of the Canadian Rheumatology Association.

The findings of these studies, although conducted prior to the Food and Drug Administration’s September 2021 announcement of a boxed warning for JAKi, do not lend support to the warning’s message of higher risks of major adverse cardiovascular events (MACE), blood clots, cancer, and death associated with JAKi.

In one study, discontinuation of JAKi-class drugs was less common than discontinuation of bDMARD-class drugs, including tumor necrosis factor inhibitors (TNFi), according to a multicenter team of investigators led by Janet Pope, MD, a professor in the division of rheumatology at the University of Western Ontario, London.

The greater durability of the JAKi relative to TNFi "seem to be driven by a greater loss of efficacy in bDMARDs over time," reported Samir Magdy Iskander, a medical student at the university, who presented the data.

JAKi Rival bDMARDs for Long-term Retention

In a separate but larger analysis, the retention rates with the JAKi tofacitinib (Xeljanz) and TNFi in two RA registries in Canada were about the same after a mean follow-up of 23.2 months (36.9% vs. 37.5%), but the tofacitinib group was at a relative disadvantage. Relative to the bDMARD group, patients taking JAKi were more likely to have had prior treatment with a bDMARD (66.9% vs. 33.9%), to have a higher median baseline Clinical Disease Activity Index (CDAI) score (22.1 vs. 20.0; P < .05), and to be older (59.5 vs. 57.6 years).

In this study, 1,318 patients with RA enrolled in the Ontario Best Practices Research Initiative (OBRI) or a Quebec cohort called RHUMADATA were evaluated, reported Mohammad Movahedi, MD, PhD, of the Institute of Health Policy, Management, and Evaluation at the University of Toronto.

"We have not yet analyzed the reasons for discontinuation, but the data show that retention is about the same, meaning that selection of one agent over the other should be tailored according to patient characteristics," Movahedi said.

Reasons for discontinuation were presented in the other observational study, which included 333 adult patients with RA from two centers in Ontario. The discontinuation rate for adverse events was approximately 20% in both groups (HR, 1.0005; P = .98). However, the discontinuation rate for lack of efficacy favored the JAKi, reaching statistical significance.

TNFi Failure for Lack of Efficacy Is Higher

"For lack of efficacy, the discontinuation rate was about 35% lower on the JAKi [HR, 0.6543; P = .029]," Iskander reported. Relative to those taking a TNFi, those on a JAKi demonstrated "greater durability regardless of gender, age, disease duration, and prior lines of therapy."

In a population of patients who have not achieved an adequate response to conventional synthetic DMARDs (csDMARDs), which describes the study population from the two Ontario centers, JAKi "may be considered as a preferable method of treatment," Iskander said.

Pointing out that many clinicians have interpreted the boxed warning as a relative contraindication for use of JAKi as first-line therapy in patients with an inadequate response to csDMARDs, Marinka Twilt, MD, PhD, the moderator of the scientific session where these data were presented, questioned the conclusion. In the boxed warning, clinicians and patients are advised to consider an increased risk of serious infections, malignancy, and cardiovascular-related mortality in individuals older than 50 years.

In response, Iskander said that the data were collected and analyzed prior to the change in labeling. He acknowledged that this study was not designed to capture long-term risks, such as cardiovascular disease or malignancy. In this analysis, the safety and tolerability of JAKi and bDMARDs appeared comparable.

NEJM Published Study Leading to Boxed Warning

Just a week prior to the CRA annual meeting, the New England Journal of Medicine published an FDA-mandated postmarketing trial of tofacitinib that was used by the agency to justify the boxed warning for JAKi with indications for artitis and other inflammatory diseases. In that open-label trial, more than 4,000 patients aged 50 years or older with at least one additional cardiovascular risk factor were randomized to 5 mg tofacitinib twice daily, 10 mg tofacitinib twice daily, or a TNFi (adalimumab or etanercept).

The efficacy of the therapies was similar, but tofacitinib failed to meet predefined noninferiority criteria for the co–primary endpoints of MACE or cancer (excluding nonmelanoma skin cancer). For tofacitinib relative to TNFi, the hazard ratio was 1.33 for MACE and 1.48 for cancers. The JAKi was also associated with higher incidences of opportunistic infections.

Iskander noted that Canadian clinical practice guidelines currently identify JAKi as a reasonable first-line alternative to bDMARDs after inadequate response to csDMARDs. While his data support that position, Twilt indicated that the benefit-to-risk ratio of JAKi might need recalculation based on the data that led the FDA to issue its boxed warning. She questioned whether the language regarding the relative role of JAKi and bDMARDs will change in coming RA guideline revisions.

Iskander reported no potential conflicts of interest. Movahedi did not list any personal conflicts of interest but acknowledged that OBRI received unrestricted grants from a variety of pharmaceutical companies, including those that manufacture bDMARDs and JAKi. Twilt reported no potential conflicts of interest.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.


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