JAK Inhibitor Promising for Polymyalgia Rheumatica Save

Tofacitinib (Xeljanz) appeared highly effective against polymyalgia rheumatica (PMR) in a small single-arm trial, researchers said, suggesting another potential alternative to long-term corticosteroids.

Among 14 patients in a phase II studyopens in a new tab or window treated with the oral Janus-associated kinase (JAK) inhibitor, mean disease activity ratings on a standard scale fell from 50.9 points at baseline to just 1.3 after 48 weeks, according to Ting Li, PhD, of Shanghai Jiao Tong University School of Medicine in China, and colleagues.

Perhaps just as important, this improvement was achieved with a steep reduction in steroid doses, the researchers reported in the Annals of the Rheumatic Diseases - from 15 mg/day of prednisone at baseline to a mean of 1.9 mg/day at week 48.

These findings, along with recent studies with a different targeted agent, point to a coming sea change for PMR treatment.

Steroids are now the "mainstay" of therapy for PMR, Li and colleagues observed. "For conventional synthetic disease-modifying anti-rheumatic drugs [DMARDs, such as methotrexate], there is no convincing evidence of efficacy," they wrote.

In 2022, however, results of two significant trials with tocilizumab (Actemra) were published, both indicating substantial efficacy. But one came with important caveats,opens in a new tab or window including less-than-comprehensive safety results, while the otheropens in a new tab or window, said Li and colleagues, had issues with the outcome assessments. Tocilizumab is also an injectable product and some patients may need or prefer oral dosing. JAK inhibitors have shown generally equivalent effectiveness with biologic drugs for many other rheumatologic conditions, making tofacitinib a logical choice for testing.

The 14 patients all were diagnosed with highly active PMR, defined as a score higher than 17 on the PMR Activity Scaleopens in a new tab or window. Three of the patients had previously tried conventional DMARDs and relapsed, while the rest were newly diagnosed. Their mean age was 69, and just under three-quarters were women.

Tofacitinib was given at 10 mg/day along with, to start, 15 mg/day of prednisone. The latter was then tapered over 20 weeks to 2.5 mg/day or less. Other agents including over-the-counter anti-inflammatory drugs were forbidden.

Achievement of PMR activity scores less than 7, defined as remission, was the primary outcome measure. By week 20, all but two of the 14 had achieved it, the researchers reported, with the remaining two getting there by week 48.

Biomarkers of inflammation and disease activity, such as levels of tumor necrosis factor-alpha, various interleukin species, and C-reactive protein, all declined with treatment in virtually every patient. So did clinical measures including patient-reported pain (from 72 on a 100-point scale at baseline to 0 at week 48), ratings of morning stiffness, and global assessments by patients and physicians.

Six of the patients stopped the daily steroids altogether during the study.

Safety findings were about as expected for a 48-week study of a JAK inhibitor. No serious or severe adverse events were seen. Five patients reported mild events such as upper respiratory infections. Elevations in serum creatinine and alanine aminotransferase were seen in one patient each, but the severity was not reported. One patient tested positive for tuberculosis.

Limitations to the study included the small number of patients and lack of placebo or other control.

Source Reference: Zhang L, et al "Efficacy and safety of tofacitinib in patients with polymyalgia rheumatica: a phase 2 study" Ann Rheum Dis 2023; DOI: 10.1136/ard-2022-223562.