CHICAGO – Oral tofacitinib demonstrated strong clinical efficacy and good safety in the first-ever formal study of a Janus kinase inhibitor in patients with active, treatment-resistant dermatomyositis, Julie J. Paik, MD, reported at the annual meeting of the American College of Rheumatology.
Dr. Julie J. Paik
Based upon the encouraging results of this small, open-label, proof-of-concept study, a larger randomized controlled trial is being planned, according to Dr. Paik, a rheumatologist at Johns Hopkins University in Baltimore.
The study included 10 dermatomyositis patients enrolled at the Johns Hopkins Myositis Clinic. All had previously failed at least two steroid-sparing drugs and/or high-dose steroids. After first going off all steroid-sparing agents and being limited to a maximum of 20 mg/day of prednisone, the participants were placed on 11 mg of open-label, extended-release tofacitinib (Xeljanz XR) once daily. Dr. Paik only reported results in 9 patients because the 10th hadn’t yet reached the 12-week mark.
The primary outcome was the rate of achievement of significant improvement at week 12 as defined using the validated International Myositis Assessment and Clinical Studies (IMACS) criteria, which require at least a 20% improvement in three of six core set measures coupled with no more than two measures worsening by 25% or more. By this standard, all nine patients met the primary endpoint. Five were rated as showing moderate improvement, and the other four demonstrated minimal improvement, based on the Total Improvement Score of the Myositis Response criteria. The median Total Improvement Score was 40, indicative of at least moderate improvement.
The mean CDASI (Cutaneous Dermatomyositis Disease Area and Severity Index) activity score – a key secondary endpoint – improved from 28 at baseline to 9.5 at week 12, which translates to a shift from moderate or severe disease to mild disease.
Levels of the alpha-chemokines CXCL9 and CXCL10, which are expressed in muscle affected by idiopathic inflammatory myopathies such as dermatomyositis, declined strongly over the course of 12 weeks of treatment to an extent that was just shy of statistical significance.
Myositis antibody titers didn’t change in response to tofacitinib therapy. Of note, six patients were positive for antitranscriptional intermediary factor 1-gamma, and five of the six were moderate responders to JAK inhibitor therapy.
Four patients were on 20 mg/day of prednisone at baseline; three of the four were able to go off steroids altogether over the course of 12 weeks.
The treatment was well tolerated, with no serious adverse events.
Asked if she thought 11 mg/day of tofacitinib was the right dose for this population of refractory dermatomyositis patients, Dr. Paik replied, “We’re not sure we have the right dose. We had one patient who didn’t have as robust a response, and I really wonder, if we gave her a higher dose, it would have made a difference.”
Extended-release tofacitinib at 11 mg/day is the approved dose for rheumatoid arthritis and psoriatic arthritis. However, 20 mg/day is approved for patients with ulcerative colitis, and Dr. Paik is lobbying for inclusion of a higher-dose arm in the randomized, controlled trial.
Prior to this formal proof-of-concept study, which was funded by Pfizer, the experience with tofacitinib in refractory dermatomyositis was limited to anecdotal case reports.
Dr. Paik reported having no financial conflicts.
SOURCE: Paik JJ et al. Arthritis Rheumatol. 2018;70(Suppl 10): Abstract L02.