JAK Inhibitor Increases Hair Growth in Alopecia Areata Patients

Baricitinib, an oral inhibitor of Janus kinase (JAK) types 1 and 2, produced substantial rates of hair growth with acceptable tolerability for patients with alopecia areata, according to the results of two phase 3 trials presented at the European Academy of Dermatology and Venereology (EADV) 2021 Annual Meeting.

In both trials, severe alopecia areata, defined as a SALT (Severity of Alopecia Tool) score of ≥50, was an enrollment requirement. The primary endpoint was a SALT score of ≤20, signifying 80% scalp coverage.

“The mean SALT score at entry was 85,” reported Brett King, MD, PhD, associate professor of dermatology, Yale University School of Medicine, New Haven, Connecticut. He explained that the SALT scale extends from 0 (no hair loss) to 100 (complete hair loss). About 45% of patients in the phase 3 trials had alopecia universalis.

In both trials, called BRAVE-AA1 and BRAVE-AA2, a response was seen with baricitinib after about 4 weeks. Response increased steadily through the entire 36 weeks of treatment. At the end of 36 weeks, when response curves still had an upward trajectory, the proportion of those treated with the 4-mg dose of baricitinib who had achieved a SALT score of ≤20 had reached 35.2% in BRAVE-AA1 and 32.5% in BRAVE-AA2.

The nearly identical BRAVE-AA1 and BRAVE-AA2 trials enrolled 654 and 546 patients, respectively. The patients were randomly assigned in a 3:2:2 ratio to receive baricitinib 4 mg, baricitinib 2 mg, or placebo. All treatments were taken once daily. Regrowth of eyebrow and eyelash hair were secondary outcomes.

There was a clear dose effect; hair growth increased more quickly with the 4-mg dose of baricitinib than with the 2-mg dose. The difference between the active therapy and placebo was significant by 16 weeks with the 4-mg dose. By 24 weeks, the advantage of the 2-mg dose over placebo also reached significance. The response rate with the 4-mg dose was nearly twice as great.

At the end of the 36-week trials, the proportion of patients treated with baricitinib 2 mg who achieved the primary endpoint was 21.7% and 17.3% in the BRAVE-AA1 and BRAVE-AA2 trials, respectively. Among patients taking placebo, the primary endpoint was met by 5.3% and 2.6%, respectively, at the end of the two trials.

The differences in responses with the 4-mg and the 2-mg doses were significantly higher compared with placebo (P ≤ .001 for both doses vs placebo).

Using a scoring system for eyebrow and eyelash hair loss, the proportion of patients who achieved a score of 0 (full coverage) or 1 (minimal gaps) was again superior in both trials for patients taking the higher dose of baricitinib. This level of response was reached by about 31% to 35% of those taking the 4-mg dose in BRAVE-AA1 and BRAVE-AA2 (P ≤ .001 vs placebo). With the lower dose, the rates were 19.1% and 13.5%, respectively. This endpoint was reached in only about 3% of patients who took placebo.

Rates of adverse events were modestly higher in the two active treatment groups in comparison with the group taking placebo. The most commonly occurring adverse events with baricitinib included upper respiratory tract infections, nasopharyngitis, urinary tract infections, and headache, according to King.

“Most of the adverse events were mild to moderate,” he said. He also reported that none of these adverse events occurred in more than 10% of patients, and there were no cases of other opportunistic infections, thromboembolic events, or gastrointestinal perforations. The discontinuation rates because of adverse events with active therapy were <3% in both trials.

JAK inhibitors are currently employed in the treatment of a variety of inflammatory diseases. Baricitinib is currently approved for the treatment of rheumatoid arthritis. Because specificity differs markedly for their inhibition of JAK kinases (JAK1, JAK2, JAK3, and Tyk2), these drugs do not appear to be interchangeable with regard to clinical effect.

Several case reports of hair regrowth with baricitinib led to a phase 2 trial, which was recently published in the Journal of the American Academy of Dermatology. In this trial, the therapy was also yielded substantial benefit for patients with alopecia areata. The benefit of baricitinib is attributed to inhibition of JAK1 and JAK2 signaling, which has been implicated in cytokine-mediated immune dysfunction leading to damage of hair follicles.

Alopecia areata is a common disorder that can have a large adverse impact on quality of life, King noted. There is no approved therapy for this condition, and so there is a large unmet need. Although longer follow-up is needed to gauge sustained efficacy and safety, he considers these results promising for a therapy with clinically meaningful benefit.

This point was reiterated by Yolanda Gilaberte Calzada, MD, PhD, head of the Dermatology Service, University Hospital Miguel Servet, Zaragoza, Spain, who was moderator of the session in which King presented these data. She expressed excitement about the promise of baricitinib, particularly with regard to the substantial proportion of patients who achieved meaningful degrees of hair regrowth.

“All of us will be happy to have options for alopecia areata,” said Gilaberte Calzada, who predicted that the higher dose of baricitinib will be selected for clinical development, given its greater efficacy with little increase in safety concerns.

Eli Lilly provided funding for the BRAVE-AA1 and -AA2 trials. King has financial relationships with Arena, Aclaris, Bristol-Myers Squibb, Concert, Pfizer, Regeneron, Sanofi Genzyme, and Eli Lilly. Gilaberte Calzada has disclosed no relevant financial relationships.

European Academy of Dermatology and Venereology (EADV) 2021 Annual Meeting: Abstract 605. Presented September 30, 2021

Ted Bosworth is a medical journalist based in New York City.

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