SAN DIEGO — , according to late breaker data presented at the annual meeting of the American Academy of Dermatology.
Although the majority respond within months, response curves have so far climbed for as long as patients are followed, allowing many with disappointing early results to catch up, according to Rodney D. Sinclair, MD, professor of dermatology at the University of Melbourne, Australia.
His remarks were derived specifically from new long-term follow-up with baricitinib, the first JAK inhibitor approved for AA, but the pattern appears to be similar with ritlecitinib, the only other JAK inhibitor approved for AA, and for several if not all JAK inhibitors in phase 3 AA trials.
“We have had patients on baricitinib where not much was happening at 18 months, but now, at 4 years, they have a SALT score of zero,” Dr. Sinclair reported
A Severity of Alopecia Tool (SALT) score of 0 signifies complete hair regrowth. On a scale with a maximum score of 100 (complete hair loss), a SALT score of 20 or less, signaling clinical success, has been a primary endpoint in many JAK inhibitor trials, including those conducted with baricitinib.
Providing the most recent analysis in patients with severe AA participating in the phase 3 BRAVE-AA1 and BRAVE-AA2 trials of baricitinib, which were published together in 2022, Dr. Sinclair broke the data down into responders, mixed responders, and nonresponders at 52 weeks. The proportion of patients who responded with even longer follow-up were then tallied.
In the as-observed responses over time, the trajectory of response continued to climb through 76 weeks of follow-up in all three groups.
Relative to the 44.5% rate of overall response (SALT ≤ 20 ) at 52 weeks, there was some further growth in every group maintained on JAK inhibitor therapy over longer follow-up. In Dr. Sinclair’s late breaking analysis, this did not include nonresponders, who stopped therapy by week 52, but 78.4% of the combined responders and mixed responders who remained on treatment had reached treatment success at 76 weeks.
Response Curves Climb More Slowly With Severe Alopecia
While improvement in SALT scores was even seen in nonresponders over time as long as they remained on therapy, Dr. Sinclair reported that response curves tended to climb more slowly in those with more severe alopecia at baseline. Yet, they still climbed. For example, 28.1% of those with a baseline SALT score of 95 to 100 had reached treatment success at week 52, but the proportion had climbed to 35.4% by week 76.
The response curves climbed more quickly among those with a SALT score between 50 and 95 at baseline than among those with more severe alopecia, but the differences in SALT scores at 52 weeks and 76 weeks among patients in this range of baseline SALT scores were small.
Basically, “those with a SALT score of 94 did just as well as those with a SALT score of 51 when followed long-term,” he said, noting that this was among several findings that confounded expectations.
Duration of AA was found to be an important prognostic factor, with 4 years emerging as a general threshold separating those with a diminished likelihood of benefit relative to those with a shorter AA duration.
“When the duration of AA is more than 4 years, the response to any JAK inhibitor seems to fall off a cliff,” Dr. Sinclair said.
To clarify this observation, Dr. Sinclair made an analogy between acute and chronic urticaria. Chronicity appears to change the pathophysiology of both urticaria and AA, making durable remissions more difficult to achieve if the inflammatory response was persistently upregulated, he said.
The delayed responses in some patients “suggests that it is not enough to control inflammation for the hair to regrow. You actually have to activate the hair to grow as well as treat the inflammation,” Dr. Sinclair said.
This heterogeneity that has been observed in the speed of AA response to JAK inhibitors might be explained at least in part by the individual differences in hair growth activation. For ritlecitinib, the only other JAK inhibitor approved for AA to date, 62% were categorized as responders in the registration ALLEGRO trials, but only 44% were early responders, meaning SALT scores of ≤ 20 by week 24, according to a summary published last year. Of the remaining 16%, 11% were middle responders, meaning a SALT score of ≤ 20 reached at week 48, and 6% were late responders, meaning a SALT score of ≤ 20 reached at week 96.
In the context of late breaking 68-week data with deuruxolitinib, an oral JAK inhibitor currently under FDA review for treating moderate to severe AA, presented in the same AAD session as Dr. Sinclair’s baricitinib data, Brett King, MD, PhD, associate professor of dermatology, Yale University, New Haven, Connecticut, described similar long-term response curves. At 24 weeks, the SALT ≤ 20 response was achieved in 34.9% of patients, but climbed to 62.8% with continuous therapy over 68 weeks.
Dr. Brett King
The difference between AA and most other inflammatory conditions treated with a JAK inhibitor is that “it takes time to treat,” Dr. King said.