Q32 Bio announced positive 36-week topline results from Part B of its SIGNAL-AA Phase 2a trial of bempikibart in severe or very severe alopecia areata on Monday, a disclosure that propelled shares $9.30 higher — an 83% gain — to a closing price of $20.51.
The trial's primary efficacy endpoint was met, with the prespecified modified intent-to-treat population posting a mean 35.3% drop in Severity of Alopecia Tool scores relative to baseline by the 36-week mark, the company said. Within that population, 40% of patients hit the SALT-20 threshold — defined as 80% or greater scalp hair coverage — and 44% cleared both the SALT30 and SALT50 bars. Across the full intent-to-treat group of all 33 enrolled patients, SALT-20 response was recorded in 30.3%.
Eligibility required baseline SALT scores of 50 to 100, and 36.4% of participants — more than one in three — had a prior history of oral JAK inhibitor use. The dosing regimen began with four consecutive weekly doses of 200mg administered subcutaneously, then transitioned to 200mg every other week through the remainder of the 32-week treatment period.
Follow-up data collected after dosing concluded offered early signals of lasting benefit, the company said, as a number of patients held onto or continued to gain hair regrowth once off therapy — among them one individual who reached full hair regrowth.
Bempikibart, which works as a fully human anti-IL-7Rα antibody to interrupt both IL-7 and TSLP signaling, also demonstrated a favorable safety profile. The safety data showed no treatment-related serious adverse events and no Grade 3 or higher adverse events. Injection-site reactions were the most frequently reported treatment-emergent adverse event, arising in 36.3% of patients; all were characterized as mild and cleared on their own without requiring intervention.
"We believe these findings highlight the opportunity to deliver a differentiated, targeted treatment option for patients who remain in need of an effective, safe, and more durable alternative to JAK inhibitors," Q32 Bio Chief Executive Officer Jodie Morrison said in a statement.
Arash Mostaghimi, MD, MPA, MPH, associate professor of dermatology and vice chair of clinical trials and innovation at Brigham and Women's Hospital, Harvard Medical School, cited the inclusion of JAK inhibitor-experienced patients as significant. "The robust efficacy data in a population that includes JAK inhibitor-experienced patients, combined with a differentiated safety profile, demonstrate the potential for bempikibart to be a first-line treatment for alopecia areata," he said in a statement.
Q32 Bio said it is targeting the first half of 2027 to initiate a registration-directed program for bempikibart, and it expects to share the full Part B dataset at an upcoming medical conference. About 700,000 people in the United States live with alopecia areata, according to the company, which cited the National Alopecia Areata Foundation.