Q32 Bio surges 60% as bempikibart hits alopecia endpoint in Phase 2

Q32 Bio Inc. reported a 35.3% mean reduction in SALT scores from baseline in the modified intent-to-treat analysis of its Phase 2a SIGNAL-AA trial, sending shares up as much as 60% on Monday. The 36-week data from Part B of the study evaluating bempikibart in 33 patients with severe or very severe alopecia areata showed 40% of patients in the mITT population achieved SALT-20, the currently accepted registration endpoint.

"These results mark a significant milestone for Q32 Bio, supporting our target efficacy and safety profile," Chief Executive Officer Jodie Morrison said on a conference call with analysts. "We believe the efficacy, durability and safety results have the potential to set the bar for biologics in the treatment of alopecia areata."

Bempikibart is a fully human anti-IL-7Rα antibody designed to block IL-7 and TSLP signaling, re-regulating adaptive immune function in T cell-mediated autoimmune diseases. The drug uses a loading regimen of 200 milligrams weekly for four weeks followed by 200 milligrams every other week for 32 weeks, administered subcutaneously. Among the 33 enrolled patients, 36.4% had prior exposure to oral JAK inhibitors — the only approved advanced therapy for the disease. The drug showed durability with no evidence of plateau at week 36, and one patient achieved complete hair regrowth, or a SALT score of zero, at week 44 during the off-drug follow-up period.

The safety profile showed no Grade 3 or higher adverse events, no serious adverse events and no discontinuations related to safety findings. Injection site reactions occurred in 36.3% of patients but were primarily single events, representing a 4% incidence across all dose administrations, and all resolved without intervention. The company said the loading regimen achieved its intended pharmacokinetic effect, with mean trough levels approximately threefold higher than in Part A and steady-state concentrations reached about 10 weeks earlier.

Alopecia areata affects about 700,000 people in the United States, according to Q32 Bio, and JAK inhibitors are currently the only approved advanced therapy. The company partnered with IQVIA on a survey of 50 dermatologists that identified improved safety, lack of black box warnings and better durability as key unmet needs. Q32 Bio forecasts a total U.S. market opportunity of at least $5 billion by 2037, compared with expected oral JAK inhibitor net sales of about $500 million in 2026.

Dr. Arash Mostaghimi, associate professor of dermatology at Harvard Medical School and vice chair of clinical trials and innovation at Brigham and Women's Hospital, said the data suggest bempikibart could provide "JAK-like efficacy" with a safety profile familiar to dermatologists who prescribe biologic therapies. "If these results bear out the way we're hoping in a Phase 3 trial, this should be the first-line treatment for patients with alopecia areata," Mostaghimi said.

Q32 Bio plans to hold an end-of-Phase 2 meeting with regulators by the end of 2026 and intends to initiate a registration-directed program in severe and very severe alopecia areata in the first half of 2027. The company is also enrolling eligible patients in an open-label extension and will use off-drug follow-up data through week 52 to define a potential chronic maintenance regimen, including options for monthly, bimonthly or quarterly dosing. The stock, which traded around $4.50 before the announcement, more than doubled on the news, though some analysts have flagged the rally as overdone given the small sample size and open-label study design.

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