Q32 Bio Inc. (Nasdaq: QTTB) presented results from Part B of its SIGNAL-AA Phase 2a clinical trial evaluating bempikibart in patients with severe or very severe alopecia areata at the European Academy of Dermatology and Venereology Congress 2026 on Sept. 30.

The open-label trial enrolled 33 patients with baseline Severity of Alopecia Tool (SALT) scores of 50–100 and a maximum current episode duration of four years. Of those enrolled, 36.4% had prior exposure to oral JAK inhibitors. Patients received bempikibart 200mg weekly for four loading doses, followed by 200mg every other week for 32 weeks, then a 16-week off-drug follow-up period.

At Week 36, the mean percent reduction in SALT score from baseline was 35.3% in the modified intent-to-treat (mITT) population. In the mITT analysis, 40% of patients achieved a SALT-20 response, while 44% achieved both SALT-30 and SALT-50 responses. Among prior JAK inhibitor responders, the mean SALT score reduction was 48.3%, compared with 4.8% in prior non-responders and 44.1% in JAK-naive patients.

During the 16-week off-drug period, 18 patients were followed. Among the 12 who had shown hair growth by Week 36, 100% maintained their response and 42% showed deepening of response. At the 16-week off-drug time point, 44% of patients achieved SALT-20, 61% achieved SALT-30, and 50% achieved SALT-50.

No serious adverse events or Grade 3 or higher treatment-related adverse events were reported. The most common treatment-emergent adverse event was injection site reaction, occurring in 36.3% of patients, with an incidence rate of 4% across all dose administrations. All injection site reactions were mild and resolved without intervention.

According to the company's press release, Q32 Bio plans to advance bempikibart into a registration-directed program for severe or very severe alopecia areata in the first half of 2027, subject to regulatory discussions planned for the second half of 2026. The company also anticipates data from the Part B open-label extension in the second half of 2027.