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Q32 Bio's bempikibart cuts SALT score 35.3% in Part B of severe alopecia trial

The open-label, 33-patient readout hit its primary endpoint with no comparator arm, and Q32 Bio now plans a registration-directed program in H1 2027.

By AppliedXLJuly 13, 2026Trial NCT06018428

Executive Summary

Bempikibart met its prespecified primary efficacy measure in an open-label cohort of patients with severe alopecia areata, including patients who had already failed JAK inhibitor therapy.
Because the readout came from a single-arm design with no placebo or active comparator, the magnitude of benefit cannot yet be separated from the disease's natural course.
Bempikibart is the only antibody blocking IL-7 and TSLP signaling in clinical testing for alopecia areata, placing it outside the JAK inhibitor class that dominates the current treatment landscape.
Q32 Bio has said it will move toward a registration-directed program in the first half of 2027, which would be the first test of this result under a controlled design.

The readout

Q32 Bio Inc. announced on July 13, 2026 that bempikibart, a fully human antibody targeting IL-7Ralpha, met its Part B primary endpoint in the SIGNAL-AA Phase 2a trial, with a mean percent reduction in SALT score from baseline of 35.3% at Week 36 in the prespecified modified intent-to-treat (mITT) analysis. SALT scores measure the percentage of scalp hair loss, and the trial enrolled patients with baseline scores of 50 to 100, corresponding to severe or very severe disease. Response-rate secondary measures showed 40.0% of mITT patients and 30.3% of all enrolled (ITT) patients achieved a SALT-20 response, a threshold reduction in scalp hair loss, at Week 36, while 44.0% of mITT patients reached both the SALT30 and SALT50 response bars. Q32 Bio chief executive Jodie Morrison called the results support for the company's "target efficacy and safety profile" and said the data reinforce bempikibart's potential in alopecia areata. Q32

Probability of Success

Endpoint Met97%

Completes90%

Clinical Significance24%

Regulatory54%

How it was done

Part B is an open-label trial, meaning all participants know they are receiving active drug and there is no comparator arm, that enrolled 33 patients with severe or very severe alopecia areata and a current disease episode lasting up to four years. Patients with prior oral JAK inhibitor treatment were eligible, and 36.4% of the 33 enrolled had that treatment history. Dosing consisted of a loading regimen of 200 mg weekly for four doses followed by 200 mg every other week through week 36, with off-drug follow-up continuing through Week 52 before optional enrollment in an open-label extension. Total enrollment of 33 patients exceeded the trial's original Part B target due to patient demand, the company said. The trial's registered enrollment target across the full SIGNAL-AA program stands at 75 patients, with a primary completion date of June 1, 2026. Q32+1

Safety and durability signal

Q32 Bio described the safety profile as generally well tolerated and consistent with prior studies, with no new safety signals, and reported favorable pharmacokinetic, pharmacodynamic, and anti-drug antibody findings. Off-drug follow-up through Week 52 is ongoing, and the company said it plans to share full Part B results, beyond the topline figures disclosed July 13, at a future medical meeting. That follow-up period will test whether the Week 36 response holds after treatment stops, a question the topline disclosure does not yet answer. Q32

The competitive frame

No other trial in clinical testing shares bempikibart's IL-7Ralpha target or its IL-7/TSLP signaling-blocker mechanism class in alopecia areata; the closest active programs in the indication, including Pfizer's ritlecitinib, work through JAK inhibition, a mechanistically distinct pathway that dominates current treatment options. Q32 Bio's own framing leans on this distinction: Harvard Medical School's Arash Mostaghimi, who reviewed the data, said the combined efficacy and safety profile in a population that included JAK-experienced patients points to bempikibart as a potential alternative to JAK inhibitors. With no validated IL-7/TSLP-directed precedent to benchmark against in this indication, the bar for the next disclosure is whether the Week 36 effect persists through the Week 52 off-drug follow-up and reproduces under the controlled design of a registration-directed program. Q32

What comes next

Q32 Bio said it intends to advance a registration-directed program in the first half of 2027, which would be the first test of bempikibart's effect under a design that includes a comparator arm. The FDA granted bempikibart Fast Track designation for alopecia areata in 2025, a designation that allows more frequent FDA interaction during development but does not itself signal an approval outcome. The trial's protocol history shows two changes to its primary completion date and one enrollment increase from 40 to 75 patients in April 2025, changes the trial's own operational model characterizes as within the routine band for a study of this design. Q32

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