Shares of Q32 Bio Inc. (QTTB) are soaring Monday after the company released positive 36-week results from Part B of its Phase 2a SIGNAL-AA trial for bempikibart, a treatment for severe alopecia areata. The data showed the antibody produced meaningful hair regrowth while maintaining a safety profile that looks pretty clean.

Alopecia areata is an autoimmune disease where the immune system mistakenly attacks hair follicles, causing hair to fall out in round patches. For patients with severe or very severe forms, treatment options are limited. That's why these results matter.

The company said the data support moving bempikibart into a registration-directed program during the first half of 2027. That's a big step toward potentially getting the drug approved.

Hair Regrowth Across Multiple Measures

Part B enrolled 33 patients with baseline Severity of Alopecia Tool (SALT) scores between 50 and 100, including some who had previously been treated with oral JAK inhibitors. The primary endpoint looked at the mean percentage change in SALT scores from baseline in the modified intent-to-treat population.

At Week 36, patients achieved a mean 35.3% reduction in SALT scores. Among modified intent-to-treat patients, 40% achieved a SALT-20 response (meaning at least 20% improvement), while 44% reached both SALT30 and SALT50 thresholds. In the broader intent-to-treat population, 30.3% hit SALT-20, with 33.3% reaching both SALT30 and SALT50.

Importantly, responses were seen in patients with both severe and very severe disease. Early follow-up data also suggested durability, with several patients maintaining or improving hair regrowth after treatment ended. One patient even achieved complete hair regrowth.

Safety Profile Stays Clean

Q32 Bio said bempikibart continued to show a generally well-tolerated safety profile consistent with earlier studies. No treatment-related serious adverse events or Grade 3 or higher adverse events were reported. That's a big deal for a drug targeting an autoimmune condition.

The study also showed favorable pharmacokinetic, pharmacodynamic, and anti-drug antibody findings. The loading-dose regimen achieved steady-state drug concentrations about 10 weeks earlier than in Part A, while anti-drug antibody levels remained negligible.

Extension Study Supports Maintenance Dosing

Q32 Bio also reported results from the completed open-label extension of SIGNAL-AA Part A. Eight patients—including prior responders, non-responders, and placebo recipients—re-entered treatment after being off therapy for 26 to 55 weeks.

Patients who had maintained hair growth before re-treatment generally preserved or further improved their results during the extension. The safety profile remained consistent with no new concerns.

As of Monday's premarket trading, Q32 Bio shares were up 71.90% at $19.27, according to market data.