-- Clinically meaningful efficacy data on the primary endpoint was observed with a mean percent reduction in SALT score from baseline of 35.3% in the prespecified mITT analysis --

-- 40.0% of patients achieved SALT-20 response at Week 36 in the mITT analysis and 30.3% of patients achieved SALT-20 response at Week 36 in the ITT analysis of all enrolled patients --

-- Generally well-tolerated safety profile, consistent with prior studies, with no new safety signals --

-- Bempikibart demonstrated a favorable PK, PD and ADA profile --

-- Data supports further development of bempikibart in alopecia areata; Company intends to advance a registration-directed program in the first half of 2027 --

-- Q32 Bio to host conference call and webcast today, July 13, 2026, at 8:00 a.m. E.T., featuring alopecia areata key opinion leader (KOL) Arash Mostaghimi, MD, MPA, MPH --

Q32 Bio Inc. (Nasdaq: QTTB) ("Q32 Bio"), a clinical stage biotechnology company focused on developing innovative therapies for alopecia areata ("AA") and other autoimmune and inflammatory diseases, announced positive 36-week topline results from Part B of the SIGNAL-AA Phase 2a clinical trial evaluating bempikibart in patients with severe or very severe AA. Bempikibart is a fully human anti-IL-7Rα antibody designed to re-regulate adaptive immune function by blocking IL-7 and TSLP signaling.

"Today's Part B 36-week topline results mark a significant milestone for Q32 Bio, supporting our target efficacy and safety profile and providing compelling evidence reinforcing the therapeutic potential of bempikibart in alopecia areata," said Jodie Morrison, Chief Executive Officer of Q32 Bio. "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. These results support advancement in alopecia areata and strengthen our conviction in bempikibart's applicability across the broader autoimmune and inflammatory landscape. We are grateful to the patients, investigators, employees, and clinical development partners who helped make today's announcement possible."

"Alopecia areata is a complex, immune driven disease with limited therapeutic options. 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," said Arash Mostaghimi, MD, MPA, MPH, Associate Professor of Dermatology and Vice Chair of Clinical Trials and Innovation, Brigham and Women's Hospital, Harvard Medical School. "For patients and prescribers seeking an effective and safe alternative to JAK inhibitors, these findings are encouraging and merit further clinical advancement."

36-Week Topline Results from Part B of the SIGNAL-AA Program:

The Part B portion of the SIGNAL-AA program is an open-label clinical trial building upon the previously completed Part A, which established proof-of-concept of bempikibart in AA. In Part B, bempikibart is being evaluated in 33 patients with severe or very severe AA (baseline Severity of Alopecia Tool (SALT) scores of 50-100) with a maximum duration of current episode of four years. Enrollment amongst patients with prior exposure to JAK inhibitor therapy were allowed; amongst the 33 enrolled patients, 36.4% had previously been treated with oral JAK inhibitors. 

Total enrollment exceeded the initial target due to patient demand. In Part B, patients are treated with bempikibart for 36 weeks, with off-drug follow-up through Week 52 before optional enrollment in the open-label extension (OLE). Dosing includes an initial loading regimen of 200mg of bempikibart dosed weekly for four doses, followed by continued dosing of 200mg every-other-week over a 32-week period, for a total dosing period of 36 weeks. Across both regimens, bempikibart was administered subcutaneously (SC).

The prespecified primary efficacy analysis was evaluated on the basis of mean percentage change from baseline in SALT scores in the modified intent-to-treat (mITT) population. Additional prespecified efficacy analyses included the proportion of patients achieving various relative and absolute SALT improvements including SALT-20 (80% of scalp hair coverage), SALT₃₀ (30% improvement in SALT score from baseline), and SALT₅₀ (50% improvement in SALT score from baseline) responses at Week 36, with follow-up through Week 52.

Key topline efficacy results from Part B of SIGNAL-AA at Week 36 include:

• Mean percent reduction in SALT score from baseline of 35.3% in the mITT analysis.
• 40.0% (10/25) of patients in the mITT analysis and 30.3% (10/33) of patients in the intent-to-treat (ITT) analysis achieved a SALT-20 response. Achievement of a SALT-20 response was observed in patients with both severe and very severe disease.
• 44.0% (11/25) of patients in the mITT analysis and 33.3% (11/33) of patients in the ITT analysis achieved SALT₃₀ response.  
• 44.0% (11/25) of patients in the mITT and 33.3% (11/33) of patients in the ITT analysis achieved SALT₅₀ response.
• Early signs of durability in the off-drug period include maintenance or deepening of response in multiple patients including one who achieved complete hair growth (SALT = 0).

Bempikibart was observed to have a generally well-tolerated safety profile in SIGNAL-AA Part B, consistent with prior studies. No new safety signals were observed. There were no serious adverse events (SAEs) or Grade 3 or higher adverse events related to treatment. The most common treatment-emergent adverse event was injection site reaction (ISR) (36.3%) which were primarily singular events, with ISR incidence of 4% across all Part B dose administrations. All ISRs reported were mild and resolved with no intervention, with the majority resolving within a day.

Bempikibart demonstrated a favorable pharmacokinetic (PK), pharmacodynamic and anti-drug antibody (ADA) profile in Part B. PK data from Part B support the loading dose regimen had its intended effect, achieving steady state concentrations approximately 10 weeks earlier than in Part A. Negligible ADA was observed in Part B.

"These results provide important further evidence that our differentiated approach to targeting the biology underlying alopecia areata has the potential to translate into meaningful and durable clinical benefit for patients," said Shelia Violette, Ph.D., Co-Founder and Chief Scientific Officer of Q32 Bio. "Despite recent advances, many patients continue to seek treatment options that combine robust efficacy with improved safety and the potential for sustained disease control. These findings strengthen our confidence in the therapeutic potential of this mechanism and its continued advancement as a differentiated treatment option for patients living with alopecia areata and other autoimmune and inflammatory diseases."

The Part B off-drug follow-up period through Week 52 remains ongoing. Additionally, enrollment of eligible patients into the OLE remains ongoing. Q32 Bio intends to advance bempikibart into a registration-directed program in the first half of 2027 and plans to share full results from Part B at a future medical meeting.

Results from SIGNAL-AA Part A OLE:

Following the emergence of Part A data suggesting durability of response in the off-drug follow-up from SIGNAL-AA Part A and given patient demand for continued dosing, Q32 Bio announced the initiation of an OLE in April 2025. The Part A OLE has been completed. Eight patients enrolled in the Part A OLE, spanning responders, non-responders, and placebo patients from the Part A treatment portion. Patients were off-drug for various time periods ranging from 26 to 55 weeks prior to re-dosing. In the Part A OLE, bempikibart continued to demonstrate a generally well-tolerated safety profile with longer-term dosing and no new safety issues. Patients who maintained hair at entry to the OLE were observed to have durable or further hair growth. In totality, the Part A OLE dataset supports the importance of a maintenance dosing regimen.