Biotechnology company Hemab Therapeutics has launched a pivotal Phase 3 clinical trial of its experimental drug sutacimig, targeting a rare inherited bleeding disorder that currently has no approved preventive treatment.

 

The trial, named SOLARA, will evaluate whether once-weekly injections of sutacimig can prevent bleeding episodes in people living with Glanzmann thrombasthenia (GT), a serious platelet function disorder that can cause unpredictable and sometimes severe bleeding.

 

Hemab said the trial will enrol approximately 75 participants aged 12 to 70 across clinical sites in the United States and other countries. The first participants have been consented and are expected to enter the initial run-in phase in the fourth quarter of 2026.

 

The launch marks the first pivotal Phase 3 trial for sutacimig (HMB-001), an investigational bispecific antibody designed to compensate for platelet dysfunction and help form stable blood-clotting plugs at the site of bleeding.

 

“Starting SOLARA, our first pivotal Phase 3 trial, is a transformative moment for the sutacimig program and for Hemab,” said Benny Sørensen, Chief Executive Officer of Hemab Therapeutics.

 

“People living with Glanzmann thrombasthenia face unpredictable, and sometimes severe, bleeding yet have no approved prophylactic option to prevent it. Sutacimig has the potential to offer new hope as a once-weekly preventive therapy. We are grateful to the patients, families, investigators and regulators whose engagement shaped this trial.”

 

The Phase 3 programme builds on data from the Phase 2 study presented at the International Society on Thrombosis and Haemostasis (ISTH) 2026 Congress.

 

In the long-term extension study, 34 participants received treatment for a median of 6.9 months, with exposure extending up to 15.9 months.

 

The results showed that treated bleeding rates declined in 92% of participants who had experienced bleeding during the run-in period. Among participants who reported high-intensity bleeding events in the 12 months before receiving sutacimig, the mean annualized rate of high-intensity treated bleeding events fell by 62% during treatment and the extension period.

 

Most adverse events were mild or moderate, with no treatment-related Grade 3 or higher events reported.

 

However, three participants experienced Grade 2 thromboembolic events. These cases occurred among participants in dose cohorts associated with higher drug exposure and/or multiple concurrent risk factors. All three were managed with routine anticoagulation and had resolved or were resolving at the data cut-off.

 

Hemab said the dose and treatment regimen selected for SOLARA were designed to maximise bleeding reduction while avoiding the high peak drug exposures associated with those events.

 

“SOLARA is the first pivotal trial of a subcutaneous prophylactic treatment in Glanzmann thrombasthenia,” said Kate Madigan, Chief Medical Officer of Hemab.

 

“We designed SOLARA with these patients in mind, with the hope that prevention can reduce the bleeds that interrupt work, school and daily life and improve quality of life. This is a significant moment for a community that has long managed bleeding after it happens.”

 

SOLARA is an open-label, single-arm, multicentre Phase 3 study involving approximately 75 patients with GT. Eligible participants must have experienced at least four treated bleeding events in the 12 months before screening.

 

The study will run in two consecutive stages, allowing each participant to serve as their own control.

 

During the initial 24-week run-in period, participants will continue receiving their existing on-demand standard of care without sutacimig. Researchers will prospectively record their treated bleeding events.

 

This will be followed by a 48-week treatment period, during which participants will receive sutacimig at a dose of 0.2 mg/kg through a once-weekly subcutaneous injection.

 

The primary endpoint will measure the annualized treated bleed rate (ATBR) during sutacimig prophylaxis against the rate recorded during the run-in period.

 

Secondary endpoints include reductions in high-intensity bleeding, the number of bleeding days, bleeding rates by type and cause, and the proportion of patients experiencing a reduction in treated bleeding events. Researchers will also assess safety, tolerability, immunogenicity and pharmacokinetics.

 

Adolescent enrolment will be subject to approval by the study's data safety monitoring committee.

 

Participants completing the 48-week treatment period will have the opportunity to continue receiving sutacimig through a separate open-label extension study.

 

The trial is being conducted under Hemab's active Investigational New Drug (IND) application.

 

For patients with Glanzmann thrombasthenia, the study represents an important step towards a potential preventive treatment rather than relying solely on managing bleeding after it occurs. However, sutacimig remains investigational, and its safety and effectiveness will need to be established through the Phase 3 trial.