The FDA has granted Roche a breakthrough drug designation for its hemophilia A treatment ACE910 among patients with factor VIII inhibitors.

Investigators for Roche earlier this year had touted long-term follow-up results from ACE910's phase I study, displaying its success in controlling needing episodes among hemophilia patients with or without factor VIII (FVIII) inhibitors. Roughly one in four patients develops the inhibitors, according to the pharmaceutical, which makes the disease especially hard to control.

In a prepared statement, Roche Chief Medical Officer Sandra Horning noted, “People with hemophilia A may require regular and frequent infusions of replacement clotting factor to reduce the risk of dangerous bleeding, and they can develop inhibitors that make replacement ineffective.”

The antibody—an anti-factor IXa/X bi-specific that mimics the function of FVIII, even in the presence of FVIII inhibitors—originally was developed a Chugai, a Roche subsidiary

The FDA has given out dozens of breakthrough drug designations over the past couple of years, pledging to make regulators more readily available to speed through the development process. In particular, the program has helped to alter the structure and timeline of cancer drugs. Roche also has laid out plans to start a phase III study for that treatment among patients with inhibitors before the end of the year, with another late stage study for patients without inhibitors launching next year.

Roche COO Daniel O’Day repeatedly has cited ACE910 as a top prospect for his company, after its lead effort on the PD-L1 checkpoint inhibitor atezolizumab.