Note: This is an edited form of a press release from Genentech. To read the original release in its entirety, click here.

Genentech announced on Friday, September 4, 2015, that the U.S. Food and Drug Administration (FDA) has granted breakthrough therapy designation to ACE910 (RG6013, RO5534262) for the prophylactic treatment of people who are 12 years or older with hemophilia A with factor VIII inhibitors. Hemophilia A, a rare genetic disorder, occurs when an essential blood clotting protein called factor VIII is either not present in sufficient amounts or is defective. People with severe hemophilia A can be susceptible to uncontrolled or difficult to control bleeding including internal bleeding, especially into the joints, which can lead to the need for joint replacements.
Breakthrough therapy designation is designed to accelerate the development and review of medicines that demonstrate early clinical evidence of a substantial improvement over current treatment options for serious diseases.
In a Phase I study, ACE910 showed promising results as a prophylactic treatment administered as a weekly subcutaneous injection in people with severe hemophilia A with and without inhibitors to factor VIII. The development of inhibitors is a serious complication of hemophilia A treatment regardless of disease severity, making it difficult, if not impossible, to achieve a level of factor VIII sufficient to control bleeding with traditional replacement therapies. Management of bleeding in people with hemophilia A who have inhibitors to factor VIII is a major challenge, and there remains a need for additional treatment options for these patients.
“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,” said Sandra Horning, M.D., chief medical officer and head of Global Product Development.
Genentech is preparing to initiate a Phase III trial of ACE910 in patients with hemophilia A with factor VIII inhibitors by the end of 2015 and a Phase III trial in patients without inhibitors in 2016. Additionally, a trial in pediatric patients with hemophilia A is planned to commence in 2016.
The breakthrough therapy designation for ACE910 was granted based on results of a Phase I study of ACE910 in people with severe hemophilia A presented at the annual meeting of the American Society of Hematology (ASH) in 2014, and the Phase I/II extension study of the same patients presented at the annual meeting of the International Society of Thrombosis and Haemostasis (ISTH) in 2015.

About ACE910

ACE910 is an investigational humanized bispecific monoclonal antibody engineered to simultaneously bind factors IXa and X. ACE910 thereby mimics the cofactor function of factor VIII and is designed to promote blood coagulation in hemophilia A patients, regardless of whether they have developed inhibitors to factor VIII. ACE910 is administered subcutaneously once weekly, and as it is distinct in structure from factor VIII, it is not expected to lead to the formation of inhibitors against factor VIII. The development program of ACE910 is assessing its potential to help overcome some of the clinical challenges faced in hemophilia care, such as the development of factor VIII inhibitors and the need for frequent venous access. ACE910 was created by Chugai Pharmaceutical Co., Ltd. and is being co-developed by Genentech.