ZURICH (Reuters) - Roche Holding AG’s emicizumab drug for treating haemophilia A showed it worked in a phase III study, the Swiss drugmaker said on Thursday.

The logo of Swiss pharmaceutical company Roche is seen outside their headquarters in Basel, January 30, 2014. REUTERS/Ruben Sprich/File Photo

Roche is hoping to win a slice of the $11 billion-a-year haemophilia drug market with the drug, also known as ACE910, which represents a threat to more traditional treatments from Novo Nordisk and Shire.

Roche’s drug is being closely watched because it could change the way the disease is treated.

“The study showed a statistically significant reduction in the number of bleeds over time in people treated with emicizumab prophylaxis compared to those receiving no prophylactic treatment,” Roche said in a statement.

The trial also met all secondary endpoints, including reducing the number of bleeds over time with emicizumab prophylaxis treatment in an intra-patient comparison in people who had received prior bypassing agent prophylaxis treatment.

The most common adverse events were injection site reactions, consistent with prior studies, it added.

Prospects for the potential blockbuster product were clouded when news emerged last month that four patients suffered serious adverse events in a clinical trial of the drug.

The problems related to thrombosis, or blood clots, with two thromboembolic events and two cases of thrombotic microangiopathy (TMA) in patients who were being treated for breakthrough bleeding in a trial of ACE910.

Roche said at the time that additional monitoring had been instigated and the cases involved patients with breakthrough bleeding who were treated using one of two so-called bypassing agents that carried thrombosis warnings.

“Neither thromboembolic event required anti-coagulation therapy and one patient restarted emicizumab. Both cases of TMA have completely resolved, and one patient restarted emicizumab,” Roche said on Thursday.

Haemophilia patients, whose blood does not clot properly, need life-saving infusions of clotting factors, but development of inhibitors in many of those being treated can interfere with efforts to control their bleeding.