FDA grants breakthrough designation to Achillion’s PNH drug

The US Food and Drug Administration (FDA) has granted Achillion Pharmaceuticals breakthrough designation for danicopan (ACH-4471) for patients with paroxysmal nocturnal haemoglobinuria (PNH). Achillion is studying danicopan combined with a C5 monoclonal antibody in a Phase II trial of patients with a suboptimal response to C5 inhibitors alone, the standard of care for the condition. The FDA’s designation is based upon positive efficacy and safety data from this ongoing study. PNH is a rare, genetic blood disease caused by somatic mutation, which results in the absence of key receptors, CD55 and CD59, on the surface of red blood cells. These are recognised by the alternative pathway (AP) as foreign and destroyed in the blood stream and in the liver. CD5 inhibitors targets intravascular haemolysis where these red blood cells are attacked in the blood stream, but, according to Achillion, 75% of those treated with C5 alone remain anaemic during treatment with a third needing blood transfusions.