Alnylam Pharmaceuticals has launched the Phase III APOLLO-B clinical trial to evaluate its RNAi therapeutic patisiran in adults suffering from transthyretin amyloidosis (ATTR amyloidosis) with cardiomyopathy.

Available under the brand name Onpattro, patisiran is designed to target and silence transthyretin (TTR) messenger RNA in order to block the generation of TTR in the liver and minimise its accumulation in the body.

The randomised, double-blind, placebo-controlled, multi-centre, global APOLLO-B trial will assess the drug’s safety and efficacy in around 300 participants. It will recruit patients with hereditary or wild-type amyloidosis.

A 0.3mg/kg dose of patisiran administered intravenously every three weeks will be compared to placebo over 24 months. Following 12 months of therapy, all participants will be given the drug in an open-label period.

The primary endpoint of the study is the change in the six-minute walk test (6-MWT) from baseline to 12 months.

APOLLO-B will also track the secondary endpoints of efficacy on quality of life measured with the Kansas City Cardiomyopathy Questionnaire Overall Summary and composite endpoints of mortality and hospitalisation.

Alnylam Pharmaceuticals TTR Program senior vice-president and general manager Eric Green said: “Based on the encouraging exploratory results on cardiac endpoints in the Phase III APOLLO study, we are investigating the potential for patisiran to treat cardiovascular-related manifestations of ATTR amyloidosis.

“The initiation of APOLLO-B represents a significant milestone in our commitment to explore the full potential of patisiran for patients living with all types of ATTR amyloidosis.”

The drug already has approvals in the US, Canada and Japan to treat hereditary ATTR amyloidosis (hATTR amyloidosis) with polyneuropathy in adults.

In addition, the European regulatory authority approved the drug for the treatment of hATTR amyloidosis in adults with stage I or II polyneuropathy.