Data from the APOLLO-B phase 3 open-label extension study of patisiran suggest a favorable safety profile of the experimental RNAi medication as well as improvements across measures of functional capacity, health status, quality of life, and cardiac stress and injury in people with hereditary transthyretin amyloidosis (hATTR) and cardiomyopathy, Alnylam Pharmaceuticals announced.

The company presented the results at the Annual Congress of the Heart Failure Association of the European Society of Cardiology. The 18-month data have also been submitted to the US Food and Drug Administration (FDA) as an amendment to the supplemental New Drug Application for patisiran for the treatment of the cardiomyopathy of hATTR.

“The results demonstrate that serum transthyretin reduction with an RNAi therapeutic has the potential to provide sustained clinical benefit through 18 months of treatment. These data, in conjunction with the observed decline in placebo-treated patients during the double-blind period, reinforce the importance of early treatment initiation in hATTR amyloidosis,” said Rena N. Denoncourt, vice president, TTR franchise lead.

The analysis confirms the benefits of patisiran established during the double-blind period, in terms of improved functional capacity, health status, and quality of life as measured in part by the 6-minute walk test and the Kansas City cardiomyopathy questionnaire overall summary.

Read more about hATTR experimental therapies

Moreover, the relative stability of N-terminal pro-B-type natriuretic peptide and troponin I levels, which indicate cardiac stress and injury, was maintained through 18 months of patisiran treatment. Patients who received placebo in the double-blind period and were transferred to patisiran during the open-label extension period showed signs of slower disease progression or relative stabilization across these same endpoints at month 18.

The safety profile of the experimental drug was favorable and consistent with the 12-month double-blind period. The study participants mostly experienced mild or moderately severe adverse events and the most common treatment-related adverse event was infusion-related reactions. There were no new safety concerns.

Previously, the pharmaceutical company announced that APOLLO-B achieved its primary endpoint and met its first secondary endpoint during the 12-month double-blind period.


Alnylam presents 18-month results from the APOLLO-B phase 3 study of patisiran in patients with ATTR amyloidosis with cardiomyopathy. News release. Alnylam Pharmaceuticals, Inc.; May 20, 2023.