Alnylam Pharmaceuticals, an RNAi therapeutics company, announced that upon the recommendation of the ENDEAVOUR phase III study Data Monitoring Committee (DMC) to suspend dosing, the company has decided to discontinue development of revusiran, an investigational RNA interference (RNAi) therapeutic that was being developed for the treatment of hereditary ATTR amyloidosis with cardiomyopathy (hATTR-CM). This decision was made yesterday evening and has been communicated to investigators, study sites, and regulatory authorities.

Following recent reports in the phase II OLE study of new onset or worsening peripheral neuropathy, the ENDEAVOUR DMC assembled yesterday at the company's request to review these reports and ENDEAVOUR data on an unblinded basis. The DMC did not find conclusive evidence for a drug-related neuropathy signal in the ENDEAVOUR trial, but informed the Company that the benefit-risk profile for revusiran no longer supported continued dosing. The Company subsequently reviewed unblinded ENDEAVOUR data which revealed an imbalance of mortality in the revusiran arm as compared to placebo.

"Patient safety comes first. We have stopped all dosing and are actively monitoring patients across revusiran studies to ensure their safety. We will also continue to evaluate ENDEAVOUR data to understand the potential cause of these findings," said John Maraganore, Ph.D., chief executive officer at Alnylam. "While this outcome is disappointing given the lack of available treatment options for patients suffering from this devastating disease, we remain committed to serving the needs of the ATTR amyloidosis community. We would like to thank patients, caregivers, investigators and study staff who have been so supportive of the revusiran program."

The decision to discontinue development of revusiran does not affect patisiran, which is currently in phase III development for the treatment of hATTR amyloidosis with polyneuropathy (hATTR-PN), or any other Alnylam investigational RNAi therapeutic program in development.

Based on a current assessment of the safety data across the Company's other programs, which include the ALN-PCSsc program partnered with The Medicines Company, there is no evidence of a drug-related neuropathy signal in over 800 treated subjects and patients with exposure of up to 34 months. This includes patisiran, which utilizes a lipid nanoparticle delivery formulation, and the seven other clinical programs in Alnylam's pipeline, which all use Enhanced Stabilization Chemistry (ESC) GalNAc delivery technology. ESC-GalNAc conjugates enable dose and exposure levels that are 12-30 times lower than revusiran, which uses Standard Template Chemistry (STC) GalNAc delivery technology. The company reaffirms its "Alnylam 2020" guidance and remains committed to the advancement of these investigational RNAi therapeutics for treatment of diseases with high unmet medical need.