Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today that it has initiated dosing in its Phase I clinical trial with ALN-TTRsc, an RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR). ATTR is caused by mutations in the TTR gene which cause abnormal amyloid protein deposits to accumulate in various tissues including peripheral nerves and heart, resulting in neuropathy and/or cardiomyopathy. ATTR represents a major unmet medical need with significant morbidity and mortality; familial amyloidotic polyneuropathy (FAP) affects approximately 10,000 people worldwide and familial amyloidotic cardiomyopathy (FAC) affects at least 40,000 people worldwide. ALN-TTRsc, which is being developed for the treatment of FAC, is a subcutaneously administered RNAi therapeutic that comprises an siRNA conjugated to a GalNAc ligand that enables receptor-mediated delivery to the liver. ALN-TTRsc is the first GalNAc-siRNA and the first subcutaneously delivered, systemic RNAi therapeutic to enter clinical development stages. “RNAi therapeutics hold great promise for the treatment of ATTR since they have demonstrated rapid, potent, and durable knockdown of TTR, the disease-causing protein. We are advancing what we believe to be the industry leading effort in ATTR; this includes ALN-TTRsc for the treatment of FAC and ALN-TTR02 for the treatment of FAP which is currently enrolling patients in a Phase II trial,” said Akshay Vaishnaw, M.D., Ph.D., Executive Vice President and Chief Medical Officer of Alnylam. “The start of this Phase I trial with ALN-TTRsc represents the first for an RNAi therapeutic that utilizes our proprietary GalNAc conjugate delivery platform. It also marks the first subcutaneously delivered, systemic RNAi therapeutic for the industry. We look forward to the continued advancement of ALN-TTRsc for the treatment of FAC.” The Phase I trial of ALN-TTRsc is being conducted in the U.K. as a randomized, double-blind, placebo-controlled, single- and multi-dose, dose-escalation study, enrolling up to 40 healthy volunteer subjects. The primary objective of the study is to evaluate the safety and tolerability of single and multiple doses of subcutaneously administered ALN-TTRsc. Secondary objectives include assessment of clinical activity of the drug as measured by serum TTR levels. Alnylam expects to present data from this trial in mid-2013. Upon completion of the Phase I trial, the company plans to start a Phase II clinical study of ALN-TTRsc in FAC patients by the end of 2013 and, assuming positive results, expects to start a pivotal trial for ALN-TTRsc in FAC patients in 2014.