Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today the publication in the Proceedings of the National Academy of Sciences (PNAS) of pre-clinical results with RNAi therapeutics targeting aminolevulinic acid synthase-1 (ALAS-1) for the treatment of hepatic porphyrias, including acute intermittent porphyria (AIP). In the paper, titled “ RNAi-mediated silencing of hepatic Alas1 effectively prevents and treats the induced acute attacks in acute intermittent porphyria mice,” Alnylam scientists and collaborators at the Icahn School of Medicine at Mount Sinai in New York City documented results from pre-clinical models of the human disease showing that RNAi therapeutics targeting ALAS-1 can completely block the abnormal production of toxic intermediates of the heme biosynthesis pathway that cause the symptoms and disease pathology of AIP. This new paper provides proof of concept for an RNAi therapeutic for the treatment of AIP.
“Our data in a mouse model of AIP, now published in PNAS, demonstrate that RNAi therapeutics targeting ALAS-1 can achieve potent, rapid, and durable suppression of the toxic heme biosynthesis intermediates that cause the symptoms and disease pathology of AIP. As such, these findings provide key pre-clinical proof-of-concept data for our ALN-AS1 program. We believe ALN-AS1 has the potential to be a transformative therapy for patients with hepatic porphyrias including AIP, an ultra-rare genetic disease with enormous unmet medical need,” said Rachel Meyers, Ph.D., Vice President, Research and RNAi Lead Development of Alnylam. “We are currently advancing our Development Candidate for ALN-AS1, which employs our Enhanced Stabilization Chemistry-GalNAc-conjugate technology. This technology enables subcutaneous dosing with improved potency and durability, and a wide therapeutic index, and is now clinically validated based on results from our hemophilia program. We are on track to file an Investigational New Drug application for ALN-AS1 in late 2014 or early 2015, and look forward to advancing this investigational medicine to patients.”
The acute hepatic porphyrias, including AIP, are ultra-rare orphan diseases caused by loss-of-function mutations in enzymes involved in heme biosynthesis, leading to accumulation of toxic heme intermediate precursors. In the case of AIP, there are approximately 5,000 patients in the U.S. and Europe that suffer acute, life-threatening porphyria attacks every year; there are approximately 500 patients afflicted with recurrent debilitating attacks, often occurring once per month. Treatment options for AIP patients suffering from an attack are limited, and include the use of heme preparations that show limited efficacy and are associated with a number of complications including phlebitis, iron overload, and infections related to the need for central venous access in some patients. Currently, there are no approved drugs available to prevent attacks from occurring. Alnylam’s approach is to knock down ALAS-1, an enzyme upstream of porphobilinogen deaminase (PBGD), the defective gene in AIP. RNAi-mediated silencing of hepatocyte ALAS-1 could reduce the abnormal production of the toxic heme intermediates, specifically aminolevulinic acid (ALA) and porphobilinogen (PBG), which mediate the symptoms and disease pathology in AIP patients as well as in some of the other acute hepatic porphyrias. Alnylam believes that a subcutaneously administered RNAi therapeutic targeting ALAS-1 has the potential to be used as a prophylactic approach to prevent attacks, and also as a therapy for acute attacks.