* Trial “big win” for field of RNAi drugs - Leerink
* $1 bln peak sales expected for patisiran in 2023 - Credit Suisse
* Alnylam shares hit more than 2-yr high (Updates share moves)
By Tamara Mathias
Sept 20 (Reuters) - Alnylam Pharmaceuticals Inc’s RNAi-based drug that targets a rare genetic disease met the main goal of a key study, in a breakthrough for the new class of medicines that works by blocking disease-causing proteins.
The company’s shares soared as much as 55.8 percent to a more than two-year high of $116.93 in afternoon trading on Wednesday.
Alnylam’s patisiran belongs to a class of drugs that uses the Nobel-prize winning RNA interference (RNAi) mechanism to manipulate ribonucleic acid, which interferes with or “silences” targeted genes, and stops the formation of proteins that can cause diseases.
Patisiran was being evaluated in a late-stage study against a placebo for the treatment of patients with hereditary ATTR (hATTR) amyloidosis with polyneuropathy.
About 50,000 people worldwide are affected by hATTR amyloidosis, Alnylam said.
Polyneuropathy, a symptom of the disease, is the simultaneous malfunction of many peripheral nerves in the body resulting in tingling, numbness and kidney dysfunction.
Leerink analyst Paul Matteis said the results were a “big win” for Alnylam and RNAi as they validated the platform, noting that the safety data looked clean and sufficient to quell any concerns.
The drugmaker said it would file a marketing application for patisiran in late 2017 and expects to launch the drug by mid-2018.
Alnylam, which has been weighed down in the past by drug safety concerns, said it plans to initiate a program targeting cardiomyopathy - another symptom of the disease - alongside polyneuropathy in a late-stage study next year.
Analysts also noted that additional cardiac data could help increase the potential eligible population for the drug.
In early September, Alnylam stopped giving doses of its fitusiran drug for a rare bleeding disorder to patients enrolled in clinical studies after the death of a patient.
Last year, Alnylam stopped developing an RNAi drug to treat hereditary amyloidosis with cardiomyopathy, due to patient fatalities.
Credit Suisse analysts said patisiran’s data seemed to have “solid safety” compared with Ionis Pharmaceuticals Inc’s rival drug, which cleared a key study but raised safety concerns.
The brokerage estimates peak sales of $1 billion in 2023 for patisiran.
Alnylam’s data sent Ionis’ shares down 9 percent to $53.74, while shares of Medicines Co, which signed an RNAi licensing deal with Alnylam, were up 5.7 percent at $35.80.
Alnylam also said it would advance patisiran in the United States, Canada and Western Europe, while French drugmaker Sanofi would commercialize it in the rest of the world. (Reporting by Tamara Mathias in Bengaluru; additinal reporting by Akankshita Mukhopadhyay; Editing by Martina D‘Couto)