Alnylam trumpets early promise for its Sanofi-partnered RNAi drug

Alnylam's ($ALNY) in-development RNAi treatment successfully staved off nerve damage related to a rare disease in an ongoing study, the biotech said, early but promising results as the company heads into Phase III with partner Sanofi ($SNY) in tow.

The drug, patisiran, is a treatment for transthyretin-mediated amyloidosis (ATTR) in patients with familial amyloidotic polyneuropathy, a rare genetic defect that can lead to deadly protein buildups, damaging nerves and tissues in the process. The latest results, from an ongoing Phase II trial, sent Alnylam's shares up about 15% on Monday morning, as investors bet that the treatment, co-signed by Sanofi's Genzyme unit, can make a difference for the roughly 10,000 people with the disease.

In Alnylam's open-label extension study, 19 ATTR patients taking patisiran reported stabilized nerve damage at 6 months, charting a roughly 1 point reduction in a measure called modified Neuropathy Impairment Score (mNIS+7). According to Alnylam, historical data would suggest a 7- to 10-point increase in mNIS+7 over the same period of time for ATTR sufferers with the same baseline levels.

Furthermore, the drug, which is designed to reduce serum levels of transthyretin (TTR), notched a sustained TTR knockdown above 80% for more than 9 months, the company said, and patisiran demonstrated itself safe and well-tolerated out to one year.

Alnylam Chief Medical Officer Akshay Vaishnaw

"We believe the potent, rapid and durable knockdown of TTR achieved by patisiran could be important since TTR protein reduction in patients with ATTR may have the potential to delay or even reverse disease progression with associated clinical benefit," Alnylam Chief Medical Officer Akshay Vaishnaw said in a statement.

Now the company is hoping to duplicate that response in Phase III, currently enrolling a late-stage trial with a primary endpoint of improving mNIS+7 and secondary goals including quality of life, mobility, hand strength and nutrition.

The drug is among of a slew of pipeline therapies Alnylam is working on alongside partner Genzyme. The Sanofi unit first stepped in on patisiran in 2012, paying $22.5 million up front for the Asian rights to the treatment with the promise of undisclosed milestones down the road. Then, earlier this year, Sanofi took a $700 million stake in Alnylam in an expression of faith in the biotech's RNAi potential, a deal that expanded Genzyme's share of patisiran to include every territory outside of Western Europe and North America.

- read the results