US-based Isis Pharma has signed a drug development deal with Biogen Idec, relating to the development of medication to treat spinal muscular atrophy.

The drug, ISIS-SMNRx, was discovered by Isis and is currently being used in a Phase I clinical trial, which started in December 2011.

As per the terms of the deal, Isis will receive an initial payment of $29m, followed by milestone payments of up to $45m. Biogen will retain the option on the license for the drug up until the first successful Phase II/III trial which, if exercised, could see Isis receive up to $225m in licence regulatory milestone payments, taking the potential total up to $299m.

Isis will continue to play the lead role in the drugs development up until the completion of Phase II/III clinical trials, with Biogen providing advice on the design of trials and how to appease strict US Food and Drug Administration stipulations.

Spinal muscular atrophy is a genetic disease that causes progressive muscle degeneration and can lead to early death in severe cases.