Isis Pharmaceuticals has initiated a phase I study of ISIS-SMNRx in patients with spinal muscular atrophy (SMA).  SMA is a severe motor-neuron disease that is the leading genetic cause of infant mortality. Isis is developing ISIS-SMNRx as a potential treatment for all types of SMA.

The phase I study of ISIS-SMNRx is a single-dose, dose-escalation study designed to assess the safety, tolerability and pharmacokinetic profile of the drug in children with SMA between the ages of 2-14 who are medically stable.  In this study, ISIS-SMNRx will be administered intrathecally as a single injection directly into the spinal fluid. Intrathecal administration of an antisense drug, ISIS-SOD1Rx, has been shown to be safe and well tolerated in an ongoing phase I study in patients with amyotrophic lateral sclerosis.