Originally published on September 19, 2013.

Isis Pharmaceuticals, Inc. announced today that follow-up preliminary data from a single dose, open-label Phase 1 study of ISIS-SMNRx in children with spinal muscular atrophy (SMA), show that most SMA children receiving the two highest doses of the drug (6 mg and 9 mg) continued to show improvements in muscle function tests up to 14 months after a single injection of the drug.  The Phase 1 data, including these preliminary follow-on data, will be presented at the International Congress of the World Muscle Society by Dr. Kathy Swoboda on Oct. 3, 2013. SMA is a severe and rare genetic neuromuscular disease characterized by muscle atrophy and weakness and is the most common genetic cause of infant mortality. ISIS-SMNRx is an antisense drug designed to treat all types of SMA.

The preliminary data reported today is from a follow-up analysis of 24 children with SMA who participated in a Phase 1 single-dose, open-label study of ISIS-SMNRx. Analysis of motor function was performed in these children nine to 14 months following a single dose of ISIS-SMNRx using the Hammersmith Functional Motor Scale-Expanded (HFMSE). The improvements in HFSME scores were dose dependent with the largest improvements observed in children in the highest dose cohort (9 mg, mean = 5.75). Most children in the 9 mg dose cohort showed continuing improvements during follow up, with no children declining.

Program Update

“We are pleased with the progress we are making on ISIS-SMNRx. Although there was no placebo group, the continuing improvement for up to a year after a single dose observed in this study is encouraging, particularly when considered within the context of the dose response,” said B. Lynne Parshall, chief operating officer at Isis. “Our ongoing Phase 2 program is proceeding well. The 6 mg dose group in our Phase 2 study in infants with type I SMA has completed dosing. Based on the safety, pharmacokinetic and pharmacodynamic profile of ISIS-SMNRx we have observed to date, we have amended the infant study to increase the dose from 9 mg to 12 mg dose. We plan to start dosing this cohort soon. In our Phase 1b/2a multiple-dose study in children with type II and type III SMA, we have completed dosing in all three dose cohorts (3 mg, 6 mg and 9 mg), and we are considering adding a 12 mg dose cohort to this study. The FDA has expressed reservations about increasing the exposure in children with type II and type III SMA, and we are in ongoing discussions with them. We plan to report data from both of these ongoing studies late this year or early next year. We also plan to begin our Phase 3 clinical program early next year.”         

Isis Pharmaceuticals exclusively licensed intellectual property from the University of Massachusetts to develop this new drug for Spinal Muscular Atrophy. Cure SMA provided over $500,000 in funding support for the University of Massachusetts’ research program responsible for creating this intellectual property.