Interim Data on Gene Therapy for SMA in Phase 1 Study Supports Safety, Potential Efficacy

Özge Özkaya, PhD avatar

by Özge Özkaya, PhD |

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SMA gene therapy trial

AveXis announced that interim data from a Phase 1 clinical trial of its gene therapy, AVXS-101, in pediatric patients with Type 1 spinal muscular atrophy (SMA) showed favorable safety and motor skill improvement. The latter was especially evident in the higher dose group, being given the proposed therapeutic dosing level.

Results collected through July 1 also revealed that AVXS-101 was well-tolerated, with no treatment-related adverse events reported.

In terms of motor improvement, findings showed a 9-point mean increase from baseline in motor function in the low-dose patient group, and an increase of 23.3 points in the high-dose group. Motor skills were measured using The Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND).

The trial (NCT02122952) is testing a gene therapy approach where a healthy copy of the SMN1 gene, which is mutated in SMA patients, is delivered into the body using a harmless virus.

One patient in the low-dose group reached a “ventilation endpoint” after July 1, the company also reported in a Cure SMA news release. A ventilation event was described as “the need of at least 16 hours of ventilation support per day for breathing for greater than two weeks.”

AveXis is now requesting to meet with the U.S. Food and Drug Administration (FDA) to discuss its SMA Type 1 clinical development pathway. The treatment was named a Breakthough Therapy by the FDA in July, a designation that eases interaction with the regulatory agency.

“We continue to be encouraged with this interim data for AVXS-101 and are eager to collaborate with the FDA via the breakthrough designation process to determine next steps in the development pathway for SMA Type 1,” Sean Nolan, president and chief executive officer of AveXis, said in the release.

He added that several key developments were expected later this year, including the presentation of motor skill milestones from the ongoing study at a scientific meeting.

AveXis also plans to start a Phase 1 safety and dosing study in SMA Type 2 patients in late 2016, and to begin further clinical testing in Type 1 patients in Europe and the U.S. next year.

“Based on our data to date, early diagnosis and treatment appear to be critical for optimal outcomes in this population,” said Dr. Suku Nagendran, the company’s senior vice president and chief medical officer.