AveXis nabs breakthrough tag for gene therapy, plans pivotal trial start in 2017

FDA headquarters, Silver Spring, MD

Gene therapy player AveXis ($AVXS) has grown into almost a $1 billion company since its IPO less than 6 months ago. Its latest bit of good news is a Breakthrough Therapy Designation for its only clinical candidate, AVXS-101 to treat spinal muscular atrophy (SMA) Type 1.

AveXis plans to start pivotal testing of AVXS-101 in the U.S. and Europe during the first half of next year. The FDA awarded Breakthrough Therapy Designation based on data from a Phase I trial for AVXS-101 that AveXis reported interim results for in May. The company plans to report final data from the ongoing Phase I trial during the first quarter of 2017.

“We are encouraged to have received Breakthrough Therapy Designation for AVXS-101, and look forward to collaborating with the FDA to determine next steps in the development pathway for AVXS-101," said AveXis President and CEO Sean Nolan. "By this action the FDA recognizes the high unmet need for effective treatment options for patients suffering from SMA."

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The Phase I study found that 9 out of 12 patients on the intended therapeutic dose reached a score of 40 on a test designed to measure motor skills of SMA Type 1 patients, while 7 out of these 12 patients achieved a score of 50. A score of 60 is considered normal.

SMA is a severe neuromuscular disease characterized by the loss of motor neurons leading to progressive muscle weakness and paralysis. SMA is caused by a genetic defect in the SMN1 gene that codes SMN, a protein necessary for survival of motor neurons. The incidence of SMA is approximately one in 10,000 live births.

AVXS-101 already has orphan designation in the U.S. and the EU. It’s intended to work by replacing the lost or defective primary SMN1 gene to create a fully functioning SMN gene in this monogenetic disease. The candidate uses a nonreplicating adeno-associated virus capsid to deliver the functional copy into the patient’s cells but without modifying the patient’s existing DNA, according to the company.

It can cross the blood-brain barrier and enter the spinal cord to target motor neurons in the central nervous system. Like most gene therapies, AVXS-101 is given as a single intravenous dose. The SMN expression is created by a modified chicken beta-actin promoter.

AveXis will submit a meeting request to the FDA later this month to discuss the development program for AVXS-101.

It had $148.2 million in cash at March 31, with a net loss for the first quarter of $20.8 million. Deerfield Management, RA Capital Management and T. Rowe Price Associates all held more than 5% of the company at March 31.

The company’s shares jumped 13% to more than $40 on the Breakthrough Therapy Designation news on July 20. That's roughly twice the $20-per-share price in its IPO, which raised $95 million in February.

- here is the release

Editor's note: An earlier version of this article included incorrect timing for the FDA meeting request from AveXis.

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