AVXS-101 is the initial proprietary gene therapy candidate from AveXis, and is currently in a Phase 1 clinical trial for the treatment of Type 1 SMA.1 The therapy, which is currently in a clinical trial for SMA, works to overcome the difficulty that drugs have in crossing the blood-brain barrier by being carried by a virus that is harmless to the human body, but can make the crossing.

How AVXS-101 Works

AVXS-101 was developed to possess four key elements of an optimal gene therapy:1

  1. Recombinant AAV9 capsid shell, a non-replicating adeno-associated virus capsid whose function is to deliver a functional copy of the human SMN gene across the blood-brain barrier to cells without modifying the patient’s existing DNA (avoiding the need for intrathecal delivery when treating infants)
  2. Human SMN transgene, a full-copy of a stable SMN gene that is introduced into the cell’s nucleus
  3. scAAV ITR (self-complementary DNA technology), a human SMN transgene that is introduced as a self-complementary double-stranded molecule for a faster onset of the effect
  4. Continuous promoter, which activates the transgene and was designed to allow continuous and sustained SMN expression

Clinical Trials for AVXS-101

The gene transfer clinical trial for SMA Type 1 (NCT02122952) is ongoing but not recruiting. Its purpose is to evaluate safety and efficacy of gene transfer in Type 1 SMA patients.

This trial, in infants up to 6 months, is an open-label study of an intravenous injection of AVXS-101, given at a low- or high-dose, through a peripheral limb vein. Short-term safety will be evaluated over a two-year period. The primary analysis for efficacy will be assessed when all patients reach 13.6 months of age. A follow-up safety analysis will be completed when the last patient reaches two years’ post-dose, and patients will then be monitored annually as per standard of care for up to 15 years.2

An interim data analysis conducted on July 1, 2016, demonstrated a favorable safety profile with no new treatment-related safety or tolerability concerns identified. Motor skill improvement was also seen, especially in the higher dose group.3

Next steps for this drug

AveXis also announced in July 2016 that the FDA had designated  AVXS-101 a Breakthrough Therapy,  based on the preliminary clinical results from the ongoing trial and potentially speeding the therapy’s development.4

AveXis expects to initiate a Phase 1 safety and dosing study of AVXS-101 via intrathecal delivery in patients with SMA Type 2 in the second half of 2016, and to initiate pivotal trials of AVXS-101 in patients with SMA Type 1 in the U.S. and Europe by mid-2017. It also plans to report 13.6-month data from all Phase 1 study patients in early 2017.

On Sept. 6, AveXis filed a financial statement form with concerns to investors, regarding changes to the development of AVXS-101 and the future of the company.6

Read the latest AVXS-101 news on SMA News Today.

Follow the latest developments for all experimental Spinal Muscular Atrophy treatments on the SMA Therapy Tracker.

SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.


  1. https://avexis.com
  2. https://clinicaltrials.gov/ct2/show/study/NCT02122952?term=avxs+101&rank=1
  3. https://smanewstoday.com/2016/08/30/20160830avexis-interim-data-phase-1-clinical-trial-sma-gene-therapy/
  4. http://www.curesma.org/news/avexis-receives-breakthrough.html
  5. http://investors.avexis.com/phoenix.zhtml?c=254285&p=irol-newsArticle&ID=2195068
  6. http://investors.avexis.com/phoenix.zhtml?c=254285&p=irol-SECText&TEXT=aHR0cDovL2FwaS50ZW5rd2l6YXJkLmNvbS9maWxpbmcueG1sP2lwYWdlPTExMTI3OTk4JkRTRVE9MCZTRVE9MCZTUURFU0M9U0VDVElPTl9FTlRJUkUmc3Vic2lkPTU3