The gene therapy is also being assessed for long-term safety data, as well as an additional delivery method.
A Biologics License Application (BLA) filing for FDA approval of AVXS-101, a gene therapy intended to treat those with spinal muscular atrophy (SMA) with a missing or mutated survival motor neuron 1 (SMN1) gene, has been submitted, according to manufacturer AveXis.1
The Novartis company announced that this is the first filing for the therapy’s intravenous delivery method, which limits its use to patients with SMA type 1. AveXis is currently also assessing the treatment in an intrathecal delivery method in a phase 1 trial, STRONG (NCT03381729). This additional method would allow access to the treatment for those with SMA types 2, 3, and 4.
"We congratulate AveXis and Novartis on reaching this milestone," said Kenneth Hobby, president of Cure SMA, the leading national non-profit dedicated to the treatment and cure of SMA. "The [intravenous] clinical trial data shows that a 1-time dose of gene therapy has the potential for a transformative impact on this life-threatening disease. We look forward to a rapid approval by the FDA, and then future positive results from the ongoing intrathecal clinical trials."
The submission is largely supported by a phase 1 study (NCT02122952), which showed that a single intravenous infusion of the therapy in 15 patients with SMA1 resulted in longer survival, superior achievement of milestones of motor function, and better motor function compared to historical data.2
Ultimately the data showed that at 20 months of age, all 15 patients were alive compared to a historical event-free survival rate of 8% to that point. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scores increased 9.8 points from at 1 month of age and 15.4 points at 3 months, compared to historical rates of score declines. Of the 12 patients who received the 2.0×1014 vg/kg dose, 11 sat unassisted, 9 rolled over, 11 were fed orally and could speak, and 2 walked independently.
Sukumar Nagendran, MD, the chief medical officer of AveXis, told SMA News Today3 in February that the 100% survival rate at 13.6 months of age and at 20 months of age “was remarkable and what we consider transformative—and frankly all the experts in the SMA field also feel the same.”
Currently, there is a long-term follow-up trial to that study (NCT03421977) enrolling by rollover invitation, called the START trial, which will assess safety data over a 15-year period.
Additionally, a phase 3 trial, STR1VE (NCT03306277), of the therapy’s intravenous administration is ongoing in 15 to 20 pre-symptomatic infants with SMA types 1, 2, and 3. The open-label, single-arm, single-dose, study will assess the therapy with primary outcome measures of independent sitting and event-free survival.
1. AveXis Files for FDA Approval of Gene Therapy to treat Spinal Muscular Atrophy Type I [press release]. Chichago, IL: AveXis Inc; Published October 18, 2018. przen.com/pr/avexis-files-for-fda-approval-of-gene-therapy-to-treat-spinal-muscular-atrophy-type-przen-33275970. Accessed October 19, 2018.
2. Mendell JR, Al-Zaidy S, Shell R. Single-dose gene-replacement therpay for spinal muscular atrophy. N Engl J Med. 2017;377(18):1713-1722. doi: 10.1056/NEJMoa1706198.
3. Marques Lopes, J. AVXS-101 Sets Out to Show It Might Be ‘Transformative’ for All SMA Types: Interview with AveXis. SMA News Today website. smanewstoday.com/2018/02/13/series-of-trials-will-show-if-avexis-gene-therapy-can-be-a-game-changer-for-sma. Published February 13, 2018. Accessed October 19, 2018.