The U.S. Food and Drug Administration (FDA) has notified AveXis that, based on review of data submitted, including the potency assay, it may initiate its planned pivotal trial of AVXS-101 for patients with SMA Type 1 using the intravenous (IV) formulation produced by the company’s Good Manufacturing Practice (GMP) commercial manufacturing process. The company plans to initiate this trial immediately.
The AveXis facility is the production site to supply the pivotal and future trials and, should AVXS-101 be approved for marketing, to meet projected commercial demand.
With the pivotal trial now starting, AveXis and the FDA are continuing discussions on key topics, including dosing, for intrathecal administration of AVXS-101 for the planned clinical trial in patients with SMA Type 2. An update on this program will be provided in the fourth quarter of 2017.
The Pivotal Trial in SMA Type 1, named STR1VE, will take place in the US in the first instance.
The open-label, single-arm, single-dose, multi-centre trial, known as STR1VE, is designed to evaluate the efficacy and safety of a one-time IV infusion of AVXS-101 of 1.1 x 1014 vg/kg, which is equivalent to the proposed therapeutic dose received by the second dosing cohort in the Phase 1 trial, in patients with SMA Type 1.
The trial will enrol a minimum of 15 patients with SMA Type 1 who are less than six months of age at the time of gene therapy and who have one or two copies of the SMN2 backup gene as determined by genetic testing and bi-allelic SMN1 gene deletion or point mutations. There will be at least a four-week dosing interval between dosing of the first three patients to allow review of the safety analysis from six time points (days one, two, seven, 14, 21 and 30), as well as early signals of efficacy, prior to dosing of the next patient.
The intent-to-treat population is defined as patients who are less than six months of age and symptomatic at the time of gene therapy, with two copies of the SMN2 gene as determined by genetic testing, bi-allelic SMN1 gene deletion and no c.859G>C mutation in SMN2.
The co-primary efficacy outcome measures of the trial will include:
- The achievement of the developmental milestone of independent sitting for at least 30 seconds at 18 months of age
- Event-free survival at 14 months of age, with an event defined as either death or at least 16 hours per day of required ventilation support for breathing for 14 consecutive days in the absence of acute reversible illness or perioperatively
Co-secondary outcome measures will include:
- The ability to thrive, defined as the ability to: remain independent from feeding support, tolerate thin liquids and maintain weight
- The ability to remain independent of ventilatory support at 18 months of age
The trial is projected to be conducted at 16 sites in the United States.