AveXis Announces Plan to Initiate Phase 1 Trial in SMA Type 2 Utilizing Intrathecal Delivery of AVXS-101
AveXis, Inc., a clinical-stage gene therapy company developing treatments for patients suffering from rare and life-threatening neurological genetic diseases, today announced the U.S. Food and Drug Administration (FDA) has notified the company that, based on review of data submitted, the company may initiate its planned Phase 1 clinical trial of AVXS-101 for patients with spinal muscular atrophy (SMA) Type 2 via the intrathecal (IT) route of administration, using material produced by the company’s Good Manufacturing Practice (GMP) commercial manufacturing process at the AveXis manufacturing facility. The company plans to initiate this trial immediately.
“We are quite pleased to initiate our first trial of AVXS-101 in patients with SMA Type 2,” said Sean Nolan, President and Chief Executive Officer of AveXis. “Our goal has been to expand the study of gene therapy beyond Type 1 infants to address the urgent medical needs of children with SMA Type 2, and we look forward to understanding the potential clinical impact of AVXS-101 in these patients who, left untreated, will never walk on their own and most will never stand without assistance.”
U.S. Phase 1 Trial in SMA Type 2 (STRONG)
The open-label, dose-comparison, multi-center Phase 1 trial – known as STRONG – is designed to evaluate the safety, optimal dosing, and proof of concept for efficacy of AVXS-101 in two distinct age groups of patients with SMA Type 2, utilizing a one-time IT route of administration. The trial will enroll 27 infants and children with a genetic diagnosis consistent with SMA, including the bi-allelic deletion of SMN1 and three copies of SMN2 without the SMN2 genetic modifier, who are able to sit but have no historical or current ability to stand or walk.
Two dosage strengths will be evaluated and patients will be stratified into two age groups: patients less than 24 months, and patients at least 24 months but less than 60 months. There will be at least a four-week interval between the dosing of the first three patients for each dose being studied and, based on the available safety data, a decision will be made whether to proceed.
The trial is projected to be conducted at 11 sites in the United States, including: Ann and Robert H. Lurie Children's Hospital of Chicago, Boston Children's Hospital, Children's Hospital of Philadelphia, David Geffen School of Medicine at UCLA, Johns Hopkins Pediatric Neurology, Nationwide Children's Hospital, Stanford University Medical Center, University of Central Florida College of Medicine, University of Texas Southwestern Medical Center, University of Utah and Washington University School of Medicine.
“This Phase 1 trial in children with SMA Type 2 will allow us to evaluate safety, optimal dosing and proof-of-concept for efficacy of AVXS-101 compared to the well-characterized natural history using the one-time intrathecal route of administration,” said Dr. Sukumar Nagendran, Chief Medical Officer of AveXis. “Because AVXS-101 targets the root cause of SMA, we are optimistic that we will observe a similar preclinical to clinical translation in this Type 2 trial as was seen in the SMA Type 1 study using intravenous administration.”
Meeting with the FDA on Type 1 Results
On December 5, 2017, the company had an end-of-Phase 1 meeting with FDA with respect to AVXS-101 for SMA Type 1. The company anticipates providing an update on feedback from FDA following the receipt of the final meeting minutes in early January.
Other Ongoing Trials
In September, the company announced a pivotal, open-label, single-arm, single-dose, multi-center trial—known as STR1VE—testing intravenous delivery of AVXS-101 in patients with SMA type 1.
STR1VE will enroll 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.
Recruitment for this trial is ongoing at 16 sites in the United States, including: Ann and Robert H. Lurie Children's Hospital of Chicago, Boston Children's Hospital, Children's Hospital Colorado, Children's Hospital of Philadelphia, Columbia University, David Geffen School of Medicine at UCLA, Duke University, Johns Hopkins Pediatric Neurology, Nationwide Children's Hospital, Oregon Health and Science University, Stanford University Medical Center, University of Central Florida College of Medicine, University of Texas Southwestern Medical Center, University of Utah, University of Wisconsin, and Washington University School of Medicine.
Cure SMA Funds Multiple Gene Therapy Approaches
Beginning in 2010, Cure SMA made a series of grants to Nationwide Children’s Hospital (NCH) to study gene therapy, also called gene transfer. Spinal muscular atrophy (SMA) is caused by a mutation in the survival motor neuron 1 gene (SMN1). Because of this mutation, the individual does not produce enough survival motor neuron (SMN) protein.
Gene transfer may increase SMN levels by using a virus, called a vector, to deliver the SMN1 gene to affected cells. Researchers at NCH discovered that Adeno-associated virus serotype 9 (AAV9) had the unique ability to cross the blood brain barrier and the Blood-Cerebrospinal Fluid Barrier (CSF).
Currently, two approaches are being studied: an injection into a vein, known as systemic delivery, and delivery directly into the cerebrospinal spinal fluid (CSF), a process known as CSF-delivered gene therapy. CSF-delivered gene therapy has shown promise for reducing the amount of drug required for larger and older patients. This could eventually make the treatment accessible to a wider population.
In total, Cure SMA has granted $845,000 for gene therapy, including support for both the systemic program and the CSF program. Using the data generated with our funding for CSF delivery, researchers were able to secure a $4 million grant from NINDS in 2013, to develop this delivery approach for human clinical trials in SMA.