Novartis plans to acquire the neurological gene therapy firm AveXis for $8.7 billion. The purchase will bolster the Swiss giant’s standing as a big pharma leader in the emerging gene therapy field.
AveXis’s leading drug candidate is its gene therapy to treat infants with spinal muscular atrophy type 1 (SMA1), a devastating genetic disease, sometimes called “floppy baby syndrome,” that causes weak muscles and difficulty breathing. Only 8% of afflicted infants survive to 20 months of age. Those that do rely on ventilation support and will never walk.
So when a prominent medical journal published a study last November showing that all 15 infants treated with AveXis’s gene therapy for SMA1 were alive after 20 months, excitement in the field was palpable (N. Engl. J. Med. 2017, DOI: 10.1056/NEJMoa1706198).
Gene therapy enthusiasm grew even more in December when Luxturna became the first gene therapy approved by the U.S. Food & Drug Administration to treat genetic disease. Developed by Spark Therapeutics, Luxturna is a pair of one-time injections, with a price tag of $850,000, that treat a rare form of inherited blindness. In January, Novartis acquired rights to develop Luxturna outside the U.S.
Novartis expects to fund the AveXis purchase with the $13 billion it will make from selling its stake in a consumer health care joint venture with GlaxoSmithKline.
SMA1 is caused by genetic mutations in the gene SMN1. AveXis packages a healthy copy of SMN1 into a viral delivery vessel called adeno-associated virus 9 (AAV9) that has the ability to cross the nervous system’s protective blood-brain barrier and enter the brain and spinal cord. It’s an obstacle that has stalled many promising therapies aimed at the nervous system.
The proposed acquisition shows that Novartis is not scared about the potential risks of high-dose gene therapy. The SMA1 therapy uses an extraordinary number of DNA-stuffed viruses—200 trillion per kilogram of body weight—to ensure that enough of the therapy actually gets into the diseased cells of the infant.
A similarly high dose caused a brief panic among investors in February when gene therapy pioneer James Wilson from the University of Pennsylvania released a study disclosing toxic, sometimes deadly, effects from an SMA therapy tested in monkeys and piglets. The AAV Wilson used is closely related to, but different from, AAV9.
The facility where AveXis manufactures AAV9 is another reason Novartis is excited about the company, as scaling up gene therapy production has been a roadblock for the field. AveXis uses a 4,500 m2 warehouse in Libertyville, Ill. for AAV9 manufacturing.
AAV9 also has promise for use in other gene therapies that target the nervous system. AveXis is developing such therapies for two neurological conditions. One is Rett syndrome, a neurodevelopmental condition that primarily affects girls. A mutation in the MECP2 gene causes the disease, and Avexis hopes to treat it by delivering a fully functioning version of MECP2.
The second is a form of the neurodegenerative disease amyotrophic lateral sclerosis (ALS) caused by a mutation in the gene SOD1. This mutation leads to toxic enzyme activity, and AveXis’s potential therapy will encode an RNA that silences the mutant SOD1 gene.