One way of treating SMA is by replacing or correcting the faulty SMN1 gene through an approach called “gene therapy” or “gene replacement therapy.” Gene replacement therapy uses a piece of DNA from a particular gene, such as SMN1 for SMA. It isn’t possible to insert the gene directly into a cell, so scientists use a carrier, called a vector, to deliver the gene to the cell. A vector is a virus that “infects” the cell with the new DNA. The virus is modified so that it doesn’t make the person sick.
One gene therapy, Zolgensma, has been approved by the U.S. Food and Drug Administration (FDA) for infants with all types of SMA under 2 years of age. Zolgensma was developed and is marketed by Novartis Gene Therapies. It is a one-time intravenous (IV) infusion.
Novartis Gene Therapies is also developing a second gene therapy program. This second program works similarly to Zolgensma. However, instead of an IV delivery, this program delivers gene therapy via an intrathecal (IT) injection, which is an injection directly into the cerebrospinal fluid through the lower back. This method of delivery could eventually make this treatment available to older and larger patients.
Currently, this method of delivery is being studied in a Phase 3 clinical trial in patients from 2 up to 18 years who have SMA Type 2, and who have never walked, and who have never received a prior treatment for SMA. If the results are positive, Novartis Gene Therapies may file for FDA approval of this delivery method.