Phase III trial shows effectiveness of single dose of gene therapy to treat spinal muscular atrophy in children and adolescents

The problem with intravenous administration is that it is always given by viral genomes per kilogram of weight, and in a patient weighing more than 13, 15, or 20 kilograms, this means that you have to administer many viral genomes intravenously, which would be very toxic to the body.

The idea is that by administering it intrathecally [directly into the cerebrospinal fluid], you can use a much lower dose and administer it to people over two years of age. This means that the gene therapy treatment will no longer be widely distributed throughout the body, but will be distributed mainly in the nervous system, which is where it is most needed, i.e. in the motor neurons. That is the first change or difference from the gene therapy that was already approved.

The other important aspect is that the population is clearly larger. Although the effects may be less spectacular, probably the most important thing is that in a condition where there is a progressive decline in muscle strength, these patients maintain it and may even improve it. This is clearly very good news, and I think it will be beneficial for many people. This does not mean that it is a panacea or that it is an exclusive treatment that only needs to be given once. It is given only once, but that does not mean that there are no other adjuvant treatments. Probably these cases that have already started and have been indicated to receive the medication after two years, which are already patients who are showing signs of the disease, will need other therapies.

Obviously, it is a very good step forward to know that you can give a single treatment with an intrathecal injection and you will really have the possibility of supplementing the SMN gene, which is the one that is missing in spinal muscular atrophy, the one that is diminished, to a sufficient amount so that it can be therapeutically effective.