Treatments alter the natural progression of SMA

Treatment of the various types of spinal muscular atrophy (SMA) with approved therapies results in an array of improvements, according to a review of 22 studies that assessed mid- and long-term (at least 12 months) outcomes in patients with SMA. Three therapies are approved for SMA: nusinersen, onasemnogene abeparvovec, and risdiplam, used alone or in combination, depending on the patient’s SMA type and other factors.

The analysis showed that nusinersen improved motor functions in patients with SMA type 1, while in SMA type 2 to type 4 disease this treatment was associated with patient stabilization or small improvements, though investigators also observed some deterioration. Onasemnogene abeparvovec improved motor functions (such as the ability to sit for at least 30 seconds or stand without support) in patients with SMA type 1, as did combination therapies in these patients. Procedure-related adverse events, generally caused by the lumbar puncture, were reported, though drug-related such events were rare. The authors noted, however, that the studies they reviewed either did not address pulmonary outcomes or reported on them “poorly.”

Thoughts from Dr. Farber
SMA is a disease we will start diagnosing earlier due to newborn metabolic screening. We now have options for this heretofore untreatable condition. The treatments look beneficial in at least the short term and it is hoped that better data will confirm their value long term, but for now I will cautiously classify them as “promising.”

Reference:
Erdos J, Wild C. Mid- and long-term (at least 12 months) follow-up of patients with spinal muscular atrophy (SMA) treated with nusinersen, onasemnogene abeparvovec, risdiplam or combination therapies: a systematic review of real-world study data. Eur J Paediat Neurol. 2022;39:1-10. doi:10.1016/j.ejpn.2022.04.006