Our objective is to evaluate the efficacy and safety of onasemnogene abeparvovec in spinal muscular atrophy type 1 (SMA1) patients.

Onasemnogene is a gene therapy approved by the U.S. Food and Drug Administration in May 2019. It offers the unique benefit of single-time dose administration. The therapy has since been approved for the treatment of SMA1 patients in multiple countries.

Overall, twenty-one studies were included with total of 565 SMA1 patients. The pooled percentage of overall survival was 98% [95% CI: 96:99]. Subgroup analysis based on previous treatment with other disease-modifying agents showed significant subgroup difference favoring those who were treated before (P-value = 0.0982). The pooled percentage of event-free survival was 78% [95% CI: 66:87]. Subgrouping according to dose (standard vs high) exhibited significant subgroup difference favoring high dose (P-value = 0.0005). Overall, serious and drug-related adverse effects showed pooled proportions of 94% [95% CI: 75:100], 30% [95% CI: 9:57], and 63% [95% CI: 49:75], respectively. Thrombocytopenia was the most frequent adverse event. For the change from baseline in CHOP-Intend score, the pooled effect estimate was 15.77 [95% CI: 12.07:19.47], and subgrouping according to previous treatment with disease-modifying agents showed significant subgroup difference (P-value = 0.0817).