US Regulator Approves Spinal Gene Therapy
Intrathecal Administration Route Expands Treatment Access for Spinal Muscular Atrophy Patients
The U.S. Food and Drug Administration (FDA) has approved the intrathecal (spinal injection) formulation of the gene therapy onasemnogene abeparvovec, manufactured by Novartis and marketed as Itvisma. The medication is specifically indicated for patients aged 2 years and older living with spinal muscular atrophy (SMA).
This approval introduces a crucial new administration option, becoming the first treatment for SMA delivered via the intrathecal route. The gene therapy is engineered to address the disease’s genetic root cause by delivering a functional copy of the SMN1 gene, thereby promoting improved motor function. The therapy had previously received approval in 2019 as a single intravenous infusion for a broader SMA population.
The FDA’s latest decision was based on positive data from the Phase 3 STEER study and supportive findings from the Phase 3b STRENGTH study. The STEER trial, which included 126 treatment-naive patients with Type 2 SMA, successfully met its primary endpoint. Specifically, patients who received the intrathecal medication showed a statistically significant improvement of 2.39 points on the Hammersmith Functional Motor Scale-Expanded (HFMSE) score, notably higher than the 0.51-point gain observed in the sham group.
The STRENGTH study evaluated the treatment’s safety and efficacy in 27 SMA patients who transitioned from previously approved therapies. The treatment maintained a consistent safety profile over the 52-week period. During this time, patients demonstrated stabilization, achieving an average increase of 1.05 points on the HFMSE score. Importantly, no deaths or study discontinuations were reported due to adverse events.
Though not part of the formal approval data, the STRONG study, which tested the drug on older patients, indicated that this group showed significant HFMSE score improvements when compared to historical control data.
Medical experts noted that this approval provides a vital new treatment option for the SMA community, significantly expanding accessibility, particularly for older patients.
