Evaluating Therapeutic Outcomes in Spinal Muscular Atrophy: An Indian Experience.

BACKGROUND AND OBJECTIVES

Spinal muscular atrophy (SMA) is a progressive neuromuscular disorder that leads to anterior horn cell loss. Recent advancements in disease-modifying therapies (DMTs) offer promising new treatment options. This study aimed to evaluate and compare the efficacy and safety profiles of risdiplam, nusinersen, and gene therapy in SMA patients with different disease severities in an Indian cohort.

METHODS

An observational retrospective study was conducted between June 2020 and October 2023, involving 47 genetically confirmed SMA patients (types 1-3). Participants received treatment with risdiplam (n = 11), nusinersen (Spinraza) (n = 25), gene therapy (n = 9), and combination therapy/bridging with risdiplam and gene therapy (n = 2). Motor function was assessed using the Hammersmith functional motor scale expanded (HFMSE) and the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders over 6 monthly follow-up intervals. Safety was monitored by tracking adverse events. As the majority were SMA types 2/3, the primary outcome was measured using HFMSE scores, with improvement defined as an absolute change in HFMSE score of ≥3 points from the baseline (first visit) to the third visit (completion of 12 months).

RESULTS

There were 47 patients aged 1-23 years (28 girls and 19 boys), who received various DMTs, with a minimum of three visits considered for analysis. All treatments resulted in motor function improvements. Gene therapy showed the most substantial benefit, with a median HFMSE score increase of 4 (2-15) compared to 3.5 (0-7.25) for nusinersen and 2.5 (0.25-8.0) for risdiplam. A positive correlation was observed between the number of SMN2 copies and baseline disease severity (Spearman's correlation = 0.57; P = 0.001). Safety profiles were consistent across all therapies, with no new concerns.

CONCLUSIONS

This study underscores the efficacy of contemporary SMA treatments and highlights the potential benefits of personalized treatment strategies, despite variability in disease severity. Future research should focus on optimizing individualized therapy approaches.