Treatment evolution in spinal muscular atrophy: insights from the SMArtCARE registry

Real-world treatments for 5q-spinal muscular atrophy (SMA) have evolved rapidly following the sequential approval of three disease-modifying treatments (DMTs): nusinersen, onasemnogene abeparvovec and risdiplam. The aim of this study was to map the sequence and timing of SMA treatments accurately using the SMArtCARE registry, a disease-specific registry for patients with SMA across 84 participating centres in Germany, Austria and Switzerland. All patients registered in SMArtCARE were included in the analysis. Patients were grouped based on their treatment regimen: those who remained on the first DMT versus those who switched DMT. The impacts of clinical and genetic factors on treatment decisions were evaluated, including age at initiation of treatment, SMN2 copy number, motor function status, the need for ventilator support or tube feeding, and the presence of scoliosis. A total of 2140 patients were included. Of these, 1294 patients (60.5%) initiated treatment with nusinersen, 514 patients (24.0%) with risdiplam and 243 patients (11.4%) with onasemnogene abeparvovec. Overall, 1366 patients (63.8%) remained on the first DMT. Most treatment switches occurred shortly after approval of a new DMT. Notably, most patients who switched showed no change in motor milestone status between the start of the first and the second DMT. In this large real-world cohort, we present the first comprehensive analysis of SMA treatment patterns across all age groups and disease severities. Although most patients remained on the first DMT, switches were observed, mainly after DMT approvals. Decisions to switch appear multifactorial and are not related directly to motor function effectiveness.