Patients on treatment with risdiplam in Italy: challenges in the interpretation of the real-world data.

Aims: (i) provide a snapshot from a large cohort of Italian patients with SMA on risdiplam in the real-world setting; (ii) identify any differences in the cohorts before and after commercial drug approval considering the different eligibility access criteria (iii) describe preliminary data on adherence to treatment and reasons for shifting from nusinersen to risdiplam.

Methods: Charts from patients on risdiplam were retrospectively reviewed. Results were then compared between patients accessing the drug during an initial restricted compassionate use program (cohort 1) and those after commercial approval, with no restrictions (cohort 2). Side effects and adherence were recorded for both cohorts as well as data on shifters.

Results: 283 patients (median age: 22 years) were included. Only a minority were walkers. Respiratory and bulbar comorbidities were more severe in cohort 1 (58% non sitters) than in cohort 2 (52% sitters). 35% and 46% of patients from cohorts 1 and 2 shifted from nusinersen to risdiplam respectively. Adherence and safety profile were good in both cohorts.

Conclusions: This is the largest cohort described so far providing insights on the characteristics of patients on risdiplam in the real world. The disability level and age were very different from those that had driven efficacy results in the trials. This may at least in part produce some evidence to account for the variable results reported so far in the realworld. Importantly, the safety profile was confirmed even in these more severely disabled and older patients compared to those in the trials.