recently published data neurology provided insights into the prevalence of spinal muscular atrophy (SMA) at the national level and the current distribution of patients treated with treatment options that began entering the field in 2016.1
Overall, 1255 patients with this disease are currently being followed in Italian centers, with an estimated prevalence of 2.12/100,000. This value was higher than the value recorded by the ISS Rare Disease Institute in 2016 (1.81; 95% CI, 0.010-0.026).
The SMA treatment paradigm has changed dramatically over the past few years with the approval of three therapies: nusinersen (Spinraza; Biogen), onasemnogen abeparvovec (Zolgensma; Abexis), and risdipram (Evrysdi; Genentech/Roche). Each of these treatments is different. Nusinersen, an antisense oligonucleotide, SMN2, Approved for all types of SMA. Zolgensma, a gene replacement therapy, also increases SMN protein, SMN1. It is currently FDA approved for patients under 2 years of age and Type 1 patients up to 3 years of age. SMN2 Copy Risdipram, a small molecule drug, is similar to nusinersen in that it increases SMN protein. SMN2; However, it is approved for all SMA types and infants under 2 months of age.
Led by Eugenio Mercuri, MD, PhD, Professor of Pediatric Neurology, Catholic University of Rome, this analysis aimed to assess the prevalence and treatment prescriptions of SMA in Italy. Thus, an online survey was distributed to 36 referral centers to determine age, type, SMN2 copy number, and processing. The survey completion rate was 100% and the period prevalence was calculated by dividing the proportion of patients with SMA in one year by the Italian population in 2021 (59,258,000).
Of the 1255 patients with 5qSMA, 604 were adults and 650 were children. SMN2 Copies available in just over three-quarters (77.45%) of the identified group. The most common types 2 were types 2 and 3, which included 470 and 467 cases, respectively, with an estimated prevalence of 0.79/100,000. Among type 2 patients, 400 (85%) received new treatment. In the type 3 cohort, 369 (79%) received new therapy. Of these two groups, nusinersen was the most used treatment, accounting for 40.75% of type 2 patients and 68.74% of type 3 patients.
The type 1 population was the smallest of the three populations, containing 284 patients and an estimated prevalence of 0.48/100,000. Of the 284, 272 received new treatment. Nusinersen was again the most used treatment (46.69%), followed by clinical trials (20.59%), Zolgensma (18.75%) and risdiplam (13.97%).
“The large number of patients currently being treated with nusinersen largely reflects the fact that nusinersen was the first drug approved and the only available option for over three years.” writes Mercuri et al.1 “At the time of the study, risdipram was only available for humane use and onasemnogen abeparvovec could only be prescribed to type I infants under 2 years of age and weighing less than 13.5 kg. decreased with decreasing severity.Further follow-up will allow us to establish how these figures will change with the recent commercial availability of risdipram.”