What is nusinersen and how does it work?
Spinraza (nusinersen) is the first medicine approved  to treat pediatric and adult patients with spinal muscular atrophy (SMA) . SMA is a rare and often fatal hereditary (genetic) disease that causes weakness and muscle wasting due to the loss of motor neurons controlling movement . Spinraza (nusinersen) is an antisense oligonucleotide (ASO) that is designed to treat SMA caused by mutations in the chromosome 5q. This mutation leads to the deficiency of a protein, the survival motor neuron (SMN) protein. Spinraza (nusinersen) alters the synthesis of the deficient protein in order to increase production of full-length SMN protein and thereby promoting the maintenance of motor neurons .
What is nusinersen's approval status?
Spinraza (nusinersen) was approved by:
for the treatment of children and adults with spinal muscular atrophy (SMA). The efficacy of nusinersen for SMA was assessed in a clinical trial (CS3B - ENDEAR) involving 121 patients with infantile-onset SMA who were diagnosed before 6 months of age and who were less than 7 months old at the time of their first dose . Patients were randomised to receive an injection of Spinraza (nusinersen), into the fluid surrounding the spinal cord, or undergo a mock procedure (sham-control) without drug injection (a skin prick) .
- FDA (USA) on December 23, 2016 
- EMA (EU) on May 30, 2017 
At the final analysis, the percentage of responders (patients achieving the pre-defined motor milestone responder criteria) among the nusinersen group was 51 % vs 0 % among the patients in the control group. Fewer patients died or received permanent ventilation among the nusinersen treated patients (39 %) compared with the control group (68 %) 
. The portion of patients that achieved improvement in total milestone score (which included the ability to kick, head control, rolling, sitting, crawling, standing or walking) was 67 % in the patients treated with nusinersen vs 17% in the sham-control group, while the portion of patients that worsened in the two groups was 1 % and 22 % respectively 
. When measured with the Children’s Hospital of Philadelphia Infant Test for Neuromuscular Disease (CHOP INTEND) score, the proportion of patients achieving a 4-point improvement was 73 % with nusinersen and 3 % without, while the proportion of those worsening was 7 % with nusinersen and 49 % without 
Positive results were achieved also in a study on patients with later onset SMA (after 6 months of age). The study CS4 (CHERISH) involved 126 patients randomised 2:1 to either nusinersen or sham-control. The main measure considered was the Hammersmith Functional Motor Scale Expanded (HFMSE). Among the patients treated with nusinersen, 57.3 % achieved an improvement from baseline of at least 3 points vs. 20.5 % of the patients in the control group