Spinal muscular atrophy (SMA) is one of the most common genetic causes of infantile death arising due to mutations in the SMN1 gene and the subsequent loss of motor neurons. With the discovery of the intronic splicing silencer N1 (ISS-N1) as a potential target for antisense therapy, several antisense oligonucleotides (ASOs) are being developed to include exon 7 in the final mRNA transcript of the SMN2 gene and thereby increasing the production of spinal motor neuron (SMN) proteins. Nusinersen (spinraza), a modified 2'-O-methoxyethyl (MOE) antisense oligonucleotide is the first drug to be approved by Food and Drug Agency (FDA) in December of 2016. Here we briefly review the pharmacological relevance of the drug, clinical trials, toxicity, and future directions following the approval of nusinersen.