Hope for children with Spinal Muscular Atrophy

Small biotech company Ionis Pharmaceuticals together with Biogen Idec today announced that their drug nusinersen (SPINRAZA) met the primary endpoint at an interim analysis of their phase 3 study called CHERISH in later-onset (consistent with Type 2) Spinal Muscular Atrophy.

Spinal Muscular Atrophy is characterized by a loss of motor neurons in the spinal cord and lower brain stem, resulting in severe and progressive muscular atrophy and weakness. An estimated 5-7 per 100’000 live births suffer from SMA which makes it the most common degenerative disease of the nervous system in children. Currently, there is no approved treatment.

The drug SPINRAZA is an antisense oligonucleotide (ASO) that is designed to alter the splicing of SMN2, a gene that is nearly identical to SMN1, in order to increase production of fully functional SMN protein. ASOs are short synthetic strings of nucleotides designed to selectively bind to target RNA and regulate gene expression. Through use of this technology, SPINRAZA has the potential to increase the amount of functional SMN protein in infants and children with SMA.

The analysis found that children receiving SPINRAZA experienced a highly statistically significant improvement in motor function compared to those who did not receive treatment while at the same time the compound demonstrated favorable safety.

The study lasts for 15 months and investigates 126 children of age between 2 and 12 years with Type 2 SMA. The interim readout is reason for hope for children suffering from SMA and their families. As per press release:

Results from the primary endpoint of the pre-specified interim analysis demonstrated a difference of 5.9 points (p= 0.0000002) at 15 months between the treatment (n=84) and sham-controlled (n=42) study arms, as measured by the Hammersmith Functional Motor Scale Expanded (HFMSE). From baseline to 15 months of treatment, patients who received SPINRAZA achieved a mean improvement of 4.0 points in the HFMSE, while patients who were not on treatment declined by a mean of 1.9 points.

So after the clinical development of PTC’s RG7800 was put on hold due to long-term animal toxicity observed in mid-2015, there is hope now that children with SMA soon can benefit from this promising drug.

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