Spinraza® is a trade name of a drug containing nusinersen which is an antisense nucleotide (a sequence of nucleic acids, just like in human DNA) that attaches to the SMN2 gene and modifies its function. Because of that, the SMN2 gene starts producing high amounts of the SMN protein. Restoration of the normal SMN protein level stops motoneuron degeneration and helps regain function.
Spinraza is the only approved drug for the treatment of spinal muscular atrophy.
The below video clip illustrates how nusinersen works to treat SMA:
Spinraza has been proven unusually effective. In controlled clinical trials, more than 60% of treated children with the most severe form of SMA had the disease course reversed. This did not happen to a single child from the control group.
Treatment effects in SMA type 2 and weak 3 were even more astounding. When treated early, children who would barely be able to mainatin sitting position learned to stand and walk unsupported. Even ambulant teenage patients with SMA type 3 had their walking ability increased 3.5-fold after three years of treatment.
At the same time, those who have completely lost motor neurons or muscle tissue due to disease progression, especially in its most severe form, are not likely to see much benefit of this therapy. Like most drugs designed for SMA, Spinraza only improves the function of the existing motor neurons but does not grow new neurons or rebuild muscles.
Spinraza is administered directly to the central nervous system through lumbar puction: an injection into the spinal cavity. This is sometimes done under local anaesthesia but in most cases no anaesthetics are needed as the injection is linked to only mild pain.
Treatment with Spinraza is initiated by four so-called loading doses: three doses administered in 14-day intervals and a fourth dose 30 days after the third one. A maintenance dose needs to be administered every four months thereafter. Treatment has to be continued for life or until an alternative treatment is available.
Spinraza is among the most expensive drugs in the world. The list price of a single dose is €90,000, or approximately £83,500. Due to its high price, the drug needs to be made available under a government-funded drug programme that would be open to all those with SMA. TreatSMA campaigns for this to happen.