In December 2016, the US Food and Drug Administration (FDA) approved nusinersen sodium for the treatment of spinal muscular atrophy (SMA), a rare genetic disease with an incidence of 1 in 6000 to 10 000 live births. The approval was supported by an interim analysis of a randomized, blinded, sham-controlled trial, whose final results were published in 2017.1,2 Policy debates have centered on the cost of nusinersen, which has a list price of $750 000 for the first year of treatment (4 doses administered intrathecally during the first 10 weeks, followed by maintenance doses every 4 months).3 There has been less discussion of the limited evidence supporting the drug’s efficacy and potential harms.