A little less than two months after receiving an FDA approval in spinal muscular atrophy, Roche’s Genentech continues to roll out data for risdiplam.
The drug, marketed as Evrysdi in the US, showed improved motor functions in infants as part of a two-year follow-up evaluation from Part 1 of a pivotal trial on which its approval is based. Numerically, there were more patients who could sit without support for five seconds, maintain upright head control, turn themselves over and stand than those at one year.
“We are highly encouraged by the results we are seeing in the second year of treatment with Evrysdi,” Genentech CMO Levi Garraway said in a statement. “We look forward to continued assessments of both survival and motor function during long-term follow up.”
These data come from the dose-escalation portion of the study and enrolled 21 infants aged 2 to 7 months at the trial’s start. Of those patients, 17 were treated with the therapeutic dose and 14 survived after two years. Two of the patients suffered fatal complications from their disease at 8 and 13 months of treatment, respectively, and a third was withdrawn from the study and died 3 and a half months later. None of the deaths were attributed to Evrysdi.
Among the 17 treated, 10 could sit without support at two years as opposed to 7 at one year. Two more infants maintained upright head control, totalling 11 at the second year. An additional three could turn themselves over, upping the number to 5 overall. And 5 infants were able to stand either supporting weight or with support, up from just 1 at the one-year mark.
Additionally, all 14 patients alive at year 2 maintained the ability to swallow, and no new safety concerns arose.
The primary endpoint, which the trial met back in January, measured the proportion of infants that could sit without support after 12 months of treatment and was the main goal of the second part of the study. This portion was single-arm, looking at 41 infants with Type 1 SMA, and was not included in Monday’s follow-up.
Though it’s only been approved for a few weeks, Evrysdi is largely expected to prove a blockbuster and disrupt the SMA market. Peak sales are estimated to be around $2 billion according to analysts, and the drug also has a cheaper price tag than its two competitors.
Evrysdi’s price maxes out at $340,000 annually, a Genentech spokesperson told Endpoints News after approval, and is scaled on a patient’s weight. The pricing scale caps when the child reaches 44 pounds, which puts the average at about $7,727.27 per pound per year for every patient. As one example, the cost for an infant weighing 15 pounds who is less than two years old would be under $100,000.
That bill is substantially cheaper than the one rung up by Novartis’ Zolgensma, which costs $2.1 million per patient — the most expensive drug in the world. Biogen’s Spinraza, meanwhile, costs $750,000 for the first year and $375,000 each year after. Spinraza and Evrysdi are approved for the treatment in adults as well, whereas Zolgensma is designed as a one-shot cure for infants.
Evrysdi also has a potentially more convenient administration method going for it in that patients ingest it orally as a liquid, whereas Zolgensma and Spinraza are taken via injection. With the Covid-19 pandemic still raging, Baird analyst Brian Skorney expects Evrysdi to take the upper hand over Spinraza due to patients being less willing to venture outside, he wrote last month.
No approved treatments for SMA existed before 2016.