PTC Therapeutics receives EMA nod for first at-home SMA treatment

April 6, 20210

PTC Therapeutics, focussed on the development of gene regulating small-molecule drugs for orphan diseases, received EMA approval for its spinal muscular atrophy (SMA) drug Evrysdi® (risdiplamfor treating patients of 2 months age or older. Evrysdi® is an RNA-splicing modifier directed towards survival motor neuron 2 (SM2). SMA is caused by mutations in chromosome 5q leading to SMN deficiency which can be corrected by a therapy such as Evrysdi® that improves the efficiency of SMN2 gene transcription and thereby induces production of full-length copies of SMN.  The drug covers a range of SMA subtypes – SMA Type 1, Type 2 or Type 3 patients with one to four SMN2 copies.  

The EMA approval is based on positive results from two pivotal studies in infantile-onset and later-onset SMA – FIREFISH (NCT02913482) that studied the safety and efficacy of the drug in 62 infants with type 1 SMA; and SUNFISH (NCT02908685) that studied the safety and efficacy in 231 volunteers aged 2 to 25 years old with type 2 and type 3 SMA. Both studies successfully met their primary endpoints, in the volunteer pool of infantile—onset SMA, 41% infants were able to sit without support 12 months after the treatment, which was noted as a meaningful clinical benefit as all untreated infants with infantile-onset are unable to sit independently. Additionally, 23 months after the treatment, 81% of infants were alive without permanent ventilation, also a significant improvement from natural progression of untreated disease.   

Evrysdi® received FDA approval in August 2020 under a fast-track designation and priority review. Roche is the exclusive commercialization partner for PTC Therapeutics to market the drug in the US market.  Among competing therapies for Evrysdi® are Biogen’s Spiranza®, launched in 2016 as the first drug to treat SMA and requires intrathecal administration. Another competitor is Novartis’ one-time gene therapy Zolengsma® approved in 2019. Evrysdi® has the advantage of being priced lower than the other two competing therapies and additionally has the advantage of being an at-home orally administered therapy. 2020 US sales of Biogen’s Spiranza® fell 15.6%, primarily attributed to competition from Zolengsma® as a one-time therapy and the at-home administered option Evrysdi® available in the US. The dip is sales revenue was also exacerbated by the impact of COVID-19 on existing patient’s access to hospitals for maintenance dosing. Biogen expects the competition from both competing therapies to increase in the future and higher patient discontinuations and drop in on-boarding of new patients in geographies outside of US too as more convenient options become available globally.  

Novartis and Roche are also competing for muscular atrophy therapies, Kesimpta® (ofatumumab) and Ocrevus® (ocrelizumab) where Novartis has a competitive advantage of being an at-home subcutaneous self-administered therapy vs Ocrevus® which is an intravenous infusion drug requiring hospital administration.  

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