Progress for treatments of rare disorders

The search for treatments for rare disorders have taken a step forward on both sides of the Atlantic.

In the United States, the Food and Drug Administration has granted Fast Track designation to Pfizer’s investigational gene therapy PF-06939926 for Duchenne muscular dystrophy (https://investors.pfizer.com/investor-news/press-release-details/2020/Pfizer-Receives-FDA-Fast-Track-Designation-for-Duchenne-Muscular-Dystrophy-Investigational-Gene-Therapy/default.aspx). PF-06939926 utilises recombinant adeno-associated virus serotype 9 (rAAV9) as a vector that targets muscle tissue to deliver a shortened human dystrophin gene under the control of a human muscle-specific promotor. The company says its Phase Ib dose-finding study demonstrated that PF-06939926 is acutely well-tolerated and achieves sustained dystrophin expression levels for up to 12 months.

Novartis has announced interim findings from its STRIVE-EU trial of onasemnogene abeparvovec (Zolgensma) for spinal muscular atrophy (SMA) (https://www.novartis.com/news/media-releases/zolgensma-data-including-patients-more-severe-sma-baseline-further-demonstrate-therapeutic-benefit-including-prolonged-event-free-survival-increased-motor). The agent, a copy of the human SMN gene, replaces the functionally abnormal SMN1 gene which causes SMA. Given as a single IV infusion, treatment has the potential to halt disease progression. The Phase III STR1VE-EU trial is evaluating Zolgensma in patients with SMA Type 1 aged less than 6 months who have one or two copies of the SMN2 backup gene and bi-allelic SMN1 gene deletion or point mutations.

Novartis says the interim analysis interim showed that 66% of patients given Zolgensma ‘achieved motor milestones not observed in the natural history of SMA Type 1’. The primary efficacy endpoint – the ability to sit independently for ≥10 seconds – was reached by 19% of participants. Furthermore, 67% were able to feed by mouth with needing support, 67% gained head control and 25% were able to roll from back to sides. One patient was able to stand with assistance, crawl and walk with assistance.

The company adds that 600 patients with SMA have now been treated with follow up for up to 5 years. The European Medicines Agency conferred orphan product status on Zolgensma in 2015 and granted conditional marketing approval for SMA in May 2020.

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