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Clinical trials

Sanofi Drops RSV Vaccine for Toddlers After Phase 3 Study Underperforms

Strategic Insights

— 1 min read

Sanofi has scrapped its respiratory syncytial virus (RSV) vaccine for toddlers, dubbed SP0125, after an independent data monitoring committee (IDMC) determined that it was unlikely to demonstrate suitable efficacy in a late-stage study. The intranasal live attenuated vaccine was being evaluated in a phase 3 study involving approximately 6,300 children aged 6 months to 22 months. Although the safety profile was deemed acceptable with no signs of vaccine-associated enhanced respiratory disease, the vaccine's performance fell short of expectations.

Key Takeaways:

  • Sanofi terminated the SP0125 program after the IDMC found it unlikely to demonstrate suitable efficacy in a phase 3 study of around 6,300 children aged 6 months to 22 months.
  • The vaccine's safety profile was deemed acceptable, and no signals of vaccine-associated enhanced respiratory disease were observed.
  • Sanofi had previously highlighted SP125 as the "first RSV vaccine designed to protect toddlers" with positive phase 1/2 data, but the phase 3 study underperformed.
  • Sanofi has continued to expand its RSV presence through other vaccine candidates, including SP0256 and SP0291.
  • The company has also invested $1.15 billion in its non-mRNA vaccine for RSV.
  • Sanofi's RSV vaccine, Beyfortus, held a unique spot as the sole prophylactic RSV antibody for children until the FDA approved Enflonsia in June for lower respiratory tract disease prevention in children born during or entering their first RSV season.

Statistics:

  • $1.15 billion: Sanofi's acquisition cost for its non-mRNA vaccine for RSV.
  • 6,300: Approximate number of children participating in the SP0125 phase 3 study.
  • 6 months to 22 months: Age range of children in the phase 3 study for the SP0125 vaccine.
  • 2027: Scheduled completion year of the SP0125 phase 3 study.

Sources:

  • Sanofi press release, via [Yahoo Finance](https://finance.yahoo.com/)
  • Sanofi's results from its vaccines R&D day in 2023, as reported by [Fierce Pharma](https://www.fiercepharma.com/)
  • Information on Enflonsia, as reported by the [FDA](https://www.accessdata.fda.gov/)

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