Dive Brief:

• Sanofi said Friday it will ask regulators around the world to review its new eczema drug amlitelimab following mixed study results that could lead to a clearance in the U.S. but spell trouble in Europe.  
• A combination of amlitelimab and topical steroids helped between one-quarter and one-third of people with eczema completely or almost completely clear their skin lesions, depending on the dose frequency received and trial they’d participated in. Amlitelimab met all its objectives in one late-stage study. too. But in a second trial, amlitelimab missed a statistical threshold sought by European regulators. A safety study also uncovered one case of a type of skin cancer in a drug recipient.
• The results show amlitelimab is “a U.S. file-able drug that can differentiate on convenience,” Jefferies analyst Michael Leuchten wrote in a note to clients. Sanofi said it intends to move forward with global submissions based on the “totality of the data.”

Dive Insight:

Sanofi already has a dominant presence treating eczema thanks to Dupixent, a drug it co-developed with Regeneron and that racked up more than 11 billion euros, or $13 billion, in sales covering all approved indications. But Dupixent loses patent protection in 2031, making it crucial for the France-based drugmaker to come through with a worthy successor.

Sanofi has billed amlitelimab as that kind of prospect. The company acquired amlitelimab through a $1.1 billion buyout of Kymab in 2021, and Sanofi has been hoping that its different mechanism and potential to be dosed less frequently might set it apart. 

That mechanism of action, blocking an immune regulating molecule called OX40L, is also being explored by Amgen. But expectations for these kinds of drugs have cooled following disappointing data from Amgen in 2024 and underwhelming amlitelimab results last September. 

Sanofi was looking to solidify its case with the newly released results. The data comes from two Phase 3 trials — SHORE and COAST 2 — and a Phase 2 safety study dubbed ATLANTIS. Differences in the analyses prepared for regulators in the U.S. and Europe stemmed from how the two agencies want to count non-responders for the purposes of calculating statistical significance.

In SHORE, amlitelimab hit both of its main goals. Compared to a placebo, people who received amlitelimab every four or 12 weeks were more likely to achieve clear or nearly clear skin as judged by an investigator, as well as a 75% or more reduction in their skin lesions.

But in COAST 2, the difference in how the non-responders were classified led amlitelimab to miss its benchmark for success with European regulators. According to Sanofi, 28% of those dosed every 12 weeks achieved the investigator-assessed goal, compared with 19% of placebo recipients, which wasn’t a statistically significant difference under the European calculation.

Sanofi’s safety study, meanwhile, included a positive signal showing that efficacy appeared to build with time and didn’t plateau after a year. But there, a case of Kaposi’s sarcoma — a cancer that forms around skin lesions — was observed in a treatment recipient. That incident could yield a “black box” safety warning from the FDA, noted Leerink Partners analyst David Risinger. 

“We suspect the market will still trade this as a show-me drug,” added Jefferies analyst Leuchten.

Two additional Phase 3 studies are ongoing and will read out results later this year.