Sanofi stock sinks 8% as amlitelimab meets trial goals but lags Dupixent efficacy

Investing.com -- Sanofi (EPA:SASY) shares fell more than 8% Thursday after the company said its experimental drug amlitelimab met the main goals of a late-stage trial in atopic dermatitis but showed lower efficacy than its blockbuster Dupixent.

The French drugmaker reported topline results from the Phase 3 COAST-1 study, which tested amlitelimab as a monotherapy in patients with moderate to severe atopic dermatitis. 

The trial met both primary endpoints at 24 weeks, showing statistically significant improvement in the Validated Investigator Global Assessment for Atopic Dermatitis, or vIGA-AD, and in the Eczema Area and Severity Index, or EASI-75, compared with placebo.

At week 24, vIGA-AD response rates were about 21% for patients receiving amlitelimab every four weeks and 23% for patients dosed every 12 weeks, compared with 9% for placebo. 

On the EASI-75 measure, amlitelimab achieved 36% for the four-week regimen and 39% for the 12-week regimen, versus roughly 19% for placebo.

Sanofi said efficacy continued to improve through week 24 without reaching a plateau. 

The company also reported that the safety profile was similar to placebo, with no differences in treatment-emergent adverse events, serious adverse events or discontinuations due to side effects.

Dupixent, which Sanofi co-markets with Regeneron, has shown a 44% to 51% benefit on the EASI-75 scale at week 16 in its pivotal trials. 

In a research note, Barclays analysts said that “lower efficacy relative to Dupixent is the sticking point, which likely limits commercial uptake to a moderate atopic dermatitis population who is willing to trade efficacy for convenience.”

The COAST-1 trial allowed enrollment of patients with an inadequate response to topical treatments or systemic therapies. 

Houman Ashrafian, head of Research and Development at Sanofi in an analyst call said it is fair to expect more variable results in atopic dermatitis studies since pivotal data for Dupixent was published nearly a decade ago, adding that new trials may include more complicated patient groups. 

Placebo responses in COAST-1 were higher than those seen in earlier Dupixent trials SOLO-1 and SOLO-2.

Sanofi said longer-term data from the ESTUARY study, which will assess maintenance of response through 48 weeks, are expected in 2026, along with results from two further late-stage trials, COAST-2 and SHORE.

Amlitelimab targets OX40 ligand, part of a drug class that has faced setbacks, including Amgen’s rocatinlimab, which underperformed in its Phase 3 HORIZON trial.

“With the AD market set to expand from $8bn today to c.$26bn by 2032 (MSe), and room for multiple blockbuster drugs, we see amlitelimab as positioned to serve as a differentiated 2L option following Dupixent failure or intolerance,” said analysts at Morgan Stanley research in a note.