Sanofi stock plummeted Thursday after the company's experimental eczema drug proved meaningfully inferior to Dupixent, a blockbuster drug Sanofi codeveloped with Regeneron Pharmaceuticals.
Sanofi tested its new drug, amlitelimab, for six months. Amlitelimab met the study's requirements after 24 weeks, but the treatment's effectiveness lagged Dupixent's at 16 weeks. This was "the bar for compelling results," Leerink Partners analyst David Risinger said in a report.
The company tested two dosing regimens. In the group that received amlitelimab every four weeks, 17% more experienced at least a 75% reduction in symptoms compared to the placebo. The second group received shots every 12 weeks and had a 20% placebo-adjusted reduction in symptoms.
But the results lagged Dupixent where 32% to 36% of patients met the same bar after 16 weeks.
"Despite the underwhelming efficacy, it is possible that amlitelimab could find a role in 2L (second treatment option) settings, particularly given the novel mechanism of action and convenience of Q12W (every 12 weeks) dosing," Risinger said.
But on today's stock market, Sanofi stock toppled 9.1%, closing at 45.33.
Can The OX40 Drug Class Survive?
Amlitelimab works by targeting the OX40 ligand, a key immune regulator. Analysts compared it to Dupixent and Eli Lilly's Ebglyss, which block specific interleukins to improve the symptoms of eczema, or atopic dermatitis.
Leerink analyst Faisal Khurshid noted 34% to 43% more of the Ebglyss recipients, in pivotal testing, showed at least a 75% improvement in symptoms compared to the placebo group. That also easily outperformed the results for Sanofi's amlitelimab.
"Based on the competitive nature of the AD (eczema) market and entrenchment of current treatment approaches, we think it may be difficult for OX40's to carve out a meaningful place within the treatment paradigm," Khurshid said in a client note.
It's promising that the every-12-weeks dose of amlitelimab patients showed improved effectiveness. This suggests "the drug may be well positioned for longer dosing, which could help it find a niche," he said. Many eczema drugs are given every two or four weeks.
This story has been updated to correct the effectiveness of Ebglyss.
Follow Allison Gatlin on X/Twitter at @AGatlin_IBD.
