MoonLake Immunotherapeutics nearly wiped its stock off the map Monday after the company posted mixed results for its highly anticipated skin disease treatment, sonelokimab.
The company tested sonelokimab in patients with hidradenitis suppurativa, or HS. In this condition, the skin became inflamed, causing painful lesions and scarring. But only one of the final-phase studies met its goal, MoonLake Immunotherapeutics said over the weekend.
MoonLake hoped to show improvement on a scale called the HiSCR75, which defines treatment success as at least a 75% reduction in inflammatory lesions. In one study, sonelokimab topped the placebo by 17%. In the second, 35.9% of sonelokimab recipients met this bar vs. 25.6% of placebo recipients.
In both cases, investors expected at least a 20% difference between the sonelokimab group and patients given a placebo.
"We view these results as clearly disappointing — arguably falling into the worst case outcome," Leerink Partners analyst Thomas Smith said in a report Sunday. "We expect significant weakness in MLTX shares tomorrow."
On today's stock market, MoonLake Immunotherapeutics shares crashed 89.9%, closing at 6.24. The news was a boon for Oruka Therapeutics, which is also working on an HS treatment. Oruka stock jumped 26.9% to 19.29.
Comparing To UCB
Analysts compared MoonLake's results to UCB's Bimzelx, an approved treatment for HS.
"Despite the mixed results, SLK appears similar on lesions to BIMZELX, but better on patient reported outcomes, safety and convenience that could still support commercial differentiation with (key opinion leader) support over time," Oppenheimer analyst Andreas Argyrides said in a client note.
He rates MoonLake Immunotherapeutics shares an outperform, but says his model is under review.
But Leerink's Smith notes Bimzelx led to a 15% to 20% improvement over the placebo on the HiSCR75 scale and, in ad hoc testing, was even better at about 22%.
Now, the regulatory path forward is uncertain for sonelokimab, Needham analyst Serge Belanger said in a report. He questioned how sonelokimab will do in current testing in psoriatic arthritis. Results from that study are due in the first half of 2026.
He noted MoonLake may need to run an additional Phase 3 study to seek approval for its HS drug.
Follow Allison Gatlin on X/Twitter at @AGatlin_IBD.
