AnaptysBio’s stuttering effort to rebuild its pipeline around imsidolimab has hit another setback. After flopping in palmoplantar pustulosis and acne, the anti-IL-36 receptor antagonist has failed to move the needle in the chronic skin disease hidradenitis suppurativa, leading the biotech to stop work on one indication and plan to out-license the asset.
Imsidolimab emerged as AnaptysBio’s top priority after the 2019 failure of etokimab in atopic dermatitis. The biotech took the candidate into phase 3 in generalized pustular psoriasis (GPP) earlier this year, albeit on the strength of an eight-patient midphase trial, but has struggled in other indications, following up the failure in acne and the rare inflammatory disorder palmoplantar pustulosis with another flop late Wednesday.
The phase 2b HARP clinical trial is the source of the latest setback. Investigators randomized 149 patients with moderate to severe hidradenitis suppurativa to receive one of two doses of imsidolimab or placebo subcutaneously each month.
After 16 weeks, the mean change in the inflammatory nodule and abscess count was no better in the treatment groups than the control arm, causing the trial to miss its primary endpoint. AnaptysBio saw mean count reductions of 5.9 and 4.1 in the high and low dose arms, respectively. However, the biotech also saw a 5.6 reduction in the placebo cohort.
Similarly, neither dose of imsidolimab outperformed placebo against a secondary endpoint that looked at the proportion of participants who had a clinical response. By that measure, both doses of the drug candidate beat placebo numerically, but the difference fell well short of statistical significance.
AnaptysBio responded to the flop by stopping development of imsidolimab in hidradenitis suppurativa. The action leaves GPP as the candidate’s last remaining active indication. Data from the phase 3 GPP trial are due in the fourth quarter of next year, but AnaptysBio has opted against taking the drug to market itself in the indication.
“While we remain optimistic that imsidolimab, an IL-36 receptor antagonist, can meaningfully impact the treatment of patients with GPP, as part of our ongoing strategic portfolio review we have made the decision to complete execution of our phase 3 program and outlicense imsidolimab prior to potential FDA approval,” Daniel Faga, interim president and CEO of AnaptysBio, said in a statement.
Offloading imsidolimab would leave AnaptysBio focused on anti-PD-1 and anti-BTLA candidates.