Imsidolimab

A U.S. database study estimated adult GPP prevalence at 150 cases per million persons, while noting that this may underestimate prevalence. A mortality meta-analysis reported all-cause mortality 1.78 times higher in GPP than in plaque psoriasis. In one patient-reported burden study, nine participants (50%) had Dermatology Life Quality Index scores indicating a moderate to extremely large impact on quality of life. U.S. economic evidence reported per-patient-per-month cost ratios of 1.36 versus plaque psoriasis and 5.58 versus controls.

In GEMINI-1, GPPPGA scores of 0 or 1 at week 4 were achieved by 8 of 15 participants (53%) receiving 300 mg IV imsidolimab, 8 of 15 participants (53%) receiving 750 mg IV imsidolimab, and 2 of 15 participants (13%) receiving placebo. The publication reported P=0.023 for each imsidolimab comparison with placebo.

In the reported GEMINI-2 randomized maintenance comparison, 8 of 8 participants receiving imsidolimab and 2 of 8 receiving placebo maintained a GPPPGA score of 0 or 1. No participants receiving imsidolimab and 5 of 8 receiving placebo experienced a flare. The poster reported that no serious adverse events led to study treatment discontinuation or withdrawal. Separately, the phase 2 GALLOP publication reported serious adverse events in two participants and no deaths.

The Dutch horizon scan lists an expected annual cost below €16,500 per patient, while stating that the price is not yet known and that costs may be comparable to spesolimab. This estimate should not be treated as an announced acquisition price or as the results of an imsidolimab budget impact model.

Imsidolimab has randomized placebo-controlled evidence for acute-flare treatment, while the reported randomized maintenance comparison comprises 16 initial responders. The regulatory update included in this report describes the BLA as under FDA review with a target action date of December 12, 2026. The trial regimens are investigational rather than approved prescribing instructions.