Will the FDA approve imsidolimab for generalized pustular psoriasis?
deadline 2026-12-12
confidence medium
tier 4 evidence
48%PolySignal estimate
⚠ Evidence cap applied: the model proposed 55%, brought back to 48% for lack of sources solid enough to justify the departure from the base rate.
Resolution criterion
Resolves YES if the FDA publishes an approval (Drugs@FDA or an official Vanda Pharmaceuticals press release) for imsidolimab in generalized pustular psoriasis (GPP) on or before 12 December 2026. A complete response letter, a postponement of the PDUFA date, or the absence of a decision count as no.
Verified starting state
BLA accepted, target action date 12 December 2026. GPP flares can be life-threatening (sepsis-like systemic inflammation, organ failure); an IL-36 receptor antagonist of the same mechanism class (spesolimab) is already approved for this indication. (Vanda Pharmaceuticals press release, 25 February 2026)
What pushes it up
- The drug's mechanism of action (IL-36 receptor antagonist) is already validated by the FDA approval of spesolimab for the same indication [starting state].
- Positive Phase 3 efficacy and safety data for imsidolimab in GPP was published in NEJM Evidence in April 2026 [tier 4, article 4].
- The European Commission granted orphan drug designation to imsidolimab for GPP in August 2026, reflecting international recognition of its potential [tier 4, article 0].
What pushes it down
- The resolution criteria are highly restrictive, meaning any postponement of the PDUFA target action date of December 12, 2026, or a Complete Response Letter (CRL) will result in a negative resolution [starting state].
- First-cycle reviews have a historically high rate of delays or non-approvals, with a base rate of only 40% [starting state].
What would move this number most
Whether the FDA will raise manufacturing (CMC) concerns or require additional analyses that could trigger a PDUFA date extension or a Complete Response Letter.
How this number is built
| Deadline | 2026-12-12 |
| Base rate | 40% |
| Best evidence | tier 4 · 2 article(s) used |
| Independent runs | 48 · 48 (spread 0 pts) |
| Confidence | medium |
| Evidence cap | applied: 55% brought back to 48% |
| Last revised | 2026-09-22 09:06 |
| Model | gemini-3.5-flash |
Sources consulted