FDA Accepts Vanda Pharmaceuticals’ BLA for Imsidolimab in Generalized Pustular Psoriasis

Vanda Pharmaceuticals announced that the US FDA has accepted the biologics license application (BLA) for imsidolimab for the treatment of generalized pustular psoriasis (GPP), a rare and potentially life-threatening inflammatory skin disease.¹ The FDA has assigned a Prescription Drug User Fee Act target action date of December 12, 2026.

Supporting Data

The BLA submission is supported by data from global clinical studies conducted across multiple regions, including the US, France, Spain, Poland, Turkey, Malaysia, Thailand, Georgia, Tunisia, Taiwan, and Morocco. The pivotal efficacy evidence comes from the GEMINI1 (NCT05352893) and GEMINI-2 (NCT05366855) trials, which evaluated imsidolimab in patients experiencing GPP flares. In these studies, a single intravenous dose of imsidolimab resulted in rapid clinical improvement, with 53% of treated patients achieving clear or almost clear skin, as measured by a Generalized Pustular Psoriasis Physician Global Assessment score of 0 or 1 at week 4. This response rate compared favorably with placebo, in which 13% of patients achieved the same end point.

Beyond rapid induction of response, the trials demonstrated the durability of the effect. Patients who continued on monthly maintenance dosing maintained disease control for approximately 2 years, with no reported flares in the active treatment arm during this period. These findings are notable given the relapsing and unpredictable nature of GPP and underscore the potential of IL-36 pathway inhibition to provide sustained disease suppression. Imsidolimab also demonstrated a favorable safety profile across studies. The incidence of treatment-emergent adverse events was acceptable in the context of a severe inflammatory disease, and the therapy was associated with a low rate of antidrug antibody development.

Addressing an Unmet Need

Although GPP is rare, prevalence estimates vary widely by geography, ranging from approximately 2 to more than 100 cases per million individuals worldwide, with higher prevalence reported in parts of Asia.² The disease burden is substantial, however, due to the severity of flares, frequent hospitalizations, and limited effectiveness of conventional therapies. As such, the acceptance of imsidolimab’s BLA is viewed as a meaningful step toward expanding targeted treatment options for this underserved patient population.

Imsidolimab is a fully humanized IgG4 monoclonal antibody designed to inhibit IL-36 receptor signaling, thereby directly targeting the pathway implicated in GPP pathogenesis. By blocking IL-36 receptor activation, imsidolimab is intended to restore inflammatory balance and rapidly suppress the cascade responsible for pustular flares. This mechanism represents a precision medicine approach aligned with the genetic and molecular understanding of the disease and differentiates imsidolimab from broader immunosuppressive strategies historically used to manage GPP. Imsidolimab’s BLA was submitted to the FDA in December 2025.³

Next Steps

Vanda holds exclusive global rights to develop and commercialize imsidolimab under a license from AnaptysBio. If approved, imsidolimab would represent Vanda’s third new drug approval within a 12-month period, following tradipitant (Nereus) for motion sickness and milsaperidone (Bysanti) for bipolar 1 disorder and schizophrenia, and would further strengthen the company’s immunology and orphan disease portfolio. Regulatory and patent exclusivity for imsidolimab is expected to extend into the late 2030s.

"The acceptance of the BLA filing for imsidolimab marks a critical milestone in our efforts to bring this innovative therapy to patients [with] GPP," Mihael H. Polymeropoulos, MD, president, CEO, and chairman of the board of Vanda Pharmaceuticals, said in the press release. "Imsidolimab builds on our growing expertise in rare orphan disorders and our anti-inflammatory portfolio. Imsidolimab represents a precision medicine approach targeting a disorder with a known genetic cause using a fully humanized monoclonal antibody against the IL-36 receptor. We look forward to potential FDA approval and leveraging our commercial infrastructure to address this debilitating condition."¹

References

1. Vanda Pharmaceuticals announces FDA acceptance of biologics license application filing for imsidolimab for the treatment of generalized pustular psoriasis. News release. Vanda Pharmaceuticals. February 25, 2026. Accessed February 25, 2026. https://www.prnewswire.com/news-releases/vanda-pharmaceuticals-announces-fda-acceptance-of-biologics-license-application-filing-for-imsidolimab-for-the-treatment-of-generalized-pustular-psoriasis-302696991.html

2. Prinz JC, Choon SE, Griffiths CEM, et al. Prevalence, comorbidities and mortality of generalized pustular psoriasis: a literature review. J Eur Acad Dermatol Venereol. 2023;37(2):256-273. doi:10.1111/jdv.18720

3. Vanda announces submission of biologics license application to the FDA for imsidolimab for the treatment of generalized pustular psoriasis. News release. Vanda Pharmaceuticals. December 15, 2025. Accessed February 25, 2026. https://www.prnewswire.com/news-releases/vanda-announces-submission-of-biologics-license-application-to-the-fda-for-imsidolimab-for-the-treatment-of-generalized-pustular-psoriasis-302641858.html