Vanda Pharmaceuticals Advances Imsidolimab for Generalized Pustular Psoriasis as FDA Accepts BLA Filing
Washington, D.C.-based Vanda Pharmaceuticals Inc. (Nasdaq: VNDA) announced on February 25, 2026, that the US FDA has accepted its Biologics License Application for imsidolimab, a fully humanized IgG4 monoclonal antibody targeting the interleukin-36 receptor (IL-36R), for the treatment of generalized pustular psoriasis (GPP) in adults. The US FDA assigned a target action date of December 12, 2026. Vanda holds an exclusive global license for the development and commercialization of imsidolimab from San Diego-based AnaptysBio, Inc. (Nasdaq: ANAB), covering worldwide rights across all territories. If approved, imsidolimab would become the third new product approved for Vanda in the past 12 months, following NEREUS (tradipitant) and BYSANTI (milsaperidone).
Financial terms of the Vanda Pharmaceuticals imsidolimab license were not disclosed in the BLA acceptance announcement. According to the original deal announcement from February 2025, Vanda paid AnaptysBio USD 10 million upfront plus USD 5 million for existing drug supply, totaling USD 15 million in initial payments. Vanda is also obligated to pay tiered royalties on net sales and additional regulatory and commercial milestone payments, the full amounts of which have not been publicly disclosed. Regulatory and patent exclusivity for imsidolimab is expected to extend into the late 2030s.
Deal Context
Imsidolimab (formerly ANB019) is a fully humanized IgG4 monoclonal antibody that inhibits IL-36 receptor signaling. GPP is a rare, chronic, life-threatening autoinflammatory skin disorder characterized by sudden flares of widespread pustules, erythema, and systemic symptoms including fever and fatigue. The molecular etiology of GPP is primarily attributed to excessive activity of the IL-36 pathway, with the majority of genetically characterized GPP cases linked to variants in the IL36RN gene encoding the IL-36 receptor antagonist (OMIM #614204).
The FDA biologics license application for imsidolimab is supported by data from the GEMINI-1 and GEMINI-2 pivotal Phase 3 studies, which were conducted across 11 countries including the United States, France, Spain, Poland, Turkey, Malaysia, Thailand, Georgia, Tunisia, Taiwan, and Morocco. In the pivotal efficacy studies, a single intravenous dose of imsidolimab led to 53% of patients achieving clear or almost clear skin (GPPPGA 0/1) at Week 4, compared to 13% on placebo. Efficacy was maintained through an approximately two-year maintenance period with monthly dosing, and no flares occurred in the active treatment arm. A long-term extension study evaluating safety and efficacy has since been terminated.
The imsidolimab BLA FDA filing represents a new therapeutic area for Vanda Pharmaceuticals, which has historically concentrated on neuroscience products including HETLIOZ (tasimelteon) for Non-24-Hour Sleep-Wake Disorder and Fanapt (iloperidone) for schizophrenia. The company's recent approvals of tradipitant and milsaperidone preceded this filing, and the imsidolimab license from AnaptysBio constitutes Vanda's entry into rare inflammatory dermatology. The February 2025 agreement is the first transaction between the two companies; AnaptysBio's most notable prior partnership has been with GSK, from which the PD-1 antibody Jemperli (dostarlimab) was discovered.
For AnaptysBio, the out-licensing of imsidolimab followed a strategic decision to divest the GPP asset after completing Phase 3 development. AnaptysBio retains eligibility for milestone and royalty payments but has transferred all development and commercialization responsibilities to Vanda.