JJP Biologics has reported positive interim findings from its ongoing phase 1b study of nebaprubart (JJP‑1212) in patients with linear IgA disease, a rare autoantibody‑driven blistering disorder with no approved therapies in the European Union.
The company said the investigational anti‑CD89 antagonist showed a favourable safety and tolerability profile alongside rapid clinical activity.
Therapeutic effects were observed within one week of dosing, including reductions in blister formation and pruritus and progressive healing of ulcerative lesions. Patients were also able to taper dapsone‑based treatment after the first dose, with sustained responses following complete withdrawal.
LAD was selected as the company’s first autoimmune indication because IgA autoantibody deposits in the skin activate neutrophils via CD89, driving tissue damage and blistering. By blocking CD89 on neutrophils, nebaprubart is designed to interrupt this inflammatory pathway at its source.
Paweł Szczepański, Chief Executive Officer of JJP Biologics, said: “The interim Phase 1b results in LAD, together with our previously reported Phase I data in healthy volunteers, provide early validation of our approach targeting the IgA/CD89 axis.
“LAD is our proof-of-mechanism showcase, and these positive interim data demonstrate the potential of nebaprubart to deliver rapid, durable responses while reducing dependence on traditionally-administered immunosuppressive agents with known toxicities.
He added: “This positions nebaprubart as a potentially transformative therapy across a broad range of IgA-mediated diseases, and we look forward to commencing a Phase 1b trial of nebaprubart for rheumatoid arthritis in Q3 2026 and a Phase 2a basket study in IgA nephropathy in Q4 2026.”
Sohail Ahmed, MD, MBA, Chief Medical Officer, added: “The consistency between the safety profile observed in healthy volunteers and the early efficacy and tolerability signals seen in LAD patients is very encouraging.
“Our Phase Ib trial showed predictable pharmacology and no dose-limiting toxicities, reducing clinical development risk. In LAD, the tapering or elimination of other treatments that are difficult for some patients to tolerate is highly meaningful for this patient population.”
The open‑label phase 1b study is assessing safety, tolerability, pharmacokinetics, immunogenicity and exploratory efficacy measures including disease activity, blister formation and quality of life. Interim LAD results follow positive top‑line phase 1 data in healthy volunteers announced in January 2026.
