Iptacopan for Immune Thrombocytopenia and Cold Agglutinin Disease: A Global Phase 2 Basket Clinical Trial

Iptacopan is a first-in-class, oral, selective inhibitor of complement factor B that has demonstrated positive efficacy across several complement-driven diseases. Here we evaluate the efficacy and safety of iptacopan monotherapy in adult patients with primary immune thrombocytopenia (ITP) and primary cold agglutinin disease (CAD). We performed a global, multicenter, phase 2 basket study enrolling patients with primary ITP or CAD after failure of ≥ 1 unique prior therapies. Primary endpoints were platelet response (≥ 50 × 10⁹/L) for ITP and hemoglobin response (≥ 1.5 g/dL increase) for CAD sustained for ≥ 2 consecutive weeks during the first 12 weeks of iptacopan treatment, without the use of rescue therapy. Other endpoints included time to first response, duration of response, pharmacokinetics, safety/tolerability, and FACIT-Fatigue. Nineteen patients were treated with iptacopan (9 ITP, 10 CAD). Among patients with CAD, most showed improvements in hemoglobin levels, with a mean increase of 2.2 g/dL from baseline to week 12; five (50%) patients achieved the primary endpoint. Improvements were also observed for other outcomes in CAD, including lactate dehydrogenase, bilirubin, reticulocytes, and FACIT-Fatigue. Conversely, no patients with ITP met the primary endpoint. Most treatment-emergent adverse events (TEAEs) were mild, the most common being headache (21%), asthenia (16%), fatigue (16%), and petechiae (16%). Iptacopan monotherapy demonstrated encouraging preliminary efficacy in primary CAD, while no protocol-defined responses were observed in primary ITP. Iptacopan may represent a promising oral option for CAD and was well tolerated in both ITP and CAD with no unexpected safety signals. Trial Registration: ClinicalTrials.gov identifier: NCT05086744.