A phase 3 randomized trial comparing inolimomab vs usual care in steroid-resistant acute GVHD.

Treatment of steroid resistant (SR) aGVHD remains an unmet clinical need. Inolimomab, a monoclonal antibody to CD25, has shown encouraging results in phase II trials. This phase III randomized, open-label, multicenter compared Inolimomab vs. usual care in adult patients with steroid-refractory aGvHD. Patients were randomized to treatment with Inolimomab or usual care [control group were all treated with Anti Thymocyte Globulin (ATG)]. The primary objective was to evaluate overall survival at 1 year without changing baseline allocated therapy. A total of 100 patients were randomized; 49 patients in the Inolimomab arm and 51 patients in the ATG arm. The primary criteria was reached by 14 patients (28.5%) in Inolimomab and 11 patients (21.5%) in the ATG arm, with a hazard ratio of 0,874 ( P =0.28). With a minimum follow-up of 1 year, 26 (53%) and 31 (60%) patients died in the Inolimomab and ATG arms, respectively. Adverse events were similar in the two arms, with fewer viral infections in the Inolimomab arm compared to the ATG arm. The primary endpoint of this randomized phase III trial was not achieved. The lack of a statistically significant effect confirms the need for development of more effective treatments for acute GvHD. This trial is registered to https://www.clinicaltrialsregister.eu/ctr-search/search as EUDRACT 2007-005009-24.