ABSTRACT NUMBER: ESOC2026A2491 LONG-TERM SAFETY OUTCOMES AFTER INTRA-ARTERIAL BONE MARROW-DERIVED MONONUCLEAR CELL THERAPY IN ACUTE ISCHEMIC STROKE: A SUBSTUDY OF THE IBIS TRIAL

Abstract Background and aims Bone marrow mononuclear cell (BM-MNC) intra-arterial transplantation has emerged as a promising stroke therapy. While short-term safety and potential neurorestorative effects have been reported, evidence regarding long-term functional outcomes remains limited. Our aim was to evaluate the effect of BM-MNC therapy on long-term functional outcome. Methods The IBIS trial was a multicentre phase IIb, randomized, controlled, investigator-initiated, assessor-blinded, clinical trial, in four stroke centres in Spain. Patients were randomized 2:1:1 to control group or intra-arterial BM-MNC transplantation (2x106 per kilogram or 5x106 per kilogram). In the present analysis, long-term safety was evaluated using the odds of achieving good functional outcome at 2 years, defined as a modified Rankin Scale (mRS) score of 0–2 and a Barthel Index (BI) score >90. Longitudinal mixed-effects logistic regression models were used to estimate treatment effects over time while accounting for within-subject correlation. Results At two years follow-up, from the primary cohort (n=77 patients), data were available for 67 and 60 patients for mRS and BI, respectively. The odds of achieving good functional outcome were similar between groups (OR 0.73, 95% CI 0.23–1.92; OR 1.02, 95% CI 0.37-2.83, for mRS and BI, respectively). Mixed-effects models showed no significant treatment-by-time interaction, indicating no evidence of delayed functional deterioration associated with cell therapy. Results were consistent across intention-to-treat and per-protocol analyses. Conclusions In this longitudinal substudy of BIS trial, intra-arterial BM-MNC therapy was not associated with delayed functional deterioration up to 2 years after AIS. These findings support the long-term safety of intra-arterial cell therapy. Conflict of interest All authors declare that we have no conflicts of interest.