Through week 104, 7 treatment-emergent serious adverse events were reported, of which 4 occurred between weeks 52 and 104. At week 104, clinical remission was reported in 14/25 (56%) patients in the darvadstrocel group and 6/15 (40%) patients in the control group.
All patients tolerated the mesenchymal stromal cell infusion well and no dose limiting toxicity was seen. Seven patients had serious adverse events of which five were hospitalisations for Crohn's disease flare. Two of these serious adverse events were possibly related to the mesenchymal stromal cells infusion. Five subjects showed clinical response 2 weeks after the infusion. Mesenchymal stromal cell phenotype, cytokine responsiveness, and peripheral blood mononuclear cell proliferation blockade were not different among the patients.
In the study, 15 patients showed a significant reduction in mean CDAI score from 370 to 203 at day 42 after MSC infusion, with scores decreasing after each infusion. 80% of patients had a clinical response, with 53% achieving clinical remission. 7 patients had endoscopic improvement, and one patient experienced a serious adverse event (2 dysplasia-associated lesions), which was unlikely caused by MSCs.
MSC injections were well tolerated but four hospitalisations for occlusion were reported. At W12, five patients presented a complete or partial resolution of the stricture [two complete and three partial]. Seven patients were re-evaluated at W48 [one dilated, one operated, and one lost to follow-up] and four patients had a complete resolution. The evolution of clinical scores between W0, W12, and W48 was not statistically significant.MSCs injection in CD stricture was well tolerated and may offer a benefit.