Phase II Multicenter, Randomized Controlled Study on Infusion of MSCs at 45 Days after Haplo-Hematopoietic Stem Cell Transplantation in the Prophylaxis of Gvhd

Background: Haploidentical hematopoietic stem-cell transplantation (haplo-HSCT) has successfully solved the problem of donor shortness. However, the increased risk of GVHD and the increased incidence of relapse after the administration of immune depressors for GVHD treatment have significantly influenced the quality of life of patients. Therefore, to prevent GVHD in patients who received haplo-HSCT, we designed a clinical trial that evaluated repeated infusions of UC-MSCs from day 45 after haplo-HSCT to prevent GVHD.

Methods: A total of 148 qualified subjects aged between 18 and 60 with haplo-HSCT in five transplant centers in the Midwest of China were enrolled and randomly assigned equally into the MSC group and the control group. The patients in the MSC group received 4 rounds of UC-MSC infusions (1×106 cells/kg every two weeks from 45 days after transplantation) and a regular GVHD prophylaxis regimen, while the patients in the control group received only a regular GVHD prophylaxis regimen. The incidence and severity of cGVHD was the primary endpoint, and the incidence and severity of aGVHD, GVHD-free and relapse-free survival (GRFS), cumulative relapse rate, overall survival (OS), progression-free survival (PFS) and transplantation complications were recorded to measure the efficacy of MSCs in GVHD prophylaxis.

Results: The overall incidence of cGVHD was 27% after MSC infusion and 43.2% in the control group (P=0.0388). The incidences of severe cGVHD and III-IV aGVHD in the patients in the MSC group were significantly decreased to 5.4% and 2.7%, respectively, while that in the control group they were 17.5% and 13.5%, respectively (P=0.0096 and P=0.0094). There was no significant difference in the cumulative relapse rate, OS or PFS between the two groups (P=0.6481, P=0.1980 and P= 0.3346).

Conclusion: In this trial, we indicated that early repeated infusions of UC-MSCs effectively decreased the incidence and severity of cGVHD, and the incidence and severity of aGVHD manifested as an improved GRFS rate for patients after haplo-HSCT. Therefore, MSC infusion is an effective GVHD prophylaxis method after haplo-HSCT.

No relevant conflicts of interest to declare.