(1) Background: Refractory acute graft-versus-host disease (R-aGvHD) remains a leading cause of death after allogeneic stem cell transplantation. Survival rates of 15% after four years are currently achieved; deaths are only in part due to aGvHD itself, but mostly due to adverse effects of R-aGvHD treatment with immunosuppressive agents as these predispose patients to opportunistic infections and loss of graft-versus-leukemia surveillance resulting in relapse. Mesenchymal stromal cells (MSC) from different tissues and those generated by various protocols have been proposed as a remedy for R-aGvHD but the enthusiasm raised by initial reports has not been ubiquitously reproduced. (2) Methods: We previously reported on a unique MSC product, which was generated from pooled bone marrow mononuclear cells of multiple third-party donors. The products showed dose-to-dose equipotency and greater immunosuppressive capacity than individually expanded MSCs from the same donors. This product, MSC-FFM, has entered clinical routine in Germany where it is licensed with a national hospital exemption authorization. We previously reported satisfying initial clinical outcomes, which we are now updating. The data were collected in our post-approval pharmacovigilance program, i.e., this is not a clinical study and the data is high-level and non-monitored. (3) Results: Follow-up for 92 recipients of MSC-FFM was reported, 88 with GvHD ≥°III, one-third only steroid-refractory and two-thirds therapy resistant (refractory to steroids plus ≥2 additional lines of treatment). A median of three doses of MSC-FFM was administered without apparent toxicity. Overall response rates were 82% and 81% at the first and last evaluation, respectively. At six months, the estimated overall survival was 64%, while the cumulative incidence of death from underlying disease was 3%. (4) Conclusions: MSC-FFM promises to be a safe and efficient treatment for severe R-aGvHD.

Posttransplant cyclophosphamide (PTCy) is a promising graft-versus-host disease (GVHD) prophylaxis in haploidentical and matched unrelated donor hematopoietic stem cell transplantation (HSCT), but its role in matched sibling donor (MSD) transplants remains unclear. We conducted a retrospective study of 413 MSD-HSCT patients receiving peripheral blood stem cell (PBSC) grafts from January 2010 to January 2023. Patients were categorized into 4 groups: group I (calcineurin inhibitor [CNI] + methotrexate [MTX] or mycophenolate mofetil [MMF]), group II (CNI + MTX or MMF + antithymocyte globulin [ATG]), group III (PTCy + ATG + CNI), and group IV (PTCy + CNI + MMF). PTCy was associated with a significant reduction in grade 2- 4 and grade 3-4 acute GVHD and moderate-to-severe chronic GVHD compared with CNI + MTX (or MMF)–containing regimens. PTCy did not increase relapse risk; PTCy reduced nonrelapse mortality, leading to improved GVHD-free/relapse-free survival (GRFS; Hazard Ratio, 0.4; P < .001). PTCy was also associated with improved overall survival. Bloodstream infections were increased with PTCy. The addition of ATG to PTCy did not further improve GRFS and was associated with a higher incidence of clinically significant cytomegalovirus (csCMV) and Epstein-Barr virus (csEBV) reactivation and a numerical increase in NRM. PTCy significantly appeared to improve GRFS in the MSD setting using PBSC grafts. The addition of ATG to PTCy increases csCMV and csEBV reactivation without further improving GRFS. Prospective trials and PTCy dose optimization are warranted.

Although ruxolitinib is emerging as the treatment of choice for steroid-refractory or -dependent chronic graft versus host disease (cGVHD) based on randomized control trial data, there is relatively little real-world data published on ruxolitinib for this indication. We wanted to evaluate the real-world efficacy and safety of ruxolitinib in cGVHD patients who have failed any previous systemic therapy for cGVHD. We retrospectively evaluated the efficacy of ruxolitinib in 115 heavily pretreated patients with steroid-refractory or -dependent chronic GVHD across 5 transplantation centers. The majority of the study population had severe cGVHD (60%) and received ruxolitinib at the fourth treatment line or beyond (82%, n = 96). The median duration of follow-up in this study population was 13 months. The overall response rate (ORR) was 48.6%, 54.9%, and 48.5% at 3, 6, and 12 months, respectively. Clinical benefit (an outcome metric combining ORR with steroid reduction) was observed in 58.7%, 64.8%, and 60.6% of patients at 3, 6, and 12 months, respectively. Approximately one third of patients (37.9%) were able to discontinue prednisone at 12 months, and 63.8% were able to taper prednisone to a daily dose <0.1 mg/kg at 12 months. Failure-free survival at 12 months was 64.6% (54.1%-73.2%). Multivariate analysis identified that patients with severe cGVHD were at a higher risk of failure because of a therapy switch, whereas a pretransplantation hematopoietic stem cell transplantation-comorbidity index score ≥ 3 was associated with a high risk of failure because of increasing risk of non-relapse mortality. Overall, this study demonstrates the therapeutic efficacy of ruxolitinib for cGVHD in a heavily pretreated real-world population.

Background: Blinatumomab, a bispecific monoclonal antibody, effectively controls refractory B cell acute lymphoblastic leukemia (ALL) and promotes measurable residual disease (MRD) negativity. This study investigated the impact of pretransplant blinatumomab on allogeneic hematopoietic cell transplantation (HCT) outcomes in B cell ALL patients. Methods: We analyzed the effect of pretransplant blinatumomab on transplant outcomes of 117 adults undergoing allogeneic HCT for B cell ALL at Princess Margaret Hospital, Toronto, between 2010 and 2021. Outcomes assessed included overall survival (OS), graft-versus-host disease and relapse-free survival (GRFS), cumulative incidences of relapse (CIR), and nonrelapse mortality (NRM). Results: The median follow-up was 36 months. Thirty-one participants (26.5%) received blinatumomab. Blinatumomab group had higher proportions of individuals with high disease risk index, primary induction failure and was more likely to receive dual T cell depletion with antithymocyte globulin and post-transplant cyclophosphamide. Two-year OS, GRFS, NRM, and CIR in the blinatumomab and nonblinatumomab groups were, respectively: 65.4% versus 45.6% (P = .05), 42.2% versus 17.3% (P = .01), 3.2% versus 43.0% (P = .007) and 34.4% versus 14.4% (P = .02). Blinatumomab was associated with a lower incidence of day-100 grade 2 to 4 and grade 3 to 4 acute graft-versus-host disease (aGVHD): 27.5% versus 56.7% (P = .009), and 10.9% versus 34.7% (P = .04), respectively. Multivariate analysis confirmed the association between pretransplant blinatumomab and improved OS and NRM. Conclusions: Pretransplant blinatumomab is associated with improved OS and lower risk of NRM in B cell ALL patients undergoing allogeneic HCT, likely reflecting lower burden of treatment-related toxicity in this population. Larger prospective trials are warranted to validate our findings.