3740 - Initial Outcomes and Toxicity of TMI/TMLI before Allogeneic Stem Cell Transplantation
Presenter(s)
S. Wang, W. G. Cao, J. Y. Chen, Y. Han, J. X. Zhu, S. C. Shan, and G. Cai; Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
Purpose/Objective(s): Total body irradiation (TBI) continues to be an important part of the conditioning regimen for patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Total marrow irradiation (TMI) and total marrow and lymphoid irradiation (TMLI) have been evaluated as ways to deliver more targeted TBI, which offers the potential of greater dose homogeneity, and reduced toxicity. This study sought to demonstrate the early outcomes and toxicity after TMI/TMLI.
Materials/Methods: From May, 2023 to October, 2024, a total of 25 patients undergoing allo-HSCT with TMI/TMLI conditioning were retrospectively analyzed. The main underlying disease types were acute myeloid leukemia 40%, acute lymphoblastic leukemia 44%, myelodysplastic syndrome 8%, chronic myeloid leukemia 4% and aplastic anemia 4%. Among the 25 patients, 14 underwent TMI and 11underwent TMLI. 19 were male and 6 were female. Median age was 49 years (range 18-64). Median TMI dose was 12.0 Gy (3-12 Gy) delivered at 1.7 to 2.0 Gy once or twice per day. The Eastern Cooperative Oncology Group (ECOG) performance score was 0 to 1 in 13 patients and 2-3 in 12 patients. 8 (32%) patients had detectable marrow minimal residual disease (MRD) and 1 (4%) had detectable cerebrospinal fluid MRD just prior to TMI. Mean organ doses (Gy) were lung 5.9, kidneys 4.0, heart 5.2, parotid 7.1, stomach 6.0, lens 2.7 and bowel 6.8. Progression free survival (PFS), overall survival (OS), non-relapse mortality (NRM), graft versus host disease (GVHD), and toxicities were assessed.
Results: Median follow-up (range) for all patients was 8.3 (0.4-16.6) months and for patients alive at the time of last follow-up (n=20), 8.7 (2.83-16.6) months. The 1-year PFS and 1-year OS were 94.4% and 75.4%. The cumulative incidence (CI) of NRM at day+100 was 12.0% (n=4, causes of death: infection 1, GVHD 1, cerebral hemorrhage 1, and heart failure 1). Acute radiation-induced toxicity occurred in 9 patients (36%), most commonly were nausea (Gr1 n = 2, Gr2 n = 2), vomiting (Gr1 n = 1, Gr2 n = 2) and parotitis (Gr2 n = 2). No radiation-induced grade 3 or greater toxicity was noted. A total of 24 patients (96.0%) had neutrophil and platelet engrafted at a median of 13 (range, 10-20) and 13.5 (range, 10-30) days. CI of grade I acute GVHD was 52% whereas the CI of grade II was 12%. Grade III or higher acute GVHD was not seen whereas marrow relapse was seen in 1 patient (4%).
Conclusion: The use of TMI/TMLI in combination has good outcomes and seems to have been well tolerated in patients undergoing allo-HSCT.