The efficacy and safety of second allogeneic hematopoietic stem cell transplantation

ABSTRACT

Background: Second allogeneic hematopoietic cell transplant (sAHCT) might be indicated following a graft failure or disease relapse after the first one;although it might emerge with high rates of morbidities and mortality. Currently, there is a limited number of publications on this matter in the literature, here we aimed to share our sAHCT experience from a single center. Methods: Data from 51 patients who were eligible for sAHCT between 2001 and 2021 was evaluated retrospectively. All data was obtained from the Ankara University Faculty of Medicine, Department of Hematology and Bone Marrow Transplant Unit. Results: 51 patients were included in the present study. Median age at sAHCT was 34 (18- 65) and female/ male ratio 19/ 32 (37.3% / 62.7%). The same donor from the first transplant was eligible for sAHCT for most patients (n= 46, 90.2 %). sAHCT indication was graft failure for 11 patients (21.6 %) whereas 40 (78.4 %) patient went on sAHCT for disease relapse. Patients' diagnoses were as follows acute myeloid leukemia (n= 26, 50.9 %), acute lymphoblastic leukemia (n=9, 17.6 %), myelodysplastic syndrome (n= 6, 11.8 %), aplastic anemia (n= 6, 11.8 %) and others (CMML, CML, biphenotypic leukemia). Median number of transplanted CD34+ hematopoietic cells was 5.77 x x106/ kg (1.11- 8.29). Stem cell source was either bone marrow (n= 5, 9.8%) or peripheral blood (n= 46, 90.2 %). Myeloablative conditioning regimens were used for most sAHCTs (n= 30, 58.8%). Median overall survival (OS) rates for graft failure and disease relapse groups were 12.8 and 18.7 months, respectively (p= 0.63). During early transplant phase, 20 patients (39.2 %) died due to bone marrow aplasia, transplant failure or other complications. 1 year OS of the entire cohort was 33.3 % whereas 2-y- OS was 21.6% (95% CI= 25-45). 2 patients (3.9 %) died due to COVID19 during transplant process. On univariate analysis, sex, time from the first transplant (<12 months/ ≥12 months), conditioning intensity, sAHCT indication did not statistically significantly influence OS. Multivariate analysis confirmed a lower ECOG score (<2) at sAHCT significantly increased OS (p= 0.001). Conclusions: Based on this single center study, sAHCT is an efficacious treatment modality especially for patients with lower ECOG scores. sAHCT may offer long term survival for both graft failure and disease relapse states.