Trends in allogeneic haematopoietic cell transplantation – analysis of the activity of the transplant centre at the University Hospital Plzeň in the period 2001– 2021

Allogeneic haematopoietic cell transplantation has evolved both in terms of indications and procedural execution. We retrospectively evaluated this development in 855 patients who underwent consecutive transplantation between 2001 and 2021 by comparing three seven-year time periods: 2001–2007 (N = 257, period/cohort A), 2008–2014 (N = 304, period/cohort B), and 2015–2021 (N = 294, period/cohort C). Over the observed periods, there was a significant increase in the median age of patients – from 50 years (range 20–68) to 53 years (19–71) and then to 55 years (20–74); P < 0.0001. Similarly, the proportion of patients aged ≥ 70 years increased from 0 in cohort A to 23 (8%) in cohort C; P < 0.0001. This reflects a decline in the use of myeloablative conditioning regimens (43% in A compared to 24%/28% in B/C; P < 0.0001). There were significant changes in donor types, with an increase in haploidentical donors in period C: 27% compared to 1%/0% in B/A (P < 0.0001). At the same time, the proportion of matched sibling donors declined (from 41% to 26%, and then 9%; P < 0.0001), while the proportion of unrelated donors remained stable (60% vs. 73% vs. 64%). The use of bone marrow as a source of haematopoietic cells increased from 11% to 20% in cohort B (P = 0.0049) and then remained stable (18%; P = 0.943). Calcineurin inhibitor/metotrexate was the standard GVHD prophylaxis for all transplant types, except for haploidentical transplants, where post-transplant cyclophosphamide was exclusively used. The use of anti-thymocyte globulin increased significantly (from 22% to a recent 55%; P < 0.0001). Throughout all periods, myeloid malignancies (AML/MDS/MPN) remained the primary indication for transplantation, with their proportion steadily increasing (39% in A vs. 62% in C; P < 0.0001). In contrast, CML and CLL showed a significant decline (11%, 4%, and 1%; P < 0.0001, respectively 14%, 13%, and 3%; P < 0.0001). The proportions of other indications – ALL, NHL, MM, HL, MPN – remained stable with no significant fluctuations (e. g., ALL 9%, 13%, and 9%; P = 0.1608). This analysis highlights the trend towards transplanting increasingly older patients and the predominance of unrelated and haploidentical transplantations. Myeloid malignancies remain the dominant indication for transplantation.