Trends in allogeneic hematopoietic cell transplantations - analysis of the activities of the transplantation center of the University Hospital Pilsen in the period 2001-2021.

Abstract

Allogeneic hematopoietic cell transplantation (alloHCT) is evolving both in terms of indications and execution. We retrospectively evaluated this evolution in 855 consecutive transplanted patients between 2001 and 2021 by comparing 3 7-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). There was a significant increase in the median age of patients over the study periods - 50 years (range 20-68) vs. 53 years (19-71) vs. 55 years (20-74), p<0,0001. Similarly, the proportion of patients ≥70 years increased from 0 in A to 23 (8 %) in C, p<0,0001. This reflects a decrease in the use of myeloablative regimens (43 % in period A vs. 24 %/28 % in periods B/C, p<0,0001). Changes in donor type were substantial, with an increase in haploidentical donors in period C: 27 % vs. 1 %/0 % in periods B/A (p<0,0001). Concurrently, the proportion of identical siblings decreased (41 % to 26 % and 9 % respectively, p<0,0001), while the proportion of unrelated donors remained stationary (60 % vs. 73 % vs. 64 %). Bone marrow as a source of hematopoietic cells increased from 11 % to 20 % in period B (p=0,0049), then became stationary (18 %, p=0.943). CNI/MTX as GVHD prophylaxis was the mainstay in all transplant types except haploidentical, where PTCY was used exclusively. However, the use of ATG has increased significantly (from 22 % to a recent 55 %, p<0,0001). In all periods, myeloid malignancies (AML/MDS/MPN) were the main indication, with a steady increase (39 % in period A vs. 62 % in period C, p<0,0001). On the other hand, CML and CLL showed a significant decrease (11 %, 4 % and 1 %, p<0,0001, respectively, 14 %, 13 % and 3 %, p<0,0001). The proportion of other indications - ALL, NHL, MM, MH, MPN - remained essentially the same with non-significant variations between periods (e.g. ALL 9 %, 13 % and 9 %, p=0,1608). The analysis documents a trend to transplant increasingly older patients and a predominance of unrelated or haploidentical transplants. Myeloid malignancies remain the dominant indication, but there has been a significant decline in CML and CLL.