Importance of CFU-GM number for prediction of hematological reconstitution after low CD34+ cell dose autotransplantation in children

Summary

Objective

The insufficiency of CD34⁺ cell numbers at the time of peripheral blood stem cell (PBSC) collection is frequently observed in children after multiple blocks of chemotherapy.

Aim

To detect the additional parameter of transplant quality for the prediction of successful hematological reconstitution after auto-PBSC transplantation with low doses of CD34⁺ cells in graft.

Methods

Forty-one children with malignances – who had received CD34⁺cells/kg <2х10⁶ – were included in our study evaluating the correlations between CD34⁺cell/kg and CFU-GM/kg at different dose levels ≥2х10⁵/kg and <2х10⁵/kg and the time of hematopoietic recovery. A Mann-Whitney U test and multivariate correlation method were used to evaluate the importance of each graft parameter for the prediction of engraftment.

Results

There was no correlation between CD34⁺ cell dose and the time of engraftment in these pts. A high level of correlation was detected between the number of CFU-GM/kg infused and the time of  neutrophil (r=-0.67, p<0.05), platelet (r=-0.3, p<0.05), and/or first reticulocyte ›2‰ (r=-0.66, p<0.05) reconstitution. Infusion of CFU-GM/kg ≥2х10⁵/kg (n=26) resulted in rapid short–term neutrophil >0.5x10⁹/l and platelet >20x10⁹/l recovery (10 days (5–13) and 22 days (8–57), respectively) compared with CFU-GM/kg <2х10⁵/kg (n=15) (13 days (11–21) and 25 days (10–95), respectively) (p<0.05).

Long-term hematopoietic recovery platelet counts >50x10⁹/l were 31 days (range: 9–81) in CFU–GM/kg ≥2х10⁵/kg infusion.

We conclude that the number of CFU-GM/kg was the most important parameter for predicting the auto-PBSC with CD34⁺ cell dose <2x10⁶/kg engraftment. The minimal recommended number of CFU-GM is 2x10⁵/kg for the efficacy of hematopoietic recovery after auto-PBSCT.

Keywords

autotransplantation, CFU-GM, insufficiency of CD34⁺ cells, engraftment