Brisk Elevation of Serum Lactate Dehydrogenase During G-CSF Priming Is a Significant Predictor for the Ensuing Successful Autologous Peripheral Blood Stem Cell Collection

Autologous stem cell transplantation plays a critical role in the management of patients with hematologic malignancies such as multiple myeloma and malignant lymphoma. The minimum number of CD34 positive cells required for transplantation is believed to be 2.0×10⁶ cells/kg. Up to 20% of the patients, however, fail to reach the number after a single collection attempt and require multiple aphereses to obtain a sufficient number of stem cells. To predict the outcome of mobilization, several pre-mobilization factors have been investigated, including peripheral blood CD34+ cell count at the time of harvest, but little is as yet known about the significance of serum lactate dehydrogenase (LDH). We, therefore, sought to evaluate the predictive potential of serum LDH for the autologous stem cell yield. Peripheral blood stem cell mobilization attempts were made from April 2002 to March 2012 for 55 consecutive patients of hematologic disorders. Primary diagnosis of our patients and their mobilization chemotherapy regimens are shown in Table 1. All patient received G-CSF (filgrastim 400μg/sq/day or lenograstim 10μg/kg/day subcutaneously). None was mobilized with G-CSF alone. Aphereses were repeated until the total stem cell yield exceeded 2×10⁶cells/kg, for maximum 3 consecutive days. Forty-four patients successfully produced the sufficient number of stem cells, while 11 patients failed (poor mobilizer). Between the two groups, there were no significant differences in pre-mobilization WBC counts and serum LDH levels. However, the ratio of the LDH level immediately before apheresis to the lowest one (“LDH-ratio”) were significantly lower in poor mobilizers than good mobilizers. Our ROC analysis showed that the cut-off value of “LDH-ratio” was 1.75. An elevation of serum LDH levels to reach “LDH-ratio”>1.75 were found to be a useful predictive factor for successful CD34+ stem cell collection. The delay in reaching “LDH-ratio”>1.75 may suggest that we should modify the mobilization regimen by, for instance, adding prelixafor.

 

Table 1     Pts’ characteristics
No. of Patients	55
Median age (range)	56(35-69)
Gender, male (%)	31(56)
Primary Disease
MM	19
NHL	26
HL	4
Others	6
Median WBC counts ×103/μL (range)	2.1(1.5-3.2)
Median LDH Level IU/L (range)	196(145-445)
PBSC mobilization regimen
ESHAP	27
HD-CY	22
G-CSF alone	0
Others	6
MM: multiple myeloma, NHL: non-hodgkin lymphoma, HL: hodgkin lymphoma, HD-CY: high dose cyclophosphamide