Higher Incidence of Relapse with Higher Doses of CD34+ Cells From Leukapheresis Products Infused in Adults with Acute Myelocytic Leukemia Autografted During the First Remission.

The cell source for autologous stem cell transplantation has shifted from bone marrow (BM) to peripheral blood (PB). For patients with AML in CR1, we previously showed that the risk of relapse was greater with PB than BM and a poorer outcome was associated with a shorter interval from CR1 to PB transplantation (≦80 days) (JCO 2009 in press).

Leukemic and normal progenitors bear the CD34+ antigen and can be mobilized together; we questioned whether there was a relation linking the doses of CD34+ cells infused to the outcome.

Out of 1262 patients autografted with PB more than 80 days post CR1 and reported to the EBMT registry using MEDB form, the dose of CD34+ cells infused was available in 772.

The CD34+ cell doses were categorized by percentiles to divide the whole group into five categories containing the same number of patients . We identified the fifth percentile (> 7.16 × 10⁶/kg) as the cut off point for Relapse Incidence (RI) and Leukemia-Free survival (LFS). Patients receiving the highest dose had a higher RI (57+/-4%, vs. 44+/-2%; p=0.008) and a lower LFS (34+/-4% vs. 49+/-2%; p=0.007).

In a multivariate analysis adjusted for differences, RI was higher in patients receiving the highest CD34+ cell dose ((hazard ratio [HR], 1.48; 95% CI, 1.12-1.95; p = 0.005).and the LFS was worse (HR, 0.72; 95% CI, 0.55-0.93; p = 0.01).

For patients with AML in CR1 autografted with PB, risk of relapse is greater and LFS is lower in those receiving the highest doses of CD34+ cells.

No relevant conflicts of interest to declare.