Outcome of hematopoietic stem cell transplantation is similar for patients with a partial in vitro T-cell-depleted graft compared with a non-T-cell-depleted graft when stratified by the refined disease risk index.

Comparisons of hematopoietic stem cell transplantation (HSCT) methods in retrospective studies are often hampered by the heterogeneity of comparison groups. The refined disease risk index (DRI) is a potentially interesting tool to compare HSCT protocols as it is based on the disease type and burden at transplant and stratifies patients into four prognostic groups for overall survival (OS). We included 265 patients with partial T-cell-depleted graft (TDEP) and 163 non-TDEP patients in a retrospective study and compared outcomes following stratification using the refined DRI. The 2-year OS rate for TDEP patients was 81.6, 60.9 and 43.3% for the low-, intermediate- and high-risk groups, respectively (P<0.001). For non-TDEP patients, the 2-year OS rate was 62.9, 48.8, 44.2 and 7.6% for the low-, intermediate-, high- and very-high-risk groups, respectively (P<0.001). There was no significant difference when comparing OS between TDEP and non-TDEP for the low-, intermediate- and high-risk groups, but TDEP patients had less acute GvHD grades II-IV. In conclusion, we confirm that the refined DRI is a valuable tool to compare the outcomes of different HSCT protocols. We demonstrate also that TDEP did not impact on the outcome of HSCT, but it did reduce the incidence of acute GvHD.

c-Jun N-terminal kinase activation failure is a new mechanism of anthracycline resistance in acute myeloid leukemia.

Chemotherapy resistance is a major challenge in acute myeloid leukemia (AML). Besides the P-glycoprotein efflux, additional cellular factors may contribute to drug resistance in AML. c-Jun N-terminal kinase (JNK) is activated after exposure of cells to chemotherapeutics. We asked whether chemoresistance in AML is attributed to intrinsic failure of the AML blasts to activate JNK. In vitro treatment of U937 AML cell line with anthracyclines induced a rapid and robust JNK phosphorylation and apoptosis. In contrast, the anthracyline-resistant derivative cell lines U937R and URD40 showed no JNK activation after exposure to anthracyclines, also at doses that resulted in high accumulation of the drug within the cells. RNA interference-based depletion of JNK1 in drug-sensitive U937 cells made them chemoresistant, whereas selective restoration of the inactive JNK pathway in the resistant U937R cells sensitized them to anthracyclines. Short-term in vitro exposure of primary AML cells (n=29) to daunorubicin showed a strong correlation between the in vitro pharmacodymanic changes of phospho-JNK levels and the response of patients to standard induction chemotherapy (P=0.012). We conclude that JNK activation failure confers another mechanism of anthracycline resistance in AML. Elucidating the ultimate mechanisms leading to JNK suppression in chemoresistant AML may be of major therapeutic value.