Gemcitabine, fludarabine and melphalan as a reduced-intensity conditioning regimen for allogeneic stem cell transplant in relapsed and refractory Hodgkin lymphoma: preliminary results

Allogeneic hematopoietic stem cell transplantation in Hodgkin lymphoma: a systematic review and meta-analysis

Allogeneic stem cell transplantation (allo-SCT) outcomes in patients with Hodgkin lymphoma (HL) remain poorly defined. We performed a meta-analysis of allo-SCT studies in HL patients. The primary endpoints were 6-month, 1-year, 2-year and 3-year relapse-free survival (RFS) and overall survival (OS). A total of 42 reports (1850 patients) was included. The pooled estimates (95% confidence interval) for 6-month, 1-year, 2-year and 3-year RFS were 77 (59-91)%, 50 (42-57)%, 37 (31-43)% and 31 (25-37)%, respectively. The corresponding numbers for OS were 83 (75-91)%, 68 (62-74)%, 58 (52-64)% and 50 (41-58)%, respectively. There was statistical heterogeneity among studies in all outcomes. In meta-regression, accrual initiation year in 2000 or later was associated with higher 6-month (P=0.012) and 1-year OS (P=0.046), and pre-SCT remission with higher 2-year OS (P=0.047) and 1-year RFS (P=0.016). In conclusion, outcomes of allo-SCT in HL have improved over time, with 5-10% lower non-relapse mortality and relapse rates, and 15-20% higher RFS and OS in studies that initiated accrual in 2000 or later compared with earlier studies. However, there is no apparent survival plateau, demonstrating the need to improve on current allo-SCT strategies in relapsed/refractory HL.

Mechanistic studies on the synergistic cytotoxicity of the nucleoside analogs gemcitabine and clofarabine in multiple myeloma: relevance of p53 and its clinical implications

Hematopoietic stem cell transplantation (HSCT) is an established treatment for multiple myeloma (MM), a plasma cell malignancy. To identify an improved pretransplant conditioning regimen, we investigated the cytotoxicity of gemcitabine (Gem) and clofarabine (Clo) combinations toward MM cell lines and patient cell samples. A strong synergism of the two nucleoside analogs, when combined at their approximate IC10 concentrations, was observed. This synergism could be partly due to the observed Gem-mediated phosphorylation and activation of deoxycytidine kinase, resulting in enhanced phosphorylation of Gem and Clo. Their cytotoxicity correlated with a robust activation of the DNA damage response pathway. [Gem+Clo] decreased the mitochondrial membrane potential with a concomitant release of proapoptotic factors into the cytoplasm and nucleus and the activation of apoptosis. Exposure of MM cells to [Gem+Clo] also decreased the level of ribosomal RNA (rRNA), which might have resulted in nucleolar stress, as reported previously, and caused a p53-dependent cell death. A reduction by approximately 50% in the cytotoxicity of Gem and Clo was observed in the presence of pifithrin α, a p53 inhibitor. Furthermore, MM cell lines with mutant p53 exhibited greater resistance to Gem and Clo, supporting a role for the p53 protein in these cytotoxic responses. Our results provide a rationale for clinical trials incorporating [Gem+Clo] combinations as part of conditioning therapy for high-risk patients with MM undergoing HSCT.