Hematopoietic stem cell mobilization with the reversible CXCR4 receptor inhibitor plerixafor (AMD3100)—Polish compassionate use experience

Recent developments in the field of targeted therapy have led to the discovery of a new drug, plerixafor, that is a specific inhibitor of the CXCR4 receptor. Plerixafor acts in concert with granulocyte colony-stimulating factor (G-CSF) to increase the number of stem cells circulating in the peripheral blood (PB). Therefore, it has been applied in the field of hematopoietic stem cell mobilization. We analyzed retrospectively data regarding stem cell mobilization with plerixafor in a cohort of 61 patients suffering from multiple myeloma (N = 23), non-Hodgkin’s lymphoma (N = 20), or Hodgkin’s lymphoma (N = 18). At least one previous mobilization attempt had failed in 83.6% of these patients, whereas 16.4% were predicted to be poor mobilizers. The median number of CD34+ cells in the PB after the first administration of plerixafor was 22/μL (range of 0–121). In total, 85.2% of the patients proceeded to cell collection, and a median of two (range of 0–4) aphereses were performed. A minimum of 2.0 × 106 CD34+ cells per kilogram of the patient’s body weight (cells/kg b.w.) was collected from 65.6% of patients, and the median number of cells collected was 2.67 × 106 CD34+ cells/kg b.w. (0–8.0). Of the patients, 55.7% had already undergone autologous stem cell transplantation, and the median time to neutrophil and platelet reconstitution was 12 and 14 days, respectively. Cases of late graft failure were not observed. We identified the diagnosis of non-Hodgkin’s lymphoma and previous radiotherapy as independent factors that contributed to failure of mobilization. The current report demonstrates the satisfactory efficacy of plerixafor plus G-CSF for stem cell mobilization in heavily pre-treated poor or predicted poor mobilizers

Human Embryonic Stem Cells Hemangioblast Express HLA-antigens

Background: It has been suggested that the initial differentiation of endothelial and hematopoietic cells during embryogenesis occurs from a common progenitor, called hemangioblast (hB). We hypothesized that these cells with dual hematopoietic/endothelial potential could be used in future regenerative medicine. Methods: We used the two-step differentiation technology to generate bipotential blast cells from human embryonic stem cells (hES). This involved short differentiation in our in vitro EB system followed by differentiation in semisolid culture medium supplemented with mixture of cytokines. Results: The occurrence of blast-colony-forming cells (BL-CFC) during EB differentiation (day 0-6) was transient and peaked on day 3. The emergence of this event was associated with expression of mesoderm gene T, and inversely correlated with expression of endoderm gene FoxA2. Similarly, the highest BL-CFC number was associated with increase in expression of early hematopoietic/endothelial genes: CD34, CD31 and KDR. The derived colonies were composed of 30-50 blast cells on day 6 in culture. These cells had homogenous appearance in Wright-Giemsa stain, but to a different extent expressed markers of immature hematopoietic and endothelial cells (CD31, CD34, VE-cadherin, Flt-1) and mature differentiated cells (CD45, CD33, CD146). We found that some of them expressed fetal and embryonic globin genes. Interestingly, these cells expressed also HLA class I molecules, however at very low levels compared to endothelial and hematopoietic cells. The blast cells could be successfully differentiated to hematopoietic cells in a CFU assay. In these conditions, blast cells formed CFU-M colonies (63.4 +/- 0.8%) containing macrophages, BFU-E colonies (19.5 +/- 3.5%) containing nucleated red blood cells, and CFU-EM colonies (17.1 +/- 2.7%) composed of macrophages and nucleated erythrocytes. Cells of CFU-EM and BFU-E colonies expressed both epsilon - and gamma- globin genes, but not adult-type gamma-globin. When in endothelial cell culture conditions, blast cells differentiated to endothelial cells which had the ability to take up Dil-Ac-LDL and to form complex vascular networks in Matrigel. Conclusion: 1) Hematoendothelial precursors exist transiently in early embryonic development and form single cell-derived colonies; 2) their differentiation can be tracked by the use of chosen molecular markers; 3) blast colonies consist of cells having properties of endothelial and hematopoietic precursors, however the issue of their ability to maintain dual properties over time needs to be further explored; 4) blast cells can potentially be used in regenerative medicine due to their low expression of HLA molecules

Outcomes of allogeneic haematopoietic stem cell transplantation from HLA-matched and alternative donors : a European Society for Blood and Marrow Transplantation registry retrospective analysis

BACKGROUND: The introduction of donors other than HLA-matched siblings has been a pivotal change in stem cell transplantation. We aimed to assess the evolution of outcomes within donor groups over time and explore whether donor-recipient HLA disparity might be advantageous in patients with aggressive disease. METHODS: In this retrospective, multicentre study, we assessed the outcomes for adult patients (≥18 years) with haematological malignancies who underwent their first allogeneic hematopoietic stem cell transplantation (HSCT) between Jan 3, 2001, and Dec 31, 2015, and were reported to the European Society for Blood and Marrow Transplantation. The donor types studied were matched sibling, matched unrelated, mismatched unrelated, haploidentical, and cord blood donors. Unrelated non-cord-blood donors and recipients were typed at the allelic level for HLA-A, HLA-B, HLA-C, and HLA-DRB1. We evaluated trends in overall survival, non-relapse mortality, relapse incidence, progression-free survival, acute and chronic graft-versus-host disease (GVHD), and GVHD-free and relapse-free survival following transplantation from various donor types (matched sibling, matched unrelated, mismatched unrelated, haploidentical, and umbilical cord blood), and compared transplantation outcomes across three epochs (epoch 1: 2001-05; epoch 2: 2006-10; and epoch 3: 2011-15). We used Kaplan-Meier estimators for survival probabilities and cumulative incidence functions accounting for competing risks for probabilities of GHVD, relapse, and non-relapse mortality, using multiple imputations by chained equations to deal with missing data. In epoch 3, we directly compared outcomes by donor group, stratified by a novel three-level disease-risk scheme. FINDINGS: We included 106 188 patients in our analysis. The median follow-up was 4·1 years (IQR 1·7-7·7). Overall survival at 3 years increased with all donor groups between epochs 2 and 3 (matched sibling: 54·0% [95% CI 53·1-54·8] to 54·6% [53·6-55·6]; matched unrelated: 49·1% [48·0-50·2] to 51·6% [50·7-52·6]; mismatched unrelated: 37·4% [35·7-39·2] to 41·3% [39·5-43·1]; haploidentical: 34·5% [31·4-37·9] to 44·2% [42·1-46·3]; and cord blood 36·3% [33·9-39] to 43·7% [40·8-46·8]). Improvement in overall survival seems to be driven by a reduction in non-relapse mortality, except in cord blood HSCT recipients, who had a lower relapse incidence. Comparing donor groups across disease-risk strata using the novel disease-risk scheme, overall survival among recipients of matched sibling transplantations remained better than other donor groups except in high-risk disease, where overall survival with matched unrelated transplantations was not different. INTERPRETATION: Overall survival following allogeneic stem cell transplantation is improving with substantial progress among recipients of haploidentical and cord blood HSCT. Nonetheless, the traditional donor hierarchy of matched sibling donors followed by matched unrelated donors and then other donors holds. Our findings warrant further investigation and could inform decision making and the development of donor-selection algorithms. FUNDING: The Varda and Boaz Dotan Research Center in Haemato-Oncology, Tel Aviv University, and the Shalvi Foundation for Research