Augmenting Autologous Stem Cell Transplantation to Improve Outcomes in Myeloma

Consolidation with high-dose chemotherapy and autologous stem cell transplantation (ASCT) is the standard of care for transplantation-eligible patients with multiple myeloma, based on randomized trials showing improved progression-free survival with autologous transplantation after combination chemotherapy induction. These trials were performed before novel agents were introduced; subsequently, combinations of immunomodulatory drugs and proteasome inhibitors as induction therapy have significantly improved rates and depth of response. Ongoing randomized trials are testing whether conventional autologous transplantation continues to improve responses after novel agent induction. Although these results are awaited, it is important to review strategies for improving outcomes after ASCT. Conditioning before ASCT with higher doses of melphalan and combinations of melphalan with other agents, including radiopharmaceuticals, has been explored. Tandem ASCT, consolidation, and maintenance therapy after ASCT have been investigated in phase III trials. Experimental cellular therapies using ex vivo–primed dendritic cells, ex vivo–expanded autologous lymphocytes, Killer Immunoglobulin Receptor (KIR)-mismatched allogeneic natural killer cells, and genetically modified T cells to augment ASCT are also in phase I trials. This review summarizes these strategies and highlights the importance of exploring strategies to augment ASCT, even in the era of novel agent induction

Lectin-type oxidized LDL receptor 1 defines a population of polymorphonuclear myeloid-derived suppressor cells in cancer patients

Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are important regulators of immune responses in cancer and have been directly implicated in the promotion of tumor progression. However, the heterogeneity of these cells and the lack of distinct markers hamper the progress in understanding the biology and clinical importance of these cells. Using partial enrichment of PMN-MDSC with gradient centrifugation, we determined that low-density PMN-MDSC and high-density neutrophils from the same cancer patients had a distinct gene profile. The most prominent changes were observed in the expression of genes associated with endoplasmic reticulum (ER) stress. Unexpectedly, low-density lipoprotein (LDL) was one of the most increased regulators, and its receptor oxidized LDL receptor 1 (OLR1) was one of the most overexpressed genes in PMN-MDSC. Lectin-type oxidized LDL receptor-1 (LOX-1) encoded by OLR1 was practically undetectable in neutrophils in peripheral blood of healthy donors, whereas 5 to 15% of total neutrophils in cancer patients and 15 to 50% of neutrophils in tumor tissues were LOX-1+. In contrast to their LOX-1− counterparts, LOX-1+ neutrophils had gene signature, potent immunosuppressive activity, up-regulation of ER stress, and other biochemical characteristics of PMN-MDSCs. Moreover, induction of ER stress in neutrophils from healthy donors up-regulated LOX-1 expression and converted these cells to suppressive PMN-MDSCs. Thus, we identified a specific marker of human PMN-MDSC associated with ER stress and lipid metabolism, which provides new insights into the biology and potential therapeutic targeting of these cells