High Log-Scale Expansion of Functional Human Natural Killer Cells from Umbilical Cord Blood CD34-Positive Cells for Adoptive Cancer Immunotherapy

Immunotherapy based on natural killer (NK) cell infusions is a potential adjuvant treatment for many cancers. Such therapeutic application in humans requires large numbers of functional NK cells that have been selected and expanded using clinical grade protocols. We established an extremely efficient cytokine-based culture system for ex vivo expansion of NK cells from hematopoietic stem and progenitor cells from umbilical cord blood (UCB). Systematic refinement of this two-step system using a novel clinical grade medium resulted in a therapeutically applicable cell culture protocol. CD56+CD3− NK cell products could be routinely generated from freshly selected CD34+ UCB cells with a mean expansion of >15,000 fold and a nearly 100% purity. Moreover, our protocol has the capacity to produce more than 3-log NK cell expansion from frozen CD34+ UCB cells. These ex vivo-generated cell products contain NK cell subsets differentially expressing NKG2A and killer immunoglobulin-like receptors. Furthermore, UCB-derived CD56+ NK cells generated by our protocol uniformly express high levels of activating NKG2D and natural cytotoxicity receptors. Functional analysis showed that these ex vivo-generated NK cells efficiently target myeloid leukemia and melanoma tumor cell lines, and mediate cytolysis of primary leukemia cells at low NK-target ratios. Our culture system exemplifies a major breakthrough in producing pure NK cell products from limited numbers of CD34+ cells for cancer immunotherapy

Clinical-grade generation of active NK cells from cord blood hematopoietic progenitor cells for immunotherapy using a closed-system culture process

Contains fulltext : 97724.pdf (publisher's version ) (Open Access)Natural killer (NK) cell-based adoptive immunotherapy is a promising treatment approach for many cancers. However, development of protocols that provide large numbers of functional NK cells produced under GMP conditions are required to facilitate clinical studies. In this study, we translated our cytokine-based culture protocol for ex vivo expansion of NK cells from umbilical cord blood (UCB) hematopoietic stem cells into a fully closed, large-scale, cell culture bioprocess. We optimized enrichment of CD34(+) cells from cryopreserved UCB units using the CliniMACS system followed by efficient expansion for 14 days in gas-permeable cell culture bags. Thereafter, expanded CD34(+) UCB cells could be reproducibly amplified and differentiated into CD56(+)CD3(-) NK cell products using bioreactors with a mean expansion of more than 2,000 fold and a purity of >90%. Moreover, expansion in the bioreactor yielded a clinically relevant dose of NK cells (mean: 2x10(9) NK cells), which display high expression of activating NK receptors and cytolytic activity against K562. Finally, we established a versatile closed washing procedure resulting in optimal reduction of medium, serum and cytokines used in the cell culture process without changes in phenotype and cytotoxic activity. These results demonstrate that large numbers of UCB stem cell-derived NK cell products for adoptive immunotherapy can be produced in closed, large-scale bioreactors for the use in clinical trials

Aberrant expression of the hematopoietic-restricted minor histocompatibility antigen LRH-1 on solid tumors results in efficient cytotoxic T cell-mediated lysis.

Contains fulltext : 79614.pdf (publisher's version ) (Closed access)CD8(+) T cells recognizing minor histocompatibility antigens (MiHA) on solid tumor cells may mediate effective graft-versus-tumor (GVT) reactivity after allogeneic stem cell transplantation (SCT). Previously, we identified LRH-1 as a hematopoietic-restricted MiHA encoded by the P2X5 gene. Here, we report that LRH-1 is aberrantly expressed on solid tumor cells. P2X5 mRNA expression is demonstrated in a significant portion of solid tumor cell lines, including renal cell carcinoma (RCC), melanoma, colorectal carcinoma, brain cancer and breast cancer. Importantly, P2X5 gene expression was also detected in a subset of primary solid tumor specimens derived from RCC, brain cancer and breast cancer patients. Furthermore, P2X5 expressing solid tumor cells can be effectively targeted by LRH-1-specific cytotoxic T lymphocytes under inflammatory conditions. The expression of HLA-B7 and CD54 on tumor cells increases upon cytokine stimulation resulting in improved T cell activation as observed by higher levels of degranulation and enhanced tumor cell lysis. Overall, hematopoietic-restricted MiHA LRH-1 is aberrantly expressed on solid tumor cells and may be used as target in GVT-specific immunotherapy after SCT

Decreased Levels of Circulating IL17-Producing CD161(+)CCR6(+) T Cells Are Associated with Graft-versus-Host Disease after Allogeneic Stem Cell Transplantation

Contains fulltext : 110799.pdf (publisher's version ) (Open Access)The C-type lectin-like receptor CD161 is a well-established marker for human IL17-producing T cells, which have been implicated to contribute to the development of graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-SCT). In this study, we analyzed CD161(+) T cell recovery, their functional properties and association with GVHD occurrence in allo-SCT recipients. While CD161(+)CD4(+) T cells steadily recovered, CD161(hi)CD8(+) T cell numbers declined during tapering of Cyclosporine A (CsA), which can be explained by their initial growth advantage over CD161(neg/low)CD8(+) T cells due to ABCB1-mediated CsA efflux. Interestingly, occurrence of acute and chronic GVHD was significantly correlated with decreased levels of circulating CD161(+)CD4(+) as well as CD161(hi)CD8(+) T cells. In addition, these subsets from transplanted patients secreted high levels of IFNgamma and IL17. Moreover, we found that CCR6 co-expression by CD161(+) T cells mediated specific migration towards CCL20, which was expressed in GVHD biopsies. Finally, we demonstrated that CCR6(+) T cells indeed were present in these CCL20(+) GVHD-affected tissues. In conclusion, we showed that functional CD161(+)CCR6(+) co-expressing T cells disappear from the circulation and home to GVHD-affected tissue sites. These findings support the hypothesis that CCR6(+)CD161-expressing T cells may be involved in the immune pathology of GVHD following their CCL20-dependent recruitment into affected tissues

Improving dendritic cell vaccine immunogenicity by silencing PD-1 ligands using siRNA-lipid nanoparticles combined with antigen mRNA electroporation.

Item does not contain fulltextDendritic cell (DC)-based vaccination boosting antigen-specific immunity is being explored for the treatment of cancer and chronic viral infections. Although DC-based immunotherapy can induce immunological responses, its clinical benefit has been limited, indicating that further improvement of DC vaccine potency is essential. In this study, we explored the generation of a clinical-grade applicable DC vaccine with improved immunogenic potential by combining PD-1 ligand siRNA and target antigen mRNA delivery. We demonstrated that PD-L1 and PD-L2 siRNA delivery using DLin-KC2-DMA-containing lipid nanoparticles (LNP) mediated efficient and specific knockdown of PD-L expression on human monocyte-derived DC. The established siRNA-LNP transfection method did not affect DC phenotype or migratory capacity and resulted in acceptable DC viability. Furthermore, we showed that siRNA-LNP transfection can be successfully combined with both target antigen peptide loading and mRNA electroporation. Finally, we demonstrated that these PD-L-silenced DC loaded with antigen mRNA superiorly boost ex vivo antigen-specific CD8(+) T cell responses from transplanted cancer patients. Together, these findings indicate that our PD-L siRNA-LNP-modified DC are attractive cells for clinical-grade production and in vivo application to induce and boost immune responses not only in transplanted cancer patients, but likely also in other settings.1 februari 201

Extracellular purines, purinergic receptors and tumor growth

Virtually, all tumor cells as well as all immune cells express plasma membrane receptors for extracellular nucleosides (adenosine) and nucleotides (ATP, ADP, UTP, UDP and sugar UDP). The tumor microenvironment is characterized by an unusually high concentration of ATP and adenosine. Adenosine is a major determinant of the immunosuppressive tumor milieu. Sequential hydrolysis of extracellular ATP catalyzed by CD39 and CD73 is the main pathway for the generation of adenosine in the tumor interstitium. Extracellular ATP and adenosine mold both host and tumor responses. Depending on the specific receptor activated, extracellular purines mediate immunosuppression or immunostimulation on the host side, and growth stimulation or cytotoxicity on the tumor side. Recent progress in this field is providing the key to decode this complex scenario and to lay the basis to harness the potential benefits for therapy. Preclinical data show that targeting the adenosine-generating pathway (that is, CD73) or adenosinergic receptors (that is, A2A) relieves immunosuppresion and potently inhibits tumor growth. On the other hand, growth of experimental tumors is strongly inhibited by targeting the P2X7 ATP-selective receptor of cancer and immune cells. This review summarizes the recent data on the role played by extracellular purines (purinergic signaling) in host–tumor interaction and highlights novel therapeutic options stemming from recent advances in this field.Oncogene advance online publication, 20 June 2016; doi:10.1038/onc.2016.206