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Background Interleukin 11 (IL-11) is a pleiotropic cytokine with anti-apoptotic, anti-inflammatory and hematopoietic potential. The IL-11 activity is determined by the expression of the IL-11R receptor alpha (IL-11Rα) and the signal transducing subunit β (gp130) on the cell membrane. A recombinant soluble form of the IL-11Rα (sIL-11Rα) in combination with IL-11 acts as an agonist on cells expressing the gp130 molecule. We constructed a designer cytokine Hyper IL-11 (H11), which is exclusively composed of naturally existing components. It contains the full length sIL-11Rα connected with the mature IL-11 protein using their natural sequences only. Such a construct has two major advantages: (i) its components are as close as possible to the natural forms of both proteins and (ii) it lacks an artificial linker what should avoid induction of antibody production. Results The H11 construct was generated, the protein was produced in a baculovirus expression system and was then purified by using ion exchange chromatography. The H11 protein displayed activity in three independent bioassays, (i) it induced acute phase proteins production in HepG2 cells expressing IL-11, IL-11Rα and gp130, (ii) it stimulated the proliferation of B9 cells (cells expressing IL-11Rα and gp130) and (iii) proliferation of Baf/3-gp130 cells (cells not expressing IL-11 and IL-11Rα but gp130). Moreover, the preliminary data indicated that H11 was functionally distinct from Hyper-IL-6, a molecule which utilizes the same homodimer of signal transducing receptor (gp130). Conclusions The biologically active H11 may be potentially useful for treatment of thrombocytopenia, infertility, multiple sclerosis, cardiovascular diseases or inflammatory disorders.

Cancer stem cells (CSCs) represent a distinctive population of tumour cells that control tumour initiation, progression, and maintenance. Their influence is great enough to risk the statement that successful therapeutic strategy must target CSCs in order to eradicate the disease. Because cancer stem cells are highly resistant to chemo- and radiotherapy, new tools to fight against cancer have to be developed. Expression of antigens such as ALDH, CD44, EpCAM, or CD133, which distinguish CSCs from normal cells, together with CSC immunogenicity and relatively low toxicity of immunotherapies, makes immune targeting of CSCs a promising approach for cancer treatment. This review will present immunotherapeutic approaches using dendritic cells, T cells, pluripotent stem cells, and monoclonal antibodies to target and eliminate CSCs.

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Allogeneic whole cell gene modified therapeutic melanoma vaccine (AGI-101H) comprising of two melanoma cell lines transduced with cDNA encoding fusion protein composed of IL-6 linked with the soluble IL-6 receptor (sIL-6R), referred to as H6 was developed. H6 served as a molecular adjuvant, however, it has altered vaccine cells phenotype towards melanoma stem cells (MSC)-like with high activity of aldehyde dehydrogenase isoenzyme (ALDH1A1). AGI-101H was applied in advanced melanoma patients with non-resected and resected disease. In the adjuvant setting, it was combined with surgery in case of recurring metastases, which were surgically removed and vaccination continued. A significant fraction of AGI-101H treated melanoma patients is still alive (11–19 years). Out of 106 living patients, 39 were HLA-A2 positive and were the subject of the study. Immunization of melanoma patients resulted in the generation of cytotoxic CD8+ T cells specific for ALDH1A1, which were detected in circulation by HLA-A0201 MHC dextramers loaded with ALDH1A188-96(LLYKLADLI) peptide. Phenotypically they were central memory CD8+ T cells. Re-stimulation with ALDH1A188-96 ex vivo resulted in IFN-γ secretion and cells degranulation. Following each vaccine dose administration, the number of ALDH1A1-CD8+ T cells increased in circulation and returned to the previous level until next dose injection (one month). ALDH1A1-CD8+ T cells were also found, however in the lower number than in vaccinated patients, in the circulation of untreated melanoma with stage IV but were not found in stage II or III and healthy donors. Specific anti-ALDH1 antibodies were present in treated patients. Long-term survival suggests immuno-targeting of MSC in treated patients.

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Therapeutic cancer vaccines have elicited renewed interest due to the development of immune checkpoint inhibitors. The role of these vaccines is to induce specific effector cells for killing cancer cells. Cancer stem cells (CSCs) are responsible for tumor growth and progression. Accordingly, they are targets for various cancer therapies, including immunotherapy. Here, we demonstrate the effectiveness of melanoma vaccines composed of genetically modified tumor cells admixed with melanoma stem-like cells (MSC) or induced pluripotent stem cells (iPSCs). Two vaccines were constructed. The first vaccine contained cells derived from B16F10 melanospheres (SFs) with CSC characteristics. The second vaccine contained syngeneic murine induced pluripotent stem cells (miPSCs). iPSCs or SF cells were admixed with B16F10 cells, modified with the designer cytokine Hyper-IL6(H6) (B16/H6). Control mice received B16/H6 cells, B16F10 cells or PBS. Immunization with either vaccine significantly inhibited tumor growth and increased disease-free survival (DFS) and overall survival (OS) in C57BL/6 mice. Mice treated with the SF or iPSC vaccine demonstrated increased activation of the immune response in the vaccination site and tumor microenvironment compared to those treated with B16/H6, B16F10 or PBS. Higher infiltration of dendritic cells (DCs) monocytes, and natural killer (NK) cells; lower numbers of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs); higher levels of the cytokines INFγ and IL-12 were observed with the novel vaccines than with the control treatments. In vitro restimulation of splenocytes derived from mice immunized with B16F10 cell, SF cell or miPSC lysates increased the proliferation of CD4+ T helper lymphocytes and secretion of cytokines. An increased serum titer of antibodies directed against B16F10 cells was found in mice immunized with the SF vaccine. The most effective DFS and OS extensions were reached with the miPSCs vaccine. The described results form the basis for a novel platform for the next generation of cancer vaccines composed of allogeneic cancer-specific cells modified with a molecular adjuvant gene and admixed with allogeneic miPSCs or SFs.