Novel Genetic Melanoma Vaccines Based on Induced Pluripotent Stem Cells or Melanosphere-Derived Stem-Like Cells Display High Efficacy in a Murine Tumor Rejection Model.

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.

Whole cell melanoma vaccine genetically modified to stem cells like phenotype generates specific immune responses to ALDH1A1 and long-term survival in advanced melanoma patients.

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 ALDH1A188-96ex 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.

Trichoderma species occurring on wood with decay symptoms in mountain forests in Central Europe: genetic and enzymatic characterization.

The aim of this study was to explore the species diversity of Trichoderma obtained from samples of wood collected in the forests of the Gorce Mountains (location A), Karkonosze Mountains (location B) and Tatra Mountains (location C) in Central Europe and to examine the cellulolytic and xylanolytic activity of these species as an expression of their probable role in wood decay processes. The present study has led to the identification of the following species and species complex: Trichoderma atroviride P. Karst., Trichoderma citrinoviride Bissett, Trichoderma cremeum P. Chaverri & Samuels, Trichoderma gamsii Samuels & Druzhin., Trichoderma harzianum complex, Trichoderma koningii Oudem., Trichoderma koningiopsis Samuels, C. Suárez & H.C. Evans, Trichoderma longibrachiatum Rifai, Trichoderma longipile Bissett, Trichoderma sp. (Hypocrea parapilulifera B.S. Lu, Druzhin. & Samuels), Trichoderma viride Schumach. and Trichoderma viridescens complex. Among them, T. viride was observed as the most abundant species (53 % of all isolates) in all the investigated locations. The Shannon's biodiversity index (H), evenness (E), and the Simpson's biodiversity index (D) calculations for each location showed that the highest species diversity and evenness were recorded for location A-Gorce Mountains (H' = 1.71, E = 0.82, D = 0.79). The preliminary screening of 119 Trichoderma strains for cellulolytic and xylanolytic activity showed the real potential of all Trichoderma species originating from wood with decay symptoms to produce cellulases and xylanases-the key enzymes in plant cell wall degradation.

Immunotargeting of cancer stem cells.

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.