TNF-alpha production-enhancing activity of 2-(1-adamantylamino)-6-methylpyridine (AdAMP) in cultures of human normal and neoplastic cells.

The purpose of this study was to determine the TNF-alpha-stimulatory effect of a novel immunomodulator 2-(1-adamantylamino)-6-methylpyridine (AdAMP) on normal and neoplastic human cells. In a panel of several human ovarian cancer cell lines, almost half of them spontaneously secreted significant amounts of TNF-alpha. When incubated with AdAMP, a 3-fold enhancement of TNF-alpha production by cells was observed. Furthermore, the phorbol myristic acetate ester (PMA)-induced release of TNF-alpha in cultures of U937 cells was increased in the presence of AdAMP. Primary monocytes isolated from peripheral blood did not respond to AdAMP. Although cytokine release was not triggered in human peripheral blood monocytes, AdAMP co-stimulated these cells to produce TNF-alpha and IL-8 during incubation with lipopolysaccharide (LPS). No effect of AdAMP was found on IL-1beta and IL-6 production by monocytes. In cultures of peripheral blood T lymphocytes, AdAMP significantly decreased the adhesion of these cells to matrix proteins in an in vitro assay. The results suggest that AdAMP, as a stimulator of cytokine secretion, may have potential application in tumor therapy.

CpG immunostimulatory oligodeoxynucleotide 1826 enhances antitumor effect of interleukin 12 gene-modified tumor vaccine in a melanoma model in mice.

PURPOSE: The effectiveness of interleukin (IL)-12-secreting tumor vaccines in the treatment of mouse tumors could be enhanced by concurrent application of cytokines and costimulatory molecules. We investigated the therapeutic potential of IL-12 gene-transduced melanoma vaccine in combination with CpG immunostimulatory oligodeoxynucleotide (ODN) 1826, an adjuvant known to favor development of Th1-biased immune response, in a B78-H1 (B78) melanoma model in mice. EXPERIMENTAL DESIGN: Mice injected with B78 melanoma cells were treated with irradiated IL-12 gene-transduced B78 cells [B78/IL-12(X)] and/or ODN 1826. Mechanisms responsible for the antitumor effects of the treatment were investigated using fluorescence-activated cell sorter analysis, a standard (51)Cr releasing assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and ELISA. RESULTS: Single injection of B78/IL-12(X) cells had no effect on tumor growth, whereas seven consecutive daily injections of ODN 1826 markedly inhibited tumor progression with occasional curative effects. When used in combination, B78/IL-12(X) cells and ODN 1826 caused additional tumor growth reduction and eradication of tumors in 62% of treated mice. The combined treatment activated local inflammatory response against tumor but also induced systemic antitumor immunity. In vitro studies have shown that when used together, B78/IL-12(X) cells and ODN 1826 induced a potent Th1 response and suggested the role of IFN-gamma in activation of the host immune response. The antitumor effects in double-treated mice were accompanied by the development of cytotoxic effectors in the spleen and activation of macrophages. CONCLUSIONS: The results provided the evidence that the combination of IL-12 gene-modified melanoma vaccine and ODN 1826 induces synergistically systemic and local antitumor immunity.

Complete tumour regressions induced by vaccination with IL-12 gene-transduced tumour cells in combination with IL-15 in a melanoma model in mice.

In the present study, IL-12 gene-transduced B78-H1 melanoma cells (B78/IL-12) were used in combination with IL-15 to treat melanoma-bearing mice. Genetically modified B78/IL-12 cells, when injected subcutaneously, induced strong activation of antitumour mechanisms resulting in complete loss of tumourigenicity. In a therapeutic model, intratumoural injection of irradiated B78/IL-12 cells significantly delayed tumour growth and led to the regression of melanoma in one case. Similarly, consecutive daily injections of IL-15 markedly inhibited tumour progression with occasional curative effects. When used in combination, vaccination with B78/IL-12 cells and treatment with IL-15 caused eradication of established tumours in all treated mice. The combined treatment with B78/IL-12 cells and IL-15 activated not only a local response against tumour, but also induced systemic antitumour immunity that led to a delay or inhibition of tumour development at a distant site. In vitro studies demonstrated that when used together, B78/IL-12 cells and IL-15 induced a shift from a type Th2 to a type Th1 response. Activation of the antitumour immune response in double-treated mice resulted, in part, from stimulation of IFN-gamma production and was accompanied by the development of cytotoxic effectors in the spleen. As shown in a macrophage tumouricidal assay, macrophages could also play a role in the antitumour effects. The results confirmed that vaccination with IL-12 gene-modified tumour cells is superior to the treatment with unmodified tumour cell vaccine and, additionally, showed that IL-15 is an excellent candidate for adjuvant therapy, inducing synergistically not only a delay of tumour growth but also its complete eradication.