A Cytokine Cocktail Augments the Efficacy of Adoptive NK-92 Cell Therapy Against Mouse Xenografts of Human Cancer.

BACKGROUND/AIM: Peripheral blood mononuclear cells (PBMCs) activated with immobilized monoclonal antibody against cluster of differentiation 3 (CD3) secrete cytokines in their culture supernatant (termed ACD3S). We examined the antitumor efficacy of ACD3S-activated NK-92 cells in vitro and in vivo. MATERIALS AND METHODS: Interleukin (IL) 2-depleted NK-92 cells were reactivated with ACD3S, analyzed for their phenotype and tested for cytotoxicity, and perforin and interferon γ (IFNγ) production. Severe combined immunodeficient (SCID) mice xenografted with human melanoma and breast cancer cells were treated with ACD3S-activated NK-92 cells and tumor growth was monitored. RESULTS: Brief activation of IL2-depleted NK-92 cells with ACD3S fully restored their in vitro cytotoxicity towards tumor cells. ACD3S-activated NK-92 cells were phenotypically similar to standard NK-92 cells, but exhibited prolonged cytotoxicity and produced higher levels of IFNγ. When adoptively transferred to tumor-bearing SCID mice, these cells retarded the growth of melanoma and breast tumors. CONCLUSION: Stimulation of NK-92 cells with ACD3S may be useful in clinical cancer therapy, as an alternative method for ex vivo natural killer cell activation.

Phenoxodiol, an anticancer isoflavene, induces immunomodulatory effects in vitro and in vivo.

Phenoxodiol (PXD) is a synthetic analogue of the plant isoflavone genistein with improved anticancer efficacy. Various properties and mechanisms of action have been attributed to the drug, the most important being its ability to sensitize resistant tumour cells to chemotherapy, which led to its fast track FDA approval for phase II/III clinical trials. In this study, we examined the effects of PXD on human peripheral blood mononuclear cells (PBMC) and its potential role in regulating immune responses. We show that PXD, at concentrations >or=1 microg/ml (4 microM), inhibited proliferation and reduced the viability of healthy donor-derived PBMC. In contrast, lower PXD concentrations (0.05-0.5 microg/ml) augmented, upon 3-day incubation, PBMC cytotoxicity. Experiments with purified CD56(+) lymphocytes revealed that PXD enhanced the lytic function of natural killer (NK) cells by directly stimulating this lymphocytic subpopulation. Furthermore, in an in vivo colon cancer model, Balb/C mice administered low-dose PXD, exhibited significantly reduced tumour growth rates and prolonged survival (in 40% of the animals). Ex vivo results showed that PXD stimulated both NK and tumour-specific cell lytic activity. We conclude that PXD, when administered at low concentrations, can act as an immunomodulator, enhancing impaired immune responses, often seen in cancer-bearing individuals.