The connection of innate and adaptive anti-cancer immunity

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Studies on the connection of innate and adaptive anti-cancer immunity include: The immunocytokine NHS-IL12 as a potential cancer therapeutic: A tumor-targeting interleuken (IL)-12 immunocytokine, NHS-IL12, was engineered by genetically fusing the human IL-12 heterodimers to the C-termini of the heavy chains of the NHS76 antibody. NHS76 is a fully human antibody selected for its specific ability to bind to DNA/histones and thereby target to tumors in vivo. A radiolabeled chimeric form of this antibody has been shown to selectively target human tumors and has been approved for the therapy of lung carcinoma in China. To visualize the subcellular localization of NHS-muIL12 in a murine model, we injected tumor-bearing mice subcutaneously (s.c.) with NHS-IL12 and distinct tumor targeting and staining in the nuclei of tumor cells was observed. This immunocytokine outperformed an equimolar dose of recombinant murine IL-12 (rMuIL-12) in anti-tumor studies of three distinct tumor models (LLC, MC38 and B16). NHS-muIL12 was found to increase serum IFN-gamma levels, upregulate MHC class I protein expression on DCs, and induce the proliferation of CD49b+ natural killer (NK) cells and CD8+ T cells, all in a dose-dependent manner. An immune cell subset depletion study confirmed that the antitumor effects of NHS-muIL12 involves CD8+ cells and NK cells, consistent with the known mechanisms of action of IL-12. Mice that were cured of their MC38 tumors showed resistance to tumor rechallenge and displayed long-lasting TAA-specific CTL memory. This enhanced efficacy observed of NHS-muIL12 vs. rMuIL-12 likely stems from the more favorable pharmacokinetic properties of the immunocytokine and its tumor-binding ability. NHS-IL12 has also been employed preclinically in combination with several standard-of-care therapies. We have shown statistically enhanced anti-tumor effects, compared to the use of either agent alone, when NHS-IL12 was used in combination with (a) fractionated radiation (Lewis lung carcinoma), (b) the TKI sunitinib (Renca renal carcinoma), and (c) docetaxel (MC38 colon cancer model). A Phase I study of NHS-IL12 is ongoing. The immune-potentiating effects on CD8+ T cells by a low dose of saracatinib might afford better protection from pathogens or cancer when combined with vaccine. Inhibition of TGF-beta1 signaling promotes central memory T-cell differentiation: This study affirmed that isolated CD8+ T cells express mRNA and produce TGF-beta following cognate peptide recognition. Blockage of endogenous TGF-beta with either a TGF-beta blocking Ab or a small molecule inhibitor of TGF-betaRI enhances the generation of CD62Lhigh/CD44high central memory CD8+ T cells accompanied with a robust recall response. Interestingly, the augmentation within the central memory T-cell pool occurs in lieu of cellular proliferation or activation, but with the expected increase in the ratio of the Eomesoderm/T-bet transcriptional factors. Yet, the signal transduction pathway(s) seems to be noncanonical, independent of SMAD or mammalian target of rapamycin signaling. Enhancement of central memory generation by TGF-beta blockade is also confirmed in human peripheral blood mononuclear cells. The findings underscore the role(s) that autocrine TGF-beta plays in T-cell homeostasis and, in particular, the balance of effector/memory and central/memory T cells. These results may provide a rationale to targeting TGF-beta signaling to enhance antigen-specific CD8+ T-cell memory against a lethal infection or cancer.