The combined therapeutic potential of an immunocytokine designed to deliver IL-12 to the necrotic regions of solid tumors with an anti-PD-L1 antibody that disrupts the immunosuppressive PD-1/PD-L1 axis yielded a combinatorial benefit in multiple murine tumor models. The murine version of the immunocytokine, NHS-muIL12, consists of an antibody (NHS76) recognizing DNA/DNA-histone complexes, fused with two molecules of murine IL-12 (NHS-muIL12). By its recognition of exposed DNA, NHS-muIL12 targets IL-12 to the necrotic portions of tumors; it has a longer plasma half-life and better antitumor efficacy against murine tumors than recombinant murine IL-12. It is shown here that NHS-muIL12, in an IFN-γâdependent mechanism, upregulates mPD-L1 expression on mouse tumors, which could be construed as an immunosuppressive action. Yet concurrent therapy with NHS-muIL12 and an anti-PD-L1 antibody resulted in additive/synergistic antitumor effects in PD-L1âexpressing subcutaneously transplanted tumors (MC38, MB49) and in an intravesical bladder tumor model (MB49). Antitumor efficacy correlated with (a) with a higher frequency of tumor antigen-specific splenic CD8+ T cells and (b) enhanced T cell activation over a wide range of NHS-muIL12 concentrations. These findings suggest that combining NHS-muIL12 and an anti-PD-L1 antibody enhances T cell activation and T cell effector functions within the tumor microenvironment, significantly improving overall tumor regression. These results should provide the rationale to examine the combination of these agents in clinical studies.
Oncotarget. 2017 Mar 28 [Epub]
Jonathan K Fallon, Amanda J Vandeveer, Jeffrey Schlom, John W Greiner
Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.