The immunocytokine NHS-IL12 as a potential cancer therapeutic

Abstract

Targeted delivery of IL-12 might turn this cytokine into a safer, more effective cancer therapeutic. Here we describe a novel immunocytokine, NHS-IL12, consisting of two molecules of IL-12 fused to a tumor necrosis-targeting human IgG1 (NHS76). The addition of the human IgG1 moiety resulted in a longer plasma half-life of NHS-IL12 than recombinant IL-12, and a selective targeting to murine tumors in vivo. Data from both in vitro assays using human PBMCs and in vivo primate studies showed that IFN-gamma production by immune cells is attenuated following treatment with the immunocytokine, suggesting an improved toxicity profile than seen with recombinant IL-12 alone. NHS-IL12 was superior to recombinant IL-12 when evaluated as an anti-tumor agent in three murine tumor models. Mechanistic studies utilizing immune cell subset-depleting antibodies, flow cytometric methods, and in vitro cytotoxicity and ELISA assays all indicated that the anti-tumor effects of NHS-IL12 were primarily CD8+ T cell-dependent and likely IL-12-mediated. Combining NHS-IL12 treatment with a cancer vaccine, radiation, or chemotherapy resulted in greater anti-tumor effects than each individual therapy alone. These preclinical findings provide a rationale for the clinical testing of this immunocytokine, both as a single agent and in combination with vaccines, radiation and chemotherapy.

Enhanced binding of necrosis-targeting immunocytokine NHS-IL12 after local tumour irradiation in murine xenograft models

“…Our in vivo data showing an enhanced accumulation of NHS-IL12 in tumours after necrosis-inducing irradiation provide an explanation for the additive effect of local tumour irradiation and immunocytokine treatment as recently described by Fallon et al [15] for the murine construct. We see a clear difference between high and low doses of radiation, yet our data do not clearly demonstrate whether high single doses or fractionated regimens are best suited for the combination with NHS-IL12.…”

“…The effect was more pronounced, when NHS-IL12 was combined with different anti-cancer treatments. When combined with irradiation, the immunocytokine showed significant growth delay in a Lewis lung carcinoma model [15]. In humanized mice, the human NHS-IL12 construct also used in this study led to tumour control via Th1-polarized immune responses leading to cancer senescence and differentiation [16].…”

“…NHS-IL12 has been shown to induce anti-tumour immunity in a CD8 + T cell-dependant manner as single therapy as well as in combination with different anti-tumour agents [15]. NHS-IL12 controlled A204 xenografts in humanized mice in combination with IL2 or IL7 by inducing tumour senescence and differentiation [16].…”

New insights into IL-12-mediated tumor suppression

“…More recently, the development of novel approaches that direct IL-12 activity to the tumor site focus on immunocytokines, for example, the fusion of the cytokine to an antibody that binds specifically to the tumor vasculature, 107,108 or to exposed deoxyribonucleic acid (DNA) in the necrotic core of a tumor. 109 The targeting of necrotic areas within the tumor is of special interest due to the lack of perfusion of solid tumors and subsequent cell death. 109 The use of antibody-targeted cytokines, however, needs to be carefully evaluated for each specific tumor context, since a high avidity and retention to the targeted tissue are essential for efficient therapeutic effects.…”

“…109 The targeting of necrotic areas within the tumor is of special interest due to the lack of perfusion of solid tumors and subsequent cell death. 109 The use of antibody-targeted cytokines, however, needs to be carefully evaluated for each specific tumor context, since a high avidity and retention to the targeted tissue are essential for efficient therapeutic effects. In a combinatorial approach, a dual cytokine-antibody fusion protein that simultaneously targeted IL-12 and IL-2 to CD30 þ lymphoma cells suppressed tumor growth more efficiently than by just targeting IL-12 or IL-2 alone.…”