The antibody‐based delivery of interleukin‐12 to solid tumors boosts NK and CD8⁺ T cell activity and synergizes with immune checkpoint inhibitors

Abstract

We describe the cloning and characterization of a novel fusion protein (termed L19‐mIL12), consisting of murine interleukin‐12 in single‐chain format, sequentially fused to the L19 antibody in tandem diabody format. The fusion protein bound avidly to the cognate antigen (the alternatively spliced EDB domain of fibronectin), retained the activity of the parental cytokine and was able to selectively localize to murine tumors in vivo, as shown by quantitative biodistribution analysis. L19‐mIL12 exhibited a potent antitumor activity in immunocompetent mice bearing CT26 carcinomas and WEHI‐164 sarcomas, which could be boosted by combination with checkpoint blockade, leading to durable cancer eradication. L19‐mIL12 also inhibited tumor growth in mice with Lewis lung carcinoma (LLC), but in this case, cancer cures could not be obtained, both in monotherapy and in combination. A microscopic analysis and a depletion experiment of tumor‐infiltrating leukocytes illustrated the contribution of NK cells and CD8+ T cells for the anticancer activity observed in both tumor models. Upon L19‐mIL12 treatment, the density of regulatory T cells (Tregs) was strongly increased in LLC, but not in CT26 tumors. A FACS analysis also revealed that the majority of CD8+ T cells in CT26 tumors were specific to the retroviral AH1 antigen.

Antibody-based delivery of Interleukin-9 to neovascular structures: therapeutic evaluation in cancer and arthritis

“…To confirm the in vivo targeting ability of F8IL9F8 in these therapies setting, ex vivo immunofluorescence studies were performed. In parallel to the therapy studies, (Figure 4), however to a degree considerably lower when compared to our previous reports with other targeted immunocytokines and different tumor models [30,[41][42][43][44][45][46].…”

Localized Interleukin-12 for Cancer Immunotherapy

“…Localized IL-12 induces profound intratumoral infiltration that can be expected to synergize with checkpoint inhibitors. Indeed, the addition of anti-PD-1 or anti-CTLA-4 improved the antitumor activity of L19-IL-12 in multiple murine tumor models (395). Similarly, systemic anti-CTLA-4 in combination with intratumoral IL-12 induced synergistic antitumor responses in GL-26 glioblastoma and SMA-560 astrocytoma models (396).…”

Immunotherapy of CT26 murine tumors is characterized by an oligoclonal response of tissue‐resident memory T cells against the AH1 rejection antigen

“…Similarly, a proportion of patients with metastatic melanoma or renal cell carcinoma can be cured using high-dose IL-2 treatment [2,3]. In animal models, cures of CT26 colorectal cancer have been described in mice receiving immune checkpoint inhibitors [4], antibody-cytokine fusions [5,6], or a combination of these two treatment modalities [4,6]. CD8 + T cells play a crucial role in the tumor rejection process [7].…”

“…Two antibodies (F8 and L19, specific to the alternatively spliced EDA and EDB domains of fibronectin, respectively) were found to selectively localize to solid tumors following intravenous administration [15,16] and were used to deliver various types of cytokine payloads to the tumor environment [17]. Indeed, the F8-mTNF and L19-mIL12 fusion proteins can be used to selectively deliver a proinflammatory cytokine payload to the tumor, helping spare normal tissues [6,18]. Both products were able to cure BALB/c mice with different types of malignancies [6,18].…”