Ako Ishihara

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Targeted delivery of CCL4 to the tumor stroma recruits CD103 ⁺ dendritic cells and enhances the efficacy of CPI immunotherapy.

Inflammation targeting through collagen affinity improves antibody therapeutic ability.

Collagen-binding ability improves serum albumin as an anti-cancer drug carrier, resulting in enhanced therapeutic efficacy.

Cancer immunotherapy with immune checkpoint inhibitors (CPIs) and interleukin-2 (IL-2) has demonstrated clinical efficacy but is frequently accompanied with severe adverse events caused by excessive and systemic immune system activation. Here, we addressed this need by targeting both the CPI antibodies anti–cytotoxic T lymphocyte antigen 4 antibody (αCTLA4) + anti–programmed death ligand 1 antibody (αPD-L1) and the cytokine IL-2 to tumors via conjugation (for the antibodies) or recombinant fusion (for the cytokine) to a collagen-binding domain (CBD) derived from the blood protein von Willebrand factor (VWF) A3 domain, harnessing the exposure of tumor stroma collagen to blood components due to the leakiness of the tumor vasculature. We show that intravenously administered CBD protein accumulated mainly in tumors. CBD conjugation or fusion decreases the systemic toxicity of both αCTLA4 + αPD-L1 combination therapy and IL-2, for example, eliminating hepatotoxicity with the CPI molecules and ameliorating pulmonary edema with IL-2. Both CBD-CPI and CBD–IL-2 suppressed tumor growth compared to their unmodified forms in multiple murine cancer models, and both CBD-CPI and CBD–IL-2 increased tumor-infiltrating CD8⁺ T cells. In an orthotopic breast cancer model, combination treatment with CPI and IL-2 eradicated tumors in 9 of 13 animals with the CBD-modified drugs, whereas it did so in only 1 of 13 animals with the unmodified drugs. Thus, the A3 domain of VWF can be used to improve safety and efficacy of systemically administered tumor drugs with high translational promise.

Immune checkpoint blockade exhibits considerable antitumor activity, but previous studies have reported instances of severe treatment-related adverse events. We sought to explore local immune checkpoint blockade, with an antibody (Ab) form that would be retained intra- or peritumorally, limiting systemic exposure. To accomplish this, we conjugated the checkpoint blockade Abs to an extracellular matrix (ECM)–super-affinity peptide derived from placenta growth factor–2 (PlGF-2_123–144). We show enhanced tissue retention and lower Ab concentrations in blood plasma after PlGF-2_123–144 conjugation, reducing systemic side effects such as the risk of autoimmune diabetes. Peritumoral injections of PlGF-2_123–144–anti-CTLA4 (cytotoxic T lymphocyte antigen 4) and PlGF-2_123–144–anti–PD-L1 (programmed death ligand 1) Abs delayed tumor growth and prolonged survival compared to the unmodified Abs in genetically engineered murine tumor models of melanoma and breast cancer. The PlGF-2_123–144–Abs increased tumor-infiltrating activated CD8⁺ and CD4⁺ T cells, resulting in a delay of distant tumor growth as well. This simple and translatable approach of engineered ECM-binding Abs may present a viable and safer approach in checkpoint blockade.