Beschreibung:
<jats:p> e14232 </jats:p><jats:p> Background: Cancer immunotherapy with immune checkpoint inhibitors (CPI) and interleukin (IL)-2 have demonstrated clinical antitumor efficacy but is frequently accompanied with severe side-effects caused by excessive and systemic immune system activation. Methods: We addressed this need by targeting both the CPI antibodies anti-CTLA4 (aCTLA4) + anti-PD-L1 (aPD-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. This approach harnesses the exposure of tumor stroma collagen to blood components due to the leakiness of the tumor vasculature. Results: We show that intravenously (i.v.) administered CBD protein accumulated in tumors in an orthotopic MMTV-PyMT breast tumor model. CBD conjugation or fusion decreased the systemic toxicity of both aCTLA4+aPD-L1 combination therapy and IL-2. CBD-conjugation to CPI abolished T cell infiltration into the liver and eliminated hepatotoxicity as well as decreased systemic cytokine release in the blood serum. CBD-fusion to IL-2 ameliorated capillary leak syndrome and pulmonary edema. These side-effects have been reported in the clinic. CBD-CPI and CBD-IL-2 significantly suppressed tumor growth compared to their unmodified forms in B16F10 melanoma, CT26 colon carcinoma and MMTV-PyMT slow growing breast cancer models, and both CBD-CPI and CBD-IL-2 increased tumor-infiltrating CD8+ T cells; increases in the ratio of effector CD8<jats:sup>+</jats:sup>T cells to T regulatory cells were observed. In an orthotopic breast tumor model, combination treatment with CPI and IL-2 eradicated tumors in 9/13 animals with the CBD-modified drugs, whereas it did so in only 1/13 animals with the unmodified drugs. Conclusions: Our data suggest that the A3 domain of VWF can be used to engineer immunotherapies (e.g. CPI and cytokine) with high translational promise as systemically-administered tumor targeting drugs with improved safety and efficacy compared to their native forms. </jats:p>