pH-Dependent Grafting of Cancer Cells with Antigenic Epitopes Promotes Selective Antibody-Mediated Cytotoxicity

Abstract

A growing class of immunotherapeutic agents work by redirecting components of the immune system to recognize specific markers on the surface of cancer cells and initiate a selective immune response. However, such immunotherapeutic modalities will remain confined to a relatively small subgroup of patients until two major hurdles are overcome: (1) the specific targeting of cancer cells relative to healthy cells, and (2) the lack of common targetable tumor biomarkers among all patients. Here, we designed a unique class of agents that exploit the inherent acidic microenvironment of solid tumors to selectively graft the surface of cancer cells with immuno-engager epitopes for directed destruction by components of the immune system. Specifically, conjugates were assembled using an antigen that recruit antibodies present in human serum, and the pH(Low) Insertion Peptide (pHLIP), a unique peptide that selectively target tumors in vivo by anchoring onto cancer cell surfaces in a pHdependent manner. We established that conjugates can recruit antibodies from human serum to the surface of cancer cells, and induce complementdependent and antibody-dependent cellular cytotoxicity by peripheral blood mononuclear cells and also an engineered NK cell line. These results suggest that these agents have the potential to be applicable to treating a wide range of solid tumors and to circumvent the problem of narrow windows of selectivity..

Universal endogenous antibody recruiting nanobodies capable of triggering immune effectors for targeted cancer immunotherapy

“…14,15 Antibodyrecruiting molecules (ARMs) are bifunctional molecules composed of cell-targeting moiety and antibody-binding component, which could bridge the target cells and immune system and induce downstream immunity to eliminate the target cells. 16,17 Many rationally designed ARMs, where preferred haptens that could be recognized by natural occurring endogenous antibodies, such as dinitrophenyl (DNP), galactose-α-1,3-galactose (αGal) and rhamnose (Rha), as an antibody-binding component, have been successfully achieved in cancer, [18][19][20][21][22] virus, 23, 24 bacterial 25,26 and others. 27 For example, we and others demonstrated that nanobody-DNP conjugates could form an in situ immune-complex with specific endogenous anti-DNP antibody existing in human serum and subsequently provoke potent ADCC and CDC cytotoxicity to target destructing cancer cells in vitro and exhibit in vivo antitumor activity in mouse xenograft models.…”

pH Low Insertion Peptide-Modified Programmed Cell Death-Ligand 1 Potently Suppresses T-Cell Activation Under Acidic Condition

“…In addition, a variety of other cargos, such as small molecule antigen (e.g. 2,4-dinitrophenyl (DNP)), can be associated with N terminus of pHLIPs and specifically targeted to the surfaces of cancer cells to induce biological responses, since tumors are putatively acidic ( 27 ). In this study, we engage the extracellular region of murine PD-L1 with the N terminus of pHLIPs and evaluate the function of this fusion protein (PD-L1-pHLIP) to suppress lymphocyte expansion and cytokine production in acidic buffer, providing a potentially innovative avenue to treat inflammatory autoimmune diseases.…”

Selective Display of a Chemoattractant Agonist on Cancer Cells Activates the Formyl Peptide Receptor 1 on Immune Cells

“…This insertion topology can therefore be used to graft a variety of molecules onto cancer cell surfaces as long as they are conjugated to the N-terminus of pHLIP. [22,38,39] Here, we show that remodeling the surface of cancer cells with a FPR ligand using a pHLIPbased targeting strategy could selectively engage an immune response towards tumors by activating FPR1 on recruited immune cells (Figure 1).…”

“…This insertion topology can therefore be used to graft a variety of molecules onto cancer cell surfaces as long as they are conjugated to the N-terminus of pHLIP. [22,38,39]…”