Covalent Stabilization of Antibody Recruitment Enhances Immune Recognition of Cancer Targets

Abstract

Antibody recruiting molecules (ARMs) represent an important class of “proximity-inducing” chemical tools with therapeutic potential. ARMs function by simultaneously binding to a hapten-specific serum antibody (Ab) (e.g., anti-dinitrophenyl (DNP)) and a cancer cell surface protein, enforcing their proximity. ARM anticancer efficacy depends on the formation of ARM:Ab complexes on the cancer cell surface, which activate immune cell recognition and elimination of the cancer cell. Problematically, ARM function in human patients may be limited by conditions that drive the dissociation of ARM:Ab complexes, namely, intrinsically low binding affinity and/or low concentrations of anti-hapten antibodies in human serum. To address this potential limitation, we previously developed a covalent ARM (cARM) chemical tool that eliminates the ARM:antibody equilibrium through a covalent linkage. In the current study, we set out to determine to what extent maximizing the stability of ARM:antibody complexes via cARMs enhances target immune recognition. We observe cARMs significantly increase target immune recognition relative to ARMs across a range of therapeutically relevant antibody concentrations. These results demonstrate that ARM therapeutic function can be dramatically enhanced by increasing the kinetic stability of ARM:antibody complexes localized on cancer cells. Our findings suggest that a) high titres/concentrations of target antibody in human serum are not neccessary and b) saturative antibody recruitment to cancer cells not sufficient, to achieve maximal ARM therapeutic function.

Antibody Recognition of Cancer Cells via Glycan Surface Engineering

“…This study complements different approaches based on other haptens or labelling methods [46] . Compared to other approaches such as ARMs or polymeric systems, [21–26,41–54] this approach presents the flexibility of a two‐step glycoengineering/labelling approach. Furthermore, the general approach described here could be leveraged by selective metabolic glycoengineering strategies targeting specifically cancer cells [34,35,46,47] .…”

“…This study complements different approaches based on other haptens or labelling methods. [46] Compared to other approaches such as ARMs or polymeric systems, [21][22][23][24][25][26][41][42][43][44][45][46][47][48][49][50][51][52][53][54] this approach presents the flexibility of a twostep glycoengineering/labelling approach. Furthermore, the…”

Antibody‐Recruitment as a Therapeutic Strategy: A Brief History and Recent Advances

“…CIRs selectively recruited anti‐DNP to the surface of HEK293T cells overexpressing PMSA, and antibody‐recruitment provided substantial levels of ADCP. Covalent stabilization of antibody recruitment, and the resulting enhancement of immune system recognition and destruction of cancer cells has been described more recently, [21] and may provide enhancement when using antibody‐binding components that are relatively low affinity and/or have fast dissociation rates.…”

Covalent Immune Proximity-Induction Strategy Using SuFEx-Engineered Bifunctional Viral Peptides

“…Problematically, the binding affinity of BMs for the immune receptor may be too weak to form ternary complexes of sufficient stability to elicit a therapeutic response. 1,7 There are three main reasons why BM affinity for immune receptors may be too weak to maximize immunotherapeutic function: (1) Endogenous concentrations of immune receptors like antibodies are often naturally below the K D governing binding. 1,16−21 This disfavors ternary complex formation.…”