A Proximity-Dependent Biosensor System for Visualizing Cell-Cell Interactions Induced by Therapeutic Antibodies

Abstract

Background and PurposeDespite the promising results of therapeutic antibodies in engaging the immune system to eliminate malignant cells, many aspects of the complex interplay between immune cells and cancer cells during antibody therapy remain incompletely understood. This study aimed to develop a biosensor system that can evaluate direct cell-cell contact and interactions between immune effector and target cells induced by therapeutic antibodies in physiologically relevant environments. Experimental ApproachThe system uses two structural complementary luciferase units (SmBit and LgBit) expressed on the respective membranes of immune effector and target cells. Upon cell-cell contact, the two subunits form active NanoLuc, generating a luminescent signal, allowing for real-time monitoring of cell-cell interactions and quantitatively assessing the pharmacological effects of therapeutic antibodies. Key ResultsWe optimized the system to ensure selectivity by adjusting the spacer lengths between two luciferase units to minimize interference from nonspecific intercellular contact. The system was able to quantitatively and longitudinally monitor cell-cell interactions between NK and target cells induced by rituximab and between T and target cells induced by blinatumomab in a three-dimensional cell culture system. The observation that NK cells exhibited faster interactions with target cells compared to T cells is intriguing and suggests potential differences in the mechanisms or kinetics of cell-cell interactions between different types of effector cells and tumor cells. Conclusions and ImplicationsThe biosensor system has the potential for broad applications to optimize antibody pharmacology and efficacy in various therapeutic areas through a deeper understanding of antibody-mediated cell-cell interactions. What is already knownO_LITherapeutic antibodies can activate the immune system to elicit cytotoxicity through inducing cell-cell interactions between immune and tumor cells. C_LIO_LIApproaches for longitudinally evaluating cell-cell interaction induced by therapeutic antibodies remain limited. C_LI What does this study addO_LIThis study develops a biosensor system for detecting cell-cell interactions induced by therapeutic antibodies in a longitudinal manner. C_LIO_LIThe system is able to monitor cell-cell interactions between NK and target cells, as well as between T and target cells, in a three-dimensional cell culture system. C_LI What is the clinical significanceO_LIThe biosensor system has the potential for broad applications in the field of antibody pharmacology by providing a deeper understanding of antibody-mediated cell-cell interactions and their dynamics. C_LI