# Potent Apoptosis Induction by a Novel Trispecific B7-H3xCD16xTIGIT 2+1 Common Light Chain Natural Killer Cell Engager

## TL;DR

A new molecule that activates natural killer cells to induce cancer cell death is developed using a combination of three immune targets.

## Contribution

A novel trispecific NK cell engager combining B7-H3, CD16, and TIGIT is developed for enhanced cancer immunotherapy.

## Key findings

- The trispecific molecule B7-H3xCD16xTIGIT induced potent apoptosis in cancer cells.
- Chicken-derived antibodies showed high affinity for B7-H3 and TIGIT.
- The molecule leverages both activating and checkpoint receptors to enhance NK cell activity.

## Abstract

Valued for their ability to rapidly kill multiple tumor cells in succession as well as their favorable safety profile, NK cells are of increasing interest in the field of immunotherapy. As their cytotoxic activity is controlled by a complex network of activating and inhibiting receptors, they offer a wide range of possible antigens to modulate their function by antibodies. In this work, we utilized our established common light chain (cLC)-based yeast surface display (YSD) screening procedure to isolate novel B7-H3 and TIGIT binding monoclonal antibodies. The chicken-derived antibodies showed single- to low-double-digit nanomolar affinities and were combined with a previously published CD16-binding Fab in a 2+1 format to generate a potent NK engaging molecule. In a straightforward, easily adjustable apoptosis assay, the construct B7-H3xCD16xTIGIT showed potent apoptosis induction in cancer cells. These results showcase the potential of the TIGIT NK checkpoint in combination with activating receptors to achieve increased cytotoxic activity.