
The C-Trap® provides the world’s first dynamic single-molecule microscope to allow simultaneous manipulation and visualization of single-molecule interactions in real time.

Cancer cells activate the integrated stress response (ISR) to adapt to stress and resist therapy. ISR signals converge on activating transcription factor 4 (ATF4), which controls cell-intrinsic transcriptional programs that are involved in metabolic adaptation, survival and growth. However, whether the ISR–ATF4 axis influences anti-tumour immune responses remains mostly unknown. Here we show that loss of ATF4 decreases tumour progression considerably in immunocompetent mice, but not in immunocompromised ones, by enhancing T cell-dependent anti-cancer immune responses. An unbiased genetic screen of ATF4-regulated genes identifies lipocalin 2 (LCN2) as the principal ATF4-dependent effector that impairs anti-tumour immunity by favouring infiltration with immunosuppressive interstitial macrophages. Furthermore, we find that LCN2 promotes T cell exclusion and immune evasion in preclinical mouse models, and correlates with decreased T cell infiltration in patients with lung and pancreatic adenocarcinomas. Anti-LCN2 antibodies promote robust anti-tumour T cell responses in mouse models of aggressive solid tumours. Our study shows that the ATF4–LCN2 axis has a cell-extrinsic role in suppressing anti-cancer immunity, and could pave the way for an immunotherapy approach that targets LCN2.
T cells play a pivotal role in tumor immunosurveillance. Multispecific cell engagers (CEs) have been adopted in the field of immuno-oncology to redirect T cells toward cancer cells, thereby unleashing the anti-tumor potential of the patient’s immune system. CE-mediated cell binding induces T cell activation and the formation of an immunological synapse, which is a prerequisite for effective tumor cell lysis.
The strength of the initial binding events between a T cell and a tumor cell dictates the efficiency of the anti-tumor response. Assessing cell avidity, i.e. the total intercellular interaction strength between two cells, gives crucial insights into the efficacy of CEs as anti-tumor therapeutic agents.
Here, we deploy LUMICKS’ high throughput avidity measurement (HTAM) technology to measure CE-induced cell avidity in a high throughput manner. We demonstrate the assay performance characteristics, i.e. specificity, precision, and range, via CE titration experiments in the context of a Jurkat T cell model system. We find that the HTAM CA assay is suitable for candidate screening in high throughput, with high sensitivity and precision.