Continuous replenishment of the dysfunctional CD8 T cell axis is associated with response to chemoimmunotherapy in advanced breast cancer

Cell Reports Medicine

Christina Metoikidou, Vadim Karnaukhov, Bram Boeckx, Eleonora Timperi, Pierre-Emmanuel Bonté, Ling Wang, Marion Espenel, Benoit Albaud, Delphine Loirat, Xiaoxiao Wang, Christos Sotiriou, Philippe Aftimos, Kevin Punie, Hans Wildiers, Viktorija Labroska, Ming-Wei Wang, Joshua J. Waterfall, Martine Piccart-Gebhart, Thierry Mora, Aleksandra Walczak, Olivier Lantz, Laurence Buisseret, Diether Lambrechts, Sebastian Amigorena, Emanuela Romano 

Summary

Chemotherapy combined with immune checkpoint blockade has shown clinical activity in breast cancer. Response, however, occurs in only a low proportion of patients. How the immune landscape of the tumor determines the immune and clinical responses to chemoimmunotherapy is not well understood. Here, using a combination of single-cell RNA sequencing (scRNA-seq) and single-cell T cell receptor sequencing (scTCR-seq), we profile 40 biopsies from 27 patients with metastatic triple-negative breast cancer (TNBC), receiving chemotherapy and anti-PD-L1 alone or in combination with anti-CD73, in a phase 2 randomized clinical trial. Our results show an enrichment of late-dysfunctional, clonally expanded CD8⁺ T cells in responder (R) patients. On treatment, R display an influx of newly emerging clonotypes, as well as expansion of the CD8⁺  precursors. Collectively, our data suggest that baseline clonal expansion could be a potential predictor of response and that both clonal reinvigoration of pre-existing tumor-reactive T cells and clonal replacement on-treatment are important for a protective response to chemoimmunotherapy.

More information at DOI: https://doi.org/10.1016/j.xcrm.2025.101973