A single-cell transcriptomic landscape of innate and adaptive intratumoral immunity in triple negative breast cancer during chemo- and immunotherapies

Laura Carpen,Patrizia Mancuso,Stefania Orecchioni,Alessandro Raveane,Saveria Mazzara,Francesco Bertolini,Stefano Pileri,Giulia Mitola,Paolo Falvo,Roman Hillje

doi:10.1038/s41420-022-00893-x

Abstract

Breast cancer (BC) constitutes a major health problem worldwide, making it the most common malignancy in women. Current treatment options for BC depend primarily on histological type, molecular markers, clinical aggressiveness and stage of disease. Immunotherapy, such as αPD-1, have shown combinatorial clinical activity with chemotherapy in triple negative breast cancer (TNBC) delineating some therapeutic combinations as more effective than others. However, a clear overview of the main immune cell populations involved in these treatments has never been provided.Here, an assessment of the immune landscape in the tumor microenvironment (TME) of two TNBC mouse models has been performed using single-cell RNA sequencing technology. Specifically, immune cells were evaluated in untreated conditions and after treatments with chemotherapy or immunotherapy used as single agents or in combination. A decrease of Treg was found in treatments with in vivo efficacy as well as γδ T cells, which have a pro-tumoral activity in mice. Focusing on Cd8 T cells, across all the conditions, a general increase of exhausted-like Cd8 T cells was confirmed in pre-clinical treatments with low efficacy and an opposite trend was found for the proliferative Cd8 T cells. Regarding macrophages, M2-like cells were enriched in treatments with low efficacy while M1-like macrophages followed an opposite trend. For both models, similar proportions of B cells were detected with an increase of proliferative B cells in treatments involving cisplatin in combination with αPD-1. The fine-scale characterization of the immune TME in this work can lead to new insights on the diagnosis and treatment of TNBC.

Highlights

Breast cancer (BC) is the most common malignancy in women, and the fifth leading cancer death worldwide [1]
In the tumor microenvironment (TME), PD-1 and its ligand PD-L1 perform a vital role in progression and survival of cancer cells; the overexpression of PD-L1 by tumor cells is used as self-defense by the tumor against the cytotoxic T cells which contribute to cell killing [14]
Looking at the sub-cluster cell proportions along the conditions (Fig. S5), one of the most relevant results was that the highly proliferative Cd8 T cells belonging to cluster 3 increased in TMEs treated with C140 and almost doubled their percentage, compared to the control, in C140 alone and C140 + V treated TMEs, underlining a possible anti-tumoral effect

Summary

INTRODUCTION

Breast cancer (BC) is the most common malignancy in women, and the fifth leading cancer death worldwide [1]. PD-1 predominantly regulates effector T cell activity within tissue and tumors by binding the programmed cell death ligand 1 (PDL1). This binding inhibits kinases involved in T cell activation [11]. PD-L1 expression on many tumors is a component of a suppressive microenvironment that leads to T cell dysfunction and exhaustion [15]. This state of exhaustion is characterized by the progressive loss of proinflammatory cytokines production, the loss of the cytotoxic activity, the decrease in the proliferative potential and an increase in apoptosis [16]. Single-cell RNA sequencing (scRNA-seq) gives the possibility to differentiate among cell populations that are not distinguishable by

Carpen et al 2

DISCUSSION

Findings

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