Chemotherapy Coupled to Macrophage Inhibition Induces T-cell and B-cell Infiltration and Durable Regression in Triple-Negative Breast Cancer

Swarnima Singh, Nigel Lee, Diego A. Pedroza, Igor L. Bado, Clark Hamor, Licheng Zhang, Sergio Aguirre, Jingyuan Hu, Yichao Shen, Yitian Xu, Yang Gao, Na Zhao, Shu Hsia Chen, Ying Wooi Wan, Zhandong Liu, Jeffrey T. Chang, Daniel Hollern, Charles M. Perou, Xiang H.F. Zhang, Jeffrey M. Rosen

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Immunosuppressive elements within the tumor microenvironment, such as tumor-associated macrophages (TAM), can present a barrier to successful antitumor responses by cytolytic T cells. Here we employed preclinical syngeneic p53 null mouse models of triple-negative breast cancer (TNBC) to develop a treatment regimen that harnessed the immunostimulatory effects of low-dose cyclophosphamide coupled with the pharmacologic inhibition of TAMs using either a small-molecule CSF1R inhibitor or an anti-CSF1R antibody. This therapeutic combination was effective in treating several highly aggressive TNBC murine mammary tumor and lung metastasis models. Single-cell RNA sequencing characterized tumor-infiltrating lymphocytes including Th cells and antigen-presenting B cells that were highly enriched in responders to combination therapy. In one model that exhibited long-term posttreatment tumor regression, high-dimensional imaging techniques identified the close spatial localization of B220þ/CD86þ-activated B cells and CD4þ T cells in tertiary lymphoid structures that were present up to 6 weeks posttreatment. The transcriptional and metabolic heterogeneity of TAMs was also characterized in two closely related claudin-low/mesenchymal subtype tumor models with differential treatment responses. A murine TAM signature derived from the T12 model was highly conserved in human claudin-low breast cancers, and high expression of the TAM signature correlated with reduced overall survival in patients with breast cancer. This TAM signature may help identify human patients with claudin-low breast cancer that will benefit from the combination of cyclophosphamide and anti-CSF1R therapy. These studies illustrate the complexity of the tumor immune microenvironment and highlight different immune responses that result from rational immunotherapy combinations. Significance: Immunostimulatory chemotherapy combined with pharmacologic inhibition of TAMs results in durable treatment responses elicited by Th cells and B cells in claudin-low TNBC models.

Original languageEnglish
Pages (from-to)2281-2297
Number of pages17
JournalCancer Research
Volume82
Issue number12
DOIs
StatePublished - 15 Jun 2022
Externally publishedYes

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