Integrated bulk and single-cell transcriptome analysis reveals the impact of cyclophosphamide on tumor microenvironment in triple-negative breast cancer models

Although preclinical investigations utilizing TNBC mouse models have demonstrated that intermittent cyclophosphamide (CTX) treatment yields superior anti-tumor effects, partly through immune stimulation, mechanisms by which CTX modulates the tumor microenvironment (TME) are not yet fully understood. In this study, we assessed the impact of optimal (140 mg/kg every 6 days, C140) and suboptimal (100 mg/kg every 6 days, C100) CTX treatment regimens on 4T1 tumors, a widely utilized orthotopic TNBC mouse model.

While the C100 regimen was better tolerated than the C140 regimen, it was less effective in inhibiting tumor growth. Through integrated bulk and single-cell RNA sequencing of tumor tissues, we discovered that CTX treatment not only inhibited cancer cell proliferation and epithelial-mesenchymal transition but also remodeled the TME by recruiting and reprogramming various immune cells, thereby enhancing the anticancer immune response in a dose-dependent manner.