Tumor-infiltrating lymphocyte therapy in triple-negative breast cancer: from mechanistic exploration to clinical translation

Breast cancer is a common malignancy among women, with triple-negative breast cancer (TNBC) representing a subtype with poor prognosis. Due to the lack of expression of targetable receptors, traditional hormone therapy and HER2-targeted therapy are ineffective against TNBC. Moreover, TNBC typically exhibits more aggressive biological behavior, with a high propensity for recurrence and metastasis, further exacerbating its poor prognosis. While chemotherapy remains the primary treatment modality, its efficacy is limited, and patients readily develop resistance. Consequently, exploring novel therapeutic strategies and targets is crucial for improving the prognosis of patients with TNBC. Tumor-infiltrating lymphocytes (TILs) are promising prognostic and predictive biomarkers of TNBC. Multiple studies have demonstrated that a higher number of TILs in early-stage TNBC is correlated with favorable outcomes. Furthermore, clinical trials have demonstrated that TIL therapy is effective in solid tumors. This review outlines the current understanding of the TIL role in TNBC, elucidates the mechanisms and clinical efficacy of TIL therapy, and discusses future research directions and challenges for TILs.