Harnessing immunity against breast cancer: from checkpoints to cell therapies

Breast cancer (BC) remains the leading cause of cancer-related mortality and a major contributor to disease burden among women worldwide. Although PD‑1/PD‑L1‑targeting immune checkpoint inhibitors have become a standard treatment for certain triple‑negative breast cancer subgroups, their use across the broader BC population is limited by intrinsic resistance, an immunosuppressive tumor microenvironment (TME), and treatment‑related adverse effects. The present review offers a comprehensive synthesis of the immunotherapeutic paradigm in BC, spanning ICIs, adoptive cellular therapies (CAR-T, CAR-NK, CAR-M, TIL, TCR-T, and CIK cells), and emerging immune modulators. We critically evaluate pivotal clinical trials, discuss cross-cutting challenges-including biomarker development, therapy resistance, and the practical limitations of cellular products-and highlight rational combinatorial strategies. By contrasting the translational readiness of diverse modalities and outlining a framework for personalized therapy, this review aims to inform future research and clinical practice in harnessing immunity against BC.