Expert consensus on the clinical application of immunotherapy in breast cancer: 2024.

Background: Significant progress has been made in immunotherapy of breast cancer (BC) with the approval of multiple immune checkpoint inhibitors (ICIs), particularly in early and metastatic triple-negative breast cancer (TNBC) settings. Most guidelines have recommended immune therapy as the important approach in BC, yet several critical aspects still require further clarification, including proper patient selection, treatment duration, optimized chemotherapy partner, predictive biomarkers, and specific considerations for Chinese patients.

Methods: (I) Establishment of expert group: the expert group consists of 32 experts from departments such as medical oncology, breast surgery, and pathology; (II) literature search: mainly conducted in English databases (such as PubMed, Embase, and Cochrane Library) and Chinese databases (such as China National Knowledge Infrastructure, China Biology Medicine disc, and Wanfang Database), with a search cutoff date of April 23, 2024; (III) assessment of evidence quality and recommendation strength: evidence quality and recommendation opinions are graded based on the evidence category and recommendation level of the Chinese Society of Clinical Oncology (CSCO) guidelines; (IV) consensus formulation: on the March 2, 2024, through online consensus meeting, the consensus content is thoroughly discussed, and opinions from all experts are solicited.

Results: The consensus meeting has resulted in 15 detailed recommendations, providing clearer guidance on the clinical application of immunotherapy in BC management. The core suggestions are as follows: for early-stage II-III TNBC and metastatic TNBC (mTNBC) in the first-line setting, programmed cell death protein 1 (PD-1) inhibitors can be considered. However, for hormone receptor-positive/human epidermal growth factor receptor 2-negative BC (HR⁺/HER2^- BC), HER2⁺ BC, and mTNBC in later lines of therapy, evidence is lacking to support the use of immunotherapy.

Conclusions: This consensus provides a comprehensive overview of BC immunotherapy, including immunotherapy for early-stage BC and late-stage BC, immune related adverse event (irAE) management, biomarkers of immunotherapy, and future directions. The consensus consolidates these deliberations into 15 evidence-based recommendations, serving as a practical guide for clinicians to more scientifically and systematically manage the clinical application of immunotherapy.