Efficacy and Safety of Extended-Dose Interval Immunotherapy Versus Standard-Dose Interval Immunotherapy for Advanced Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), defined by the lack of ER, PR and HER2 expression, is refractory to endocrine therapy and anti-HER2 agents. Chemotherapy was once the mainstay for advanced TNBC, but its limited efficacy necessitates optimized therapeutic strategies. TNBC's high TIL infiltration and elevated PD-L1 expression confer sensitivity to immune checkpoint inhibitors (ICIs), with ICI-chemotherapy combinations initially establishing first-line standard status. Emerging clinical evidence shows that ICI-antibody-drug conjugate (ADC) combinations outperform ICI-chemotherapy regimens, yet immune-related adverse events (irAEs) remain a critical clinical challenge. Expert consensus recommends continuing ICI therapy in advanced TNBC patients achieving CR, PR or SD after ICI-based combination therapy until disease progression or intolerable toxicity. Mechanistically, once ICIs reach target receptor saturation, dose escalation or high-frequency administration fails to boost efficacy but raises toxicity risk. Thus the investigators hypothesize that an ICI maintenance strategy with fixed dose and extended intervals can preserve efficacy, reduce toxicity, improve patient compliance, enhance quality of life and alleviate economic burden for advanced TNBC patients with CR/PR/SD after ICI-chemotherapy or ICI-ADC treatment.