Pan-cancer single-cell atlas reveals sex-biased SPP1+ macrophage-associated crosstalk and its implications for immunotherapy

Abstract Advancements in cancer biology have increasingly highlighted the crucial role of sex in influencing cancer progression and therapeutic outcomes. Nevertheless, current research remains largely focused on overall populations, overlooking the impact of sex. This gap underscores the need for a detailed understanding of how sex differences manifest within the tumor microenvironment (TME). We performed a comprehensive analysis of sex differences by integrating a large-scale single-cell RNA sequencing atlas comprising 1,662 samples from fourteen human cancer types. Systematic profiling of the TME was conducted to identify sex-specific differences, including SPP1 + macrophages. Furthermore, we compared anti-PD-1 immunotherapy responses between male and female mice, including a macrophage-specific Spp1 knockout model. Our analysis revealed pronounced sex-specific differences in key TME components, with females showing significantly higher proportions of myofibroblastic cancer-associated fibroblasts, SPP1 + macrophages, and exhausted CD4 + T cells than males. Experimentally, anti-PD-1 therapy was more effective in males than females in mice, and macrophage-specific Spp1 knockout could sensitize female mice to anti-PD1 immunotherapy. This study reveals that sex shapes TME composition and drives divergent therapeutic responses, establishing sex as a critical variable in personalized cancer care and supporting sex-informed strategies to improve immunotherapeutic outcomes.