Comprehensive Analysis of the Immune Microenvironment Reveals that CD52 is a Marker for Breast Cancer Treatment with Immune Checkpoint Inhibitors

Background:Breast cancer (BC) is one of the most common tumors in women. Recent years, immune checkpoint inhibitors (ICIs) have brought good news to BC patients. Although significant achievements have been made through treatment with ICIs, some people who experience serious immune-related adverse events (IrAEs) are still insensitive to this approach. The response to ICI treatment depends on the type of tumor microenvironment (TME). Methods:WGCNA (weighted gene co-expression network analysis), ESTIMATE algorithm, LASSO regression analysis, survival analysis, functional enrichment analysis are conducted to analyze the BC data in the TCGA database. Immunohistochemistry was used to verify the expression of CD52 in BC.Results:WGCNA and ESTIMATE algorithm found that the CD52 is closely related to the immune microenvironment. CD52 highly expressed in various breast cancer subtypes, and patients with high expression of CD52 have longer survival time. Compared with the low-CD52 group, the high-CD52 group had more immune cell infiltration. TIMER database verification results showed that CD8+ T cells, activated memory CD4 T cells, memory B cells, γδ T cells, and Tregs were positively correlated with CD52 expression, while M2 macrophages were negatively correlated. CD52 can change the trend of TIC (CD8+ T) and tumor-associated macrophage (TAM) infiltration with respect to the survival time of breast cancer patients. Based on the expression of CD52, we explored the relationship between CD52 and the adaptive immune response (AIR). CD52 is a marker of AIR stratification in breast cancer patients. We constructed a CD52-related adaptive immune response gene signature (CD52rAIRGsig) which is an independent prognostic factor for breast cancer and related to genome instability and the immune cells infiltration in the TME. CD52 and CD52rAIRGsig were associated with PD-1 signaling and immune checkpoint inhibitor markers, which proves that patients with high CD52 expression and low risk of CD52rAIRGsig are more suitable for ICI treatment. We then screened chemotherapeutics for personalized medicine based on CD52rAIRGsig. Conclusion:Therefore, we have discovered a new marker to guide the treatment and prognosis of breast cancer patients with ICIs. This provides a combined treatment strategy including different combinations of ICIs combined with chemotherapeutic drugs to treat breast cancer.