Integrated molecular and immune profiling identifies FOXA1 as a complementary co-target to MUC1 for bispecific...

In breast cancer immunotherapy, Mucin 1 (MUC1) is a well-established target with promising preclinical results; however, single targeting of MUC1 has demonstrated limited efficacy in clinical trials, largely due to tumor heterogeneity, diverse glycosylation patterns, and an immunosuppressive TME. Identification of complementary co-targets enables bi-specific or dual-target immunotherapy, limiting antigen escape, improving specificity, and reducing relapse. Here, we employed a comprehensive multi-layered analytical approach to evaluate MUC1 expression, clinical relevance, and methylation status, followed by systematic screening of MUC1-correlated genes. Antigenicity prediction and protein-protein interaction analyses identified Forkhead Box A1 (FOXA1) as a potential functional partner. Expression analysis revealed concordant patterns of MUC1 and FOXA1 across breast cancer samples, while network mapping demonstrated shared interactions with adhesion-associated proteins, including CTNNB1, CTNND1, and CDH1, suggesting roles in epithelial organization and tumor progression. Further validation using gene expression datasets from Indian breast cancer cohorts confirmed consistent expression and correlation patterns, supporting reproducibility across populations. Immune profiling revealed an inverse association between MUC1-FOXA1 co-expression and immune-related gene signatures, with high co-expression linked to reduced infiltration of dendritic cells, CD4⁺ and CD8⁺ T cells, macrophages, and natural killer cells, indicative of an immunosuppressive microenvironment. Negative correlations with MHC Class I genes further suggested impaired antigen presentation. Epitope prediction identified high-affinity peptides from both targets with strong MHC Class I binding potential. Collectively, these findings support the associated role of MUC1 and FOXA1 as dual immunotherapeutic targets in breast cancer.