Breast Cancer: Molecular Pathogenesis and Targeted Therapy.

Breast cancer (BC) is the most prevalent cancer in women and remains the leading cause of cancer-related mortality globally. Its development is influenced by multiple factors, including genetics, environmental, aging, and modulation of various signaling pathways. The heterogeneity of BC together with the emergence of treatment resistance and recurrence have prompted researchers to explore and develop new therapeutic approaches. Recently, oncology research has primarily focused on the development of targeted therapies against molecular abnormalities in BC. These therapies include monoclonal antibodies, tyrosine kinase inhibitors, antibody-drug conjugates, PI3K/Akt/mTOR pathway inhibitors, CDK 4/6 inhibitors, PARP inhibitors, antiangiogenic agents, and various other targeted drugs. Immunomodulatory strategies, including immune checkpoint inhibitors (anti-PD-1/PD-L1), CTLA-4 blockers, adoptive T-cell therapy, and cancer vaccines, stimulate immune response against cancer cells. Epigenetic therapies like DNMT and HDAC inhibitors have also shown promise in BC treatment. This review highlights how innovative approaches like targeting intratumoral heterogeneity, liquid biopsy for resistance mutation detection, bypass mechanisms ( activation following CDK4/6 inhibition), artificial intelligence-based drug discovery, patient-derived organoids, and adaptive trial designs are shaping BC treatment. By combining molecular insights with precision therapeutics, these advancements offer significant potential to address resistance, improve efficacy, and enhance patient outcomes.