Emerging Targeted and Multimodal Therapeutic Strategies in Breast Cancer: A Comprehensive Review

Breast cancer treatment has advanced substantially with the development of targeted and multimodal strategies, yet tumor heterogeneity and therapeutic resistance continue to limit long-term outcomes. This review provides a concise and critical overview of established and emerging targeted therapies, with emphasis on resistance mechanisms, innovations in drug delivery, and integrative therapeutic approaches. Established modalities, including endocrine therapy, HER2-directed antibody and antibody-drug conjugate therapies, and chemotherapy, are summarized alongside key subtype-specific challenges. Emerging targets such as PARP, CDK4/6, WBP2, and Trop2, as well as metabolic and tumor-microenvironment-oriented strategies, are evaluated for their potential to overcome resistance. Advances in immunotherapy, including checkpoint inhibitors, bispecific antibodies, and CAR-T cell therapies, are examined with attention to mechanistic rationale and limitations across breast cancer subtypes. Progress in nanotechnology-based delivery systems, exosome-mediated transport, and multimodal predictive frameworks, including miRNA regulatory networks, is further assessed for its relevance to personalized treatment. Overall, this review synthesizes current molecular insights and therapeutic innovations to inform the development of more effective and durable targeted treatments for breast cancer.