Therapeutic Resistance in Melanoma: Molecular Mechanisms and Emerging Pharmaceutical Strategies

Cutaneous melanoma remains a global health challenge. Although BRAF/MEK-targeted therapies and immune checkpoint inhibitors (ICIs) have improved outcomes in advanced disease, durable responses remain difficult to achieve for most patients. Therapeutic resistance represents the central barrier to long-term disease control. This review comprehensively examines the molecular and immunologic mechanisms underlying melanoma resistance and integrates these insights with emerging pharmaceutical strategies designed to overcome them. We explore the genetic landscape of melanoma, including oncogenic alterations in BRAF, NRAS, NF1, CDKN2A, and PTEN, and explain how dysregulation of the MAPK and PI3K/AKT/mTOR signaling axes drives therapeutic escape. Phenotypic plasticity is discussed as a critical epigenetic driver of drug tolerance. The tumor microenvironment (TME) is examined as an active co-conspirator in resistance, encompassing immunosuppressive cell populations, cancer-associated fibroblasts, and metabolic competition. Resistance mechanisms to targeted therapy, including MAPK reactivation, bypass signaling, transcriptional reprogramming, and metabolic rewiring, are reviewed alongside tumor-intrinsic and tumor-extrinsic mechanisms of ICI resistance. Emerging therapeutic strategies are surveyed, including next-generation RAF and ERK inhibitors, dual-pathway blockade, and metabolic therapies targeting oxidative phosphorylation. Innovations in molecular imaging, liquid biopsy, and artificial intelligence-driven biomarker discovery are highlighted as pivotal tools for real-time resistance monitoring and adaptive treatment. By linking mechanistic insights with translational advances, this review advocates for combination strategies and adaptive clinical frameworks to achieve more durable disease control in melanoma.