Cancer Therapy-Related Cutaneous Toxicities: Prognostic Biomarkers, Immunologic Endotypes, and Novel Therapeutic Strategies

Background/Objectives: Cutaneous adverse events (cAEs) are among the most common toxicities associated with modern anticancer therapies and can significantly affect quality of life, treatment adherence, and therapeutic outcomes. This narrative review aims to provide an updated overview of the mechanisms, clinical manifestations, prognostic implications, and management strategies of cancer therapy-related cutaneous toxicities, with a particular focus on precision oncodermatology. Methods: A narrative review of the recent literature was performed, integrating evidence from clinical studies, meta-analyses, pharmacovigilance investigations, consensus guidelines, and translational research. The review examines cutaneous toxicities associated with immune checkpoint inhibitors, targeted therapies, antibody–drug conjugates, and other emerging anticancer treatments. Results: Four major axes were identified: immune disinhibition, epithelial signaling inhibition, cytotoxic epithelial injury, and cytokine-driven immune activation. Cutaneous immune-related adverse events (cirAEs) emerged as potential biomarkers of treatment efficacy, particularly vitiligo, lichenoid, and psoriasiform eruptions. Increasing evidence supports the use of steroid-sparing biologic therapies, including dupilumab, omalizumab, anti-IL-17 agents, and Janus kinase inhibitors, although prospective validation remains limited. Recent advances in immunologic endotyping have identified distinct inflammatory pathways that may enable personalized therapeutic approaches. Antibody–drug conjugates represent an expanding source of unique dermatologic toxicities requiring dedicated management strategies. Emerging biomarkers, including cytokine signatures and microRNAs, may further refine risk stratification and treatment selection. Conclusions: The management of cancer therapy-related cutaneous toxicities is evolving toward a precision medicine model integrating clinical phenotype, immunologic endotype, and biomarker profiling. Early multidisciplinary intervention and mechanism-based therapeutic strategies may improve patient outcomes while preserving anticancer efficacy. Prospective studies are needed to validate biomarker-guided and steroid-sparing approaches in oncodermatology.