Immune Checkpoint Inhibitors in Malignant Melanoma: Anti-PD-1, Anti-CTLA-4 and Anti-LAG-3 Therapies

Despite advances over the past decade, malignant melanoma remains associated with poor survival outcomes and an increasing incidence, particularly in older populations. Traditional radio- and chemotherapeutic approaches have shown limited efficacy, whereas immunotherapy has emerged as a promising treatment option owing to the immunogenic nature of most melanoma subtypes. This review aims to explore the biological rationale for immune checkpoint inhibition in melanoma and its therapeutic implications. Advances in understanding physiologic immune checkpoint regulation through co-stimulatory and co-inhibitory pathways have led to the development of effective immune checkpoint inhibitors (ICIs), particularly those targeting PD-1 and CTLA-4. These agents have significantly improved overall survival in melanoma; however, a substantial proportion of patients either fail to respond or eventually develop resistance. Ongoing clinical studies are elucidating mechanisms of immune evasion, refining response prediction biomarkers, and exploring combination strategies to overcome resistance and enhance durable remission. Immune checkpoint inhibition represents a major therapeutic milestone in malignant melanoma, transforming outcomes for many patients. Nevertheless, resistance and non-responsiveness remain key clinical challenges. Continued investigation into tumor–immune system interactions and rational combination approaches will be critical for optimizing the efficacy and durability of ICIs in melanoma treatment.