The Role of Immune Checkpoint Inhibitors in Renal Cancer: Innovation, Resistance Mechanisms, and Next-generation Strategies

Renal cell carcinoma (RCC) is a prevalent and aggressive malignancy, often diagnosed at advanced stages with limited curative options. The development of immune checkpoint inhibitors (ICIs), especially those that target the PD-1/PD-L1 axis, has significantly transformed the therapeutic landscape of RCC, offering improved survival and disease control. However, a significant percentage of individuals either develop acquired resistance or have primary resistance, limiting the long-term efficacy of ICI-based therapies. This review explores the status of ICI treatment in RCC, summarizing key clinical milestones and response variability. Mechanisms contributing to resistancesuch as defective antigen presentation, immunosuppressive tumor microenvironment, and T cell exhaustion are examined in detail. To address these limitations, combination therapies involving VEGF inhibitors and dual checkpoint blockade (e.g., PD-1/CTLA-4) have demonstrated enhanced antitumor activity in clinical trials. Moreover, the potential of next-generation immune checkpoint targets, such as TIGIT, TIM-3, and LAG-3, to improve immune response is being intensively studied. In parallel, emerging technologies such as artificial intelligence-driven biomarker discovery, personalized neoantigen vaccines, and microbiome modulation are shaping the future of precision immunotherapy in RCC. These innovations aim to identify predictive markers, tailor therapies, and improve patient outcomes. By integrating mechanistic understanding with clinical and technological advancements, a more durable and personalized immunotherapy strategy may be achievable. This review provides a comprehensive overview of ongoing challenges, recent breakthroughs, and future directions for ICIs in RCC, highlighting the need for a multi-pronged approach to overcome resistance and optimize treatment efficacy.