Immunotherapy has revolutionized cancer treatment, yet its efficacy is frequently compromised by metabolic mechanisms that drive resistance. Understanding how tumor metabolism shapes the immune microenvironment is essential for developing effective therapeutic strategies. This review examines key metabolic pathways influencing immunotherapy resistance, including glucose, lipid, and amino acid metabolism. We discuss their impact on immune cell function and tumor progression, highlighting emerging therapeutic strategies to counteract these effects. Tumor cells undergo metabolic reprogramming to sustain proliferation, altering the availability of essential nutrients and generating toxic byproducts that impair cytotoxic T lymphocytes (CTLs) and natural killer (NK) cell activity. The accumulation of lactate, deregulated lipid metabolism, and amino acid depletion contribute to an immunosuppressive tumor microenvironment (TME). Targeting metabolic pathways, such as inhibiting glycolysis, modulating lipid metabolism, and restoring amino acid balance, has shown promise in enhancing immunotherapy response. Addressing metabolic barriers is crucial to overcoming immunotherapy resistance. Integrating metabolic-targeted therapies with immune checkpoint inhibitors may improve clinical outcomes. Future research should focus on personalized strategies to optimize metabolic interventions and enhance antitumor immunity.

Cancer-related anorexia-cachexia syndrome (CACS) is a debilitating condition afflicting up to 80% of advanced-stage cancer patients. Characterized by progressive weight loss, muscle wasting, and metabolic abnormalities, CACS significantly compromises patients’ quality of life and treatment outcomes. This comprehensive review navigates through its intricate physiopathology, elucidating its stages and diagnostic methodologies. CACS manifests in three distinct stages: pre-cachexia, established cachexia, and refractory cachexia. Early detection is pivotal for effective intervention and is facilitated by screening tools, complemented by nutritional assessments and professional evaluations. The diagnostic process unravels the complex interplay of metabolic dysregulation and tumor-induced factors contributing to CACS. Management strategies, tailored to individual patient profiles, encompass a spectrum of nutritional interventions. These include dietary counseling, oral nutritional supplements, and, when necessary, enteral nutrition and a judicious use of parenteral nutrition. Specific recommendations for caloric intake, protein requirements, and essential nutrients address the unique challenges posed by CACS. While pharmacological agents like megestrol acetate may be considered, their use requires careful evaluation of potential risks. At its core, this review underscores the imperative for a holistic and personalized approach to managing CACS, integrating nutritional interventions and pharmacological strategies based on a nuanced understanding of patient’s condition.