Introduction: Therapeutic targeting of inhibitors of the immune response has reached the clinical setting. Inhibitors of the novel receptor LAG3, which negatively regulates T-cell activation, are under investigation. Here we explore the presence and prognostic role of LAG3 in cancer.Methods: A systematic search of electronic databases identified publications exploring the effect of LAG3 on overall survival (OS) and (for early-stage cancers) disease-free survival (DFS). Hazard ratios (HR) were pooled in a meta-analysis using generic inverse-variance and random effect modeling. Subgroup analyses were conducted based on disease site and tumor type.Results: Fifteen studies met the inclusion criteria. LAG3 was associated with better overall survival [HR 0.81, 95% confidence interval (CI) 0.66–0.99; P = 0.04], with subgroup analysis showing no significant differences between disease-site subgroups. The beneficial effect of LAG3 on OS was of greater magnitude in early-stage malignancies (HR 0.73, 95% CI 0.60–0.88) than in the metastatic setting (HR 1.20, 95% CI 0.70–2.05), but this difference was not statistically significant (subgroup difference p = 0.18). LAG3 did not have a significant association with DFS [HR 1.02, 95% confidence interval (CI) 0.77–1.37; P = 0.87], with subgroup analysis showing worse DFS in patients with lymphoma and improved DFS in those with breast cancer.Conclusions: High expression of LAG3 is associated with favorable overall survival in several solid tumors. A trend toward an association in early-stage disease suggests the importance of immune surveillance in this setting.

As immunotherapy agents are incorporated into the routine oncological practice, the number of patients at the risk of immune-related adverse events has increased dramatically. However, the prompt identification and effective management of severe autoimmune complications remain a challenge. We report the case of a patient with metastatic lung adenocarcinoma who experienced a fatal autoimmune storm 3 weeks after the first dose of anti-programmed death receptor-1 (PD-1) agent pembrolizumab, which included thyroiditis, hepatitis, myositis, myocarditis, pneumonitis, and myasthenia gravis. Aggressive autoimmunity was supported by extensive T-cell and macrophage tissue infiltrates and autoantibody positivity. Remarkably, no residual tumor was found at autopsy. This case illustrates the potential harm caused by immunotherapy and our limited knowledge on its prevention, treatment, and association to antitumor efficacy.

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