Background Novel immune checkpoint blockade strategies are being evaluated in clinical trials and include targeting the lymphocyte activation gene 3 (LAG-3) checkpoint, alone or in combination with PD-1/PD-L1 blockade. We investigated LAG-3 expression and its prognostic value in a large series of breast cancer patients, and correlated LAG-3 expression with key biomarkers including PD-1 and PD-L1. Experimental design LAG-3 expression was evaluated by immunohistochemistry on two tissue microarray series incorporating 4322 breast cancer primary excision specimens (N = 330 in the training and N= 3992 in the validation set) linked to detailed clinicopathologic, biomarker and long-term clinical outcome data. PD-1 and PD-L1 expressions were also evaluated by immunohistochemistry. Stromal or intra-epithelial tumor infiltrating lymphocytes (sTILs or iTILs) expressing LAG-3 or PD-1 were assessed by absolute count. PD-L1 expression was evaluated as the percentage of positive carcinoma cells per core. Kaplan-Meier curves and Cox proportional hazard models were used for survival analyses. Results After locking down interpretation cut-offs on the training set, LAG-3+ iTILs were found in 11% of cases in the validation set. In both sets, LAG-3+ iTILs were significantly associated with negative prognostic factors: young age, large tumor size, high proliferation, HER2E and basal-like breast cancer subtypes. In multivariate analyses, breast cancer patients with LAG-3+ iTILs had a significantly improved breast cancer-specific survival [hazard ratio (HR): 0.71, 95% CI 0.56-0.90], particularly among estrogen receptor-negative patients (HR: 0.50, 95% CI 0.36-0.69). Furthermore, we found that 53% of PD-L1+ and 61% of PD-1+ cases were also positive for LAG-3+ iTILs. Concurrent infiltration of LAG-3+ and CD8+ iTILs was significantly associated with increased breast cancer-specific survival (HR: 0.49, 95% CI 0.32-0.74). Conclusion LAG-3+ iTILs are enriched in estrogen receptor-negative breast cancers and represent an independent favorable prognostic factor. In addition, a high proportion of PD-1/PD-L1+ tumors are co-infiltrated with LAG-3+ TILs, supporting potential immune checkpoint blockade combination strategies as a treatment option for breast cancer patients.

中文翻译：

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乳腺癌中 LAG-3+ 肿瘤浸润淋巴细胞：临床与 PD-1/PD-L1+ 肿瘤的相关性和关联性。

背景 新的免疫检查点阻断策略正在临床试验中进行评估，包括靶向淋巴细胞激活基因 3 (LAG-3) 检查点，单独或与 PD-1/PD-L1 阻断联合使用。我们研究了 LAG-3 在大量乳腺癌患者中的表达及其预后价值，并将 LAG-3 表达与包括 PD-1 和 PD-L1 在内的关键生物标志物相关联。实验设计 LAG-3 表达通过免疫组织化学对两个组织微阵列系列进行评估，该系列包含 4322 个乳腺癌原发切除标本（训练中 N = 330，验证集中 N = 3992）与详细的临床病理学、生物标志物和长期临床结果相关联数据。PD-1 和 PD-L1 表达也通过免疫组织化学进行评估。通过绝对计数评估表达 LAG-3 或 PD-1 的基质或上皮内肿瘤浸润淋巴细胞（sTIL 或 iTIL）。PD-L1 表达被评估为每个核心的阳性癌细胞百分比。Kaplan-Meier 曲线和 Cox 比例风险模型用于生存分析。结果锁定训练集的解释截止后，在验证集中 11% 的案例中发现了 LAG-3+ iTIL。在这两组中，LAG-3+ iTILs 与阴性预后因素显着相关：年轻、肿瘤大小、高增殖、HER2E 和基底样乳腺癌亚型。在多变量分析中，具有 LAG-3+ iTILs 的乳腺癌患者的乳腺癌特异性生存率显着提高 [风险比 (HR): 0.71, 95% CI 0.56-0.90]，特别是在雌激素受体阴性患者中（HR：0.50, 95% CI 0.36-0.69）。此外，我们发现 53% 的 PD-L1+ 和 61% 的 PD-1+ 病例对 LAG-3+ iTILs 也呈阳性。LAG-3+ 和 CD8+ iTIL 的同时浸润与乳腺癌特异性存活率增加显着相关（HR：0.49，95% CI 0.32-0.74）。结论 LAG-3+ iTILs 在雌激素受体阴性乳腺癌中富集，是一个独立的有利预后因素。此外，高比例的 PD-1/PD-L1+ 肿瘤与 LAG-3+ TIL 共同浸润，支持潜在的免疫检查点阻断联合策略作为乳腺癌患者的治疗选择。LAG-3+ 和 CD8+ iTIL 的同时浸润与乳腺癌特异性存活率增加显着相关（HR：0.49，95% CI 0.32-0.74）。结论 LAG-3+ iTILs 在雌激素受体阴性乳腺癌中富集，是一个独立的有利预后因素。此外，高比例的 PD-1/PD-L1+ 肿瘤与 LAG-3+ TIL 共同浸润，支持潜在的免疫检查点阻断联合策略作为乳腺癌患者的治疗选择。LAG-3+ 和 CD8+ iTIL 的同时浸润与乳腺癌特异性存活率增加显着相关（HR：0.49，95% CI 0.32-0.74）。结论 LAG-3+ iTILs 在雌激素受体阴性乳腺癌中富集，是一个独立的有利预后因素。此外，高比例的 PD-1/PD-L1+ 肿瘤与 LAG-3+ TIL 共同浸润，支持潜在的免疫检查点阻断联合策略作为乳腺癌患者的治疗选择。