AXL受体酪氨酸激酶是癌症复发的新型驱动因素，但其分子机制尚不清楚。在本研究中，我们调查了AXL如何调控非小细胞肺癌（NSCLC）和三阴性乳腺癌（TNBC）的疾病进展和预后。我们从TCGA数据集中对AXL转录组进行分析，发现AXL在NSCLC和TNBC中表达明显升高，与恶劣预后、上皮间质转化（EMT）和免疫耐受性肿瘤微环境（TME）相关。对AXL进行减少表达或使用两种独立的AXL抗体（名称为anti-AXL和AXL02）处理，都可在AXL高表达的NSCLC和TNBC细胞系中减少细胞迁移和EMT。在4T1 TNBC的小鼠模型中，给予anti-AXL抗体可大大抑制肺转移的形成和生长，伴随下游信号活化、EMT和增殖指数的降低，以及增加的凋亡和激活的抗肿瘤免疫力。我们发现AXL在肿瘤结节浸润的M2巨噬细胞中丰富激活。特定的anti-AXL抗体在体外阻止了骨髓来源的巨噬细胞（BMDM）M2偏极化。针对M2巨噬细胞的AXL与肿瘤细胞的靶向治疗，可以显著抑制CSF-1的产生并消除TME中的M2巨噬细胞，从而促进了M1型巨噬细胞、成熟树突状细胞、细胞毒性T细胞和B细胞的协调增强。我们利用一个特定结合平台制备了一种新型、人源化的AXL-ADC（AXL02-MMAE）。AXL02-MMAE对一系列AXL高表达的肿瘤细胞系具有强大的细胞毒性（IC50 < 0.1 nmol/L），并能抑制多种NSCLC和胶质瘤肿瘤的体内生长（最小有效剂量<1 mg/kg）。与化疗相比，AXL02-MMAE在抑制大型肿瘤的收缩方面效果更佳，可消除依赖AXL-H肿瘤细胞的M2巨噬细胞浸润，并积累丰富的炎症型巨噬细胞和成熟树突状细胞。我们的结果支持了针对AXL的靶向治疗在治疗晚期NSCLC和TNBC方面的应用。 © 2023。作者，独家授权给中国科学院上海药物研究所和中国药理学会。

The receptor tyrosine kinase AXL is an emerging driver of cancer recurrence, while its molecular mechanism remains unclear. In this study we investigated how AXL regulated the disease progression and poor prognosis in non-small cell lung cancer (NSCLC) and triple negative breast cancer (TNBC). We performed AXL transcriptome analysis from TCGA datasets, and found that AXL expression was significantly elevated in NSCLC and TNBC correlating with poor prognosis, epithelial-mesenchymal transition (EMT) and immune-tolerant tumor microenvironment (TME). Knockdown of AXL or treatment with two independent AXL antibodies (named anti-AXL and AXL02) all diminished cell migration and EMT in AXL-high expressing NSCLC and TNBC cell lines. In a mouse model of 4T1 TNBC, administration of anti-AXL antibody substantially inhibited lung metastases formation and growth, accompanied by reduced downstream signaling activation, EMT and proliferation index, as well as an increased apoptosis and activated anti-tumor immunity. We found that AXL was abundantly activated in tumor nodule-infiltrated M2-macrophages. A specific anti-AXL antibody blocked bone marrow-derived macrophage (BMDM) M2-polarization in vitro. Targeting of AXL in M2-macrophage in addition to tumor cell substantially suppressed CSF-1 production and eliminated M2-macrophage in TME, leading to a coordinated enhancement in both the innate and adaptive immunity reflecting M1-like macrophages, mature dendritic cells, cytotoxic T cells and B cells. We generated a novel and humanized AXL-ADC (AXL02-MMAE) employing a site-specific conjugation platform. AXL02-MMAE exerted potent cytotoxicity against a panel of AXL-high expressing tumor cell lines (IC50 < 0.1 nmol/L) and suppressed in vivo growth of multiple NSCLC and glioma tumors (a minimum efficacy dose<1 mg/kg). Compared to chemotherapy, AXL02-MMAE achieved a superior efficacy in regressing large sized tumors, eliminated AXL-H tumor cell-dependent M2-macrophage infiltration with a robust accumulation of inflammatory macrophages and mature dendritic cells. Our results support AXL-targeted therapy for treatment of advanced NSCLC and TNBC.© 2023. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.