Basal-like breast cancer (BLBC) shows brain metastatic (BM) capability and overexpresses EGFR and death-receptors 4/5 (DR4/5); however, the anatomical location of BM prohibits efficient drug-delivery to these targetable markers. In this study, we developed BLBC-BM mouse models featuring different patterns of BMs and explored the versatility of estem cell (SC)–mediated bi-functional EGFR and DR4/5-targeted treatment in these models. Most BLBC lines demonstrated a high sensitivity to EGFR and DR4/5 bi-targeting therapeutic protein, E_VDR_L [anti-EGFR VHH (E_V) fused to DR ligand (DR_L)]. Functional analyses using inhibitors and CRISPR-Cas9 knockouts revealed that the E_V domain facilitated in augmenting DR4/5-DR_L binding and enhancing DR_L-induced apoptosis. E_VDR_L secreting stem cells alleviated tumor-burden and significantly increased survival in mouse models of residual-tumor after macrometastasis resection, perivascular niche micrometastasis, and leptomeningeal metastasis. This study reports mechanism based simultaneous targeting of EGFR and DR4/5 in BLBC and defines a new treatment paradigm for treatment of BM.

基底样乳腺癌 (BLBC) 表现出脑转移 (BM) 能力并过表达 EGFR 和死亡受体 4/5 (DR4/5)；然而，BM 的解剖位置阻碍了对这些可靶向标记物的有效药物递送。在本研究中，我们开发了具有不同 BM 模式的 BLBC-BM 小鼠模型，并探索了这些模型中 estem 细胞 (SC) 介导的双功能 EGFR 和 DR4/5 靶向治疗的多功能性。大多数 BLBC 系表现出对 EGFR 和 DR4/5 双靶向治疗蛋白 E _V DR _L [与 DR 配体 (DR _L ) 融合的抗 EGFR VHH (E _V ) ] 的高敏感性。使用抑制剂和 CRISPR-Cas9 敲除的功能分析表明，EV_结构域有助于增强 DR4/5-DR_L结合和增强 DR _L诱导的细胞凋亡。E _V DR _L分泌干细胞在大转移切除、血管周围微环境微转移和软脑膜转移后残留肿瘤的小鼠模型中减轻了肿瘤负担并显着提高了存活率。该研究报告了 BLBC 中基于 EGFR 和 DR4/5 的同时靶向机制，并定义了治疗 BM 的新治疗模式。