抗 HER2 疗法，包括 HER2 抗体药物偶联物 (ADC)、曲妥珠单抗 emtansine (T-DM1) 和曲妥珠单抗 deruxtecan (T-DXd)，已改善 HER2 过表达 (HER2) 转移性乳腺癌患者的生存结果。然而，对基于抗 HER2 的疗法的内在或获得性耐药仍然是这些患者的临床挑战，因为疾病进展后没有护理标准。本研究的目的是阐明 HER2  BC 患者和临床前模型对 T-DM1 和 T-DXd 的耐药机制，并确定在 HER2 导向的 ADC 耐药 HER2  乳腺癌中，抑制增强 T-DXd 抗肿瘤活性的靶点对乳腺癌患者组织样本进行靶向 DNA 和全转录组测序，以研究抗 HER2 治疗后出现的遗传畸变。我们生成了 T-DM1 和 T-DXd 耐药 HER2 乳腺癌细胞系。为了阐明它们的耐药机制并确定增强 T-DXd 功效的潜在协同激酶靶标，我们使用了荧光原位杂交、微滴数字 PCR、蛋白质印迹、全基因组测序、cDNA 微阵列和合成致死激酶组 RNA 干扰筛选。此外，还使用细胞活力、集落形成和异种移植测定来确定 T-DXd 组合的协同抗肿瘤作用。我们发现抗 HER2 治疗后患者体内 HER2 表达降低，DNA 修复相关基因扩增。 HER2 导向的 ADC 抗性 HER2 乳腺癌细胞系中 ERBB2 基因扩增的减少是通过 DNA 损伤和表观遗传机制实现的。在 HER2 导向的 ADC 耐药 HER2 乳腺癌细胞系中，我们的无偏 RNA 干扰筛选将 DNA 修复途径确定为经典途径中的潜在靶点，以增强 T-DXd 的功效。我们验证了与单药相比，T-DXd 与共济失调毛细血管扩张症和 Rad3 相关抑制剂 elimusertib 的组合可导致显着的体外乳腺癌细胞死亡 (P < 0.01) 和体内 (P < 0.01)。通路有助于 HER2 导向的 ADC 耐药。我们的数据证明在临床试验中探索 T-DXd 与 DNA 修复靶向药物的联合治疗来治疗 HER2 导向的 ADC 耐药 HER2 乳腺癌。© 2024。作者。

Anti-HER2 therapies, including the HER2 antibody-drug conjugates (ADCs) trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd), have led to improved survival outcomes in patients with HER2-overexpressing (HER2+) metastatic breast cancer. However, intrinsic or acquired resistance to anti-HER2-based therapies remains a clinical challenge in these patients, as there is no standard of care following disease progression. The purpose of this study was to elucidate the mechanisms of resistance to T-DM1 and T-DXd in HER2+ BC patients and preclinical models and identify targets whose inhibition enhances the antitumor activity of T-DXd in HER2-directed ADC-resistant HER2+ breast cancer in vitro and in vivo.Targeted DNA and whole transcriptome sequencing were performed in breast cancer patient tissue samples to investigate genetic aberrations that arose after anti-HER2 therapy. We generated T-DM1 and T-DXd-resistant HER2+ breast cancer cell lines. To elucidate their resistance mechanisms and to identify potential synergistic kinase targets for enhancing the efficacy of T-DXd, we used fluorescence in situ hybridization, droplet digital PCR, Western blotting, whole-genome sequencing, cDNA microarray, and synthetic lethal kinome RNA interference screening. In addition, cell viability, colony formation, and xenograft assays were used to determine the synergistic antitumor effect of T-DXd combinations.We found reduced HER2 expression in patients and amplified DNA repair-related genes in patients after anti-HER2 therapy. Reduced ERBB2 gene amplification in HER2-directed ADC-resistant HER2+ breast cancer cell lines was through DNA damage and epigenetic mechanisms. In HER2-directed ADC-resistant HER2+ breast cancer cell lines, our non-biased RNA interference screening identified the DNA repair pathway as a potential target within the canonical pathways to enhance the efficacy of T-DXd. We validated that the combination of T-DXd with ataxia telangiectasia and Rad3-related inhibitor, elimusertib, led to significant breast cancer cell death in vitro (P < 0.01) and in vivo (P < 0.01) compared to single agents.The DNA repair pathways contribute to HER2-directed ADC resistance. Our data justify exploring the combination treatment of T-DXd with DNA repair-targeting drugs to treat HER2-directed ADC-resistant HER2+ breast cancer in clinical trials.© 2024. The Author(s).