Background: Adjuvant trastuzumab is the standard of care for HER2+ breast cancer (BC) patients. However, >50% of patients become resistant. This study aimed at the identification of the molecular factors associated with disease relapse and their further investigation as therapeutically exploitable targets. Methods: Analyses were conducted on formalin-fixed paraffin-embedded tissues of the primary tumors of relapsed (cases) and not relapsed (controls) HER2+ BC patients treated with adjuvant trastuzumab. The nCounter Human Breast Cancer Panel 360 was used. Logistic regression and partitioning around medoids were employed to identify the genes associated with disease recurrence. Cytotoxicity experiments using trastuzumab-resistant cell lines and a network pharmacology approach were carried out to investigate drug efficacy. Results: A total of 52 patients (26 relapsed and 26 not relapsed) were analyzed. We found that a higher expression of HDAC6 was significantly associated with an increased risk of recurrence, with an adjusted OR of 3.20 (95% CI 1.38–9.91,p= 0.016). Then, we investigated the cytotoxic activity of the selective HDAC6 inhibitor Nexturastat A (NextA) on HER2+ cell lines, which were both sensitive and trastuzumab-resistant. A sub-cytotoxic concentration of NextA, combined with trastuzumab, showed a synergistic effect on BC cell lines. Finally, using a network pharmacology approach, we identified HSP90AA1 as the putative molecular candidate responsible for the synergism observed in vitro. Conclusions: Our findings encourage the exploration of the role of HDAC6 as a prognostic factor and the combinatorial use of HDAC6 selective inhibitors combined with trastuzumab in HER2+ BC, in particular for those patients experiencing drug resistance.
背景：辅助曲妥珠单抗治疗是HER2阳性乳腺癌患者的标准疗法。然而，超过50%的患者会产生耐药性。本研究旨在识别与疾病复发相关的分子因素，并进一步探索其作为潜在治疗靶点的可能性。 方法：研究对接受辅助曲妥珠单抗治疗后复发（病例组）与未复发（对照组）的HER2阳性乳腺癌患者的原发肿瘤福尔马林固定石蜡包埋组织进行分析。采用nCounter人类乳腺癌360基因检测面板进行检测，运用逻辑回归和围绕中心点的分割聚类方法识别与疾病复发相关的基因。通过曲妥珠单抗耐药细胞系的细胞毒性实验及网络药理学方法，探究药物疗效机制。 结果：共纳入52例患者（26例复发，26例未复发）。研究发现HDAC6高表达与复发风险增加显著相关，校正后比值比为3.20（95%置信区间1.38-9.91，p=0.016）。进一步研究选择性HDAC6抑制剂Nexturastat A（NextA）对曲妥珠单抗敏感及耐药HER2阳性细胞系的细胞毒性作用，发现亚细胞毒性浓度的NextA与曲妥珠单抗联用对乳腺癌细胞系产生协同效应。最后通过网络药理学方法，确定HSP90AA1是介导体外协同效应的潜在分子靶点。 结论：本研究结果支持进一步探索HDAC6作为预后标志物的价值，并提示选择性HDAC6抑制剂与曲妥珠单抗联合治疗HER2阳性乳腺癌的潜力，尤其适用于产生耐药性的患者群体。
HDAC6 as a Prognostic Factor and Druggable Target in HER2-Positive Breast Cancer
肿瘤(癌症)患者之家