曲妥珠单抗耐药机制及HER2阳性乳腺癌耐药后的治疗策略

曲妥珠单抗治疗人表皮生长因子受体2(Human epidermal growth factor receptor 2,HER2)阳性乳腺癌的效果确切,但高耐药率限制了其临床应用。本文对HER2阳性乳腺癌曲妥珠单抗耐药机制进行回顾与总结,并分析耐药后HER2阳性乳腺癌的治疗策略,以期为进一步的研究及临床治疗方案制定提供参考。     

曲妥珠单抗耐药后HER 2阳性转移性乳腺癌靶向治疗策略

人表皮生长因子受体2（human epidermal growth factor receptor 2,HER 2）是一种跨膜酪氨酸激酶受体,可以激活下游一系列信号通路,导致肿瘤细胞增殖和存活。HER 2阳性乳腺癌是乳腺癌的特殊类型,恶性程度高,预后差。抗HER 2单克隆抗体曲妥珠单抗能够改善该类乳腺癌治疗效果,但最终仍难逃耐药的结局。近年来,针对曲妥珠单抗耐药机制的研究、新型靶向药物的研发以及治疗策略的探索,在克服曲妥珠单抗耐药性方面取得了重大进展,本文将对其耐药后治疗策略及临床试验数据进行综述。     

曲妥珠单抗治疗HER2+乳腺癌的临床进展

临床研究显示曲妥珠单抗与化疗联合用于人表皮生长因子受体2(HER2)+转移性乳腺癌的治疗以及早期乳腺癌的新辅助和辅助治疗,能显著延长患者的生存时间.其与内分泌治疗联合治疗HER2+且雌激素受体阳性的转移性乳腺癌,疗效优于单纯内分泌治疗.曲妥珠单抗联合其他靶向治疗药物,能够逆转肿瘤对曲妥珠单抗的耐药.疾病进展后继续应用曲妥珠单抗仍可使患者生存受益.     

曲妥珠单抗获得性耐药机制及应对策略

摘 要：曲妥珠单抗是靶向人表皮生长因子2(HER2)的单克隆抗体药物,对HER2表达阳性乳腺癌及胃癌治疗效果确切。然而多数患者在用药1年内出现了获得性耐药,导致其疗效降低甚至无效。研究表明,信号通路异常激活;表皮生长因子受体(EGFR)及其配体异常表达及肿瘤诱发上皮—间质转化(EMT)均可成为曲妥珠单抗耐药的重要机制,联合使用PI3K/AKT/mTOR通路抑制剂及其相关生存信号通路抑制剂可逆转曲妥珠单抗耐药。本文就曲妥珠单抗耐药机制及逆转耐药策略进行综述。     

HER2阳性乳腺癌治疗的研究进展

[摘要] 人表皮生长因子受体2（human epidermal growth factor receptor 2,HER2）阳性乳腺癌侵袭性高,预后差。随着抗HER2药物的不断出现及广泛应用,HER2 阳性乳腺癌患者的预后出现了非常显著的改善。10 年随访结果证实1 年曲妥珠单抗辅助治疗可以显著降低疾病复发风险;对于术后的高危人群,曲妥珠单抗联合帕妥珠单抗或者曲妥珠单抗序贯来那替尼可以进一步减少复发。5 年随访结果表明帕妥珠单抗+曲妥珠单抗为基础的新辅助治疗可使病理完全缓解（pathological complete response,pCR）转化为长期生存获益;白蛋白紫杉醇代替普通紫杉醇与抗HER2 药物联用可以进一步提高pCR率;而抗HER2 药物联合内分泌治疗尚不能达到与联合化疗在新辅助治疗中疗效,即使联合CDK4/6 抑制剂,对于pCR的提高依然有限。曲妥珠单抗+帕妥珠单抗联合紫杉类药物是晚期HER2 阳性乳腺癌的标准一线方案;对于老年、体弱的患者,节拍环磷酰胺可以作为紫杉类药物的替代品;拉帕替尼+曲妥珠单抗联合内分泌治疗可以作为HER2 阳性伴激素受体阳性的选择,疗效优于曲妥珠单抗联合内分泌治疗;T-DM1 无论是作为二线治疗还是三线及以后的治疗均提高了患者生存获益,是治疗晚期、耐药HER2阳性乳腺癌的首选。     

曲妥珠单抗耐药的机制和对策研究进展

曲妥珠单抗是人表皮生长因子受体2(HER2)过表达乳腺癌患者的重要治疗手段之一.但即使是HER2高表达或是基因扩增的患者,曲妥珠单抗单药的有效率也仅为12%～34%,中位缓解期约9个月,许多患者在接受治疗的12个月内出现疾病进展.对曲妥珠单抗的耐药机制进行研究,有助于我们为曲妥珠单抗耐药的患者寻找新的治疗药物和方法.     

曲妥珠单抗在HER2阳性胃癌中耐药机制研究进展

曲妥珠单抗是晚期人表皮生长因子受体2（HER2）阳性胃癌患者治疗的一线用药,耐药问题是曲妥珠单抗治疗中面临 的主要挑战。曲妥珠单抗治疗的耐药机制除了与HER2自身状态有关外,也与PI3K/AKT、MEK/ERK等经典信号通路以及有丝 分裂相关的非经典信号通路的异常激活有关,胃癌肿瘤微环境中代谢及免疫调控的改变也会导致患者对曲妥珠单抗耐药,目前 抗体药物偶联物等新型治疗方案可以克服并改善曲妥珠单抗的耐药性。本文聚焦曲妥珠单抗在HER2阳性胃癌中的耐药机制及 其克服曲妥珠单抗耐药新型疗法的研究进展,为临床优化曲妥珠单抗治疗HER2阳性胃癌提供了新思路。     

曲妥珠单抗的耐药机制及其逆转策略

曲妥珠单抗(trastuzumab;商品名为Herceptin,赫赛汀)是靶向人表皮生长因子受体2(human epidermal growth factor receptor2,HER2)的人源化单克隆抗体,与化疗药物联用可显著提高患者的无进展生存期.然而,曲妥珠单抗的原发性和获得性耐药严重制约了其临床疗效及应用.PI3 K/AKT/mTOR信号通路的异常活化、HER家族成员间的相互作用、药物压力下代偿性生存信号的激活、肿瘤干细胞表型形成等均可能成为曲妥珠单抗耐药的重要机制.随着曲妥珠单抗耐药机制研究的不断深入,克服耐药的治疗手段也越来越丰富.有研究表明,曲妥珠单抗与其他靶向HER2胞外域的单克隆抗体或靶向其他HER家族成员的抗体类药物联用可增强曲妥珠单抗的疗效.应用PI3 K/AKT/mTOR信号通路的小分子抑制剂或耐药相关促生存信号通路的特异性抑制剂可有效逆转耐药发生,延长患者的疾病无进展生存期.深入研究曲妥珠单抗耐药的机制,不断探索逆转耐药的治疗策略,可为乳腺癌个性化治疗方案的建立提供依据.本文将对曲妥珠单抗耐药机制及克服耐药的研究进展做一介绍.     

HER2过表达乳腺癌曲妥珠单抗耐药后靶向治疗策略

 曲妥珠单抗与化疗药物联用后提高了人类表皮生长因子受体2（HER2）过表达乳腺癌的反应率,但在开始治疗后数月易出现治疗性耐药,限制了患者的总生存期。曲妥珠单抗耐药机制主要与HER家族以外的蛋白酪氨酸激酶受体信号通路活化、PI3K-AKT通路扩增等有关。酪氨酸激酶抑制剂、磷脂酰肌醇3-激酶抑制剂等分子靶向药物作为曲妥珠单抗耐药者的替代治疗手段,单药疗效均不甚满意。多个大型临床试验证实,新型分子靶向药物联合应用能明显限制,甚或最终消除曲妥珠单抗初始治疗耐药性问题。     

HER⁃2阳性乳腺癌免疫治疗药物的研究进展

曲妥珠单抗及帕妥珠单抗等药物的应用使HER?2阳性乳腺癌患者的生存得到了显著的提高,但靶向药耐药事件仍时有发生.免疫治疗作为一种新的治疗手段,对HER?2阳性乳腺癌患者具有重大临床意义.作为被动免疫治疗的一种有效手段,单克隆抗体曲妥珠单抗、帕妥珠单抗及T?DM1等药物的临床应用使HER?2阳性乳腺癌患者的生存有了明显改...     

HER2-positive breast cancer: from trastuzumab to innovatory anti-HER2 strategies

Overexpression of HER2 is encountered in approximately 20% of invasive breast cancers. It is an independent adverse prognostic factor and, more importantly, it is currently the best predictive factor for the activity of trastuzumab, an anti-HER2 monoclonal antibody (MoAb), which has revolutionized the treatment of this breast cancer subgroup. Increasing knowledge of molecular pathways involving the HER family of growth factor receptors has paved the way toward new efficient targeted therapies. Herein, we will review the targeted therapies of clinical importance for HER2-positive breast cancer, which include anti-HER2 MoAbs and tyrosine kinase inhibitors that directly interfere at the receptor level. Clinicians are still facing many uncertainties concerning the optimal use of these new agents, and scientists are working on dissecting the mechanisms of resistance developed by HER2-positive cancer cells. Interesting perspectives in the treatment of HER2-positive breast cancer will be discussed. They consist of designing HER2 peptide-based vaccines, targeting downstream pathway molecules beyond the membrane receptor, and exploring synergistic antineoplasic strategies.     

Treatment of Her2-Positive Breast Cancer: What’s on the Horizon

Almost 30% of all breast cancers are noted to overexpress human epidermal growth factor receptor 2 (Her2), an epidermal growth factor receptor that is part of the HER family of tyrosine kinases. Her2 exerts its effect by forming heterodimers with other HER family members, resulting in the activation of a number of signaling pathways that are important for tumor progression and survival. Her2 overexpression has been linked with a more aggressive breast cancer phenotype and with decreased survival in patients with Her2-positive tumors. Trastuzumab and lapatinib are approved targeted agents for treatment of Her2-overexpressing breast cancer. The use of trastuzumab in this patient population resulted in phenomenal responses and paved the way for use of molecularly targeted therapies in the treatment of many other cancers. However, despite the tremendous progress attained, disease progression, even with trastuzumab and lapatinib treatment, is inevitable in metastatic breast cancer. Thus, research efforts have focused on finding alternative therapies to trastuzumab and lapatinib for the treatment of Her2-positive breast cancer. Efforts aimed at understanding the mechanism of action of trastuzumab and lapatinib and the causes of resistance have led to the identification of several promising agents for the treatment of patients with Her2-positive breast cancer.     

Mechanisms of disease: understanding resistance to HER2-targeted therapy in human breast cancer

Trastuzumab is a monoclonal antibody targeted against the human epidermal growth factor receptor (HER) 2 tyrosine kinase receptor, which is overexpressed in approximately 25% of invasive breast cancers. The majority of patients with metastatic breast cancer who initially respond to trastuzumab, however, demonstrate disease progression within 1 year of treatment initiation. Preclinical studies have indicated several molecular mechanisms that could contribute to the development of trastuzumab resistance. Increased signaling via the phosphatidylinositol 3-kinase/Akt pathway could contribute to trastuzumab resistance because of activation of multiple receptor pathways that include HER2-related receptors or non-HER receptors such as the insulin-like growth factor 1 receptor, which appears to be involved in a cross-talk with HER2 in resistant cells. Additionally, loss of function of the tumor suppressor PTEN gene, the negative regulator of Akt, results in heightened Akt signaling that leads to decreased sensitivity to trastuzumab. Decreased interaction between trastuzumab and its target receptor HER2, which is due to steric hindrance of HER2 by cell surface proteins such as mucin-4 (MUC4), may block the inhibitory actions of trastuzumab. Novel therapies targeted against these aberrant molecular pathways offer hope that the effectiveness and duration of response to trastuzumab can be greatly improved.     

HER2 therapy: Molecular mechanisms of trastuzumab resistance

Trastuzumab is a monoclonal antibody targeted against the HER2 tyrosine kinase receptor. The majority of patients with metastatic breast cancer who initially respond to trastuzumab develop resistance within one year of treatment initiation, and in the adjuvant setting 15% of patients still relapse despite trastuzumab-based therapy. In this review, we discuss potential mechanisms of antitumor activity by trastuzumab, and how these mechanisms become altered to promote therapeutic resistance. We also discuss novel therapies that may improve the efficacy of trastuzumab, and that offer hope that the survival of breast cancer patients with HER2-overexpressing tumors can be vastly improved.     

Tykerb for breast cancer

There are four members of the ErbB family: the epidermal growth factor(EGF)receptor(also called HER1 or EGFR), HER2, HER3 and HER4. Dimerization is the process whereby two HER receptor molecules associate to form a noncovalent complex. HER dimers are the active receptor forms required for transmission of external stimuli to the interior of the cell. HER dimerization occurs upon ligand binding and both HER homodimers and heterodimers can be formed in the process. However, HER2 appears to be the preferred dimerization partner of the other HER family members. Fifteen～20% of all breast cancers are HER2 positive and have a poor prognosis. Trastuzumab is an excellent, rationally-designed targeted cancer treatment. It is a recombinant, humanized, anti-HER2 monoclonal antibody that specifically binds to the extracellular area of HER2. However, the overall trastuzumab response rate is low, and the causes of trastuzumab resistance are poorly understood. Thus, there is a need for alternative anti-HER2 strategies for trastuzumab-resistant disease. Lapatinib is an orally administered small-molecule, reversible inhibitor of both EGFR and HER2 tyrosine kinase, and its activities include subsequent inhibition of its down- stream MAPK-ERK1/2, and the AKT signaling pathway. Lapatinib is more active when used in combination with capecitabine. For women with trastuzumab pre-treated HER2-positive breast cancer, Here, I will review the basics of EGFR and HER, and the treatment strategy for HER2-positive breast cancer with lapatinib.     

Nuclear HER4 mediates acquired resistance to trastuzumab and is associated with poor outcome in HER2 positive breast cancer

The role of HER4 in breast cancer is controversial and its role in relation to trastuzumab resistance remains unclear. We showed that trastuzumab treatment and its acquired resistance induced HER4 upregulation, cleavage and nuclear translocation. However, knockdown of HER4 by specific siRNAs increased trastuzumab sensitivity and reversed its resistance in HER2 positive breast cancer cells. Preventing HER4 cleavage by a γ-secretase inhibitor and inhibiting HER4 tyrosine kinase activity by neratinib decreased trastuzumab-induced HER4 nuclear translocation and enhanced trastuzumab response. There was also increased nuclear HER4 staining in the tumours from BT474 xenograft mice and human patients treated with trastuzumab. Furthermore, nuclear HER4 predicted poor clinical response to trastuzumab monotherapy in patients undergoing a window study and was shown to be an independent poor prognostic factor in HER2 positive breast cancer. Our data suggest that HER4 plays a key role in relation to trastuzumab resistance in HER2 positive breast cancer. Therefore, our study provides novel findings that HER4 activation, cleavage and nuclear translocation influence trastuzumab sensitivity and resistance in HER2 positive breast cancer. Nuclear HER4 could be a potential prognostic and predictive biomarker and understanding the role of HER4 may provide strategies to overcome trastuzumab resistance in HER2 positive breast cancer.     

Trastuzumab: triumphs and tribulations

The human epidermal growth factor receptor 2 (HER2) tyrosine kinase receptor is overexpressed in approximately 20-30% of human breast cancers, and is associated with reduced survival. Hence, numerous therapeutic strategies have been tested for their ability to target the HER2 protein. The humanized monoclonal antibody trastuzumab (Herceptin) was the first HER2-targeted agent approved for clinical use in breast cancer patients. Response rates to single-agent trastuzumab range from 12 to 34% for metastatic breast cancer (MBC), and significant improvements in survival rates are achieved in patients with early-stage HER2-overexpressing breast cancer in the adjuvant setting. Despite its initial efficacy, acquired resistance to trastuzumab develops in a majority of patients with MBC, and a large subset never responds, demonstrating primary resistance. Molecular mechanisms of trastuzumab antineoplastic activity and potential mechanisms contributing to its resistance will be discussed in this review. Novel agents that may enhance trastuzumab efficacy will also be discussed.     

Trastuzumab (Herceptin) and breast cancer: mechanisms of resistance

The detection of overexpression of human epidermal growth factor receptor 2 (HER2) in some breast cancer tumors has led to the development of a targeted treatment that is tumor selective, effective at extending life expectancy in the patients with advanced or early breast cancers. Trastuzumab (Herceptin), a humanized monoclonal antibody to HER2 is indicated for patients whose tumor demonstrates an amplified copy number for the HER2 oncogene and/or overexpresses the HER2 oncoprotein. Despite a high level of efficacy in combination with chemotherapy, trastuzumab as single agent has limited effectiveness (up to 30% response rates) and patients who respond to trastuzumab will relapse despite continued treatment. The mechanism of trastuzumab action is not fully understood but has been related to cell cycle inhibition. As to mechanisms of resistance, little is known but many preclinical data raised different hypothesis. Thus, the co-expression of growth factor receptors (EGFR family, IGF-1 R), and the activation of PI3K-Akt pathway, mainly by loss of PTEN function may be responsible for the resistance phenotype. It would be interesting to identify the mechanisms of trastuzumab resistance in breast tumors in order to reverse or prevent it. The characterization of these mechanisms would also provide novel strategies for alternative treatments.