Clinical trials of VEGF receptor tyrosine kinase inhibitors in pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer-related deaths in Western countries and is among the deadliest diseases in humans. At present, gemcitabine is the standard chemotherapy for advanced pancreatic cancer, although (despite its use) prognosis continues to be dismal with a median survival of < 6 months. While targeting tumor vasculature has provided improved outcomes in colon, lung, breast and renal cell cancers, trials of angiogenesis inhibitors have lagged behind in pancreatic cancer. This review provides the rationale for exploring antiangiogenic therapies in the treatment of pancreatic cancer as well as summarizes present clinical development of VEGF receptor tyrosine kinase inhibitors and their application to pancreatic cancer.     

酪氨酸激酶抑制剂类新药的研发现状

蛋白激酶在多种疾病,特别是肿瘤发生发展过程中起重要作用,以其为药物靶点的激酶抑制剂则成为近年药物研发的热点。目前已有11个小分子激酶抑制剂上市,其中9个为酪氨酸激酶抑制剂。激酶抑制剂具有高选择性、副作用少的特点。已上市药物已经在慢性粒细胞白血病、非小细胞肺癌、肾细胞癌等多种疾病的治疗中显示出其较传统治疗药物的优越性,部分已成为治疗肿瘤的一线用药。本文对小分子酪氨酸激酶抑制剂类新药的研发现状进行综述。     

表皮生长因子受体酪氨酸激酶抑制剂在肿瘤治疗中的应用

表皮生长因子受体 (EGFR)酪氨酸激酶 ,是细胞外信号传递到细胞内的重要枢纽 ,它在信号传导、细胞增殖、分化以及各种调节机制中发挥重要作用 ,在多种癌细胞中过度表达。许多研究表明 ,抑制EGFR酪氨酸激酶活性 ,可抑制肿瘤生长。目前 ,已有几种EGFR酪氨酸激酶抑制剂进入了临床试验。本文对几种EGFR酪氨酸激酶小分子抑制剂在肿瘤治疗中的研究进展做一综述。     

表皮生长因子受体酪氨酸激酶家族与肿瘤治疗

表皮生长因子受体(EGFR,ErbB)酪氨酸激酶家族在多种肿瘤中有表达或高表达.在特异性配体的诱导下能够发生家族成员的二聚化,从而激活细胞内下游信号转导途径,调控细胞的增殖、分化、迁移等生物效应.异常的ErbB受体信号与肿瘤的发生、发展有着密切的关系.随着EGFR的人源化单抗Erbitux和针对EGFR的小分子抑制剂Tarceva的成功上市,以ErbB受体为靶点的抗肿瘤药物成为了近年来肿瘤治疗研究中的热点领域.     

表皮生长因子受体(EGFR)酪氨酸激酶抑制剂的研究进展

表皮生长因子受体（EGFR）酪氨酸激酶介导的信号转导与肿瘤发生发展密切相关，抑制该受体活性可以有效地抑制肿瘤。近年来，许多以此为靶点的新抗肿瘤药物陆续被开发，在多种肿瘤治疗中取得了令人鼓舞的疗效。综述了EGFR的结构和作用以及近年来EGFR酪氨酸激酶抑制剂的研究进展。     

血管内皮细胞生长因子受体酪氨酸激酶抑制剂的研究进展

血管内皮细胞生长因子受体（VEGFR）家族的受体酪氨酸激酶与多种恶性肿瘤的发生、发展及预后等密切相关。近年来，许多以此为靶点的新的抗肿瘤药物和治疗方法陆续被开发。综述了作用于VEGFR的酪氨酸激酶抑制剂bevacizumab，PTK787，BAY43-9006，SU11248和ZD6474的研究进展。     

Protein tyrosine kinase inhibitors as anticancer agents

There are > 700 protein kinases and 100 protein phosphatases encoded within the human genome. By catalysing protein phosphorylation and dephosphorylation, they play a pivotal role in intracellular signalling and in the regulation of signal transduction pathways. Activation of oncogenes coding for such proteins can lead to the production of kinases that are continually active in the absence of a normal stimulus, leading to increased cell proliferation and/or decreased apoptosis. Receptor and non-receptor protein tyrosine kinases (PTKs) are essential enzymes in cellular signalling processes that regulate cell growth, differentiation, migration and metabolism. Their inhibition by specific inhibitors was recently shown to constitute a new modality for cancer treatment. A patent literature review comprising the years 2000 – 2003 is presented here, as the major drug houses are currently involved in the design and development of novel types of such compounds with applications as antitumour agents.     

血管内皮生长因子受体酪氨酸激酶抑制剂的研究进展

血管生成在肿瘤的生长、转移和演进中起着非常重要的作用.文中简要阐述了血管内皮生长因子受体(VEGFR)酪氨酸激酶介导的RAS/Raf/MAPK,P13K/AKT,PLC-γ及Src信号转导途径,根据结构类型统计和介绍了已经上市或处于临床研究的VEGFR酪氨酸激酶小分子抑制剂,包括吲哚酮类、喹唑啉类、哒嗪类、吲唑类、烟碱类和吡咯并嘧啶类等典型结构,分别阐述了这几类结构中代表性化合物的临床前研究和临床研究的数据.     

Emerging oral VEGF inhibitors for the treatment of renal cell carcinoma

Introduction: The incidence of renal cell carcinoma (RCC) has increased in recent years and, unfortunately, many patients initially present with metastatic disease. When surgery is not an option, treatment involves administration of targeted therapies. The vascular endothelial growth factor (VEGF) pathway has been identified as an important mediator for the development of RCC. Numerous agents target VEGF-mediated signaling, yet resistance and progressive disease still persists. Novel small molecule VEGF inhibitors with high affinity for the VEGF receptor (VEGFR) have been discovered and are currently under investigation for the management of RCC.

Areas covered: The VEGFR pathway, its aberrant signaling, and the agents under development that inhibit VEGFR signaling are discussed. The mechanism(s), pharmacokinetics, pharmacodynamics, efficacy, and toxicity of these investigational agents are also reviewed.

Expert opinion: Management of metastatic RCC involves combination immunotherapy or administration of oral VEGFR inhibitors and largely depends on risk stratification. Emerging and investigational oral VEGFR inhibitors, given as monotherapy or in combination with immunotherapy, could augment current treatment approaches and may mitigate toxicities associated with VEGFR inhibition.     

Tyrosine kinase inhibitors in cancer treatment (Part II)

In the last few years, enormous progress in the field of signal transduction inhibition has been made. Many companies have entered the field. Along with the epidermal growth factor receptor (EGFR) tyrosine kinase, many other tyrosine kinases have been identified as interesting targets for drug discovery projects. X-ray data of more than 40 crystal structures of protein kinases, in most cases complexed with an inhibitor, have been published. Pharmacophore models for the binding of inhibitors in the ATP-binding site of protein kinases have been developed that are generally applicable, enabling the rational design of tyrosine as well as serine/threonine kinase inhibitors. It has been proven by numerous examples that the ATP-binding of protein kinases is an exciting target for the design of anticancer drugs. In many cases, it has also been demonstrated that through rational design it is possible to modify a lead structure in such a way that inhibitors with an altered selectivity profile are obtained. Chemical optimisation of several lead structures led to development candidates with potent in vitro and in vivo activity fulfilling the pharmacodynamic, pharmacokinetic, toxicological and technical (synthesis, formulation) requirements for a clinical candidate. Currently, there are seven tyrosine kinase inhibitors in early phases of clinical trials. In addition, several candidates are close to entering Phase I trials this year or at the beginning of next year. It is expected that positive results from clinical trials will greatly contribute to the clinical proof of concept of the value of signal transduction inhibition and will greatly stimulate further research in this area. This review is a continuation of a review with the same title of last year and summarises published patent literature and related publications between 1997 and September 1998.     

Vascular endothelial growth factor tyrosine kinase inhibitors

Tyrosine kinase inhibitors of the vascular endothelial growth factor (VEGF) receptor remain an attractive area of research in cancer. Merck has had an ongoing programme related to small-molecule inhibitors of the VEGF receptor kinase and has filed numerous applications in this area. The present application relates to a salt of a compound claimed explicitly in a previous application from Merck. The present application is focused on hydrochloride salts of this compound and claims several polymorphs of this salt. Such applications directed to specific polymorphs usually indicate a compound that may be of significant interest to the Merck VEGF programme.     

表皮生长因子受体酪氨酸激酶抑制剂相关性皮肤毒性的全球研究现状和诊治进展

随着肿瘤分子生物学理论研究和生物工程技术的进展,分子靶向治疗已成为未来肿瘤诊治的风向标。然而,皮肤毒性作为分子靶向治疗药物,特别是人表皮生长因子受体酪氨酸激酶抑制剂(EG-FR-TKI)类药物最常见的不良反应,已严重影响患者的诊疗效果和生活质量,甚至导致药物减量或中止治疗。近年来,人们对EGFR-TKI相关性皮肤毒性的关注角度正悄然发生改变,从最初的疗效评价标准未给予治疗到现今重视生活质量给予个体化系统治疗,体现了人们对肿瘤患者的诊治逐渐转向"以患者为中心,以医生为辅助,以靶向治疗为利器"的个体化、人文化治疗理念。本研究主要从皮肤毒性的发病机制、评估标准和治疗原则3个方面对EGFR-TKI相关性皮肤毒性的全球研究现状和诊治进展进行汇总,供临床医师参考。     

Tyrosine kinase inhibitors to treat liver cancer

Importance of the field: Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide. Although patients with early-stage disease have a good prognosis, there has been no effective therapy available for those with advanced disease. Despite the death risk of patients with advanced HCC being reduced with sorafenib therapy, many patients eventually turn out to be refractory to this therapy. Thus, treatment of HCC remains an urgent health concern.

Areas covered in this review: Recent improvement in understanding the pathophysiology of HCC at the molecular level has fostered the development of molecular targeted therapies that specifically block the disrupted pathways.

What the reader will gain: This review summarizes the preclinical and clinical data from 2004 to 2009 on the efficacy and safety of the emerging drug for the treatment of HCC, including small molecule inhibitors (erlotinib, sunitinib, sorafenib, vandetanib, cediranib, brivanib and dovitinib) and the rationale for combination therapies for patients with advanced HCC.

Take home message: Understanding the mechanisms of action, safety and efficacy of these new agents and new methods of combining these drugs may help prolong overall survival of patients with HCC and reduce disease recurrence after surgery or ablative therapies.     

Emerging alternatives to tyrosine kinase inhibitors for treating chronic myeloid leukemia

Introduction: BCR-ABL-directed tyrosine kinase inhibitors (TKIs) have revolutionised therapy for chronic myeloid leukemia. However, despite the availability and efficacy of this class of agents, lifelong treatment is still required in a significant proportion of patients

Areas covered: We give an overview of the currently available BCR-ABL-directed TKIs and other conventional therapies for CML. We proceed to review the current market and some of the scientific rationale for new drug development before outlining a number of novel therapies, considered broadly as immunotherapies and targeted agents. Published English-language literature was reviewed regarding currently available TKIs; clinical trials repositories were reviewed to identify novel agents recently investigated or under active study.

Expert opinion: We recommend discussion with patients and enrolment on an appropriate clinical trial where feasible. In situations where no trials are available, or if patients decline enrolment, we recommend use of an appropriate BCR-ABL directed TKI, selected on the basis of an evaluation of patient risk factors and side effect profile. Allogeneic stem cell transplant continues to have a role though this is generally limited to cases with advanced phases of disease or in cases with resistance-conferring mutations.     

EGFR基因突变与肿瘤靶向治疗

表皮生长因子受体(epidermal growth factor receptor,EGFR)属于受体酪氨酸激酶超家族,在多种恶性肿瘤中表达。配体与EGFR结合诱导形成二聚体和构象变化,活化酪氨酸激酶及信号转导途径,产生细胞增殖、侵润、转移及抗凋亡等效应。EGFR酪氨酸激酶抑制剂(tyrosine kinase inhibitors,TKIs)类靶向药物,如吉非替尼和厄洛替尼等已应用于临床。临床研究显示仅10%~30%患者对TKIs敏感,部分位于EGFR激酶结构域的活化突变与药物敏感性相关。检测EGFR基因突变有助于预测对药物敏感性和提高疗效。随着治疗绝大多数敏感的患者获得继发耐药性,其中约半数有继发突变T790M,降低药物对靶分子的亲和力,其他许多位于EGFR下游信号途径或旁激活途径的分子也参与耐药形成。因此,未来个体化用药和准确预测敏感性,不仅仅要分析EGFR基因,而且要综合考虑下游和其他信号途径的基因,如PI3K,K-RAS,BRAF,MET和PTEN等。     

表皮生长因子受体酪氨酸激酶抑制剂的耐药机制及其治疗策略

表皮生长因子受体酪氨酸激酶抑制剂在治疗非小细胞肺癌中取得了较好的疗效,但最终仍会出现耐药导致的肿瘤进展。目前的研究发现其中涉及的耐药机制多样,本文就近年来在非小细胞肺癌小分子酪氨酸激酶抑制剂治疗中存在的耐药机制及其治疗策略进行综述。     

小分子EGFR酪氨酸激酶抑制剂盐酸埃罗替尼

盐酸埃罗替尼是一种小分子表皮生长因子酪氨酸激酶可逆抑制剂,通过抑制酪氨酸激酶的磷酸化,阻断信号传导,抑制肿瘤生长.临床前研究表明其对表皮生长因子酪氨酸激酶有抑制作用;临床研究显示该药对多种肿瘤有抗肿瘤活性,不良反应较轻,与化疗药物合用不增加毒性.2004年经FDA批准上市,用于一线化疗失败的局部晚期或转移性非小细胞肺癌的治疗.     

The potential role of the EGFR/ERBB2 heterodimer in breast cancer

Epidermal growth factor receptor (EGFR) and ErbB2 are the best-characterised members of the ErbB family of receptor tyrosine kinases. Both receptors are frequently deregulated in human cancers and both are targets for anticancer drugs. ErbB2 amplification and overexpression are associated with a poor prognosis in breast cancer patients. Over the last decade, evidence has revealed that ErbB2 interacts with EGFR in order to achieve its full oncogenic potential. Therefore, assessment of EGFR and ErbB2 coexpression can potentially predict the outcome of the disease as well as success of therapies better than the assessment of single receptors. Moreover, it is not single-agent therapies, targeting one receptor, but combinations or several receptor-targeted therapies that may be the best way to fight cancer.     

C-MET inhibitors for advanced non-small cell lung cancer

Introduction: The role of the c-mesenchymal-epithelial transition factor (c-MET) signaling pathway in tumor progression and invasion has been extensively studied. C-MET inhibitors have shown anti-tumor activity in NSCLC both in preclinical and in clinical trials. However, given the molecular heterogeneity of NSCLC, it is likely that only a specific subset of NSCLC patients will benefit from c-MET inhibitors. Emerging data also suggest that MET inhibitors in combination with EGFR-TKIs (epidermal growth factor receptor tyrosine kinase inhibitors) may have a role in therapy for both EGFR-TKI resistant and EGFR-TKI naïve patients. The challenges ahead are in the identification of the molecular subtypes that benefit most.

Areas covered: This review summarizes the current understanding of c-MET biology in relation to studies evaluating c-MET inhibitors in the treatment of NSCLC.

Expert opinion: MET inhibitors have the potential to benefit subsets of NSCLC patients with specific genetic alterations. Exon-14 skipping mutations appear so far to be the most promising molecular subset that is sensitive to MET inhibitors, whereas overexpression, amplification and point mutations of MET seem more challenging subgroups to target. Combination with other target agents, such as EGFR inhibitors, may represent a promising therapeutic strategy in specific areas (e.g. EGFR-TKI resistance).     

Therapeutic targeting of receptor tyrosine kinases in lung cancer

Lung cancer is a difficult illness with a poor overall survival. Even though combination strategies with chemotherapy, radiation therapy and surgery have all been utilised, the overall outcome for this disease continues to be relatively disappointing. In order to make a difference in the treatment of lung cancer, novel therapeutics will have to be developed. Through basic biological studies, a number of receptor tyrosine kinases have been implicated in the pathogenesis and progression of lung cancer. In this review, the authors summarise the mechanisms of several major receptor tyrosine kinases in lung cancer, especially epidermal growth factor receptor, Her2/neu, MET, vascular endothelial growth factor and KIT. The biology associated with these receptors is described, and the various novel therapeutic inhibitory strategies that are ongoing in preclinical and clinical studies for lung cancer are detailed. Through understanding of receptor tyrosine kinases and the utilisation of specific inhibitors, it is hopeful that a dramatic impact will be made on the biology and therapy for lung cancer.