ErbB2: Zielstruktur für die Therapie beim Magenkarzinom

Most patients with gastric cancer present at an inoperable advanced stage. Although there is a proven benefit for chemotherapy in advanced gastric cancer, mortality remains high and new forms of treatment with acceptable toxicity are needed. Trastuzumab, a monoclonal antibody against HER2, monotherapy and in combination with chemotherapy showed antitumor activity in human gastric cancer models in vitro and in vivo. In clinical phase II trials the combination of trastuzumab and cisplatin showed a reponse with good tolerance. The phase III ToGA trial compared randomized combination chemotherapy protocols with fluorouracil or capecitabine and cisplatin plus or minus trastuzumab in patients with an adenocarcinoma of the gastric or gastro-oesophageal junction expressing HER2. The trial showed a benefit in overall survival in selected patients for the addition of trastuzumab to chemotherapy. The trial led to the approval of trastuzumab by the European Medicines Agency (EMA). Trastuzumab is the first approved biological agent targeting HER2 in gastric cancer.     

Targeting receptor tyrosine kinases in gastric cancer

Molecularly targeted therapeutic agents are constantly being developed and have been shown to be effective in various clinical trials.One group of representative targeted oncogenic kinases,the receptor tyrosine kinases(RTKs),has been associated with gastric cancer development.Trastuzumab,an inhibitor of ERBB2,has been approved for the treatment of gastric cancer,although other receptor tyrosine kinases,such as epidermal growth factor receptor,vascular endothelial growth factor,platelet-derived growth factor receptor,c-Met,IGF-1R and fibroblast growth factor receptor 2,are also activated in gastric cancer.The promising results of the trastuzumab clinical trial for gastric cancer resulted in the approval of trastuzumab-based therapy as a first-line treatment for human epidermal growth factor receptor 2-positive patients.On the other hand,the trial examining bevacizumab in combination with conventional chemotherapy did not meet its primary goal of increasing the overall survival time of gastric cancer patients;however,a significantly higher response rate and a longer progression-free survival were observed in the bevacizumab arm of the trial.Other clinical trials,especially phaseⅢtrials that have tested drugs targeting RTKs,such as cetuximab,panitumumab,gefitinib,erlotinib,figitumumab,sorafenib,sunitinib and lapatinib,have shown that these drugs have modest effects against gastric cancer.This review summarizes the recent results from the clinical trials of molecularly targeted drugs and suggests that further improvements in the treatment of advanced gastric cancer can be achieved through the combination of conventional drugs with the new molecularly targeted therapies.     

Molecular targeting to treat gastric cancer

Trastuzumab that targets human epidermal growth factor receptor 2 (HER2) protein is the only approved molecular targeting agent for treating gastric cancer in Japan and the outcomes have been favorable. However, trastuzumab is effective for only 10% to 20% of the population with gastric cancer that expresses HER2 protein. Molecular targeting therapy with bevacizumab against vascular endothelial growth factors (VEGF) and with cetuximab and panitumumab against the epidermal growth factors pathway that have been approved for treating colorectal cancer are not considered effective for treating gastric cancer according to several clinical trials. However, ramucirumab that targets VEGF receptor-2 prolonged overall survival in a large phase III clinical trial and it might be an effective molecular targeting therapy for gastric cancer. The significance of molecular targeting therapy for gastric cancer remains controversial. A large-scale randomized clinical trial of novel molecular targeting agents with which to treat gastric cancer is needed.     

Clinicopathologic features and treatment outcomes of patients with human epidermal growth factor receptor 2‐positive adenocarcinoma of the esophagus and gastroesophageal junction

Human epidermal growth factor receptor 2 (HER2) is overexpressed in 21% of gastric and 33% of gastroesophageal junction (GEJ) adenocarcinomas. Trastuzumab has been approved for metastatic HER2‐positive gastric/GEJ cancer in combination with chemotherapy. This retrospective analysis was undertaken to better define the clinicopathologic features, treatment outcomes, and prognosis in patients with HER2‐positive adenocarcinoma of the esophagus/GEJ. Pathologic specimens from 156 patients with adenocarcinoma of the esophagus/GEJ treated on clinical trials with chemoradiation and surgery were tested for HER2. Seventy‐six patients also received 2 years of gefitinib. Baseline characteristics and treatment outcomes of the HER2‐positive and negative patients were compared both in aggregate and separately for each of the two trials. Of 156 patients, 135 had sufficient pathologic material available for HER2 assessment. HER2 positivity was found in 23%; 28% with GEJ primaries and 15% with esophageal primaries (P= 0.10). There was no statistical difference in clinicopathologic features between HER2‐positive and negative patients except HER2‐negative tumors were more likely to be poorly differentiated (P < 0.001). Locoregional recurrence, distant metastatic recurrence, any recurrence, and overall survival were also statistically similar between the HER2‐positive and the HER2‐negative groups, in both the entire cohort and in the gefitinib‐treated subset. Except for tumor differentiation, HER2‐positive and negative patients with adenocarcinoma of the esophagus and GEJ do not differ in clinicopathologic characteristics and treatment outcomes. Given the demonstrated benefit of trastuzumab in HER2‐positive gastric cancer and the similar incidence of HER2 overexpression in esophageal/GEJ adenocarcinoma, further evaluation of HER2‐directed therapy in this disease seems indicated.     

曲妥珠单抗靶向治疗胃癌的进展

人表皮生长因子受体2（HER2）参与多种肿瘤的发生、发展。根据ToGA试验结果,欧盟和美国于2010年先后批准曲妥珠单抗用于HER2阳性的晚期胃腺癌和胃食管交界处癌患者的一线治疗。然而,目前胃癌中尚无统一的HER2检测评分系统,其耐药机制需进一步研究。本文就近年来曲妥珠单抗靶向治疗胃癌的进展作一综述。     

Molecularly targeted therapies in advanced gastric cancer

Gastric cancer is a prevalent and deadly disease with poor survival of patients with metastatic disease. Although distinct epidemiologic and histologic subtypes of gastric cancer can be identified, the disease is commonly grouped together as a single disease and treated as on entity. However, as molecularly targeted therapies are applied to gastric cancer, this disease heterogeneity has increasingly become clinically relevant. In this review, we summarize the development of agents targeting the human epidermal growth factor receptor (HER) family HER 2 and epidermal growth factor receptor EGFR), vascular endothelial growth factor (VEGF), MET and regulators of cell cycle as they are integrated into therapeutic studies with the goal of improving therapeutic options for this disease. We summarize the rationale for targeting these pathways, in the context of an emerging paradigm of gastric cancer as three unique disease subtypes. The results of the clinical trials evaluating these agents, including completed and ongoing evaluations, are summarized.     

Personalizing therapies for gastric cancer: Molecular mechanisms and novel targeted therapies

Globally,gastric cancer is the 4thmost frequently diagnosed cancer and the 2ndleading cause of death from cancer,with an estimated 990000 new cases and738000 deaths registered in 2008.In the advanced setting,standard chemotherapies protocols acquired an important role since last decades in prolong survival.Moreover,recent advances in molecular therapies provided a new interesting weapon to treat advanced gastric cancer through anti-human epidermal growth factor receptor 2(HER2)therapies.Trastuzumab,an anti-HER2 monoclonal antibody,was the first target drug in the metastatic setting that showed benefit in overall survival when in association with platinum-5-fluorouracil based chemotherapy.Further,HER2 overexpression analysis acquired a main role in predict response for trastuzumab in this field.Thus,we conducted a review that will discuss the main points concerning trastuzumab and HER2 in gastric cancer,providing a comprehensive overview of molecular mechanisms and novel trials involved.     

Therapie des Magenkarzinoms

From a global perspective, gastric cancer including adenocarcinoma of the esophagogastric junction is the fourth most common malignant tumor and the second most common cause of cancer-related death. Due to the lack of specific symptoms of early cancer, most gastric cancers are diagnosed in advanced stages. Staging should include high-resolution computed tomography of the thorax, abdomen, and pelvis and documented video-endoscopy and endoscopic ultrasound. In mucosal gastric cancer, endoscopic resection can replace surgical resection. In more advanced stages, perioperative chemotherapy has been established as a standard of care. In the metastatic setting, treatment goals are palliative. Chemotherapy can prolong survival, improve symptoms, and enhance the quality of life. Combination chemotherapy including a platinum salt plus fluoropyrimidine is the standard of care. About 16?% of gastric cancers exhibit overexpression of the growth factor receptor HER2. Trastuzumab has shown to prolong survival when combined with chemotherapy in HER2-positive gastric cancer.     

Advanced gastric cancer:Current treatment landscape and future perspectives

Gastric cancer currently ranks fourth in cancer-related mortality worldwide. In the western world, it is most often diagnosed at an advanced stage, after becoming metastatic at distant sites. Patients with advanced disease(locally advanced or metastatic) have a somber prognosis, with a median overall survival of 10-12 mo, and palliative chemotherapy is the mainstay of treatment. In recent years, novel approaches using inhibition of human epidermal growth factor receptor 2(HER2) have demonstrated significant improvements in progression-free and overall survival, compared with chemotherapy alone, in first-line treatment of patients with overexpression of HER2. In addition, both second-line chemotherapy and treatment with the vascular endothelial growth factor receptor-inhibitor ramucirumab demonstrated significant benefits in terms of overall survival, compared with best supportive care, in randomized studies. Moreover, ramucirumab in combination with chemotherapy demonstrated further significant benefits in terms of progression-free and overall survival, compared with chemotherapy alone, in second-line treatment for patients with metastatic gastric cancer. A recently published molecular classification of gastric cancer is expected to improve patient stratification and selection for clinical trials and provide a roadmap for future drug development. Nevertheless, despite these developments the prognosis of patients with advanced gastric cancer remains poor. In this review we discuss current standards of care and outline major topics of drug development in gastric cancer.     

Advances in the Management of HER2-positive Advanced Gastric and Gastroesophageal Junction Cancer

In the past, patients with advanced or metastatic gastric or gastroesophageal junction cancer have had few treatment options and generally poor survival rates. The human epidermal growth factor receptor 2 (HER2) has been identified as a potential therapeutic target because of its overexpression or gene amplification in 6% to 35% of gastric or gastroesophageal junction cancers, although the methods of assessment and prognostic value of HER2 have been subject to debate. The phase III Trastuzumab for Gastric Cancer (ToGA) trial showed that adding the HER2-targeted humanized monoclonal antibody trastuzumab to chemotherapy significantly improves survival without negatively impacting quality of life in patients with advanced gastric or gastroesophageal junction cancer. As a result, trastuzumab is now the sole HER2-targeted therapy approved in several countries for this indication. The ToGA trial also demonstrated that patients who expressed higher levels of HER2 (determined by immunohistochemical screening) received the greatest benefit from trastuzumab therapy. This finding underlines the importance of accurate HER2 testing. Because of the unique characteristics of gastric cancer, a new gastric cancer-specific scoring system for HER2 expression was proposed during the ToGA trial. The aim of this review is to inform the gastroenterologist of the potential role of HER2-targeted therapy, to discuss the importance of accurate and reliable HER2 testing, and to discuss ongoing studies with HER2-targeted therapies that may have an impact on the future treatment of HER2-positive gastric cancer.     

Role of human epidermal growth factor receptor 2 in gastric cancer:Biological and pharmacological aspects

Amplification of the human epidermal growth factor receptor 2(HER2)gene and overexpression of the HER2protein is found in 15%-20%of patients with gastric and gastroesophageal junction cancer.The degree of HER2 overexpression and amplification varies with the location of the carcinoma,with higher expression in the gastroesophageal and proximal parts compared to the distal parts of the stomach.Further,HER2 overexpression and amplification also seems to be related to the Lauren histological classification,with higher levels found in the intestinal phenotype compared to the diffuse and mixed types.The prognostic properties of HER2 overexpression and amplification are still under debate,but a large number of studies seem to indicate that HER2 is a negative prognostic factor.The usefulness of HER2 targeted therapy in gastric cancer was demonstrated in the ToGA trial,where HER2-positive patients with advanced gastric and gastroesophageal junction adenocarcinoma were randomized to receive5-FU/capecitabine and cisplatin,either alone or in combination with trastuzumab.A statically significant gain in overall survival was seen in patients who received the combined treatment of trastuzumab and chemotherapy.Patients with a strong overexpression of the HER2 protein(IHC3+)specifically benefited from the treatment,with a median overall survival of 17.9 mo.As a consequence of the positive results of the ToGA trial,patients with advanced gastric or gastroesophageal junction adenocarcinoma are now routinely tested for HER2.The ToGA trial must be characterized as a landmark in the treatment of gastric cancer and it has paved the way for a number of new HER2 targeted compounds such as pertuzumab,ado-trastuzumab emtansine,lapatinib,afatinib,and dacomitinib,which are currently undergoing phaseⅡandⅢclinical testing.Overall,this review will discuss the current status of HER2 in gastric and gastroesophageal junction cancer and the future direction in relation to HER2 target therapy.     

HER2 expression in gastric cancer in Indian population—An immunohistochemistry and fluorescence in situ hybridization study

Aim

Human epidermal growth factor receptor (HER2, also known neu, ERBB2) protein expression in gastric cancer is associated with poor prognosis, aggressive disease and poor response to chemotherapy. Trastuzumab, a monoclonal antibody against HER2, in combination with chemotherapy is currently advocated as a new standard option for patients with HER2-positive advanced gastric and gastroesophageal junction carcinoma. Frequency of HER2 expression in gastric cancer has been reported from different geographic zones with a wide range of 13?% to 91?%. There are no reported data of HER2 protein expression in gastric cancer tissue from India. The purpose of this study was to evaluate the frequency of HER2 expression in gastric cancer.

Methods

The frequency of HER2 expression in 52 patients with gastric adenocarcinoma was prospectively evaluated over a six month period at Asian Institute of Gastroenterology from January 2010 to July 2010, using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH).

Results

HER2 overexpression was confirmed in 23 of 52 (44.2?%) patients. Two patients had equivocal result by IHC (2+), one of whom was positive on analysis by FISH. There was no difference in HER2 overexpression (positivity) or negativity in relation to age, gender, tumor site, histological subtype, tumor differentiation, serosal involvement or lymph nodal status. HER2 overexpression rates were similar for intestinal type as compared to diffuse histological type (OR 1.84), as also for proximal as compared to distal gastric cancers (OR 0.81).

Conclusion

HER2 overexpression was observed in significant number of advanced gastric adenocarcinoma patients. There was no difference in HER2 overexpression in relation to clinicopathological parameters.     

Recent advances and future trends in the targeted therapy of metastatic gastric cancer

The better understanding of the molecular mechanisms behind gastric cancer has led to the development of new therapeutic strategies that are likely to improve patient outcomes in the near future. Recently, targeting the HER2 and the VEGF pathways with trastuzumab and ramucirumab, respectively, have been found to improve survival, while directed therapies against a number of other pathways are under clinical evaluation. These include the hepatocyte growth factor and its receptor c-MET, the insulin-like growth factor 1, the fibroblast growth factor, the mammalian target of rapamycin (mTOR), the epidermal growth factor receptor, and other pathways, as well as relevant immunotherapeutic strategies. This article reviews recent advances and future trends of these concepts for gastric cancer and adenocarcinoma of the gastroesophageal junction.     

Surgical resection of advanced gastric cancer following trastuzumab/oxaliplatin/capecitabine combination therapy

Late-stage gastric adenocarcinoma patients have a poor prognosis because of high recurrence rates. To improve long-term outcomes, perioperative chemotherapies are combined with surgery. Human epidermal growth factor receptor 2 (HER2) overexpression had been noted in gastric cancer; therefore, trastuzumab has been used occasionally in this setting. A 63-year-old male Chinese patient, who was diagnosed with adenocarcinoma in the gastric antrum, as well as lymph node metastases along the left gastric and hepatic artery, and left adrenal area, was admitted to our hospital. HER2 expression was positive, and cluster amplification was detected in a fluorescence in situ hybridization assay. The patient received three cycles of a neoadjuvant trastuzumab/oxaliplatin /capecitabine regimen. He subsequently underwent distal gastrectomy, D2+ lymphadenectomy, left adrenalectomy, cholecystectomy and Billroth II anastomosis. Treatment was continued with another five postoperative cycles of the same medication and trastuzumab application for 1 year. No recurrence has been observed 18 mo after the operation. Trastuzumab as perioperative and adjuvant medication, in combination with oxaliplatin and capecitabine for a HER2-overexpressing advanced gastric adenocarcinoma, led to recurrence-free survival of at least 18 mo after surgery.     

Clinical management of advanced gastric cancer: The role of new molecular drugs

Gastric cancer is the fourth most common malignant neoplasm and the second leading cause of death for cancer in Western countries with more than 20000 new cases yearly diagnosed in the United States. Surgery represents the main approach for this disease but, notwithstanding the advances in surgical techniques, we observed a minimal improvement in terms of overall survival with a significant increasing of relapsing disease rates. Despite the development of new drugs has significantly improved the effectiveness of chemotherapy, the prognosis of patients with unresectable or metastatic gastric adenocarcinoma remains poor. Recently, several molecular target agents have been investigated; in particular, trastuzumab represents the first target molecule showing improvements in overall survival in human epithelial growth factor 2-positive gastric cancer patients. New molecules targeting vascular epithelial growth factor, mammalian target of rapamycin, and anti hepatocyte growth factor-c-Met pathway are also under investigation, with interesting results. Anyway, it seems necessary to select more accurately the population to treat with new agents by the identification of new biomarkers in order to optimize the results. In this paper we review the actual “scenario” of targeted treatments, also focusing on the new agents in development for gastric cancer and gastro-esophageal carcinoma, discussing their efficacy and potential applications in clinical practice.     

Targeted therapies in gastric cancer and future perspectives

Advanced gastric cancer(AGC) is associated with a high mortality rate and, despite multiple new chemotherapy options, the survival rates of patients with AGC remains poor. After the discovery of targeted therapies, research has focused on the new treatment options for AGC. In the last two decades, many targeted molecules were developed against AGC. Currently, two targeted therapy molecules have been approved for patients with AGC. In 2010, trastuzumab was the first molecule shown to improve survival in patients with HER2-positive AGC as part of a first-line combination regimen. In 2014, ramucirumab was the second targeted molecule to improve survival rates and was suggested as treatment for patients with AGC who had progressed after firstline platinum plus fluoropyrimidine with or without anthracycline chemotherapy. Ramucirumab was the first targeted therapy acting as a single agent in patients with advanced gastroesophageal cancers. Although these two molecules were introduced into clinical use, many other promising molecules have been tested in phase Ⅰ-Ⅱ trials. It is obvious that in the near future many different targeted therapies will be in use for treatment of AGC. In this review, the current status of targeted therapies in the treatment of AGC and gastroesophageal junction tumors, including HER(2-3) inhibitors, epidermal growth factor receptor inhibitors, tyrosine kinase inhibitors, antiangiogenic agents, c-MET inhibitors, mammalian target of rapamycin inhibitors, agents against other molecular pathways fibroblast growth factor, Claudins, insulin-like growth factor, heat shock proteins, and immunotherapy, will be discussed.     

Advanced HER2-positive gastric cancer: Current and future targeted therapies

The prognostic value of human epidermal growth factor receptor 2 (HER2) in gastric cancer is controversial. Consensus guidelines have standardized the testing of HER2 status in gastric cancer. Overexpression of this receptor occurs in approximately 20% of gastric and gastro-esophageal junction adenocarcinomas, predominantly those of the intestinal type. Recently, trastuzumab has emerged as the first targeted drug to improve overall survival when combined with chemotherapy in advanced HER2-positive gastric cancer. Primary and secondary resistance to trastuzumab has become a major problem and new strategies to overcome this resistance are needed. A high percentage of advanced HER2-positive gastric cancer patients who progress on trastuzumab therapy are candidates for second-line therapy. New families of targeted drugs, including tyrosine kinase inhibitors (TKIs) such as lapatinib and PF-00299804, mammalian target of rapamycin (mTOR) pathway inhibitors such as everolimus, heat-shock protein 90 (HSP90) inhibitors such as AUY922, HER dimerization inhibitors such as pertuzumab, and antibody-chemotherapy conjugates such as trastuzumab-emtansine (T-DM1), could offer alternative second-line treatments when trastuzumab-based first-line therapy fails.     

Trastuzumab (Herceptin®): overcoming resistance in HER2-overexpressing breast cancer models

Evaluation of: Fujimoto-Ouchi K, Sekiguchi F, Yamamoto K et al.: Preclinical study of prolonged administration of trastuzumab as combination therapy after disease progression during trastuzumab monotherapy. Cancer Chemother. Pharmacol. 66, 269-276 (2010). Trastuzumab, a humanized antibody targeted against human epidermal receptor (HER)2, is used in combination with chemotherapy to treat patients with breast cancers overexpressing HER2. Despite initial clinical responses, disease progresses in a significant proportion of patients treated with trastuzumab and chemotherapy. Evidence of resistance to trastuzumab has not deterred a widespread clinical practice in the treatment of metastatic breast cancer - at least before lapatinib entered the clinic - which consists of continued administration of trastuzumab in combination with another chemotherapeutic drug. At present, it is not known if patients benefit from this practice. The present preclinical study demonstrates that, in the MDA-MB-361 and KPL-4 HER2(+) breast cancer models, induced resistance to trastuzumab monotherapy can be overcome by a combination of trastuzumab and granulocyte colony stimulating factor or chemotherapy. The response to trastuzumab and granulocyte colony stimulating factor appears to involve the host's immune system and antibody-dependent cellular cytotoxicity. The mechanisms underlying the response to trastuzumab and chemotherapy remain unclear.     

A narrative review of advances in treatment and survival prognosis of HER2-positive malignant lung cancers

Human epidermal growth factor receptor 2 (HER2), as a receptor tyrosine kinase of EGF receptor family, whose mutation is often associated with even if less frequency but poor prognosis and shorter survival in pulmonary malignant tumor. HER2 status include mutation, overexpression, amplification and also some rare genotypes, detected by next generation sequencing (NGS), immunohistochemistry (IHC), and also fluorescence in situ hybridization (FISH). Different genotypes represent different therapeutic targets and indicate different clinical prognosis concluded by previous studies. Unfortunately, no standard guidelines for first-line treatment are widely recognized, and current therapeutic schedules include chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Especially for patients with advanced metastasis, chemotherapy is based as a systemic therapy using studies of breast cancer or EGFR-positive lung adenocarcinoma as a template. Studies already explored treatment including EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib and afatinib, and also trastuzumab and its conjugation like HER2-targeted antibody-drug conjugate trastuzumab emtansine (T-DM1) and conjugate trastuzumab deruxtecan (T-DXd). Also, he researches explored combination therapy with chemotherapy and TKIs or monoclonal antibodies. This review describes commonly used therapies for HER2-positive/HER2-overexpression patients and general relationship between genotypes of HER2, drug selection and final prognosis in order to provide suggestions for future diagnosis and treatment.     

HER2 therapies and gastric cancer:A step forward

Gastric cancer usually is diagnosed in advanced stages and thus current medical practice affords limited therapeutic options.However,recent studies established the role of human epidermal growth factor receptor 2(HER2)in clinical management.Trastuzumab,an antiHER2 monoclonal antibody,acquired a main role in advanced gastric cancer harboring HER2 overexpression and/or amplification improving survival to 17.1 mo according to trastuzumab for gastric cancer phaseⅢtrial results.Also,new promising drugs,such as c-Met inhibitors,are in development and assessment for this setting.Certainly,novel drugs will emerge in the next feel years for help oncologists improve clinical management of advanced gastric cancer providing higher survival and quality of life.In this mini-review we will discuss some issues in this regard and provide an actual overview of this setting.