Therapeutic options for HER-2 positive breast cancer: Perspectives and future directions

During the last 15 years we have witnessed an unprecedented expansion in the drugs developed to target human epidermal growth factor receptor-2 (HER-2) positive breast cancer. Trastuzumab, pertuzumab, ado-trastuzumab emtansine and lapatinib are currently food and drug administration (FDA)-approved for the treatment of breast cancer patients with HER-2 over-expressed. However, given the amount of information gathered from years of uninterrupted clinical research, it is essential to have periodic updates that succinctly recapitulate what we have learnt over these last years and help us to apply that information in our daily practice. This review will pursue that objective. We will summarize the most relevant and updated information related to the state of the art management of HER-2 positive breast cancer in all the clinical scenarios including the adjuvant, neoadjuvant and metastatic settings. But we will also critically appraise that literature in order to highlight some key clinical concepts that should not be overlooked. Lastly, this review will also point out some of the most promising strategies that are currently being tested and may soon become available.     

曲妥珠单抗对HER-2胞外域水平不同的肿瘤细胞系的影响

目的探讨曲妥珠单抗(trastuzumab)对细胞膜p185人表皮生长因子受体2(HER-2)强阳性表达,以及HER-2胞外域(ECD)水平不同的肿瘤细胞系SKBR3和SKOV3细胞的生长、克隆形成及细胞内HER-2蛋白水平的影响。方法SKBR3和SKOV3细胞经曲妥珠单抗处理后,统计细胞数目及克隆形成率。双抗夹心ELISA法检测细胞培养上清中HER-2 ECD水平,Western blot检测细胞HER-2蛋白水平。结果高HER-2 ECD水平的SKBR3细胞生长及克隆形成率明显被曲妥珠单抗抑制,在相对分子质量为90 000和40 000左右分别有1条未知磷酸化蛋白明显降低或基本消失,而细胞生长及克隆形成率未受影响的SKOV3细胞中此蛋白无明显变化。SKBR3和SKOV3细胞中p185 HER-2蛋白、磷酸化-p185蛋白、磷酸化-p95蛋白水平并未见明显降低。曲妥珠单抗不仅与SKOV3细胞培养上清中的HER-2 ECD反应,也与p68/ECDⅢa蛋白反应。经曲妥珠单抗处理后,SKBR3细胞HER-2 ECD水平明显降低,但将曲妥珠单抗处理前、后的细胞数目调整到基本一致时,HER-2 ECD水平未发生明显变化。结论曲妥珠单抗抑制肿瘤细胞生长可能与阻止相对分子质量为90 000和40 000左右的未知磷酸化蛋白表达有关;p68/ECDⅢa蛋白也可能存在曲妥珠单抗识别位点;HER-2 ECD水平降低可能与SKBR3细胞数目减少有关。     

Next generation molecular targeted agents for breast cancer: focus on EGFR and VEGFR pathways

Here we reviewed the recent progress of molecular targeting drugs, including trastuzumab, lapatinib, erlotinib and bevacituzumab. Fortunately, Her-2 positive cases of metastatic or relapsed cases, those with the worse prognosis, are responsive to trastuzumab-based chemotherapy. Lapatinib will likely be effective against trastuzumab-resistant cases and brain metastases. Furthermore, the introduction of bevacituzumab will improve VEGF-VEGFR- associated tumor growth.     

Epithelial growth factor receptor (EGFR) pathway and renal cell carcinoma

The epidermal growth factor receptor (EGFR) pathway is a very well-known pathway implicated in proliferation, growth and metastatic development of various tumor types. Consequently, EGFR pathway inhibitors have provided clinical benefits in many tumor types. EGFR expression is reported in up to 95% of renal cell carcinoma (RCC) and is considered high (3+) in up to 60%. In preclinical models, the EGFR pathway appears implicated in tumor development. Its mode of action includes the common EGFR signal transduction cascades, but it also interacts with the angiogenic pathway, especially the vascular endothelial growth factor receptor (VEGFR) pathway. Monotherapy with EGFR pathway inhibitors does not appear to modify the history of metastatic RCC (MRCC) and does not justify further experiments in this setting. The issues now requiring attention are the degree to which the EGFR pathway is involved in RCC tumors expressing high EGFR levels—a phase III study suggests that it influences outcome in these patients—and the clinical benefit of associating antiangiogenic therapy and EGFR pathway inhibitors in the light of successive phases II trials. In conclusion, the EGFR pathway is probably not a major pathway in RCC development compared to the antiangiogenic pathways, but could play a role in association with antiangiogenics or in the event of progression after antiangiogenic therapy. Additional preclinical data is needed to support these hypotheses.     

The growth inhibitory effect of lapatinib, a dual inhibitor of EGFR and HER2 tyrosine kinase, in gastric cancer cell lines

HER2 overexpression is observed in 5-25% of gastric cancers. Lapatinib is a dual inhibitor of the epidermal growth factor receptor and HER2 tyrosine kinase. We examined the antitumor effect of lapatinib in gastric cancer cell lines. Lapatinib induced selective and potent growth inhibition in two HER2-amplified gastric cancer cell lines (SNU-216 and NCI-N87). Lapatinib inhibited the phosphorylation of HER2, EGFR and downstream signaling proteins, resulting in G1 arrest in both cell lines with down-regulation of cMyc and induction of p27kip1. Lapatinib also induced apoptosis in NCI-N87 which has high HER2 amplification ratio. Lapatinib combined with 5-fluorouracil, cisplatin, oxaliplatin or paclitaxel showed an additive or synergistic effect. These results provide a rationale for the future clinical trials of lapatinib combined with cytotoxic drugs in the treatment of HER2-positive gastric cancer.     

Multiple molecular mechanisms underlying trastuzumab and lapatinib resistance in JIMT-1 breast cancer cells

Trastuzumab plays an important role in breast cancer therapy. However, a significant fraction of patients do not respond to therapy or they tend to develop resistance shortly after beginning therapy. Although some resistance mechanisms have been described, it is unclear whether these mechanisms can coexist. In this study, we analyzed the resistance mechanisms in the breast cancer cell line JIMT-1, a model of intrinsic trastuzumab resistance. We compared the JIMT-1 cell line with a panel of eight HER-2 positive breast cancer cell lines. All cell lines were characterized for the phosphatidylinositol 3-kinase (PIK3CA) mutation status, expression levels of the phosphatase and tensin homolog on chromosome 10 (PTEN) and neuregulin-1 (NRG1) mRNA, HER-2 gene copy number, and protein expression. The results were correlated to the sensitivity to trastuzumab and lapatinib as well as the potency of trastuzumab-mediated antibody-dependent cellular cytotoxicity (ADCC) evoked by trastuzumab. JIMT-1 cells showed several co-existing drug resistance mechanisms, including an activating mutation of the PIK3CA gene, low expression of PTEN, high expression of NRG1, and relatively low expression of HER-2 receptor protein (despite gene amplification). All these features were present at variable levels in other cell lines, whereas JIMT-1 was unique in displaying all these factors at the same time. Unexpectedly, ADCC reaction by normal lymphocytes was equally strong in all HER-2 positive cell lines, without any correlation to molecular markers or direct sensitivity to the drugs. Resistance to trastuzumab and lapatinib is probably caused by several co-existing molecular mechanisms. Direct sensitivity to trastuzumab and lapatinib was not correlated with ADCC.     

Lapatinib inhibits receptor phosphorylation and cell growth and enhances antibody-dependent cellular cytotoxicity of EGFR- and HER2-overexpressing esophageal cancer cell lines

Lapatinib is a dual tyrosine kinase inhibitor of the EGFR and HER2 tyrosine kinase domains. EGFR is expressed in 33.3% and HER2 in 30.3% of esophageal squamous cell carcinomas (ESCCs). To explore the potential utility of Lapatinib for therapy of ESCC patients, we evaluated the effect of Lapatinib on a panel of ESCC cell lines. EGFR and HER2 expression by the cell lines was established, and the effects of Lapatinib on inhibition of the phosphorylation of HER2, antiproliferative effect, apoptosis-inducing activity and accumulation of HER2 and EGFR on cell surface were evaluated. Additionally, the combined effect of Lapatinib together with Herceptin or Cetuximab on cell-mediated cytotoxicity was evaluated. Lapatinib inhibited HER2 phosphorylation in HER2-overexpressing, HER2 gene amplification positive ESCC cell line. Lapatinib also inhibited cell proliferation, induced apoptosis and caused the surface accumulation of HER2 and EGFR in ESCC cell lines. Addition of Lapatinib increased Herceptin-mediated antibody-dependent cell-mediated cytotoxicity by 15-25% with three ESCC target cell lines. Similarly, Cetuximab-mediated antibody-dependent cell-mediated cytotoxicity also increased by 15-30% in two ESCC cell lines on addition of Lapatinib. Cumulatively, the data indicate that Lapatinib has activity in EGFR- and/or HER2-expressing ESCC cells, and the combination therapy of Lapatinib and Cetuximab/Herceptin is a promising strategy in ESCC.     

EGFR and colon cancer: a clinical view

Signalling pathways that emerge from EGFR activation are critical in colon cancer (CC) biology. Its targeting with specific drugs has opened a new window in the treatment of this disease. In this regard, monoclonal antibodies (mAb) have evidenced a high degree of efficiency opposed to the uselessness of tyrosine-kinase inhibitors. Cetuximab is the mAb that has evidenced most activity in CC. After its initial approval as an irinotecan-resistance reversal agent, cetuximab has demonstrated its efficiency from the first line to heavily pretreated patients. In the first line, its addition may increase response rate to chemotherapy, improving liver metastases resection rate. Another promising approach has been suggested from combination schedules with bevacizumab. Panitumumab has been recently approved for CC. Although there is limited clinical experience, the latest data have confirmed its activity in heavily pretreated patients resulting in a clinical benefit vs. best support care. In spite of the clinical benefits, adverse events and the high sanitary cost derived from these drugs force the selection of patients with the highest probability of benefit. At the moment, when EGFR expression evidenced by immunohistochemistry has no value, skin toxicity and, fundamentally, K-Ras mutations may hint at critical information for confirmatory prospective studies. Supported by an unrestricted educational grant from GlaxoSmithKline.     

曲妥珠单抗治疗４５例ＨＥＲ-２阳性乳腺癌安全性的初步观察

目的　探讨ＨＥＲ-２阳性乳腺癌患者应用曲妥珠单抗治疗的安全性。方法　４５例ＨＥＲ-２阳性乳腺癌患者接受３周１次的曲妥珠单抗治疗,首次以负荷剂量８ｍｇ／ｋｇ给药,然后每３周给予６ｍｇ／ｋｇ静脉滴注,观察其毒副反应,特别是对心脏功能的影响。结果　４５例中接受治疗＞１年为４例（８.９％）,６～１２个月为１７例（３７.８％）,＜６个月为２４例（５３.３％）。有２例在第１次用药时出现寒战和发热;６例患者治疗后左心射血分数下降,其中２例下降超过１０％;１９例治疗过程中出现轻度ＳＴ-Ｔ波改变,但未出现心力衰竭。结论　曲妥珠单抗对ＨＥＲ-２阳性国人乳腺癌患者心脏功能有一定影响,应在治疗中注意监测观察,但总体安全性良好。     

Expression of D-type cyclins in colon cancer and in cell lines from colon carcinomas

Cyclins D1, D2 and D3 play important roles in cell proliferation and differentiation. Although their abnormal expression has been linked to cancer development and progression in a number of tissues, the expression of cyclin D2 and D3 proteins in colon cancer has not yet been characterised. In this study, we examined cyclin D1, D2 and D3 protein expression by Western blot analysis in tumour and adjacent normal colon tissues of 57 patients. In addition, we examined D-type cyclins protein expression in HT29 and LoVo39 cell lines from colon carcinomas, as a function of induced proliferation and differentiation. In both cell lines, the expression of the three D-type cyclins increased as a result of induced proliferation, whereas the expression of cyclin D3 increased as a result of induced differentiation. In colon tumours, cyclin D1 was overexpressed in 44%, cyclin D2 was overexpressed in 53% and cyclin D3 was overexpressed in 35% of the cases. We also found that in 16% of the cases, cyclin D3 protein expression was reduced in the tumour, as compared to the adjacent normal tissue. Examination of D-type cyclin protein overexpression in relation to the TNM stage of the tumours revealed that overexpression of cyclins D1 and/or D2, but not cyclin D3, is linked to colon carcinogenesis and that overexpression of cyclin D2 may be related to a higher TNM stage of the tumour.     

A modified Trastuzumab antibody for the immunohistochemical detection of HER-2 overexpression in breast cancer

The immunohistochemical determination of HER-2 to identify patients with advanced breast cancer candidates for Trastuzumab treatment proved neither accurate nor fully reliable, possibly because none of the current reagents detects the specific antigenic site target of Trastuzumab. To circumvent this problem, we conjugated the NH2 groups of Trastuzumab with biotin, and the compound obtained, designated BiotHER, was added directly to tissue sections. Biotin-labelling was revealed with horseradish peroxidase-conjugated streptavidin. Specificity and sensitivity of BiotHER immunostaining with respect to HER-2 amplification were tested on 164 breast carcinoma samples. BiotHER staining was detected on the tumour cell membrane of 12% of all specimens and in 49% specimens with gene amplification, while absent in nonamplified tumours. Predictivity of BiotHER status with respect to the clinical outcome was analysed in 54 patients with HER-2 amplified advanced breast cancer treated with Trastuzumab plus chemotherapy. BiotHER staining, detected in 50% of tumours with HER-2 amplification, was an independent predictor of clinical outcome. In fact, BiotHER positivity was independently associated with increased likelihood of tumour response and reduced risk of tumour progression and death. Biotinylated Trastuzumab can thus be used for immunohistochemical detection of HER-2 overexpression in breast cancer, and has the potential to identify patients likely to benefit from Trastuzumab treatment.     

Correlation between quantitative HER-2 protein expression and risk for brain metastases in HER-2+ advanced breast cancer patients receiving trastuzumab-containing therapy

Background.

Patients with human epidermal growth factor receptor (HER)-2⁺ breast cancer are at particularly high risk for brain metastases; however, the biological basis is not fully understood. Using a novel HER-2 assay, we investigated the correlation between quantitative HER-2 expression in primary breast cancers and the time to brain metastasis (TTBM) in HER-2⁺ advanced breast cancer patients treated with trastuzumab.

Methods.

The study group included 142 consecutive patients who were administered trastuzumab-based therapy for HER-2⁺ metastatic breast cancer. HER-2/neu gene copy number was quantified as the HER-2/centromeric probe for chromosome 17 (CEP17) ratio by central laboratory fluorescence in situ hybridization (FISH). HER-2 protein was quantified as total HER-2 protein expression (H2T) by the HERmark^® assay (Monogram Biosciences, Inc., South San Francisco, CA) in formalin-fixed, paraffin-embedded tumor samples. HER-2 variables were correlated with clinical features and TTBM was measured from the initiation of trastuzumab-containing therapy.

Results.

A higher H2T level (continuous variable) was correlated with shorter TTBM, whereas HER-2 amplification by FISH and a continuous HER-2/CEP17 ratio were not predictive (p = .013, .28, and .25, respectively). In the subset of patients that was centrally determined by FISH to be HER-2⁺, an above-the-median H2T level was significantly associated with a shorter TTBM (hazard ratio, [HR], 2.4; p = .005), whereas this was not true for the median HER-2/CEP17 ratio by FISH (p = .4). Correlation between a continuous H2T level and TTBM was confirmed on multivariate analysis (HR, 3.3; p = .024).

Conclusions.

These data reveal a strong relationship between the quantitative HER-2 protein expression level and the risk for brain relapse in HER-2⁺ advanced breast cancer patients. Consequently, quantitative assessment of HER-2 protein expression may inform and facilitate refinements in therapeutic treatment strategies for selected subpopulations of patients in this group.     

Advances in first-line treatment for patients with HER-2+ metastatic breast cancer

Background.

The prognosis for breast cancer patients overexpressing human epidermal growth factor receptor (HER)-2 has changed with anti–HER-2–targeted therapy. Although anti–HER-2 therapy with trastuzumab and chemotherapy is the standard first-line treatment, the best therapeutic regimen has yet to be defined, and new strategies are evolving.

Methods.

A literature review of well-established and recently published trials, reviews, and ongoing clinical trials addressing first-line treatment for HER-2⁺ metastatic breast cancer patients was performed.

Results.

Taxanes are the agents most commonly used in combination with trastuzumab, but other chemotherapy drugs, such as anthracyclines, vinorelbine, and gemcitabine and triple-combination therapies including platinum compounds, capecitabine, and taxanes have been studied. The combination of aromatase inhibitors with anti–HER-2 therapies is a new therapeutic option for some patients who coexpress HER-2 and hormone receptors, although its activity observed in randomized clinical trials seems to be inferior to that of chemotherapy plus anti–HER-2 therapies. In addition, new anti–HER-2 therapies have shown activity in HER-2⁺ tumors, both alone and in combination with trastuzumab.

Conclusions.

Trastuzumab plus chemotherapy is the current standard of care for the upfront treatment of HER-2⁺ breast cancer patients, though other anti–HER-2–targeting agents may appear as new standards in the upcoming years.     

Trastuzumab emtansine (T-DM1): a novel agent for targeting HER2+ breast cancer

Increased understanding of the molecular mechanisms of tumorigenesis has led to the development of novel agents that target tumor cells with minimal effects on normal cells. The success of this approach is exemplified by the development of monoclonal antibodies directed toward antigens expressed selectively by tumor cells. The conjugation of these monoclonal antibodies with potent cytotoxic drugs has the potential to further improve efficacy while retaining a favorable safety profile. Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate (ADC) currently in clinical development. It combines the humanized antibody trastuzumab, which targets the human epidermal growth factor receptor 2 (HER2) receptor on cancer cells, and the potent antimicrotubule agent DM1 using a unique highly stable linker. When T-DM1 binds to HER2, a proportion of the receptors are thought to be internalized by the process of receptor endocytosis, followed by the intracellular release of an active form of DM1, which in turn kills the tumor cell. This review presents the rationale for the development of T-DM1 and summarizes the preclinical and clinical data for this novel agent for the treatment of breast cancer.     

The effect of a dimeric Affibody molecule (ZEGFR:1907)2 targeting EGFR in combination with radiation in colon cancer cell lines

The epidermal growth factor receptor (EGFR) is frequently overexpressed in colorectal cancer and is therefore an attractive target for treatment. (ZEGFR:1907)2 is a newly developed dimeric affibody molecule with high affinity to the extracellular part of EGFR. In this study, we evaluated the cytotoxic effects of (ZEGFR:1907)2 in combination with external radiation and the possible inhibitory effects in the EGFR signalling pathways in the colon cancer cell lines HT-29 and HCT116. The effects were compared with an EGFR antibody (cetuximab) and the tyrosine kinase inhibitors (erlotinib and sunitinib). These cell lines are genotypically different with respect to e.g. KRAS and BRAF mutational status, recently shown to be of clinical significance for therapeutic effects. Both cell lines express approximately 100,000-150,000 EGFRs per cell but differ in the radiation response (HCT116, SF2=0.28 and HT-29, SF2=0.70). Exposure to (ZEGFR:1907)2 produced a small, but significant, reduction in survival in HCT116 but did not affect HT-29 cells. Similar results were obtained after exposure to EGF and the EGFR antibody cetuximab. The EGFR tyrosine kinase targeting inhibitor erlotinib and the multi-tyrosine kinase inhibitor sunitinib reduced survival in both cell lines. However, none of the drugs had any significant radiosensitizing effects in combination with radiation. Akt and Erk are central proteins in the EGFR downstream signalling and in the cellular response to ionizing radiation. The activation of Akt (Ser 473) and Erk (Thr202/Tyr204) by radiation was both dose- and time-dependent. However the activation of EGFR was not clearly affected by radiation. Neither (ZEGFR:1907)2 nor any of the other drugs were able to completely inactivate Akt or Erk. On the contrary, erlotinib stimulated Akt phosphorylation in both cell lines and in HCT116 cells Erk was activated. Overall the results illustrate the complexity in response to radiation and drugs in cells with differential phenotypic status.     

HER-2 receptor expression, localization, and activation in colorectal cancer cell lines and human tumors

The HER-2/neu oncogene encodes a 185 kD protein that is phosphorylated upon ligand binding to other HER/erbB members and regulates cell growth and differentiation. Given that HER-2 receptor blockade can inhibit the growth of colon cancer cell lines and tumor xenografts, we investigated the frequency, localization and phosphorylation status of HER-2 in colon cancer cell lines and in human tumors. Protein expression was analyzed in relation to mRNA levels, HER-2 amplification, and clinicopathological variables. Colon cancer cell lines constitutively expressed HER-2 proteins and none showed HER-2 amplification by fluorescence in situ hybridization. Cell fractionation and immunoblotting showed HER-2 in both the membrane and cytosolic compartments. Primary colorectal carcinomas (n = 96) and their metastases (n = 25) were examined by immunohistochemistry. Strong membrane HER-2 staining was detected in 5 (5%) of primaries and in 3 (12%) metastases (p = 0.36). Membrane but not cytoplasmic localization was strongly associated with HER-2 gene amplification (p = 0.007). Cytoplasmic HER-2 staining was found in 61 (63.5%) of primary tumors and localization was confirmed by immunoelectron microscopy that also showed plasma membrane HER-2. Using real-time quantitative RT-PCR, HER-2 mRNA was increased in tumors with membrane compared to cytoplasmic staining (r = 0.66, p = 0.001). Cytoplasmic HER-2 was associated with tumor differentiation (p = 0.018), but not other clinicopathological variables. By immunoblotting, heterogeneity was seen in HER-2 levels with downregulation in 4 of 7 tumors relative to normal epithelia that uniformly expressed HER-2. Phosphorylated HER-2 was detected in approximately 50% of tumors and in normal mucosa. In conclusion, HER-2 is expressed constitutively in colon cancer cell lines and demonstrates relatively distinct localization patterns in human tumors. Strong membrane immunoreactivity is associated with high levels of HER-2 mRNA and gene amplification whereas cytoplasmic HER-2 is detected frequently and seems to be a marker of tumor differentiation.     

结肠癌奥沙利铂耐药细胞系的建立及其生物学特性的研究

Background and Objective:Chemotherapy is the main treatment for colon cancer,while multidrugresistance is the main reason for chemotherapy failure and tumor relapse.This study was to establish two oxaliplatinresistant colon cancer cell lines and evaluate their biological characteristics.Met hods:Oxaliplatin-resistant colon cancer cell lines SW620/L-OHP and lovo/L-OHP were established in vitro by continuous exposure to oxaliplatin(L-OHP) of low and gradually increased concentration.Growth curve,cross-resista...