HER-2 therapy. HER-2/neu diagnostics in breast cancer

HER-2/neu status of the primary breast cancer (PBC) is determined by immunohistochemistry and fluorescent in situ hybridization. Because of a variety of technical factors, however, the PBC may not accurately reflect the metastatic tumor in terms of HER-2/neu status. Recently published guidelines recommend that tumors be defined as HER-2/neu positive if 30% or more of the cells are 3+. Circulating levels of the HER-2 extracellular domain can be measured in serum using a test cleared by the US Food and Drug Administration, and increased serum HER-2/neu levels to above 15 ng/ml can reflect tumor progression. Studies comparing tissue HER-2/neu status of the PBC and HER-2/neu levels above 15 ng/ml in metastatic breast cancer patients are also reviewed.     

HER-2/neu diagnostics in breast cancer

HER-2/neu status of the primary breast cancer (PBC) is determined by immunohistochemistry and fluorescent in situ hybridization. Because of a variety of technical factors, however, the PBC may not accurately reflect the metastatic tumor in terms of HER-2/neu status. Recently published guidelines recommend that tumors be defined as HER-2/neu positive if 30% or more of the cells are 3+. Circulating levels of the HER-2 extracellular domain can be measured in serum using a test cleared by the US Food and Drug Administration, and increased serum HER-2/neu levels to above 15 ng/ml can reflect tumor progression. Studies comparing tissue HER-2/neu status of the PBC and HER-2/neu levels above 15 ng/ml in metastatic breast cancer patients are also reviewed.     

HER-2/neu promotes androgen-independent survival and growth of prostate cancer cells through the Akt pathway

HER-2/neu has been implicated in the activation of androgen receptor (AR) and in inducing hormone-independent prostate cancer growth. Here we report that HER-2/neu activates Akt (protein kinase B) to promote prostate cancer cell survival and growth in the absence of androgen. Blocking of the Akt pathway by a dominant-negative Akt or an inhibitor LY294002 abrogates the HER-2/neu-induced AR signaling and cell survival/growth effects in the absence or presence of androgen. Akt specifically binds to AR and phosphorylates serines 213 and 791 of AR. Thus, Akt is a novel activator of AR required for HER-2/neu signaling to androgen-independent survival and growth of prostate cancer cells.     

HER-2/neu receptor in prostate cancer development and progression to androgen independence

Development of prostate cancer and progression to androgen-independent disease is correlated with increased expression of growth factors and receptors capable of establishing autocrine and/or paracrine growth-stimulatory loops. A thorough review was made of the current literature and recent abstract presentations at scientific meetings focusing on the role of the HER-2/neu (c-erbB2) receptor in prostate cancer and the potential clinical usefulness of its specific inhibitors. In the past 10 years, conflicting results on HER-2/neu expression in prostate cancer have been reported. More recently, four studies have shown experimental evidence of HER-2/neu in the development of prostate cancer and, more specifically, in the progression to a hormone-refractory clinical behavior. Furthermore, it has been proposed that HER-2 family and androgen receptors function synergistically in the absence of androgen, which suggests a cross-talk between the HER-2/neu and androgen receptor pathways. Finally, clinical trials are in progress in prostate cancer patients to test novel agents that selectively interfere with HER-2/neu activity.     

Down-regulation of HER2/neu expression induces apoptosis in human cancer cells that overexpress HER2/neu

The HER2/neu oncogene is overexpressed in a significant fraction of human tumors; such overexpression is thought to play a role in the aberrant proliferation of cancer cells. The effects of HER2/neu-specific phosphorothioate antisense oligodeoxyribonucleotides on HER2/neu expression, tumor cell proliferation, and activation of apoptotic cell death pathways have been examined. Antisense treatment down-regulates HER2/neu expression in a dose-dependent and sequence-specific manner. HER2/neu antisense treatment specifically inhibits the growth of tumor lines that overexpress HER2/neu, but it has little effect on the growth of tumor cells that express low levels of HER2/neu. Down-regulation of HER2/neu expression is not only cytostatic, but it also results in the activation of apoptotic cell death pathways in cells that overexpress HER2/neu. These results suggest that, in addition to stimulating tumor cell proliferation, HER2/neu overexpression in cancer cells acts as an antiapoptotic cell survival factor.     

Soluble HER-2/neu neutralizes biologic effects of anti-HER-2/neu antibody on breast cancer cells in vitro

Amplification and over-expression of the HER-2/neu proto-oncogene are associated with poor prognosis in women with both node-positive and node-negative breast cancer. Therefore, the encoded surface glycoprotein represents an attractive target for cancer immunotherapies. Furthermore, the extracellular domain of HER-2/neu is released from the cell surface by proteolytic cleavage. In the present experiments, we investigated the potential biologic effects of soluble HER-2/neu with particular emphasis on its interaction with anti-HER-2/neu antibodies. A monoclonal antibody specific for the extracellular domain of HER-2/neu dose dependently inhibited the proliferation of highly HER-2/neu-expressing SK-BR-3 and BT-474 breast cancer cells but had no effect on the proliferation of weakly to moderately HER-2/neu-expressing MCF-7, HBL-100 and ZR-75-1 breast cells. Addition of SK-BR-3 or BT-474 cell supernatants with high concentrations of soluble HER-2/neu led to a neutralization of anti-HER-2/neu antibody–mediated inhibition of proliferation due to a binding of soluble HER-2/neu by the antibody, which could be demonstrated by immunoprecipitation. Furthermore, the ability of anti-HER-2/neu antibodies to mediate antibody-dependent cellular cytotoxicity (ADCC) by lymphokine-activated killer cells was assessed. Cytolysis of SK-BR-3 tumor cells was increased significantly in the presence of anti-HER-2/neu antibodies. Similar to the proliferation inhibition, ADCC was neutralized by addition of soluble HER-2/neu-containing supernatants. Our data suggest that tumors rich in HER-2/neu might thus escape certain steps of immunologic control by neutralizing biologic activities of anti HER-2/neu antibodies due to the presence of soluble HER-2/neu. Int. J. Cancer 73:875–879, 1997. © 1997 Wiley-Liss, Inc.     

HER-2/neu肿瘤疫苗的研究进展

摘 要　原癌基因HER-2/neu在多种恶性肿瘤中有扩增及过表达,近30%的原发性乳腺癌患者有HER-2/neu过表达。针对HER-2靶点的特异性人源化抗体曲妥株单抗（trastuzumab;又名赫赛汀,Herceptin）在上世纪90年代已用于临床治疗。目前针对HER-2的肽疫苗、蛋白疫苗、细胞疫苗、DC相关疫苗、以及DNA疫苗等的研究,均已取得一定进展,如小肽E75（p369-399）与GM-CSF联合应用,在HLA-A2(+)/A3(+)乳腺癌患者的Ⅱ期临床试验中显示出一定疗效;针对编码HER-2的DNA疫苗已经进入临床试验阶段,这些疫苗均有可能成为乳腺癌治疗的又一个重要手段。但这些疫苗距临床实际使用尚有一定的距离,有许多问题有待解决和需要进一步的临床验证。     

HER-2/neu and topoisomerase IIalpha in breast cancer

In breast cancer, the predominant genetic mechanism for oncogene activation is through an amplification of a gene. The HER-2 (also known as ErbB2/c-erbB2/HER-2/neu) oncogene is the most frequently amplified oncogene in breast cancer, and its overexpression is associated with poor clinical outcome. In addition to its important role in breast cancer growth and progression, HER-2 is also a target for a new form of chemotherapy. Breast cancer patients have been treated with considerable success since 1998 with trastuzumab, a recombinant antibody designed to block signaling through HER-2 receptor. HER-2 has also been implicated in altering the chemosensitivity of breast cancer cells to different forms of conventional cytotoxic chemotherapy, particularly of topoII-inhibitors (e.g., anthracyclines). Topoisomerase II gene is located just by the HER-2 oncogene at the chromosome 17q12–q21 and is amplified or deleted in almost 90% of the HER-2 amplified primary breast tumors. Recent data suggests that amplification and deletion of topoisomerase II may account for both relative chemosensitivity and resistance to anthracycline therapy, depending on the specific genetic defect at the topoII locus. Expanding our understanding of HER-2 amplification also changes its role in the pathogenesis of breast cancer. HER-2 is an oncogene that clearly can drive tumor induction and growth and is also a target for a new kind of chemotherapy, but its function as a marker for chemoselection may be due to associated genetic changes, of which topoisomerase II is a good example. Moreover, despite potential evidence that genes other than HER-2, such as topoisomerase II, may be more important predictors of therapeutic response in breast cancer, HER-2 status still has a very significant role in therapeutic selection, mainly as the major criterion for administering trastuzumab in treating breast cancer. Thus, the clinical and therapeutic importance of the HER-2 and topoisomerase II status to breast cancer management should only increase in the next few years.     

HER-2/neu oncogene expression in advanced breast cancer

Tumor tissue from patients with advanced breast cancer was analyzed for HER-2/neu and p53 expression. The tissue samples from primary tumor and from axillary lymph nodes or distant metastases from 118 breast cancer patients were obtained. Sections from formalin-fixed, paraffin-embedded materials were immunostained for HER-2/neu and p53 oncoprotein expression. Staining results were correlated with survival times and disease-free survival times, flow cytometric synthesis phase fractions, and DNA ploidy. No correlation could be found between HER-2/neu and p53 or any other tested factor, but grade I primary cancers that were positive for HER-2/neu showed a tendency for better outcome. The HER-2/neu staining of the metastases was independent of the staining of the primary tumor. HER-2/neu can be used as a prognostic marker for advanced breast cancer, when the primary tumor is well differentiated.     

Monoclonal antibody to HER-2/neu receptor enhances radiosensitivity of esophageal cancer cell lines expressing HER-2/neu oncoprotein

PURPOSE: The role of HER-2/neu in the response of esophageal cancer to radiation is not well known. The purpose of this study was to evaluate the effect of an anti-HER-2/neu antibody trastuzumab on the proliferation, cell cycle distribution, and radiosensitivity of esophageal cancer cell lines. EXPERIMENTAL DESIGN: Expression of HER-2/neu protein by four esophageal squamous cancer cell lines (KE4, TE8, TE9, and TE10) and an esophageal adenocarcinoma cell line (SKGT4) was assessed using immunohistochemical (IHC) analysis and flow cytometry. We also evaluated HER-2/neu oncogene expression by fluorescence in situ hybridization. As a control for HER-2/neu protein expression and gene amplification, breast cancer cell lines (MCF7, MDA MB175VII, and SKBR3) were also examined. The cytotoxity of trastuzumab (0.1-200 microg/mL) was estimated by the MTT assay, and the cell cycle distribution was determined by flow cytometry. The effect of 10 microg/mL trastuzumab combined with radiation was assessed by a clonogenic assay. RESULTS: Flow cytometry and IHC revealed that two esophageal cancer cell lines (TE9 and SKGT4) showed HER-2/neu expression (IHC 1+ and mean fluorescence intensity of 11-20), while the other esophageal cancer cell lines were negative for HER-2/neu expression. Although trastuzumab alone had no effect on the esophageal cancer cell lines, the combination of 10 microg/mL trastuzumab with radiation showed a synergistic effect on the HER-2/neu expressing cell lines. CONCLUSIONS: This study suggested that trastuzumab plus irradiation may be effective for the treatment of esophageal cancers, including adenocarcinoma and squamous cell cancer with HER-2/neu expression.     

HER-2/neu (p185neu) protein expression in the natural or treated history of prostate cancer.

PURPOSE: Amplification of HER-2/neu gene and overexpression of its encoded product, the p185neu (HER-2/neu) tyrosine kinase membrane receptor, have been associated with tumor progression in certain neoplasms. We conducted this study to investigate patterns of HER-2/neu protein expression in prostate cancer, analyzing different points in the natural and treated history of the disease. EXPERIMENTAL DESIGN: Radical prostatectomy cases (83) and 20 metastatic lesions were studied for the association between HER-2/neu protein overexpression detected by immunohistochemistry and clinicopathological parameters, including time to prostate-specific antigen (PSA) relapse. RESULTS: HER-2/neu protein overexpression, defined as complete membrane staining in >10% of tumor cells using the Food and Drug Administration-approved Dako kit, was found in 9 of 45 (20%) of evaluable hormone na?ve primary tumors and 23 of 34 (67%) primary tumors after androgen-deprivation therapy (P = 0.0001). Of the 20 metastatic lesions, positivity was noted in 16 (80%) of the cases. On univariate analysis, HER-2/neu overexpression was associated with pretreatment PSA (P = 0.011) and time to PSA relapse (P = 0.02). After controlling for pretreatment PSA, the association between hormone treatment and HER-2/neu was still observed. No association was found between HER-2/neu overexpression and Gleason score, capsular invasion, and tumor proliferative index determined by Ki67. CONCLUSIONS: These data suggest that there is significant HER-2/neu overexpression in primary tumors that persist after androgen deprivation. It also emphasizes the importance of characterizing tumors at determined points in the natural or treated history of prostate cancer when targeting treatment to specific biological processes.     

Pre-existent immunity to the HER-2/neu oncogenic protein in patients with HER-2/neu overexpressing breast and ovarian cancer

Immunomodulatory strategies, such as antibody therapy and cancer vaccines, are increasingly being considered as potential adjuvant therapies in patients with advanced stage breast cancer to either treat minimal residual disease or prevent relapse. However, little is known concerning the incidence and magnitude of the pre-existent breast cancer specific immune response in this patient population. Using the HER-2/neu oncogenic protein as a model, a well-defined tumor antigen in breast cancer, we questioned whether patients with advanced stage HER-2/neu overexpressing breast and ovarian cancers (III/IV) had evidence of pre-existent immunity to HER-2/neu. Forty-five patients with stage III or IV HER-2/neu overexpressing breast or ovarian cancer were evaluated for HER-2/neu specific T cell and antibody immunity. Patients enrolled had not received immunosuppressive chemotherapy for at least 30 days (median 5 months, range 1–75 months). All patients were documented to be immune competent prior to entry by DTH testing using a skin test anergy battery. Five of 45 patients (11%) were found to have a significant HER-2/neu specific T cell response as defined by a stimulation index 2.0 (range 2.0–7.9). None of eight patients who were HLA-A2 had a detectable IFN secreting T-cell precursor frequency to a well-defined HER-2/neu HLA-A2 T cell epitope, p369-377. Three of 45 patients (7%) had detectable HER-2/neu specific IgG antibodies, range 1.2–8.9g/ml. These findings suggest that patients with advanced stage HER-2/neu overexpressing breast and ovarian cancer can mount a T cell and/or antibody immune response to their tumor. However, in the case of the HER-2/neu antigen, the pre-existent tumor specific immune response is found only in a minority of patients.     

SUCI02选择性抑制HER-2/neu受体酪氨酸激酶磷酸化及其对HER-2/neu过表达乳腺癌细胞生长的影响

背景与目的：HER-2／neu受体过度表达与肿瘤的发生发展、对化疗的敏感性以及患者预后有关;我们通过大量筛选,发现SUCI02[N-(4-乙氧苯基)-2-羟基酸胺]能抑制HER2／neu受体酪氨酸激酶磷酸化。本研究拟探讨SUCI02对HER-2／nell过度表达的肿瘤细胞生长的影响。方法：用免疫沉淀、免疫印迹法检测：HER-2／neu受体酪氨酸激酶磷酸化、酪氨酸激酶蛋白水平的变化;MTT法检测SUCI02对乳腺癌细胞的抑制作用。结果：SUCI02能抑制HER-2／neu受体的自身磷酸化,在乳腺癌MDA—MB．453m1细胞中,SUCI02对HER-2／neu受体自身磷酸化的IC50为4．34μg／ml,对HER-2／neu的表达没有任何影响。在用SUCI02处理MDA-MB-453ml细胞30min后,用培养液洗掉药物,继续培养不同时间,结果可见洗掉药物后30min,SUCI02对HER-2／neu受体磷酸化的抑制就开始恢复。SUCI02处理MDA-MB-453ml细胞后其下游靶分子MAPK和AKT激活明显受抑制,呈现剂量依赖性。SUCI02对EGFR受体酪氨酸磷酸化在最高剂量用到40μg／ml下没有明显的抑制作用。应用MTT法检测了SUCI02对过度表达HER-2／neu的MDA-MB-453ml细胞的生长抑制作用,同时应用过表达EGFR的乳腺癌MDA—MB-468细胞作为对照,结果可见SUCI02对HER-2／neu过表达的肿瘤细胞相对于过表达EGFR的肿瘤细胞有更明显的抑制作用。结论：SUCI02选择性抑制HER-2／neu受体酪氨酸激酶磷酸化,阻断其下游信号途径,对过度表达HER-2／neu的肿瘤细胞具有更强的生长抑制作用。     

HER-2/neu is a tumor rejection target in tolerized HER-2/neu transgenic mice

HER-2/neu (neu-N) transgenic mice, which express the nontransforming rat proto-oncogene, develop spontaneous focal mammary adenocarcinomas beginning at 5-6 months of age. The development and histology of these tumors bears a striking resemblance to what is seen in patients with breast cancer. We have characterized the immunological responses to HER-2/neu (neu) in this animal model. neu-positive tumor lines, which were derived from spontaneous tumors that formed in neu-N animals, are highly immunogenic in parental, FVB/N mice. In contrast, a 100-fold lower tumor challenge is sufficient for growth in 100% of transgenic animals. Despite significant tolerance to the transgene, neu-specific immune responses similar to those observed in breast cancer patients can be demonstrated in neu-N mice prior to vaccination. Both cellular and humoral neu-specific responses in transgenic mice can be boosted with neu-specific vaccination, although to a significantly lesser degree than what is observed in FVB/N mice, indicating that the T cells involved are less responsive than in the nontoleragenic parental strain. Using irradiated whole-cell and recombinant vaccinia virus vaccinations we are able to protect neu-N mice from a neu-expressing tumor challenge. T-cell depletion experiments demonstrated that the observed protection is T cell dependent. The vaccine-dependent neu-specific immune response is also sufficient to delay the onset of spontaneous tumor formation in these mice. These data suggest that, despite tolerance to neu in this transgenic model, it is possible to immunize neu-specific T cells to achieve neu-specific tumor rejection in vivo. These transgenic mice provide a spontaneous tumor model for identifying vaccine approaches potent enough to overcome mechanisms of immune tolerance that are likely to exist in patients with cancer.     

HER-2/neu in bladder carcinoma

A total of 66 bladder cancer patients were studied to verify possible relationships between HER-2/neu alterations and pathological characteristics, and to define a poor prognosis patient subgroup with respect to time to recurrence, time to progression and survival. Tumor and healthy tissue specimens were analyzed for HER-2/neu DNA amplification and protein overexpression by Southern and Western blot techniques and evaluated statistically. 13% of cases were amplified and 39% were overexpressed. HER-2/neu alterations were not significantly associated with pathological staging or tumor grading. Multifocal tumors had a higher percentage and overexpression with respect to monofocal tumors. Actuarial analyses did not show a significant statistical correlation between HER-2/neu amplification and overexpression and clinical outcome. Clinical evaluation of HER-2/neu status showed that this gene is not related to tumor relapse, progression or patient survival.     

HER-2/neu oncogene protein and prognosis in breast cancer

Amplification of the HER-2/neu oncogene was recently reported to predict poor clinical outcome in node-positive breast cancer patients. Since expression of the oncogene as its protein product might be even more closely related than gene amplification to disease progression, we have now examined levels of the HER-2/neu oncogene protein for its prognostic potential in both node-positive and node-negative breast cancer. Using Western blot analysis, levels of this protein were determined in 728 primary human breast tumor specimens. We examined relationships between this protein and other established markers of prognosis, as well as clinical outcome. In node-negative patients (n = 378), the HER-2/neu protein failed to predict disease outcome. However, in node-positive patients (n = 350), those patients with higher HER-2/neu protein had statistically shorter disease-free (P = .0014) and overall survival (P less than .0001) than patients with lower levels of the protein. Higher HER-2/neu protein was found in tumors without estrogen receptor (ER) (P = .02) or progesterone receptor (PgR) (P = .0003), and in patients with more than three positive lymph nodes (P = .04). A significant correlation between levels of the HER-2/neu gene protein and amplification of the gene itself was also found (n = 48, P less than .001). Multivariate analyses in these patients showed that the HER-2/neu protein is a significant independent predictor of both the disease-free and the overall survival in node-positive breast cancer, even when other prognostic factors are considered.     

Follow-up study of HER-2/neu amplification in primary breast cancer

Amplification of the HER-2/neu oncogene was determined in 362 tumors from patients with primary breast cancer (185 node-positive patients and 177 node-negative patients). The overall amplification rate was 33% (30% for node-negative patients; 31% for patients with 1-3 positive nodes; 40% for patients with greater than 3 positive nodes). Gene copy number was not associated with axillary lymph node status, steroid receptor status, or patient age but was weakly correlated with the size of the primary tumor. Amplification of the HER-2/neu gene did not correlate with either disease-free or overall survival in univariate or multivariate analyses. The results were unambiguously negative for patients with node-negative disease. Although the univariate results for node-positive patients were marginally significant (P = 0.07), the significance was not retained in multivariate analyses. Thus, while HER-2/neu amplification may be biologically important in primary breast cancer, it will only be of marginal utility as a prognostic factor for predicting clinical outcome.     

Serum level of HER-2/neu in patients with gastric cancer: correlation with HER-2/neu overexpression in gastric carcinoma tissue.

Serum HER-2/neu (c-erbB-2) levels in patients with gastric cancer were evaluated by an enzyme-linked immunosorbent assay and tissue levels of HER-2/neu in the same cohort were determined by immunohistochemistry. Nine (16%) of 57 gastric carcinomas had an overexpression of HER-2/neu detected immunohistochemically. Of these 9 patients, 6 had elevated serum HER-2/neu levels, while 45 of 48 tissue samples with negative staining exhibited normal serum HER-2/neu levels. These results indicated that overall accuracy, positive predictive value, and negative predictive values of their serum measurements were 89, 67 and 94%, respectively. Serum levels of HER-2/neu were correlated with tissue overexpression of HER-2/neu in patients with gastric cancer.     

Overexpression of HER-2/neu in uterine serous papillary cancer.

PURPOSE: Uterine serous papillary carcinoma (USPC) is a highly aggressive variant of endometrial cancer and histologically similar to high-grade ovarian cancer. HER-2/neu, the transmembrane receptor encoded by the c-erbB2 gene, is overexpressed by immunohistology in approximately 25% of ovarian cancers. In this study, we have evaluated the expression of HER-2/neu in several fresh, established, paraffin-embedded, fixed USPCs. In addition, we have tested the sensitivity of USPC cells to Herceptin treatment. EXPERIMENTAL DESIGN: Ten consecutive USPC specimens were assessed by immunohistochemistry for the intensity of expression of HER-2/neu. In addition, three USPC cell lines were analyzed for expression of HER-2/neu by flow cytometry as well as for sensitivity to Herceptin-mediated, complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity (ADCC), and inhibition of cell proliferation. RESULTS: Eight of 10 (80%) of the USPCs assessed immunohistochemically for the intensity of expression of HER-2/neu stained heavily for HER-2/neu (2+ to 3+). Fresh and established primary USPC cell lines were found to express significantly more HER-2/neu receptor by flow cytometry (on the average, 10-fold greater) when compared with HER-2/neu-positive primary or established breast and ovarian cancer cell lines (P < 0.001). Importantly, although these USPC cell lines were resistant to chemotherapy in vivo and to natural killer- and complement-mediated cytotoxicity in vitro, they were found to be highly sensitive to Herceptin-mediated ADCC. USPC cell proliferation was also inhibited by Herceptin. A significant enhancement of ADCC was demonstrated when effector cells were exposed to low doses of IL-2 in vitro. Physiological concentrations of human serum IgG did not inhibit Herceptin-mediated ADCC against USPC. CONCLUSIONS: On the basis of these findings and previous reports showing a positive in vivo correlation between efficacy of Herceptin therapy and the level of HER-2/neu overexpression by tumor cells, we propose that Herceptin might be a novel and attractive therapeutic strategy in patients harboring chemotherapy-resistant, recurrent, or metastatic USPC.