P27(kip1) down-regulation is associated with trastuzumab resistance in breast cancer cells

Trastuzumab (Herceptin) is a recombinant humanized monoclonal antibody directed against HER-2. The objective response rate to trastuzumab monotherapy is 12-34% for a median duration of 9 months, by which point most patients become resistant to treatment. We created two trastuzumab-resistant (TR) pools from the SKBR3 HER-2-overexpressing breast cancer cell line to study the mechanisms by which breast cancer cells escape trastuzumab-mediated growth inhibition. Both pools maintained her-2 gene amplification and protein overexpression. Resistant cells demonstrated a higher S-phase fraction by flow cytometry and a faster doubling time of 24-36 h compared with 72 h for parental cells. The cyclin-dependent kinase inhibitor p27(kip1) was decreased in TR cells, and cyclin-dependent kinase 2 activity was increased. Importantly, exogenous addition of p27(kip1) increased trastuzumab sensitivity. Additionally, resistant cells displayed heightened sensitivity to the proteasome inhibitor MG132, which induced p27(kip1) expression. Thus, we propose that trastuzumab resistance may be associated with decreased p27(kip1) levels and may be susceptible to treatments that induce p27(kip1) expression.     

First-line, single-agent Herceptin(trastuzumab) in metastatic breast cancer: a preliminary report

Following confirmation of the appropriate dosage, safety and potential efficacy of Herceptin(trastuzumab) in small-scale phase I and II trials involving patients with refractory disease, a large trial was conducted in 222 patients with breast cancer who had relapsed after one or two chemotherapy regimens for their metastatic disease. The results showed a positive and durable overall response rate (15% according to a response evaluation committee (REC) assessment) using trastuzumab monotherapy (initial dose 4 mg/kg intravenously (i.v.) followed by 2 mg/kg i.v. weekly). In another recently completed phase II trial, 113 patients were randomised to two dose levels (initial dose of 4 mg/kg i.v. dose followed by 2 mg/kg i.v. weekly, or initial dose of 8 mg/kg followed by 4 mg/kg i.v. weekly) of single-agent trastuzumab as first-line therapy for metastatic disease. The preliminary overall response rate was 23% based on investigator assessment, and tolerability was excellent as in previous trials; efficacy was similar in both dose groups, but the side-effects tended to be more frequent in the higher dose group. The preferred dosage is therefore the same as that currently recommended, i.e. an initial dose of 4 mg/kg i.v. followed by 2 mg/kg weekly i.v. until disease progression.     

Herceptin (trastuzumab)

Trastuzumab is a recombinant humanized monoclonal antibody directed against HER2. Several issues about its optimal use,mechanism of action or resistance still await convincing answers. Results of large-scale randomized trials and preclinical study might answer these questions. This review summarizes current knowledge about trastuzumab treatment.     

First-line, single-agent Herceptin(R) (trastuzumab) in metastatic breast cancer. a preliminary report

Following confirmation of the appropriate dosage, safety and potential efficacy of Herceptin(R) (trastuzumab) in small-scale phase I and II trials involving patients with refractory disease, a large trial was conducted in 222 patients with breast cancer who had relapsed after one or two chemotherapy regimens for their metastatic disease. The results showed a positive and durable overall response rate (15% according to a response evaluation committee (REC) assessment) using trastuzumab monotherapy (initial dose 4 mg/kg intravenously (i.v.) followed by 2 mg/kg i.v. weekly). In another recently completed phase II trial, 113 patients were randomised to two dose levels (initial dose of 4 mg/kg i.v. dose followed by 2 mg/kg i.v. weekly, or initial dose of 8 mg/kg followed by 4 mg/kg i.v. weekly) of single-agent trastuzumab as first-line therapy for metastatic disease. The preliminary overall response rate was 23% based on investigator assessment, and tolerability was excellent as in previous trials; efficacy was similar in both dose groups, but the side-effects tended to be more frequent in the higher dose group. The preferred dosage is therefore the same as that currently recommended, i.e. an initial dose of 4 mg/kg i.v. followed by 2 mg/kg weekly i.v. until disease progression.     

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.     

Clinical trials of Herceptin(trastuzumab)

This report summarises the clinical efficacy and safety findings from clinical trials of the new anti-HER2 monoclonal antibody Herceptin(trastuzumab). Data from pivotal trials indicate that trastuzumab is active when added to chemotherapy in patients with advanced metastatic breast cancer. In particular, the combination significantly prolonged the median time to disease progression, increased the overall response rate, increased the duration of response, and improved median survival time by approximately 25% compared with chemotherapy alone. Furthermore, trastuzumab is active as a single agent in women with HER2-positive metastatic breast cancer, inducing durable objective tumour responses. In total, 15% of patients who had received extensive prior treatment for metastatic disease had an objective response. The median duration of response was 9.1 months following administration of single-agent trastuzumab. Notably, 2% of patients were free of disease progression at 6 months. The safety profile of trastuzumab either given alone or in combination was favourable.     

Weekly paclitaxel (Taxol) with or without trastuzumab (Herceptin) in advanced breast cancer: a community-based observation study

BACKGROUND: We evaluated the efficacy and safety of weekly paclitaxel therapy in women with locally advanced or metastatic breast cancer in an unselected hospital-based patient population. PATIENTS AND METHODS: Using a specific search tool we were able to find 49 cases in our department-based database MedicoHelp containing more than 36,000 files. All cases were evaluable. The mean number of involved sites was 2.4 (range 1-4) and 38/49 patients had visceral predominant disease. 44 patients received prior antitumor therapies, 33 patients had received prior anthracycline- and/or taxane-containing chemotherapy. Weekly paclitaxel was given at a mean dose of 80 mg/m(2) (day 1, 8, 15, repeated every 28 days), 38 patients with HER2 overexpression had a combination therapy with trastuzumab (Herceptin). Median treatment duration with paclitaxel was 4.4 months (range 0.25-9 months). A dose reduction was necessary in 5 patients. RESULTS: Therapy was tolerated well, with a 12% incidence of hematologic grade 3/4 toxicity and 22% cumulative nonhematologic grade 3 toxicity (asthenia: 5 patients, mucosa/skin: 3 patients, neurotoxicity: 3 patients). Other toxicities were rare. The overall response rate was 63%. 22% of the patients achieved disease stabilization. Symptom improvement was seen in 73% of patients. The mean time to progression was 6.0 months (range 0.25-23 months). CONCLUSIONS: Weekly paclitaxel (mostly in combination with trastuzumab) is a well-tolerated regimen and had a surprisingly high efficacy in this observation study in heavily pre-treated patients. Symptom improvement was seen in the majority of patients who responded to the treatment.     

A review of the use of trastuzumab (Herceptin) plus vinorelbine in metastatic breast cancer.

The combination of trastuzumab (Herceptin) and vinorelbine (Navelbine) in the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) is valuable for several reasons. There is proven synergism of these agents in preclinical models, both agents are well tolerated and there is minimal overlapping toxicity. This article reviews clinical experience with trastuzumab and vinorelbine from phase II/III trials including >450 assessable patients. Results across the trials show objective response rates for the combination in the range of 44%-86% (51%-86% as first-line treatment) and a median duration of response of 10-17.5 months. Approximately 50% of patients experience grade 3/4 neutropenia, which is of short duration and manageable. Symptomatic cardiac events are infrequent (seven episodes of grade 3 toxicity across all trials). Overall, trastuzumab-vinorelbine combination therapy offers patients with HER2-positive MBC, an effective and well-tolerated treatment that is suitable for prolonged duration of use.     

Molecular mechanisms underlying IGF-I-induced attenuation of the growth-inhibitory activity of trastuzumab (Herceptin) on SKBR3 breast cancer cells

The clinical usefulness of trastuzumab (Herceptin; Genentech, San Francisco, CA) in breast cancer treatment is limited by the rapid development of resistance. We previously reported that IGF-I signaling confers resistance to the growth-inhibitory actions of trastuzumab in a model system, but the underlying molecular mechanism remains unknown. We used SKBR3/neo cells (expressing few IGF-I receptors) and SKBR3/IGF-IR cells (overexpressing IGF-I receptor) as our experimental model. IGF-I antagonized the trastuzumab-induced increase in the level of the Cdk inhibitor p27(Kip1). This resulted in decreased association of p27(Kip1) with Cdk2, restoration of Cdk2 activity and attenuation of cell-cycle arrest in G(1) phase, all of which had been induced by trastuzumab treatment in SKBR3/IGF-IR cells. We also found that the decrease in p27(Kip1) induced by IGF-I was accompanied by an increase in expression of Skp2, which is a ubiquitin ligase for p27(Kip1), and by increased Skp2 association with p27(Kip1). A specific proteasome inhibitor (LLnL) completely blocked the ability of IGF-I to reduce the p27(Kip1) protein level, while IGF-I increased p27(Kip1) ubiquitination. This suggests that the action of IGF-I in conferring resistance to trastuzumab involves targeting of p27(Kip1) to the ubiquitin/proteasome degradation machinery. Finally, specific inhibitors of MAPK and PI3K suggest that the IGF-I-mediated reduction in p27(Kip1) protein level by increased degradation predominantly involves the PI3K pathway. Our results provide an example of resistance to an antineoplastic therapy that targets one tyrosine kinase receptor by increased signal transduction through an alternative pathway in a complex regulatory network.     

Herceptin (trastuzamab) in advanced breast cancer

Herceptin (trastuzamab, Genentech, San Francisco, CA, USA) prolongs survival in metastatic breast cancer patients whose tumours overexpress the HER2/neu protein. Compared with chemotherapy alone, patients receiving chemotherapy and Herceptin have a significantly longer time to progression, a higher response rate and a longer duration of response. These effects are most marked in first-line treatment of metastatic disease. The addition of Herceptin is associated with few additional side-effects, apart from cardiac toxicity in patients concurrently receiving anthracyclines. As such, it seems reasonable for Herceptin to become considered as one of the routine treatment options in metastatic breast cancer. It would therefore be appropriate for HER2 status testing to be incorporated into the assessment of all patients with metastatic disease. The use of this medication will be limited by its cost. Furthermore, data are lacking on appropriate treatments durations in responders.     

Clinical trials of Herceptin(R) (trastuzumab)

This report summarises the clinical efficacy and safety findings from clinical trials of the new anti-HER2 monoclonal antibody Herceptin(R) (trastuzumab). Data from pivotal trials indicate that trastuzumab is active when added to chemotherapy in patients with advanced metastatic breast cancer. In particular, the combination significantly prolonged the median time to disease progression, increased the overall response rate, increased the duration of response, and improved median survival time by approximately 25% compared with chemotherapy alone. Furthermore, trastuzumab is active as a single agent in women with HER2-positive metastatic breast cancer, inducing durable objective tumour responses. In total, 15% of patients who had received extensive prior treatment for metastatic disease had an objective response. The median duration of response was 9.1 months following administration of single-agent trastuzumab. Notably, 2% of patients were free of disease progression at 6 months. The safety profile of trastuzumab either given alone or in combination was favourable.     

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.     

Olive oil's bitter principle reverses acquired autoresistance to trastuzumab (Herceptin™) in HER2-overexpressing breast cancer cells

Background  

A low incidence of breast cancer in the Mediterranean basin suggests that a high consumption of Extra Virgin Olive Oil (EVOO) might confer this benefit. While the anti-HER2 oncogene effects of the main ω-9 fatty acid present in EVOO triacylglycerols (i.e., oleic acid) have been recently described, the anti-breast cancer activities of EVOO non-glyceridic constituents -which consist of at least 30 phenolic compounds-, remained to be evaluated.     

Combination immunotherapy using autologous tumor-stimulated lymphocytes and trastuzumab (Herceptin) for the patients with recurrent breast cancer

PURPOSE: We report two patients with refractory recurrent breast cancer (HER2/neu: +) postoperatively, who had failed response to the available conventional chemotherapy of CAF (cyclophosphamide, adriamycin, 5-fluorouracil) and docetaxel, etc. They markedly responded to the combination immunotherapy using intraperitumoral injections of autologous tumor cell-stimulated T lymphocyte (AuTL) and trastuzumab (Herceptin), an anti-HER2 monoclonal antibody. METHODS: AuTLs were administrated directly into the recurrent tumor by intraperitumoral injections biweekly and trastuzumab was infused systemically every week. The treatments were repeated for 6 and 11 injections in the patients, respectively. The total administered T cells had reached to 3.8 x 10(9) and 6.4 x 10(9), respectively. The dosage of trastuzumab was 2 mg/kg in each patient. RESULTS: The carcinomatous pleural effusion had disappeared and was well controlled in patient 1 and a marked regression in injected fields in comparison to the size of the recurrent tumor before treatment was observed in patient 2. The tumor marker proteins (CEA, CA15-3, TPA) had also decreased significantly. The adverse effects of the immunotherapy were tolerable with grades 1-2 infusion reaction of fever, tachycardia and hypotension, but no cardiac dysfunction was observed. CONCLUSIONS: Clinical responses of recurrent breast cancer were observed in two patients after receiving the intra-peritumoral AuTL injection plus trastuzumab immunotherapy. These results showed that refractory recurrent breast cancer may be controlled effectively and safely by repeating the cellular immunotherapy combined with trastuzumab and suggested utility of combining these agents in clinical trial.     

miR-375靶向YAP1调控上皮-间质转化参与乳腺癌细胞曲妥珠单抗的耐药

背景与目的:曲妥珠单抗作为人表皮生长因子受体2(human epidermal growth factor receptor 2,HER2)常用靶向抗体药物,其耐药问题日益凸显.探讨miR-375靶向Yes相关蛋白1(Yes-associated protein 1,YAP1)介导上皮-间质转化(epithelial-...     

Combining trastuzumab (Herceptin) with hormonal therapy in breast cancer: what can be expected and why?

Hormonal therapy and the humanised anti-HER2 monoclonal antibody trastuzumab (Herceptin) represent one of the oldest and one of the newest treatment modalities for breast cancer, respectively. Recent data have suggested that HER2 overexpression is associated with resistance to hormonal therapy and there is considerable preclinical evidence to support the existence of interaction or 'cross talk' between HER2 and estrogen-receptor (ER) signalling pathways in breast cancer. Preclinical data also demonstrate that adding trastuzumab to hormonal therapy results in greater antitumour activity than either agent alone. The existence of an inverse relationship between ER expression and HER2 overexpression has also been well established clinically. Thus, a range of clinical trials are now ongoing to determine whether the addition of trastuzumab to hormonal therapy will provide breast cancer patients with benefits in clinical practice. This review describes the rationale for these trials and discusses the potential of therapeutic regimens combining trastuzumab with hormonal therapy.     

A population-based study on the first forty-eight breast cancer patients receiving trastuzumab (Herceptin) on a named patient basis in Sweden

Several studies have presented data on the efficacy and tolerability of trastuzumab within clinical trials. As a minority of patients is included in these trials, we undertook this retrospective study to describe trastuzumab therapy in clinical routine and its tolerability. We reviewed the medical records of the first 48 patients in Sweden who received treatment with trastuzumab on a named patient basis with (n =29) and without (n =19) chemotherapy. Forty-six patients had metastatic disease and had failed to respond to several prior regimens before starting antibody treatment. Two patients had locally advanced breast cancer failing on given neoadjuvant therapy. Patients with breast cancers with strong (3 +) c-erbB-2 overexpression tended to have an improved survival from start of trastuzumab treatment versus those with a moderate (2 +) overexpression (p =0.09). Adverse events were registered in 22 patients (46%). The most common and acute side effects were fever and chills (7 patients, 15%). The toxicity seemed reasonable but two patients (4%) suffered serious cardiac events, both of them having received previous treatment with antracyclines.     

Cooperative inhibitory effect of ZD1839 (Iressa) in combination with trastuzumab (Herceptin) on human breast cancer cell growth.

BACKGROUND: Co-expression of the epidermal growth factor receptor (EGFR) and of ErbB-2 is found in a subset of primary human breast cancer. MATERIALS AND METHODS: The antiproliferative effects of anti-EGFR and anti-ErbB-2 agents were evaluated using a monolayer assay. The effects of these agents on the activation of EGFR, ErbB-2, AKT and p42/p44 MAP kinases (MAPK) were investigated by western blot analysis. RESULTS: We found that both ZD1839 (Iressa), a specific EGFR tyrosine kinase inhibitor, and trastuzumab (Herceptin) (TRA), a humanized anti-ErbB-2 monoclonal antibody, were able to inhibit the growth of SK-Br-3 and BT-474 breast carcinoma cells, which express both EGFR and ErbB-2. Treatment of breast carcinoma cells with a combination of ZD1839 and TRA resulted in a synergistic inhibitory effect. Treatment of SK-Br-3 cells with ZD1839 produced a significant, dose-dependent reduction of the tyrosine phosphorylation of both EGFR and ErbB-2. Phosphorylation of MAPK and AKT were significantly reduced in SK-Br-3 cells following treatment with ZD1839, whereas treatment with TRA produced a reduction of AKT but not MAPK phosphorylation. Finally, treatment with ZD1839, but not with TRA, produced a significant increase in fragmented DNA in breast carcinoma cells. However, a more pronounced increase in the levels of fragmented DNA was observed following combined treatment with ZD1839 and TRA. CONCLUSIONS: These data suggest that combined treatment with drugs that target EGFR and ErbB-2 might result in an efficient inhibition of tumor growth in those breast carcinoma patients whose tumors co-express both receptors.