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PubMed2003

In vitro effects of trastuzumab and vinorelbine in trastuzumab-resistant breast cancer cells.

PURPOSE: The majority of patients who initially respond to trastuzumab will progress within 1 year. Currently, patients who progress after trastuzumab-based therapy are often maintained on trastuzumab combined with a different chemotherapeutic agent, such as vinorelbine. However, evidence supporting the continued use of trastuzumab in these breast cancers is lacking. METHODS: We created a preclinical model of trastuzumab resistance using the SKBR3 HER-2-overexpressing breast cancer cell line. Dose-response and cell cycle alterations in response to trastuzumab and/or vinorelbine were assessed. RESULTS: In contrast to the parental SKBR3 cells, vinorelbine-mediated growth inhibition and apoptosis were not significantly enhanced by the addition of trastuzumab in the trastuzumab-resistant pools. CONCLUSIONS: These results suggest that the continued treatment of trastuzumab-resistant breast cancers with trastuzumab-containing regimens may not be effective. A randomized clinical trial of trastuzumab plus vinorelbine versus vinorelbine alone should be conducted in patients with HER-2-overexpressing breast cancer to determine the optimal duration of trastuzumab therapy upon progression.

Antibodies, Monoclonal↗
PubMed2005

Randomized phase II study of weekly docetaxel plus trastuzumab versus weekly paclitaxel plus trastuzumab in patients with previously untreated advanced nonsmall cell lung carcinoma.

BACKGROUND: Trastuzumab is a monoclonal antibody directed against the human epidermal growth factor receptor-2 (HER-2). Nonsmall cell lung carcinoma (NSCLC) overexpresses HER-2 protein in approximately 20% of cases. In the current study, the authors combined trastuzumab with weekly taxanes in an attempt to improve outcomes over standard chemotherapy in patients with advanced NSCLC. METHODS: The primary objective was to determine whether docetaxel plus trastuzumab or paclitaxel plus trastuzumab was the superior regimen based on response and toxicity, and to determine whether either regimen was appropriate for further testing in a randomized Phase III trial. After stratification based on the results of HER-2 immunohistochemistry, chemotherapy-naive patients were randomized to receive trastuzumab plus docetaxel or trastuzumab plus paclitaxel. The study was designed so patients with or without HER-2 overexpression would be distributed equally between the study arms. RESULTS: Immunohistochemistry for HER-2 protein expression was attempted for 182 pathologic samples from 169 patients. Twenty-eight of the 179 evaluable samples (16%) revealed 2+ or 3+ staining. The objective response rate was 23% (7 of 30 patients) in the patients treated with docetaxel plus trastuzumab and 32% (11 of 34 patients) in the patients treated with paclitaxel plus trastuzumab (P=0.76, Wilcoxon test). No difference was noted in the median survival (16 mos vs. 14 mos) or 1-year survival (57% vs. 55%) (P=0.998). Toxicities were mild in both treatment arms. No difference with regard to response rates or survival was noted between HER-2-positive (2+ or 3+) and HER-2-negative (0-1+) patients. CONCLUSIONS: The expression of HER-2 protein in patients with advanced NSCLC in this study was found to be similar to that reported in previous series. The response rates and toxicities for patients treated with docetaxel and trasuzumab or paclitaxel and trasuzumab were not significantly different, though survival in both arms was better than expected. HER-2 expression status did not appear to affect outcomes for this uniform group of patients who were treated in a comparable fashion. Because of the infrequency of HER-2 overexpression, and the absence of improved outcomes in patients with NSCLC who were treated with trastuzumab plus chemotherapy in other studies, neither regimen tested will be advanced to a Phase III trial.

Antibodies, Monoclonal↗
PubMed2004

PTEN activation contributes to tumor inhibition by trastuzumab, and loss of PTEN predicts trastuzumab resistance in patients.

The ErbB2-targeting antibody, trastuzumab (Herceptin), has remarkable therapeutic efficacy in certain patients with ErbB2-overexpressing tumors. The overall trastuzumab response rate, however, is limited and what determines trastuzumab response is poorly understood. Here we report that PTEN activation contributes to trastuzumab's antitumor activity. Trastuzumab treatment quickly increased PTEN membrane localization and phosphatase activity by reducing PTEN tyrosine phosphorylation via Src inhibition. Reducing PTEN in breast cancer cells by antisense oligonucleotides conferred trastuzumab resistance in vitro and in vivo. Patients with PTEN-deficient breast cancers had significantly poorer responses to trastuzumab-based therapy than those with normal PTEN. Thus, PTEN deficiency is a powerful predictor for trastuzumab resistance. Additionally, PI3K inhibitors rescued PTEN loss-induced trastuzumab resistance, suggesting that PI3K-targeting therapies could overcome this resistance.

Animals↗
PubMed2006

Continued use of trastuzumab (herceptin) after progression on prior trastuzumab therapy in HER-2-positive metastatic breast cancer.

Whether to continue trastuzumab after objective evidence of disease progression or not is an important unanswered clinical question for women with metastatic disease. This question is also relevant for those who relapse after adjuvant trastuzumab-containing therapy. Unfortunately, there is little evidence to guide decision-making. The modest toxicity and the possible, but unproven, benefit from the continued use of trastuzumab may account for the currently wide spread practice of continued administration of this drug after progression. However, there is no convincing evidence to support the use of extended trastuzumab therapy after progression. At least two randomized trials with no trastuzumab in the control arms were attempted but failed to accrue patients. In the absence of results from a randomized clinical trial, a central registry program that collects information longitudinally from a large number of patients with HER-2 positive breast cancer during the course of their disease was initiated (RegistHER, www.registher.com) to learn about the long term side effects and benefits of prolonged trastuzumab therapy. The anticipated introduction of second generation HER2-targeted agents into the clinic also raises a new question; will switching to these agents be more effective than continuation of trastuzumab? Clinical trials are currently planned to address question prospectively.

Antibodies, Monoclonal↗
PubMed2005

Single-agent trastuzumab versus trastuzumab plus cytotoxic chemotherapy in metastatic breast cancer: a single-institution experience.

Trastuzumab has shown significant single-agent activity in patients with Her-2/neu overexpressing metastatic breast cancer, and increased response rates, progression-free and overall survival when added to standard chemotherapy. Despite higher response rates, the combination with chemotherapy has higher toxicity and it remains unknown whether single-agent trastuzumab is equally effective as the combined treatment in terms of progression-free and overall survival. We therefore carried out a retrospective multivariate analysis of 117 patients with Her-2/neu overexpressing metastatic breast cancer who were treated with trastuzumab with or without chemotherapy at a single institution between November 1999 and December 2003. Response rates tended to be higher in patients receiving trastuzumab in combination with chemotherapy (34 versus 8%, p=0.060). However, this did not translate into a benefit in progression-free survival: median (95% confidence interval) progression-free survival was 6.2 (4.45-7.95) months in patients receiving trastuzumab plus chemotherapy versus 4.2 (1.77-6.63) months in those receiving single-agent trastuzumab (p=0.560). Likewise, no significant difference in overall survival was observed: 27.0 (19.9-34.0) versus 23.1 (16.2-30.0) months (p=0.809). We conclude that in the absence of extensive visceral involvement necessitating a higher response rate, single-agent trastuzumab may be a safe and less-toxic alternative to its combined use with other chemotherapy agents. This needs to be confirmed in prospective randomized trials.

Adult↗
PubMed2006

Proteasome inhibitor bortezomib increases PTEN expression and enhances trastuzumab-induced growth inhibition in trastuzumab-resistant cells.

PTEN (phosphatase and tension homolog deleted on chromosome 10) has been shown to be inactivated in a wide range of cancers and the role of this gene product is associated with the suppression of the phosphatidylinositol-3-kinase (PI3K)/Akt pathway in many cancers. Recently, some reports demonstrated that the degree of PTEN expression could predict trastuzumab chemosensitivity in ErbB2-overexpressing breast cancer. Here, we demonstrate the possible involvement of a proteasome inhibitor (PS341) in PTEN expression and elucidate the influence of PI3K/Akt, one of the main cascades of the ErbB2 downstream pathway, and discuss the role of the proteasome inhibitors in trastuzumab resistance. ErbB2-overexpressing SKBR3 human breast cancer cells and trastuzumab-resistant SKBR3/R cells were analyzed in this study. We show that the expression of phosphorylated Akt was highly increased in trastuzumab-resistant cells, although the expression of PI3K, phosphorylated PI3K and non-phosphorylated Akt was unchanged in comparison with wild-type SKBR3 cells. However, following treatment with PS341, the level of phosphorylated Akt was decreased in a dose-dependent manner. Conversely, the level of PTEN was increased in the same fashion. PS341 showed sufficient cytotoxicity in resistant cells in combination with trastuzumab and the efficacy of trastuzumab was inclined to be better in resistant cells under PS341 treatment. Remarkable activity of Akt was observed in trastuzumab-resistant SKBR3 breast cancer cells and this phenomenon could be associated with the decreased expression of PTEN. The proteasome inhibitor PS341 could increase the level of PTEN and inhibit the downstream pathway of ErbB2, interfering with phosphorylation of Akt.

Antibodies, Monoclonal↗
PubMed2004

Phase II study of celecoxib and trastuzumab in metastatic breast cancer patients who have progressed after prior trastuzumab-based treatments.

PURPOSE: Preclinical studies demonstrate a link between overexpression of HER-2/neu and cyclooxygenase-2 (COX-2) activity. To explore the possibility that COX-2 is a therapeutic target, we conducted a phase II study of celecoxib, a selective COX-2 inhibitor, and trastuzumab in patients with HER-2/neu-overexpressing metastatic breast cancer that had progressed while receiving trastuzumab. EXPERIMENTAL DESIGN: Eligible patients had bi-dimensionally measurable or evaluable HER-2/neu-overexpressing metastatic breast cancer. HER-2/neu overexpression, defined as 2+ or 3+ by the HercepTest, was required. Patients had to have progressed despite prior trastuzumab-based therapy. Treatment consisted of celecoxib (400 mg twice daily) and trastuzumab. RESULTS: Twelve patients were enrolled (42% status post 1 regimen for metastatic disease 58% status post > 2 prior regimens (range of 2-6). Eleven patients were evaluable. There were no responses. Median duration of treatment was 9 weeks. One patient had stable disease at 3 months but progressed at 6 months. A second patient stopped treatment at 3 months because of unresolved grade 2 rash, felt to be related to celecoxib. Toxicities were generally grade 1 or 2. One patient (8%) experienced grade 3 toxicity (abdominal pain). CONCLUSIONS: Celecoxib combined with trastuzumab is well tolerated. However, this combination in patients with HER2/neu-overexpressing, trastuzumab-refractory disease, was not active.

Adult↗
PubMed2006

Randomized phase III study of trastuzumab, paclitaxel, and carboplatin compared with trastuzumab and paclitaxel in women with HER-2-overexpressing metastatic breast cancer.

PURPOSE: This randomized, multicenter, phase III trial evaluated the efficacy and safety of trastuzumab and paclitaxel with or without carboplatin as first-line therapy for women with HER-2-overexpressing metastatic breast cancer (MBC). PATIENTS AND METHODS: HER-2 overexpression was defined as immunohistochemical staining scores of 2+ or 3+. Between November 1998 and May 2002, 196 women with HER-2-overexpressing MBC were randomly assigned to six cycles of either trastuzumab 4 mg/kg loading dose plus 2 mg/kg weekly thereafter with paclitaxel 175 mg/m2 every 3 weeks (TP), or trastuzumab 4 mg/kg loading dose plus 2 mg/kg weekly thereafter with paclitaxel 175 mg/m2 and carboplatin area under the time-concentration curve = 6 every 3 weeks (TPC) followed by weekly trastuzumab alone. RESULTS: Baseline characteristics of the 196 patients were well balanced between study arms. Objective response rate (ORR) was 52% (95% CI, 42% to 62%) for TPC versus 36% (95% CI, 26% to 46%) for TP (P = .04). Median progression-free survival (PFS) was 10.7 months for TPC and 7.1 months for TP (hazard ratio [HR], 0.66; 95% CI, 0.59 to 0.73; P = .03). Improved clinical outcomes with TPC were most evident in HER-2 3+ patients, with an ORR of 57% (95% CI, 45% to 70%) v 36% (95% CI, 25% to 48%; P = .03) and median PFS of 13.8 v 7.6 months (P = .005) for TPC and TP, respectively (HR, 0.55; 95% CI, 0.46 to 0.64). Both regimens were well tolerated, and febrile neutropenia and neurotoxicity occurred infrequently; grade 4 neutropenia occurred more frequently with TPC (P < .01). CONCLUSION: The addition of carboplatin to paclitaxel and trastuzumab improved ORR and PFS in women with HER-2-overexpressing MBC. This well-tolerated regimen represents a new therapeutic option.

Adult↗
PubMed2001

Evaluation of HER2 status: for the treatment of metastatic breast cancers by humanized anti-HER2 Monoclonal antibody (trastuzumab) (Pathological committee for optimal use of trastuzumab).

For the treatment of patients with metastatic breast cancer by humanized anti- human epidermal growth factor receptor type 2 (HER2) antibody (trastuzumab), it is important to evaluate HER2 status adequately. "A guideline for HER2 testing" and "HER2 atlas" produced by the "Pathological committee for optimal use of trastuzumab" are introduced in this report. Appropriate evaluations of biological markers are essential for targeting therapy.

Antibodies, Monoclonal↗
PubMed2004

Trastuzumab plus tamoxifen: anti-proliferative and molecular interactions in breast carcinoma.

HER2 overexpression has been associated with anti-estrogen resistance in human breast cancer, and it has been suggested that the combined treatment of an anti-HER2 antibody plus tamoxifen has enhanced anti-cancer efficacy in breast cancer. The detailed anti-proliferative interactions between trastuzumab and tamoxifen were analyzed with the isobologram and Chou and Talalay methods, which assess the presence of synergy, addition or antagonism. We used the breast cancer cell lines that are estrogen receptor (ER)-positive and HER2-positive. We also analyzed the molecular changes on the HER2 and (ER) signaling pathways that are induced by trastuzumab plus tamoxifen. In terms of cancer cell proliferation, the simultaneous combination of trastuzumab and tamoxifen on BT-474 cells was more growth inhibitory (44%) than the treatment with trastuzumab (24%) or tamoxifen (31%) alone. Isobologram analysis of simultaneous trastuzumab plus tamoxifen exposure showed, however, that there were antagonistic interactions at an effect level of 30% (IC30). Using Chou and Talalay analysis we also observed antagonistic interactions at lower levels of cell kill, although there were additive effects at highest levels of cell kill. Trastuzumab followed by tamoxifen showed antagonism at all effects levels. Tamoxifen followed by trastuzumab showed antagonism at lower levels of cell kill, and additivity at higher levels of cell kill. Similar interactions were observed using T47D cells. The molecular effects of the combined treatment with trastuzumab plus tamoxifen on the levels of HER2 and ER signaling showed that, with respect to HER2 protein levels, trastuzumab downregulated HER2 by 27%, tamoxifen upregulated HER2 by 40%, and the combination of trastuzumab plus tamoxifen did not induce changes in HER2 respect to control. With respect to HER2 mRNA, trastuzumab upregulated HER2 mRNA to 367%, tamoxifen to 166%, and the combination to 401%. With respect to HER2 phosphorylation, trastuzumab upregulated HER2 phosphorylation to 352%, tamoxifen to 202% and the combination to 633%. Epidermal growth factor receptor levels were not changed by trastuzumab or tamoxifen alone, and were upregulated to 138% by the combination. The protein levels and activity of extracellular recptor kinase were not modified by trastuzumab, tamoxifen or the combination. Finally, estrogen receptor protein and mRNA levels were downregulated to about 50% by trastuzumab, tamoxifen or the combination. Taken together, our results show that in ER-positive breast cancer cells overexpressing HER2, trastuzumab plus tamoxifen have antagonistic interactions when used in combination, and that this antagonism may be related with an increase in HER2 signaling pathways that occurs when tamoxifen is added to trastuzumab.

Antibodies, Monoclonal↗
PubMed2003

Combined trastuzumab and paclitaxel treatment better inhibits ErbB-2-mediated angiogenesis in breast carcinoma through a more effective inhibition of Akt than either treatment alone.

BACKGROUND: Trastuzumab (Herceptin; Genentech, South San Francisco, CA) is a humanized anti-ErbB-2 monoclonal antibody that has demonstrated antitumor function, especially in combination with other chemotherapies such as paclitaxel (Taxol; Bristol Myers-Squibb, Princeton, NJ), in patients with tumors that overexpress ErbB-2. Because the repeated administration of low-dose chemotherapy, such as paclitaxel, endorsed an antiangiogenic effect in vitro, and because trastuzumab was shown to inhibit angiogenesis in tumor xenografts, the authors investigated whether ErbB-2-mediated angiogenic responses would be inhibited more effectively by the combined treatment of paclitaxel plus trastuzumab. METHODS: Tumor xenografts were established in 37 severe combined immunodeficiency mice by injecting the mammary fat pad with ErbB-2-overexpressing human breast carcinoma cells. Mice then were treated with an immunoglobulin (IgG) control, trastuzumab, paclitaxel, or a combination treatment of trastuzumab plus paclitaxel. Tumorigenicity, lung metastasis, and tumor microvessel density (MVD) were evaluated. Vascular endothelial growth factor (VEGF) secretion, endothelial cell migration after treatment, and the status of phosphorylated Akt were evaluated in vitro to determine mechanisms underlying the inhibition of ErbB-2-induced angiogenesis. RESULTS: Mice treated with the trastuzumab plus paclitaxel combination exhibited significantly reduced mean tumor volumes compared with mice treated with the IgG control (419.5 mm(3) vs. 786.6 mm(3), P < 0.0001). Mice treated with trastuzumab had a mean tumor volume of 543.9 mm(3), and mice treated with paclitaxel had a mean tumor volume of 574.9 mm(3). Tumors from the trastuzumab-plus-paclitaxel group also had significantly decreased mean MVD compared with the control (30 +/- 8 MVD vs. 44 +/- 12 MVD, P < 0.05). The trastuzumab group had tumors with a MVD of 35 +/- 7, similar to the paclitaxel-treated group (35 +/- 9). Forty-four percent of the mice in the trastuzumab-plus-paclitaxel group had metastases to the lungs compared with 50%, 63%, and 75% of the mice in the paclitaxel, trastuzumab, and control groups, respectively. In vitro, the ErbB-2-overexpressing cells treated with combined trastuzumab plus paclitaxel secreted less VEGF than the cells treated with trastuzumab, paclitaxel, or control (185.9 pg/mL vs. 233.2 pg/mL, 261.3 pg/mL, and 286.4 pg/mL, respectively). In addition, the conditioned media from the combination group stimulated less mean endothelial cell migration (31.0 cells vs. 47.0 cells, 39.2 cells, and 67.5 cells, respectively). Furthermore, Akt phosphorylation contributed to VEGF up-regulation and Akt phosphorylation was reduced more effectively by combined trastuzumab plus paclitaxel treatment compared with the other treatments. CONCLUSIONS: Combined trastuzumab plus paclitaxel treatment more effectively inhibited ErbB-2-mediated angiogenesis than either treatment alone, which resulted in more pronounced tumoricidal effects. This effect may be mediated via the reduction of phosphorylated Akt.

Animals↗
PubMed2004

Randomized phase II trial of gemcitabine-cisplatin with or without trastuzumab in HER2-positive non-small-cell lung cancer.

BACKGROUND: Trastuzumab provides significant clinical benefits in HER2-positive metastatic breast cancer patients when administered in combination with chemotherapy. Chemotherapy has also been shown to be beneficial in some patients with advanced non-small-cell lung cancer (NSCLC). The present randomized phase II trial examined the effect of adding trastuzumab to a standard chemotherapeutic combination (gemcitabine-cisplatin) in patients with HER2-positive NSCLC. PATIENTS AND METHODS: Patients with untreated stage IIIB/IV HER2-positive NSCLC received up to six 21-day cycles of gemcitabine 1250 mg/m(2) (days 1 and 8) and cisplatin 75 mg/m(2) (day 1). Patients in the trastuzumab arm received trastuzumab 4 mg/kg intravenously (i.v.) followed by 2 mg/kg/week i.v. until progression. RESULTS: Of 619 patients screened, 103 were eligible. Fifty-one patients were treated with trastuzumab plus gemcitabine-cisplatin and 50 with gemcitabine-cisplatin alone. Efficacy was similar in the trastuzumab and control arms: response rate 36% versus 41%; median time to progression 6.3 versus 7.2 months; and median progression-free survival (PFS) 6.1 versus 7 months. Response rate (83%) and median PFS (8.5 months) appeared relatively good in the six trastuzumab-treated patients with HER2 3+ or fluorescence in situ hybridization (FISH)-positive NSCLC. Addition of trastuzumab to gemcitabine-cisplatin was well tolerated, side-effects were as expected, and trastuzumab did not exacerbate the known toxicity of gemcitabine and cisplatin. Symptomatic cardiotoxicity was observed in one trastuzumab-treated patient. Serum trastuzumab concentrations in the presence of gemcitabine-cisplatin were comparable to those of trastuzumab alone. CONCLUSIONS: Trastuzumab plus gemcitabine-cisplatin is well tolerated. Clinical benefit was not observed. Although HER2 3+/FISH-positive patients may benefit from trastuzumab, the subgroup is too small to provide definitive information. No significant effect of gemcitabine-cisplatin on trastuzumab pharmacokinetics was observed.

Adult↗
PubMed2004

Phase II trial of trastuzumab followed by weekly paclitaxel/carboplatin as first-line treatment for patients with metastatic breast cancer.

PURPOSE: To determine the response rate of trastuzumab as first-line therapy in patients with HER-2 overexpressing metastatic breast cancer. To assess the feasibility and toxicity of weekly paclitaxel/carboplatin with or without trastuzumab following initial treatment with trastuzumab. PATIENTS AND METHODS: Sixty-one patients received trastuzumab (8 mg/kg followed by 4 mg/kg/wk) for 8 weeks. Responding patients received 8 additional weeks of trastuzumab (4 mg/kg/wk), and then proceeded to receive trastuzumab (2 mg/kg) in combination with paclitaxel 70 mg/m(2) and carboplatin (area under the curve, 2) weekly for 6 weeks followed by 2 weeks rest. Stable patients after the initial 8 weeks of trastuzumab proceeded to treatment with trastuzumab, paclitaxel, and carboplatin. Patients with disease progression during the initial 8 weeks had the trastuzumab discontinued and were treated with weekly paclitaxel/carboplatin. RESULTS: Weekly paclitaxel/carboplatin with or without trastuzumab was well tolerated. Fifty-two patients were assessable for response and all 61 patients were assessable for survival. Seventeen (33%) of 52 patients experienced a minor/partial response to single-agent trastuzumab and received 8 additional weeks of single-agent trastuzumab. Fifteen (29%) of 52 patients had stable disease and proceeded to receive paclitaxel/carboplatin/trastuzumab. Thirty-one patients with measurable disease were assessable for response after initial single-agent trastuzumab followed by paclitaxel/carboplatin/trastuzumab. An overall response rate of 84% (eight complete responses/18 partial responses), median time to progression of 14.2 months, and median overall survival of 32.2 months was reported with the triplet combination. In the patients treated with paclitaxel/carboplatin alone after disease progression on initial single-agent trastuzumab, an overall response rate of 69% (one complete response/10 partial responses), median time to progression of 8.3 months, and median overall survival of 22.2 months was reported. Median time to progression for all 61 patients is 10 months and the median overall survival is 26.7 months. CONCLUSION: This trial confirms the activity and tolerability of weekly paclitaxel/carboplatin alone or in combination with trastuzumab in women with HER-2 overexpressing metastatic breast cancer.

Adult↗
PubMed2007

Ratio of trastuzumab levels in serum and cerebrospinal fluid is altered in HER2-positive breast cancer patients with brain metastases and impairment of blood-brain barrier.

Patients receiving trastuzumab for HER2-overexpressing metastatic breast cancer seem to suffer from an increased risk of brain metastases, even in cases with responsive disease. To evaluate whether trastuzumab is able to penetrate the blood-brain barrier, we measured trastuzumab levels in the serum and in cerebrospinal fluid of metastatic breast cancer patients with brain metastases receiving trastuzumab for HER2-overexpressing metastatic breast cancer. In a pilot study, metastatic breast cancer patients with brain metastases and HER2-overexpressing tumors (HercepTest; Dako, Copenhagen, Denmark) were included. At different time points, trastuzumab levels in the serum and cerebrospinal fluid were measured using a newly developed immunoenzymatic test for trastuzumab. Six out of eight patients were evaluable for determination of trastuzumab level in the serum and cerebrospinal fluid. Before radiotherapy, median trastuzumab level in the serum was 52 054 ng/ml compared with 124 ng/ml in cerebrospinal fluid (ratio 420 : 1). After completion of radiotherapy, median trastuzumab level was 20 185 ng/ml in the serum and 226 ng/ml in cerebrospinal fluid, respectively (ratio 76 : 1). With concomitant meningeal carcinomatosis, trastuzumab level in the serum after radiotherapy was 17 431 and 356 ng/ml in cerebrospinal fluid (ratio 49 : 1). For the first time, we present clinical evidence that trastuzumab levels in cerebrospinal fluid are increased under conditions of an impaired blood-brain barrier such as meningeal carcinomatosis or radiotherapy. This evidence supports the concept of continuing trastuzumab therapy in patients with brain metastases treated by radiotherapy. Monitoring of trastuzumab levels in the serum and cerebrospinal fluid may enable individualized therapy strategies in metastatic breast cancer patients with brain metastases, and lead to a better understanding of trastuzumab pharmacokinetics in the cerebrospinal fluid and serum.

Adult↗
PubMed2005

Reversibility of trastuzumab-related cardiotoxicity: new insights based on clinical course and response to medical treatment.

PURPOSE: Trastuzumab is an important biologic agent with significant activity in breast cancers that overexpress the HER2/neu marker. However, trastuzumab is associated with cardiotoxicity that has not yet been fully explored. We present our experience with patients who developed trastuzumab-related cardiotoxicity. PATIENTS AND METHODS: Over a 4-year period, 38 patients with HER2/neu-positive breast cancer were referred for suspected trastuzumab-related cardiotoxicity. All patients had previously received anthracycline-based chemotherapy. Results After doxorubicin but before trastuzumab, the mean (+/- standard deviation) left ventricular ejection fraction (LVEF) was 0.61 +/- 0.13, and the LVEF decreased to 0.43 +/- 0.16 after trastuzumab (P < .0001). After withdrawal of trastuzumab, the LVEF increased to 0.56 +/- 0.11. Mean time to recovery of LVEF was 1.5 months and was temporally associated with medical treatment in 32 (84%) of the 38 patients but occurred without treatment in six patients (16%). Increases in LVEF were noted in 37 of the 38 patients. Twenty-five of these patients were re-treated with trastuzumab; three patients had recurrent left ventricular dysfunction, but 22 patients (88%) did not. All re-treatment patients continued on their therapeutic regimen for heart failure when rechallenged with trastuzumab. Nine patients underwent endomyocardial biopsy. Ultrastructural changes were not seen. CONCLUSION: Patients who develop cardiotoxicity while receiving trastuzumab therapy generally improve on removal of the agent. The mechanism of trastuzumab-related cardiac dysfunction is different from that of anthracycline cardiotoxicity, in part, demonstrated by the absence of anthracycline-like ultrastructural changes. Reintroducing trastuzumab may be appropriate for some individuals who previously have experienced trastuzumab-related cardiac dysfunction.

Adult↗
PubMed2002

Trastuzumab: a review of its use in the treatment of metastatic breast cancer overexpressing HER2.

UNLABELLED: Trastuzumab is a humanised monoclonal antibody developed to target the HER2 receptor which is overexpressed by some cancer cells, including 25 to 30% of breast cancers. Binding with high affinity to the extracellular domain of HER2, trastuzumab inhibits the proliferation of tumour cells that overexpress HER2. A large well designed multicentre study found that the addition of trastuzumab to either an anthracycline plus cyclophosphamide or to paclitaxel, as first-line therapy for metastatic breast cancer overexpressing the HER2 receptor, significantly increased time to disease progression, rate of objective response, duration of response and survival compared with chemotherapy alone. Single-agent trastuzumab was associated with an objective response in 15% of extensively pretreated patients with metastatic breast cancer overexpressing HER2, and 26% of previously untreated patients. Patients with a HER2 overexpression level of 3+ using immunohistochemical (IHC) assay or a positive HER2 result using fluorescence in situ hybridisation (FISH), benefit more from trastuzumab therapy than those with tumours overexpressing at a level of 2+. Trastuzumab has demonstrated synergistic action with several chemotherapy agents preclinically but the optimal combination clinically is yet to be determined. Trastuzumab is generally well tolerated by most patients; the most significant adverse effects being acute fever and/or chills and the potential to cause cardiac dysfunction. Serious adverse events, including anaphylaxis and death, have occurred in 0.25% of patients. Symptomatic or asymptomatic cardiac dysfunction occurred in 27% of patients receiving an anthracycline and cyclophosphamide combined with trastuzumab. Thus, combination therapy with anthracyclines is not recommended. Symptomatic or asymptomatic cardiac dysfunction occurred in 13% of patients receiving trastuzumab plus paclitaxel and in 4.7% of patients receiving trastuzumab alone. CONCLUSION: Intravenous trastuzumab is effective as a single-agent, and in combination with chemotherapy it significantly improves the median time to disease progression and survival time in patients with metastatic breast cancer overexpressing the HER2 receptor compared with chemotherapy alone. Cardiotoxicity is the main concern with therapy; particularly in patients with pre-existing cardiac dysfunction, the elderly and in combination with, or following, anthracyclines. Trastuzumab is indicated for use with paclitaxel as first-line therapy or as a single agent in second- or third-line treatment regimens for patients with metastatic breast cancer overexpressing HER2. Investigation is ongoing to ascertain the optimal combination regimen containing trastuzumab and antineoplastic agents. In addition, current research is focusing on the optimal timing, sequencing and duration of therapy as well as administration in the neoadjuvant and adjuvant setting.

Antibodies, Monoclonal↗
PubMed2001

Insulin-like growth factor-I receptor signaling and resistance to trastuzumab (Herceptin).

BACKGROUND: Trastuzumab (Herceptin), an anti-HER2/neu receptor monoclonal antibody that inhibits growth of ErbB2-overexpressing breast cancer, is used to treat such cancers. Development of resistance to trastuzumab, however, is common. We investigated whether insulin-like growth factor-I (IGF-I), which activates cell survival signals, interferes with the growth-inhibitory action of trastuzumab. METHODS: MCF-7/HER2-18 and SKBR3 human breast cancer models were used to assess cell proliferation, colony formation in soft agar, and cell cycle parameters. Throughout, we used trastuzumab at a dose of 10 microg/mL and IGF-I at a dose of 40 ng/mL. All statistical tests were two-sided. RESULTS: Trastuzumab inhibited the growth of MCF-7/HER2-18 cells, which overexpress HER2/neu receptors and express IGF-I receptors (IGF-IRs), only when IGF-IR signaling was minimized. For example, in 1% fetal bovine serum (FBS), trastuzumab reduced cell proliferation by 42% (P =.002); however, in 10% FBS or IGF-I, trastuzumab had no effect on proliferation. In SKBR3 cells, which overexpress HER2/neu receptor but express few IGF-IRs, trastuzumab reduced proliferation by 42% (P =.008) regardless of IGF-I concentration. When SKBR3 cells were genetically altered to overexpress IGF-IRs and cultured with IGF-I, trastuzumab had no effect on proliferation. However, the addition of IGF-binding protein-3, which decreased IGF-IR signaling, restored trastuzumab-induced growth inhibition. CONCLUSIONS: In breast cancer cell models that overexpress HER2/neu, an increased level of IGF-IR signaling appears to interfere with the action of trastuzumab. Thus, strategies that target IGF-IR signaling may prevent or delay development of resistance to trastuzumab.

Antibodies, Monoclonal↗