Trastuzumab regimens for HER2-overexpressing metastatic breast cancer

Combination treatment with chemotherapy and trastuzumab is now standard therapy for the first-line treatment of women with HER2-overexpressing metastatic breast cancer. Combination therapy with trastuzumab has been shown to increase response rates, time to progression, quality of life, and overall survival for such patients. Several combination regimens have been developed, and newer combination regimens have recently been reported and are being studied in ongoing clinical trials. Newer trastuzumab-based regimens include triplet combinations with taxanes and platinum salts and regimens combining other innovative therapies. Among the increasing array of available combinations, several have proven appropriate for first-line therapy. To date, the optimal combination region has not been defined. Moreover, several questions remain regarding best scheduling, treatment duration, and use of trastuzumab at disease progression. This review briefly outlines the evolving role of trastuzumab in the treatment of HER2-overexpressing metastatic breast cancer.     

Biweekly docetaxel and weekly trastuzumab treatment in HER 2-overexpressing metastatic breast cancer patients

Docetaxel and trastuzumab can be considered to be active drugs for HER 2-overexpressing metastatic breast cancer (MBC). This study was conducted to determine the activity of combination therapy with docetaxel and trastuzumab in MBC patients by assessing the response rate (RR), time to progression (TTP) and safety. We administered the combination of docetaxel 30-40 mg/m(2) biweekly and trastuzumab using a 4 mg/kg loading dose and thereafter 2 mg/kg weekly. Between October 2001 and December 2004, 14 patients with HER 2 positive (3+ by immunohistochemistry) MBC were enrolled in this study. The overall RR was 50.0% (7/14), with 1 CR, 6 PR, 3 NC and 4 PD. Median follow-up time was 15.0 months, while the median TTP was 10.8 months,and the median OS 21.8 months.     

Risk of second breast cancer according to estrogen receptor status and family history

A recent study reported an increased risk of contralateral estrogen-negative breast cancer after a first primary estrogen-negative breast cancer. Our study aims to confirm this result and to evaluate how the risk of second breast cancer occurrence is affected by family history of breast cancer and anti-estrogen treatment. We included all 4,152 women diagnosed with breast cancer between 1995 and 2007, using data from the population-based Geneva Cancer Registry. We compared the incidence of second breast cancer among patients according to estrogen receptor (ER) status with that expected in the general population by age-period Standardized Incidence Ratios (SIRs). Among the cohort, 63 women developed second breast cancer. Patients with ER-positive first tumors had a decreased risk of second breast cancer occurrence (SIR: 0.67, 95% CI: 0.48–0.90), whereas patients with ER-negative primary tumors had an increased risk (SIR: 1.98, 95% CI: 1.19–3.09) limited to ER-negative second tumors (SIR: 7.94, 95% CI: 3.81–14.60). Patients with positive family history had a tenfold (SIR: 9.74, 95% CI: 3.57–21.12) higher risk of ER-negative second tumor which increased to nearly 50-fold (SIR: 46.18, 95% CI: 12.58–118.22) when the first tumor was ER-negative. Treatment with anti-estrogen decreased the risk of second ER-positive tumors but not ER-negative tumors. The risk of second ER-negative breast cancer is very high after a first ER-negative tumor, in particular among women with strong family history. Surveillance and prevention of second cancer occurrence should consider both ER status of the first tumor and family history.     

Simultaneous targeting of estrogen receptor and HER2 in breast cancer

Approximately 50% of HER2-positive breast cancers express estrogen receptor (ER) and these tumors are characterized by short-lived responses to hormonal agents. Preclinical models have shown that dual targeting of ER and HER2 could reverse and delay the development of drug resistance. Two studies (TAnDEM & EGF3008) have recently been published addressing the combined use of an aromatase inhibitor (AI) and an anti-HER2-targeted agent. Both studies showed that the combined approach is associated with improvement in response rate and progression-free survival compared with an AI alone with an acceptable toxicity profile. These results would indeed extend the treatment options for patients with ER/HER2-positive metastatic breast cancer. In this article, we discuss how the improved understanding of the complex cross-talk between ER and HER2 has resulted in better clinical outcomes. We analyze clinical evidence regarding the combined use of AIs and anti-HER2-targeted agents. We also touch on possible mechanisms of resistance and ways to improve research in this field.     

Trastuzumab,an appropriate first-line single-agent therapy for HER2-overexpressing metastatic breast cancer

Overexpression of the HER2/Neu (ErbB2) proto-oncogene is associated with breast cancer progression and poor patient prognosis. Herceptin (trastuzumab) is a humanized IgG1 against the ectodomain of the HER2 receptor. In combination with chemotherapy, it induces regression of HER2-overexpressing metastatic breast tumors and prolongs patient survival. Single-agent Herceptin in patients with HER2-amplified breast tumors also induces a definite objective response and clinical benefit rates, and is well tolerated. These data suggest that Herceptin is an effective first-line single-agent therapy for a predictable cohort of metastatic breast cancers and can therefore be used as a platform for therapeutic discovery against tumors that overexpress HER2.     

Clinical activity of trastuzumab and vinorelbine in women with HER2-overexpressing metastatic breast cancer.

PURPOSE: To determine the response rate and toxicity profile of trastuzumab administered concurrently with weekly vinorelbine in women with HER2-overexpressing advanced breast cancer. PATIENTS AND METHODS: Forty women with HER2-positive (+3 by immunohistochemistry, n = 30; +2 or positive, n = 10) breast cancer were enrolled onto a study of trastuzumab (4 mg/kg x 1, 2 mg/kg weekly thereafter) and vinorelbine (25 mg/m2 weekly, with dose adjusted each week for neutrophil count). Eighty-two percent of women had received prior chemotherapy as part of adjuvant (30%), metastatic (25%), or both (28%) treatment, including substantial portions of patients who had previously received either anthracyclines (20%), taxanes (15%), or both types (38%) of chemotherapy. RESULTS: Responses were observed in 30 of 40 patients (overall response rate, 75%, conditional corrected 95% confidence interval, 57% to 89%). The response rate was 84% in patients treated with trastuzumab and vinorelbine as first-line therapy for metastatic disease, and 80% among HER2 +3 positive patients. High response rates were also seen in women treated with second- or third-line therapy, and among patients previously treated with anthracyclines and/or taxanes. Combination therapy was feasible; patients received concurrent trastuzumab and vinorelbine in 93% of treatment weeks. Neutropenia was the only grade 4 toxicity. No patients had symptomatic heart failure. Grade 2 cardiac toxicity was observed in three patients. Prior cumulative doxorubicin dose in excess of 240 mg/m2 and borderline pre-existing cardiac function were associated with grade 2 cardiac toxicity. CONCLUSION: Trastuzumab in combination with vinorelbine is highly active in women with HER2-overexpressing advanced breast cancer and is well tolerated.     

Brain metastases in patients who receive trastuzumab-containing chemotherapy for HER2-overexpressing metastatic breast cancer

Background  Recently, a high rate of brain metastases has been reported among patients with human epidermal growth factor receptor (HER2)-overexpressing metastatic breast cancer who were treated with trastuzumab. The present study examined risk factors for the development of brain metastasis in patients with HER2-overexpressing breast cancer who were treated with trastuzumab. Methods  We retrospectively reviewed 204 patients with HER-2-overexpressing breast cancer who were treated with a trastuzumab-containing regimen between 1999 and 2006. Patients with clinical symptoms were diagnosed as having brain metastases when brain magnetic resonance imaging (MRI) or a computed tomography (CT) scan revealed positive findings for brain metastases. The median follow-up time of this cohort was 53.6 months. Results  Among the patients who received a trastuzumabcontaining regimen, 74 patients (36.3%) developed brain metastases. The median survival from the diagnosis of brain metastases was 13.5 months (95% confidence interval [CI], 12.2–14.7 months). The median time interval between the beginning of trastuzumab treatment and the diagnosis of brain metastases was 13.6 months (range, 0.0–45.8 months). Among patients with brain metastases, the median overall survival period was 39 months. A multivariate logistic regression analysis showed that age (≤50 years), recurrent breast cancer, and liver metastases were significant risk factors for the development of brain metastases. Conclusion  Patients with HER2-overexpressing breast cancer treated with trastuzumab had a high incidence of brain metastases (36.3%). Routine screening for brain metastases 1 year after the start of trastuzumab treatment, may be warranted in younger patients (≤50 years) who had recurrent breast cancer with liver metastases.     

Effects of leptin on human breast cancer cell lines in relationship to estrogen receptor and HER2 status

Obesity is a risk factor for postmenopausal breast cancer and is associated with poor prognosis. Leptin, a cytokine synthesized in adipose tissue, has been implicated as a link between obesity and breast cancer. In the present study, the effects of leptin on cell proliferation and proteins associated with leptin signaling and/or breast cell growth were investigated in ER-positive, MCF-7, T47-D and MDA-MB-361, and ER-negative, MDA-MB-231 and SK-BR-3, breast cancer cell lines. MDA-MB-361 and SK-BR-3 also overexpress HER2/neu. For proliferation assays, 96-well plates were used and for protein determinations cells were synchronized in 6-well plates for 18-24 h in serum-free medium. Leptin was added at 0, 5, 10, 25, 50 and 100 ng/ml for 24 and 48 h. For Western blot analyses, protein extracts were probed for Ob-Rb, Ob-R, leptin, Jak2, PI3K, Stat3, p-Stat3, PCNA, cyclin D1, Cox-2, VEGF, Bcl-2, Bcl-xL, Bax, insulin, IGF-I, IGFBP3, IGF-IRalpha, aromatase, CYP1A1 and CYP1B1. Overall, except for MCF-7 cells, leptin stimulated proliferation in all lines. MCF-7 cells expressed higher levels of Ob-Rb, Jak2, PI3K, Stat3 and p-Stat3 in a dose-dependent manner to 50 ng/ml at 24 h; and IGF-IRalpha increased at 24 h. Cyclin D1 and Cox-2 levels increased with leptin treatment. Higher CYP1B1 expression was observed at both 24 and 48 h. In MDA-MB-231 cells, p-Stat3 and Bcl-xL were increased at 48 h; whereas PCNA and cyclin D1 expression increased in leptin-treated cells at 24 and 48 h. In T47-D cells, Jak2 and Stat3 were elevated at higher leptin concentrations at 24 and 48 h. However, p-Stat3 and PCNA demonstrated an increase only in 48-h leptin-treated cells. Furthermore, cyclin D1 exhibited higher expression at both 24 and 48 h, while Bcl-xL expression was lower with increasing concentrations of leptin at 48 h. In MDA-MB-361 cells, Ob-Rb and VEGF increased at 24 and 48 h; whereas PI3K, Stat3, PCNA and insulin levels increased in leptin-treated MDA-MB-361 cells after 48 h. Bcl-2 and IGF-IRalpha were decreased at 24 h and a dose-dependent increase at 48 h was noted. Higher expression of CYP1B1 was observed with leptin for 24 h. In SK-BR-3 cells, Ob-R increased at both 24 and 48 h. A similar trend was found for IGF-I and IGFBP3 expression. Higher levels of Jak2 and PI3K were observed after 24 h. Interestingly, there was a gradual increase of leptin expression at 24 h, but a gradual decrease at 48 h in relation to the dose of leptin. In contrast, PCNA and IGF-IRalpha showed a decline at 24 h and an increase at 48 h. Elevated levels of cyclin D1, VEGF and Bax were detected at 48 h in cells and increased Cox-2 expression was observed at 24 h. These data indicate that leptin may influence breast cancer development in relation to ER status as well as to the presence or absence of HER2. Continued study on leptin may be helpful for a better understanding of breast cancer development in obese women.     

Trastuzumab,an appropriate first-line single-agent therapy for HER2-overexpressing metastatic breast cancer

Overexpression of the HER2/Neu (ErbB2) proto-oncogene is associated with breast cancer progression and poor patient prognosis. Herceptin (trastuzumab) is a humanized IgG1 against the ectodomain of the HER2 receptor. In combination with chemotherapy, it induces regression of HER2-overexpressing metastatic breast tumors and prolongs patient survival. Single-agent Herceptin in patients with HER2-amplified breast tumors also induces a definite objective response and clinical benefit rates, and is well tolerated. These data suggest that Herceptin is an effective first-line single-agent therapy for a predictable cohort of metastatic breast cancers and can therefore be used as a platform for therapeutic discovery against tumors that overexpress HER2.     

Study of three-weekly docetaxel and weekly trastuzumab treatment in HER 2-overexpressing metastatic breast cancer patients

Docetaxel and trastuzumab can be considered to be active drugs for HER 2-overexpressing metastatic breast cancer (MBC). This study was conducted to determine the activity of combination therapy with docetaxel and trastuzumab in MBC patients (pts) by assessing the response rate (RR), time to progression (TTP) and safety. We administered the combination of docetaxel 70 mg/m2 every 3 weeks and trastuzumab using a 4 mg/kg loading dose and thereafter 2 mg/kg weekly. One cycle was three weeks. Between March 2002 and May 2003, 40 pts with HER 2-positive (3+by immunohistochemistry 39, FISH+1) MBC were enrolled in this study, and 39 pts proved eligible. The overall RR was 72% (28/39) [95%CI 55.1%-85.0%], with 6 CR, 22 PR, 7 SD, 1 PD and 3 NE. The median follow-up time was 14.3 months, while the TTP was 6.5 months (range, 0.6-19.8), median OS has not yet been reached. The number of pts assessable for safety was 40. Hematological Grade 3-4 toxicities were leukopenia 87.5% (35/40) and neutropenia 82.5% (33/40). Non-hematological Grade 3 toxicities were weight gain in 2 pts, and anorexia, neuropathy, fever and rash in one pt each. The combination of docetaxel and trastuzumab was a well-tolerated and very active regimen for the treatment of pts with HER 2-overexpressing MBC.     

Risk factors for brain relapse in HER2-positive metastatic breast cancer patients

Brain relapse is a common occurrence in HER2-positive breast cancer patients. However, the factors determining the risk of brain metastasis in these patients remain to be established. The aim of this study was to assess the impact of particular clinical and pathological factors on the risk of brain relapse in HER2-positive advanced breast cancer patients. The study group included 264 consecutive HER-2 positive metastatic breast cancer patients, most of whom (210; 80%) were administered trastuzumab, usually in combination with chemotherapy. Time from the diagnosis to distant relapse ranged from 0 to 142 months (median 16 months). The most common dominant site of metastatic disease was viscera (80%), followed by soft tissue (11%) and bones (10%). After a median follow-up of 3.1 years, the symptomatic brain relapse occurred in 103 patients (39%). Median time from treatment dissemination to brain relapse was 15 months (range, 0–81 months), and the cumulative 1-year, 3-year and 5-year risk of brain relapse was 17, 42 and 55%, respectively. The average annual risk of brain relapse for surviving patients during consecutive 7 years of follow-up was 10.0% (95% CI, 6.6–13.5%). In the univariate analysis the only variable significantly related to the increased risk of brain relapse was time from initial diagnosis to distant relapse shorter than 2 years (HR = 1.55, 95% CI, 1.03–2.33, P = 0.034). Patients with dominant site of disease in soft tissue or bones tended to have lower risk of relapse (HR = 0.54 and 0.62; P = 0.098 and 0.203, respectively) compared to patients with visceral metastases. Treatment with trastuzumab was not associated with reduced risk of brain relapse (HR = 0.91, 95% CI, 0.47–1.77, P = 0.78). In the multivariate analysis, time from initial diagnosis to distant relapse shorter than 2 years remained the only significant variable related to increased risk of brain relapse (adjusted HR = 1.62, 95% CI, 1.07–2.44; P = 0.022). HER2-positive breast cancer patients remain at high and continuous risk of brain relapse for a prolonged period of time after diagnosis of disease dissemination. Short time from initial diagnosis to distant relapse is related to increased risk of brain relapse. Molecular predictors are sorely needed to better characterize patients with high probability of early brain relapse. Presented in part in oral form at the 2007 European Cancer Conference, Barcelona, Spain.     

Activity of fulvestrant in HER2-overexpressing advanced breast cancer

BackgroundHuman epidermal growth factor receptor 2 (HER2) overexpression increases the aggressiveness of breast cancer cells resulting in poorer prognosis. Patients with HER2-positive disease are less responsive to endocrine therapies. Trastuzumab monotherapy results in objective responses in only ∼15% of patients. Fulvestrant retains activity in cells overexpressing HER2 that are resistant to other endocrine treatments. This retrospective study evaluated response to fulvestrant treatment among HER2-positive patients with advanced breast cancer (ABC).Patients and methodsClinical experience data from 10 treatment centres were pooled. Postmenopausal patients with predominantly hormone receptor-positive and HER2-positive disease were included. Clinical benefit (CB) was defined as the proportion of patients achieving a response to treatment (partial or complete) or stable disease lasting ≥6 months.ResultsData for 102 patients were analysed. Fulvestrant resulted in an overall CB rate of 42% (43/101) in HER2-positive patients and 40% (25/63) in patients with visceral disease. Median duration of treatment was 14.5 months (range 6–44 months). Fulvestrant showed activity up to the fourth line of endocrine therapy and up to the seventh line of overall therapy.ConclusionsResults indicate that fulvestrant may be a suitable treatment option in extensively pre-treated patients with HER2-positive, hormone receptor-positive ABC. Further exploration of its use in this patient population is warranted.     

HER2 overexpressing metastatic breast cancer

Opinion statement More than 40,000 women in the United States die each year from metastatic breast cancer. Elucidation of HER2 and its role in malignant transformation has helped define a subset of aggressive breast cancer that may be relatively resistant to non-anthracycline-based therapies and hormonal agents, but responds to targeted molecular therapy. Trastuzumab, an antibody against HER2, has proven effective as single agent therapy in women with HER2 overexpressed metastatic breast cancer. Moreover, in combination with chemotherapy, trastuzumab has been shown to delay disease progression and improve overall survival for women with HER2-positive advanced breast cancer. The combination of chemotherapy and trastuzumab is emerging as a standard of care in women with HER2 overexpressed metastatic breast cancer. Several combination regimens using trastuzumab with taxanes, vinca alkaloids, or platinum compounds have demonstrated efficacy in first- and second-line treatment settings. However, the development of anthracycline-based combinations has been limited by concerns of related cardiotoxicity. Newer multi-agent regimens are in development. The optimal combination, duration, and sequence of trastuzumab therapy remain unknown in patients with HER2-positive metastatic disease. The role of continuing treatment after disease progression is also unclear. Evidence from some retrospective analyses suggest HER2-positive tumors are relatively resistant to tamoxifen and perhaps more responsive to aromatase inhibitors, although such data are inconclusive. HER2 status should not be used routinely for clinical decision making regarding hormonal therapy options. Several ongoing trials are attempting to address these and other issues related to HER2 testing to select the most appropriate candidates for these emerging therapies. While many questions remain, the treatment of HER2 overexpressing metastatic breast cancer is rapidly evolving, and represents a new approach to treatment in oncology.     

Concordant HER2 status between metastatic breast cancer cells in CSF and primary breast cancer tissue

It is not known whether the HER2 status of malignant CSF cells coincides with that of the original breast carcinoma cells. We investigated whether CSF cytology specimens were suitable to evaluate HER2 status by fluorescence in situ hybridization (FISH) in patient with leptomeningeal metastasis (LM). Both formalin-fixed paraffin-embedded (FFPE) breast cancer tissue and liquid based CSF cytology specimens were evaluated for HER2 status in 16 patients with LM. We evaluated HER2 gene amplification using FISH on destained CSF cytology slides containing a minimum of 20 malignant cells per slide, and compared these with the HER2 status by immunohistochemistry (IHC) or FISH in FFPE tissues. HER2 was considered positive when the HER2:CEP17 ratio was ≥2.0 or IHC 3+. Of 16 cases, four were HER2 positive and 12 were HER2 negative by FISH analysis in CSF cytology. All CSF-positive cases were HER2 positive by IHC in FFPE tissue. Of 12 HER2 FISH-negative cases in CSF cytology, 10 were HER2 negative (IHC 0 or 1+) and two were IHC 2+ in FFPE tissue. Two IHC 2+ cases had HER2:CEP17 ratios of 1.27 and 2.1, respectively, by FISH in FFPE tissue. As a result, the HER2 status concordance rate between metastatic breast cancer cells in CSF and FFPE primary tissue by IHC and FISH was very high. When CSF cytology specimens were appropriately prepared and had adequate cellularity without dry artifacts, the CSF cytology was suitable to evaluate HER2 status by FISH analysis in patients with LM.     

Cardiac toxicity of trastuzumab-related regimens in HER2-overexpressing breast cancer

The pivotal trial by Slamon and colleagues of trastuzumab combined with chemotherapy in metastatic breast cancer showed a high incidence of congestive heart failure (CHF) among patients who had received trastuzumab and anthracycline-based therapy simultaneously. As a result, the development of nonanthracycline-based treatment options for patients with HER2-overexpressing breast cancer has garnered significant attention. This review discusses the cardiac toxic effects of trastuzumab and trastuzumab-related regimens and how their mechanisms of action and physiologic effects differ from cardiac toxicity typically associated with anthracycline use. An overview of cardiac safety data from selected trials of trastuzumab in combination with a taxane after anthracyclines for HER2-overexpressing early-stage breast cancer shows rates of symptomatic or severe CHF of < 4% and asymptomatic declines in left ventricular ejection fractions of > 10 points in < or = 30% of patients. For metastatic breast cancer, severe CHF has been reported in 2% of patients and ejection fraction declines in 6%-18% of patients. However, interstudy comparisons of chemotherapy-induced cardiac dysfunction are difficult because of the use of different definitions of cardiac dysfunction and different parameters for assessing cardiac safety. Recent data on cardiac safety of taxane/trastuzumab-based combination regimens demonstrate that the docetaxel/carboplatin/trastuzumab triple combination can offer clinical efficacy with a low risk of cardiac dysfunction in patients with HER2-overexpressing early-stage breast cancer as well as in patients with metastatic breast cancer.     

A phase II study of lapatinib and bevacizumab as treatment for HER2-overexpressing metastatic breast cancer

Preclinical data have demonstrated that the combination of antihuman epidermal growth factor receptor-2 (anti-HER2) and antivascular endothelial growth factor (anti-VEGF)--targeted agents has antitumor activity; these data indicate certain patients with HER2-overexpressing breast cancer may derive clinical benefit from this combination. The purpose of this single-arm phase II study was to determine the efficacy and safety of the dual-targeting combination of lapatinib and bevacizumab. Women with HER2-overexpressing advanced breast cancer received 1,500 mg oral lapatinib daily plus 10 mg/kg IV bevacizumab every 2 weeks. The primary endpoint was progression-free survival (PFS) at week 12; secondary endpoints included overall tumor response rate (ORR), clinical benefit rate (CBR), duration of response, time-to-response, PFS, and safety. Circulating tumor cells (CTC) and circulating endothelial cells (CEC) were measured at baseline and during study treatment as potential response markers. Fifty-two patients with stage IV disease were enrolled. The 12-week investigator-assessed PFS rate was 69.2% (95% confidence interval [CI]: 54.9, 81.3). Median PFS was 24.7 weeks (95% CI: 20.4, 35.1), and the CBR was 30.8% (95% CI: 18.7, 45.1). Of 45 patients with measurable disease, 6 were determined to have a partial response per Response Evaluation Criteria in Solid Tumors (ORR: 13.3%; 95% CI: 5.1, 26.8). The most common adverse events (AEs) included diarrhea, rash, and fatigue; most of these were either grade 1 or 2. Clinical responses were correlated with decreases in CTC and CEC. Lapatinib plus bevacizumab was active in patients with HER2-overexpressing breast cancer. The AE profile of the combination was consistent with the known profiles for these agents.