Isolated central nervous system metastases in patients with HER2-overexpressing advanced breast cancer treated with first-line trastuzumab-based therapy.

PURPOSE: The aim of this study was to characterize the prevalence and predictors of central nervous system (CNS) metastasis among women with HER2-overexpressing metastatic breast cancer receiving trastuzumab-based therapy. METHODS: The frequency and time course of isolated CNS progression were characterized among women with HER2-positive metastatic breast cancer, receiving chemotherapy with or without trastuzumab as first-line treatment for metastatic disease in two clinical trials. The first trial was a multicenter randomized phase III study of chemotherapy (doxorubicin/cyclophosphamide or paclitaxel) +/- trastuzumab, and the second was a multicenter phase II trial of vinorelbine + trastuzumab. All patients had measurable disease and were free of symptomatic CNS disease at initiation of study treatment. RESULTS: Nearly 10% of patients receiving trastuzumab in combination with chemotherapy developed isolated CNS metastases as first site of tumor progression. Progression in the CNS tended to be a later event than progression at other sites among women receiving trastuzumab-based therapy. Trastuzumab-based treatment did not substantially delay onset of CNS metastases as initial site of progression. Following diagnosis with primary breast cancer, tumors with HER2 gene amplification tend to be associated with greater risk of isolated CNS progression compared with those lacking gene amplification. CONCLUSIONS: Patients with HER2-overexpressing metastatic breast cancer are at risk for isolated CNS progression, reflecting improved peripheral tumor control and patient survival through use of trastuzumab-based therapy, and a relative lack of CNS activity with trastuzumab. Clinicians should be aware of this association. Better treatments for CNS recurrences are needed.     

Cardiotoxicity of concomitant radiotherapy and trastuzumab for early breast cancer

Background

Trastuzumab therapy given in combination with one of several chemotherapy regimens is currently considered the standard of care for the treatment of early-stage, human epidermal growth factor receptor-2 (HER2) -positive breast cancer. The treatment with trastuzumab is due to a significant impact on the survival part of the standard adjuvant treatment of patients with HER2-positive breast cancer. Patients treated with postoperative breast or chest wall irradiation receive trastuzumab concomitant with radiotherapy. In a small proportion of patients trastuzumab causes cardiotoxicity. Preclinical findings indicate a radiosensibilizing effect of trastuzumab in breast cancer cells, but it is not yet clear whether it radiosensibilizes cells of healthy tissues too.

Conclusions

Special attention is required when left breast or left thoracic wall is irradiated in patient receiving trastuzumab, because long-term effects of the concurrent treatment with trastuzumab and radiotherapy are not yet known. In an era where more patients are surviving a diagnosis of breast cancer, better understanding and earlier detection of therapy-induced cardiac toxicity will be of paramount importance.     

Implementation of trastuzumab in conjunction with adjuvant chemotherapy in the treatment of non-metastatic breast cancer in the Netherlands

Trastuzumab in conjunction with adjuvant chemotherapy markedly improves outcome. In the Netherlands, a national guideline was released in September 2005 stating that trastuzumab should be given in conjunction with adjuvant chemotherapy in women with HER2-positive breast cancer. Aim of this study was to identify the number of women with HER2-positive breast cancer and to evaluate the level of implementation of adjuvant trastuzumab in clinical practice nationwide. Women diagnosed with primary breast cancer between September 2005 and January 2007 were selected from the Netherlands Cancer Registry (NCR). HER2 status, adjuvant treatment and reasons to withhold trastuzumab were registered. 14,934 Breast cancer patients were diagnosed in this period of whom 1,928 (13%) had a HER2-positive tumour. Of all HER2-positive women receiving adjuvant chemotherapy, 66 (6%) did not receive trastuzumab. This percentage decreased from 10% at the time of introduction of the guideline to 4% in the study period September 2005–December 2006. Most common reasons to withhold trastuzumab were cardiovascular disease (29%) and patient refusal (21%). Of all HER2-positive patients who received adjuvant chemotherapy, 94% received trastuzumab. The implementation of trastuzumab in clinical practice was realized within 8 months after introduction of the new guideline.     

Central nervous system metastases in women with HER-2 positive metastatic breast cancer after treatment with trastuzumab

Background: Historically, central nervous system (CNS) metastases have been reported to occur in 10–16% of women with metastatic breast cancer (MBC) with a median survival of less than 1 year after diagnosis of CNS disease. A higher rate of CNS metastases has been described in women with metastatic breast cancer (MBC) over‐expressing HER‐2 who receive trastuzumab therapy. Aims: The aim of this study was to examine the frequency of and potential risk factors for CNS metastases in these women. Our a priori hypotheses were that in MBC patients treated with trastuzumab, CNS metastases occurred (i) more frequently than historical controls, and (ii) in women with controlled systemic disease. Methods: A retrospective cohort study of 28 consecutive patients with MBC over‐expressing HER‐2 and treated with trastuzumab and chemotherapy was performed. Results: A total of 22/25 (88%) patients who initially responded to trastuzumab had progressed within a median of 11.2 months after starting trastuzumab therapy. Central nervous system metastases occurred in 11/28 (39%) patients and the remaining 11 patients had progressed elsewhere. At diagnosis of CNS metastases, 9/11 (82%) had controlled systemic disease (CR = 2, PR = 6, SD = 1). There were trends for patients with CNS metastases to have greater than one site of metastatic disease at the commencement of trastuzumab therapy (P = 0.06), and to be hormone receptor negative at initial diagnosis (P = 0.14). The median time to diagnosis of CNS metastases after the commencement of trastuzumab therapy was 12 months (range 6–19 months). The median survival after diagnosis of CNS metastases was 12 months (range 2–22 months). Conclusions: This study demonstrates a high rate of CNS metastases (39%) in HER‐2 positive MBC patients treated with trastuzumab. At CNS metastases most patients had controlled systemic disease and the median survival after CNS relapse was 1 year. We suggest aggressive management of CNS disease in this population. Additional strategies to decrease the incidence of CNS metastases in these patients may include prophylactic whole brain irradiation and the development of novel pharmacological agents with successful CNS penetration.     

Dose-Reduced Trastuzumab Emtansine: Active and Safe in Acute Hepatic Dysfunction

Breast cancer is the most common cancer in women worldwide. The majority of deaths attributed to breast cancer are a result of metastatic disease, and 30% of early breast cancers (EBC) will develop distant disease. The 5-year survival of patients with metastatic disease is estimated at 23%. Breast cancer subtypes continue to be stratified histologically on oestrogen, progesterone and human epidermal growth factor-2 (HER2) receptor expression. HER2-positive breast cancers represent 25% of all breast cancer diagnoses. The therapies available for metastatic breast cancer (MBC) are expanding, in particular within the field of HER2-positive disease, with the approval of trastuzumab, pertuzumab, lapatinib and trastuzumab emtansine (TDM-1). Recently, TDM-1 has been shown to improve progression-free survival in HER2 MBC when compared to capecitabine and lapatinib in clinical studies. Its main toxicities are deranged liver function tests and thrombocytopenia. There have also been cases of acute liver failure. Therefore, its use in acute hepatic dysfunction, to our knowledge, has been neither studied nor reported. We report a patient with progressive HER2-positive MBC who had previously responded to multiple HER2-targeted therapies that presented with acute hepatic dysfunction. She was treated with dose-reduced TDM-1 safely, with clear evidence of rapid biochemical, clinical and radiological response. This allowed dose escalation of TDM-1, and the patient maintains an ongoing response.Key Words: Human epidermal growth factor-2, Metastatic breast cancer, Hepatic dysfunction, Trastuzumab emtansine     

Therapeutic approaches for HER2-positive brain metastases: Circumventing the blood–brain barrier

We aim to summarize data from studies of trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)–positive metastatic breast cancer (MBC) and brain metastasis and to describe novel methods being developed to circumvent the blood–brain barrier (BBB). A literature search was conducted to obtain data on the clinical efficacy of trastuzumab and lapatinib in patients with HER2-positive MBC and brain metastasis, as well as the transport of therapeutic molecules across the BBB. Trastuzumab-based therapy is the standard of care for patients with HER2-positive MBC. Post hoc and retrospective analyses show that trastuzumab significantly prolongs overall survival when given after the diagnosis of central nervous system (CNS) metastasis; this is probably attributable to its control of extracranial disease, although trastuzumab may have a direct effect on CNS disease in patients with local or general perturbation of the BBB. In patients without a compromised BBB, trastuzumab is thought to have limited access to the brain, because of its relatively large molecular size. Several approaches are being developed to enhance the delivery of therapeutic agents to the brain. These include physical or pharmacologic disruption of the BBB, direct intracerebral drug delivery, drug manipulation, and coupling drugs to transport vectors. Available data suggest that trastuzumab extends survival in patients with HER2-positive MBC and brain metastasis. Novel methods for delivery of therapeutic agents into the brain could be used in the future to enhance access to the CNS by trastuzumab, thereby improving its efficacy in this setting.     

Trastuzumab Retreatment after Relapse on Adjuvant Trastuzumab Therapy for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: Final Results of the Retreatment after Herceptin Adjuvant Trial

AimsTrastuzumab, in combination with chemotherapy, is the standard of care for patients with early and metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The Retreatment after HErceptin Adjuvant trial assessed the efficacy and safety of trastuzumab plus a taxane as first-line treatment for patients with metastatic breast cancer (MBC) who had relapsed after adjuvant trastuzumab for HER2-positive early breast cancer.Materials and methodsIn total, 43 patients with HER2-positive MBC who had received previous adjuvant trastuzumab for ≥10 months, with a relapse-free interval of ≥6 months after the last adjuvant trastuzumab dose, were recruited. Eligible patients (n = 41) were assigned to receive trastuzumab, either weekly or every 3 weeks, in combination with docetaxel or paclitaxel until disease progression.ResultsAt the final analysis, with a median follow-up time of 40 months, a positive response was observed in 25/41 patients (61%; 95% confidence interval: 48.7–80.4%), stable disease in 7/41 (17.1%) and progressive disease in 6/41 (14.6%). Three patients had missing response assessments (one had no measurable lesions at baseline and two had no post-baseline tumour assessments). The median progression-free survival (PFS) was 8.0 months (95% confidence interval: 6–11 months) and the median overall survival was 25.0 months (16–33 months). No correlation was found between response rate, PFS or overall survival and the duration of adjuvant trastuzumab treatment, trastuzumab-free interval, relapse-free interval, hormone receptor status or type of pre-metastatic treatment. The most common adverse events (all grades) were alopecia (32%) and diarrhoea (32%). Six patients (14.6%) developed at least one serious adverse event. No congestive heart failure or any unexpected adverse events were reported.ConclusionTrastuzumab, in combination with a taxane, is an effective and well-tolerated first-line treatment for MBC in patients who relapse after trastuzumab-based adjuvant therapy.     

Lipid-conjugated telomerase template antagonists sensitize resistant HER2-positive breast cancer cells to trastuzumab

HER2 amplification in breast cancer is associated with a more aggressive disease, greater likelihood of recurrence, and decreased survival compared to women with HER2-negative breast cancer. Trastuzumab is a monoclonal antibody that inhibits HER2 activity, making this compound an important therapeutic option for patients with HER2-positive breast cancer. However, resistance to trastuzumab develops rapidly in a large number of breast cancer patients. The objective of this study was to determine whether GRN163L, a telomerase template antagonist currently in clinical trials for cancer treatment, can augment the effects of trastuzumab in breast cancer cells with HER2 amplification. GRN163L was effective in inhibiting telomerase activity and shortening telomeres in HER2-positive breast cancer cells. We show that GRN163L acts synergistically with trastuzumab in inhibiting HER2-positive breast cancer cell growth. More importantly, we show that GRN163L can restore the sensitivity of therapeutic-resistant breast cancer cells to trastuzumab. These findings implicate that telomerase template antagonists have potential use in the treatment of cancers that have developed resistance to traditional cancer therapy.     

Possible available treatment option for early stage,small, node-negative,and HER2-overexpressing breast cancer

Trastuzumab is known for its clinical activity in women with HER2-overexpressing breast cancer. Randomized clinical trials have shown significant improvement in disease-free and overall survival with trastuzumab administered in conjunction with adjuvant chemotherapy for early-stage HER2-positive breast cancer. However, there is no direct evidence of clinical benefit from adjuvant trastuzumab in patients with node-negative, HER2-overexpressing, small (T1a-b) breast cancers. Previous literature shows that most breast cancers with node-negative small tumors have a good prognosis, but HER2-overexpressing disease might still be worse in this population. Some recent retrospective studies showed that an adjuvant trastuzumab-based regimen has a better prognostic effect, even in patients with node-negative, HER2-overexpressing, small breast cancers, although absolute survival differences were small. On the basis of the available literature, we believe that trastuzumab should be considered for patients with minimal HER2-overexpressing disease, although tools for accurate selection of patients at risk of relapse still need to be developed.     

Use of trastuzumab beyond disease progression: observations from a retrospective review of case histories

HER2 overexpression is associated with poor breast cancer prognosis and is the target for the humanized monoclonal antibody trastuzumab. This novel agent, when administered until disease progression in combination with chemotherapy, extends the survival of women with HER2-positive metastatic breast cancer (MBC). However, the optimal duration of trastuzumab therapy remains to be confirmed. We conducted a retrospective case review study of women with HER2-positive MBC who continued to receive trastuzumab beyond disease progression. Objectives were to assess whether treatment beyond disease progression shows any evidence of efficacy and to evaluate the feasibility of this approach. One hundred five patients (median age, 47 years; range, 24-77 years) were identified in 13 centers. Women had received /=1 more trastuzumab regimen. Trastuzumab treatment beyond progression appears to be of value, producing responses and clinical benefit, and is well tolerated without significant cardiac toxicity. The feasibility of this approach warrants examination in prospective trials.     

Defining prognosis for women with breast cancer and CNS metastases by HER2 status

BackgroundThe purpose of this retrospective study was to determine, in a cohort of patients with breast cancer and central nervous system (CNS) metastases, the effect of trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-positive disease and to compare this with that of patients with HER2-negative disease.MethodsFive hundred and ninety-eight patients with invasive breast cancer, CNS metastases and known HER2 status were identified. Time to CNS metastases and survival after CNS metastases were estimated by the Kaplan–Meier method, and Cox models were fitted to determine the association between HER2 status, trastuzumab treatment and outcomes after adjustment for other patient characteristics.ResultsIn the multivariable model, patients with HER2-negative disease [Hazard ratio (HR) 1.50, 95% confidence interval (CI) 1.15–1.95, P = 0.003] and patients with HER2-positive disease who did not receive trastuzumab (HR 2.13, 95% CI 1.51–3.00, P < 0.0001) had shorter times to CNS metastases compared with patients with HER2-positive disease who had received trastuzumab as first-line therapy for metastases. Furthermore, patients with HER2-negative disease (HR 1.66, 95% CI 1.31–2.12, P < 0.0001) and patients with HER2-positive disease who had never received trastuzumab (HR 1.34, 95% CI 0.78–2.30, P = 0.28) had an increased hazard of death compared with patients with HER2-positive disease who had received trastuzumab before or at the time of CNS metastases diagnosis.ConclusionIn our cohort of patients with breast cancer and CNS metastases, patients with HER2-positive disease treated with trastuzumab had longer times to development of and better survival from CNS metastases compared with patients with HER2-positive disease who had never received trastuzumab and patients with HER2-negative breast cancer.     

Incidence and risk of central nervous system metastases as site of first recurrence in patients with HER2-positive breast cancer treated with adjuvant trastuzumab

BackgroundCentral nervous system (CNS) disease as the site of first relapse after exposure to adjuvant trastuzumab has been reported. We carried out comprehensive meta-analysis to determine the risk of CNS metastases as the first site of recurrence in patients with HER2-positive breast cancer who received adjuvant trastuzumab.MethodsEligible studies include randomized trials of adjuvant trastuzumab administered for 1 year to patients with HER2-positive breast cancer who reported CNS metastases as first site of disease recurrence. Statistical analyses were conducted to calculate the incidence, relative risk (RR), and 95% confidence intervals (CIs) using fixed-effects inverse variance and random-effects models.ResultsA total of 9020 patients were included. The incidence of CNS metastases as first site of disease recurrence in HER2-positive patients receiving adjuvant trastuzumab was 2.56% (95% CI 2.07% to 3.01%) compared with 1.94% (95% CI 1.54% to 2.38%) in HER2-positive patients who did not receive adjuvant trastuzumab. The RR of the CNS as first site of relapse in trastuzumab-treated patients was 1.35 (95% CI 1.02–1.78, P = 0.038) compared with control arms without trastuzumab therapy. The ratio of CNS metastases to total number of recurrence events was 16.94% (95% CI 10.85% to 24.07%) and 8.33% (95% CI 6.49% to 10.86%) for the trastuzumab-treated and control groups, respectively. No statistically significant differences were found based on trastuzumab schedule or median follow-up time. No evidence of publication bias was observed.ConclusionsAdjuvant trastuzumab is associated with a significant increased risk of CNS metastases as the site of first recurrence in HER2-positive breast cancer patients.     

Trastuzumab as first-line therapy in HER2-positive metastatic breast cancer patients

Trastuzumab is a humanized monoclonal antibody against the extracellular domain of hEGF receptor-2 (HER2). Trastuzumab in combination with chemotherapy has proven efficacy in treating both early and metastatic HER2-positive breast cancer. In the metastatic setting, the addition of trastuzumab to chemotherapy is associated with a statistically significant longer time to disease progression, higher rate of objective response and improvement in overall survival. Trastuzumab efficacy is not influenced by hormone receptor status, but differences in median overall survival exist between HER2-positive and HER2-negative states. Reassessment of the benefit of re-exposing patients with metastatic breast cancer to trastuzumab following relapse in the adjuvant setting is necessary. Ongoing research into new HER2-targeted therapies and trials involving combination anti-HER2 drug therapy without chemotherapy show promise. This review is focused on the available results obtained with the use of trastuzumab in the subset of HER2-positive breast cancer patients with metastatic disease.     

Central nervous system metastases in breast cancer patients administered trastuzumab

Amplification or over-expression of the HER2/neu receptor is present in 20-30% of invasive breast cancers and in 60% of intraductal breast carcinomas. Patients with HER2/neu gene aberrations have more aggressive disease, frequent disease recurrence and a shorter survival. Trastuzumab (herceptin) is a monoclonal antibody selectively directed against the HER2/neu receptor. The addition of trastuzumab to chemotherapy in HER2/neu-positive advanced breast cancer patients has increased complete and partial response rates, and prolonged time to progression and overall survival. However, a relatively common failure site in patients administered trastuzumab is the central nervous system (CNS). CNS metastases in these patients seem to develop despite responses achieved in extracerebral sites. This pattern of failure has mainly been attributed to the lack of trastuzumab penetration to the CNS owing to the high molecular weight (145 kDa) of this molecule. Additionally, increased risk of CNS relapse may be associated with improved systemic control of extracerebral metastases and prolonged survival without brain protection (a sanctuary site). Finally, it was postulated that HER2/neu over-expression and/or amplification might predispose to brain metastases. The aim of this article is to discuss the pathophysiology of this phenomenon and its clinical implications.     

The Global Need for a Trastuzumab Biosimilar for Patients With HER2-Positive Breast Cancer

Trastuzumab improves survival outcomes for patients with HER2-positive (HER2⁺) breast cancer, yet not all such women receive this important therapy. Trastuzumab was approved by the US Food and Drug Administration in 1998 and the European Medicines Agency in 2000 as treatment for HER2⁺ metastatic breast cancer (MBC). Observational studies between 2000 and 2015 in patients with HER2⁺ MBC suggest that nearly 12% in the United States, 27% to 54% in Europe, and 27.1% to 49.2% in China did not receive trastuzumab or any other HER2-targeted agent as first- and/or later-line for treatment of metastatic disease. In 2006, both agencies approved trastuzumab as adjuvant therapy for patients with HER2⁺ early breast cancer (EBC). Observational studies on real-world treatment patterns for HER2⁺ EBC between 2005 and 2015 suggest that 19.1% to 59.5% of patients across regions of North America, Europe, Australia, New Zealand, and China did not receive (neo)adjuvant trastuzumab. Data suggest that some patient subgroups, including older patients, those with HER2⁺/hormone receptor-positive disease, and women with small and/or node-negative HER2⁺ tumors, were less likely to receive anti-HER2 therapy. Barriers to accessing trastuzumab are multifactorial and include issues related to drug funding and high treatment costs for patients that have been reported worldwide. Herein, we review available literature on the use of, and barriers to, treatment with trastuzumab in patients with HER2⁺ breast cancer. We also discuss how the availability of safe and effective biosimilars might increase access to trastuzumab and allow greater use of anti-HER2 therapy, potentially improving patient outcomes.     

Multifactorial central nervous system recurrence susceptibility in patients with HER2-positive breast cancer: epidemiological and clinical data from a population-based cancer registry study

BACKGROUND:

A series of retrospective studies have reported that patients with human epidermal growth factor receptor 2(HER2)‐positive breast cancer are at a greater risk of central nervous system (CNS) metastases. Trastuzumab, which does not cross the blood‐brain barrier, has been associated with this increased risk.

METHODS:

The authors evaluated incidence, survival, and risk factors for CNS metastases in the incident breast cancer population systematically collected by the Parma Province Cancer Registry over the 4‐year period between 2004 and 2007.

RESULTS:

A total of 1458 patients with a diagnosis of stage I to III invasive breast cancer were analyzed for study purposes. At a median follow‐up of 4.1 years, CNS events were observed in 1.3% and 5% of HER2‐negative patients and HER2‐positive patients, respectively (P < .0001). The administration of trastuzumab either as adjuvant therapy or for metastatic disease was associated with a significantly increased risk of CNS involvement at first disease recurrence and after first extracranial recurrence, respectively. According to multivariate analysis, HER2‐positive status and trastuzumab treatment, high Ki‐67 index, and hormone receptor negativity remained independent risk factors for the development of CNS metastasis.

CONCLUSIONS:

To the authors' knowledge, this is the first population‐based cancer registry study analyzing factors associated with CNS recurrence in a general population of newly diagnosed breast cancer patients with known HER2 status. The data from the current study provide evidence that patients with HER2‐positive breast cancer have a significantly higher incidence of CNS metastasis after treatment with trastuzumab. Improvements in systemic control and overall survival associated with trastuzumab‐based therapy may lead to an “unmasking” of CNS disease recurrence that would otherwise remain clinically silent before a patient's death. Cancer 2011. © 2010 American Cancer Society.     

Paget’s disease of the nipple

The widespread use of trastuzumab in the past decade has led to a significant and measureable improvement in the survival of patients with human epidermal growth factor receptor-2 (HER2) overexpressing breast cancer, and in many ways has redefined the natural history of this aggressive breast cancer subtype. Historically, survival in patients with HER2-positive disease was dictated by the systemic disease course, and what appears to be the central nervous system (CNS) tropism associated with HER2-amplified tumors was not clinically evident. With improved systemic control and prolonged survival, the incidence of brain metastases has increased, and CNS disease, often in the setting of well-controlled extracranial disease, is proving to be an increasingly important and clinically challenging cause of morbidity and mortality in patients with HER2-positive advanced breast cancer. This review summarizes the known clinical data for the systemic treatment of HER2-positive CNS metastases and includes information about ongoing clinical trials of novel therapies as well as emerging strategies for early detection and prevention.     

Dose-dense adjuvant chemotherapy in HER2-positive early breast cancer patients before and after the introduction of trastuzumab: Exploratory analysis of the GIM2 trial

Dose-dense adjuvant chemotherapy is standard of care in high-risk early breast cancer patients. However, its role in HER2-positive patients is still uncertain. In this exploratory analysis of the GIM2 trial, we investigated the efficacy of dose-dense chemotherapy in HER2-positive breast cancer patients with or without exposure to trastuzumab. In the GIM2 trial, node-positive early breast cancer patients were randomized to receive four cycles of (fluorouracil)epirubicin/cyclophosphamide followed by four cycles of paclitaxel administered every 2 (dose-dense) or 3 (standard-interval) weeks. After approval of adjuvant trastuzumab, protocol was amended in April 2006 to allow use of trastuzumab for 1 year after chemotherapy completion in HER2-positive patients. The efficacy of dose-dense chemotherapy in terms of disease-free survival (DFS) and overall survival (OS) was assessed according to HER2 status and trastuzumab use. Out of 2,003 breast cancer patients, HER2 status was negative/unknown in 1,551 patients; among the 452 patients with HER2-positive breast cancer, chemotherapy alone or followed by trastuzumab was given to 320 and 132 patients, respectively. Median follow-up was 8.1 years. No significant interaction between HER2 status, trastuzumab use and chemotherapy treatment was observed for both DFS (p = 0.698) and OS (p = 0.708). Nevertheless, there was no apparent benefit in the HER2-positive group treated with trastuzumab (DFS: HR, 0.99; 95% CI 0.52–1.89; OS: HR, 0.95; 95% CI 0.37–2.41). Although dose-dense chemotherapy was associated with a significant survival improvement in high-risk breast cancer patients, its benefit appeared to be smaller (if any) in patients with HER2-positive disease who received adjuvant trastuzumab.     

EGFR,pMAPK, pAkt and PTEN status by immunohistochemistry: correlation with clinical outcome in HER2-positive metastatic breast cancer patients treated with trastuzumab

BackgroundIn an attempt to identify markers of resistance to trastuzumab, we evaluated both the profiling of human epidermal growth factor receptor 2 (HER2)-positive tumor cells measuring the relative levels of EGFR, pMAPK, pAkt and PTEN and their correlations with clinical outcome in HER2-positive metastatic breast cancer patients treated with trastuzumab.Patients and methodsTumor tissues for this retrospective analysis were available from 45 out of 76 patients with metastatic breast cancer treated from April 1999 to March 2006 with trastuzumab-based therapy at our Institution. Evaluations of EGFR, pMAPK, pAkt and PTEN status by immunohistochemistry (IHC) were carried out on all 45 tissue samples and their correlations with response to trastuzumab, incidence of central nervous system (CNS) metastases, time to progression (TTP), overall survival from diagnosis of breast cancer (OS1), from diagnosis of metastatic disease (OS2) and from the start of trastuzumab (OS3) were analyzed.ResultsWe observed that TTP (P = 0.001) and median OS2 and OS3 were significantly longer in patients responsive to trastuzumab-based regimen compared with nonresponsive patients. EGFR, pMAPK, pAkt and PTEN status by IHC were not significantly associated with response to trastuzumab, TTP, overall survival (OS1, OS2, OS3) and CNS metastases incidence. A trend for shorter OS3 was observed for pMAPK-positive patients compared with pMAPK-negative patients (22.8 versus 31.2 months; P = 0.076). Median OS1 resulted shorter in 22 pAkt-positive patients (69.8 months) compared with 23 pAkt-negative patients (108.2 months); P = 0.091. It is likely that high expression of pMAPK (pMAPK-positive status) or pAkt (pAkt-positive status) could identify a subgroup of HER2-positive tumors with high activity of proliferation and survival pathways and with resistance to trastuzumab.ConclusionsIn HER2-positive metastatic breast cancers, EGFR, pMAPK, pAkt and PTEN status evaluated by IHC was not significantly associated with response to trastuzumab, TTP, OS and CNS metastases incidence. However, HER2 status determined by IHC and/or FISH assays may not be sufficient to predict response to trastuzumab-based therapy.