The Emerging Role of Monitoring Serum HER-2/neuOncoprotein Levels in Women with Metastatic Breast Cancer

Serum HER-2 Extracellular Domain: Relationship with Clinicobiological Presentation and Prognostic Value before and after Primary Treatment in 701 Breast Cancer Patients

Purpose

To determine the clinical correlations and prognostic value of serum HER-2 (sHER-2) before and after primary breast cancer treatment.

Methods

sHER-2 from 701 consecutive patients with stage I-III tumors (median follow-up 7.7 years) was assayed by an enzyme-linked immunosorbent assay (Immuno 1, Bayer Diagnostics).

Results

The median pretreatment sHER-2 concentration was 8.30 ng/mL (range 3.15–82.00 ng/mL). Forty-seven patients (6.7%) had sHER-2 concentrations >12 ng/mL (cutoff level). Pretreatment sHER-2 correlated positively with CA 15.3 (p=0.0169), pathological tumor size (p=0.0082), number of invaded lymph nodes (pN, p=0.0160) and histological grading (p=0.0086). Kaplan-Meier analyses indicated that pretreatment sHER-2 was of prognostic value for contralateral breast cancer (p=0.0018), metastasis-free survival (MFS) (p=0.0008) – particularly lung (p=0.0082) and liver metastases (p=0.0035) – and overall disease-specific survival (DSS) (p=0.0020). According to pN status, pretreatment sHER-2 was of prognostic value only for pN-positive patients (p=0.0017). When combined with estradiol or progesterone receptor status, patients with elevated sHER-2 and receptor-negative tumors had a significantly shorter DSS (p<0.0001 for both receptors). Post-treatment sHER-2 also had individual prognostic value for MFS (p=0.0144) and DSS (p=0.0212). In multivariate analysis, only sHER-2 after primary treatment was an independent prognostic variable for MFS and DSS (p=0.0078 and p=0.0058, respectively).

Conclusion

sHER-2 elevation in early breast cancer correlates with the principal criteria of tumor aggressiveness, thus permitting selection of patients with a high risk of visceral metastases and contralateral breast tumors. Post-treatment sHER-2 is an independent prognostic factor enabling to identify patients likely to benefit from aggressive adjuvant treatments.

ERBB3: A potential serum biomarker for early detection and therapeutic target for devil facial tumour 1 (DFT1)

Devil Facial Tumour 1 (DFT1) is one of two transmissible neoplasms of Tasmanian devils (Sarcophilus harrisii) predominantly affecting their facial regions. DFT1's cellular origin is that of Schwann cell lineage where lesions are evident macroscopically late in the disease. Conversely, the pre-clinical timeframe from cellular transmission to appearance of DFT1 remains uncertain demonstrating the importance of an effective pre-clinical biomarker. We show that ERBB3, a marker expressed normally by the developing neural crest and Schwann cells, is immunohistohemically expressed by DFT1, therefore the potential of ERBB3 as a biomarker was explored. Under the hypothesis that serum ERBB3 levels may increase as DFT1 invades local and distant tissues our pilot study determined serum ERBB3 levels in normal Tasmanian devils and Tasmanian devils with DFT1. Compared to the baseline serum ERBB3 levels in unaffected Tasmanian devils, Tasmanian devils with DFT1 showed significant elevation of serum ERBB3 levels. Interestingly Tasmanian devils with cutaneous lymphoma (CL) also showed elevation of serum ERBB3 levels when compared to the baseline serum levels of Tasmanian devils without DFT1. Thus, elevated serum ERBB3 levels in otherwise healthy looking devils could predict possible DFT1 or CL in captive or wild devil populations and would have implications on the management, welfare and survival of Tasmanian devils. ERBB3 is also a therapeutic target and therefore the potential exists to consider modes of administration that may eradicate DFT1 from the wild.

Circulating HER2 Extracellular Domain: A Specific and Quantitative Biomarker of Prognostic Value in all Breast Cancer Patients?

The HER2 oncoprotein has emerged as an essential biomarker in the treatment of breast cancer patients. Once the primary breast cancer is removed, there is an increasing need to detect breast cancer recurrence as early as possible with the hope that earlier intervention with new anti-HER2 therapies will improve quality of life and increase overall survival. Numerous publications have shown that increasing blood levels of circulating HER2 is an early indicator of progression, particularly in HER2-positive patients and that the rise and fall parallels the clinical course of disease and independent of therapy. Many studies show that the HER2 status of the primary tumor may not fully and accurately reflect the HER2 status of recurrent cancer. Thus, elevated serum HER2 levels may be an early signal of the emergence of a HER2-positive metastatic tumor and therefore alert the physician to re-assess HER2 status using a tissue test.

Clinical usefulness of human epidermal growth factor receptor-2 extracellular domain as a biomarker for monitoring cancer status and predicting the therapeutic efficacy in breast cancer

We assessed the clinical usefulness of human epidermal growth factor receptor-2 extracellular domain (HER2ECD) as a biomarker for detecting cancer and monitoring disease status and for predicting the efficacy of anticancer treatment in breast cancer. Five-hundred and eighty serum samples from 252 patients with breast cancer were examined for the concentration of HER2ECD to compare with conventional tumor markers (CEA, CA15-3, NCC-ST439 and BCA225). Also, in 19 patients with HER2-overexpressed advanced or recurrent breast cancer who were treated with trastuzumab, clinical outcomes were evaluated retrospectively to determine whether their serum HER2ECD levels predict clinical responses. The proportion of patients with elevated HER2ECD levels was 15.1%, which was compatible with those with elevated conventional marker levels. In patients with HER2-overexpressed breast cancer, the positive rate of HER2ECD was significantly higher (24.1%) than those of conventional markers (7.4-12.9%), suggesting the usefulness of HER2ECD for detecting cancer in this population. HER2-overexpressed patients responding to trastuzumab (12 of 19 patients) showed significantly higher serum HER2ECD level (p = 0.033) and longer time to progression (TTP) (p = 0.039) and overall survival (OS) (p = 0.031) than did patients not responding (seven patients). Furthermore, higher response rates were observed in patients with elevated HER2ECD levels than in patients without elevated HER2ECD levels (91.3% vs. 14.3%, p = 0.032), whereas there was no difference in survival between the two groups. The results suggest that HER2ECD is a useful biomarker not only for detecting breast cancer recurrence but also for predicting tumor responses to trastuzumab.

Human epidermal growth factor receptor 2 (HER2) extracellular domain levels are associated with progression-free survival in patients with HER2-positive metastatic breast cancer receiving lapatinib monotherapy

BACKGROUND

Changes in serum human epidermal growth factor receptor 2 (HER2) levels associated with clinical outcomes, including objective response rate, progression-free survival (PFS), and overall survival have been reported in patients with metastatic breast cancer (MBC) receiving trastuzumab and chemotherapy. This study investigated whether baseline or changes in serum HER2 correlated with overall response rate (ORR) and/or PFS in patients with MBC receiving first-line lapatinib monotherapy.

METHODS

The EGF20009 study investigated lapatinib monotherapy in 138 HER2-positive patients with MBC previously untreated for their metastatic disease. Serum was collected and assessed at baseline and every 4 weeks for 16 weeks after treatment initiation. Disease assessment was performed at weeks 8 and 12 and every 12 weeks thereafter. A ≥ 20% decrease or increase in serum HER2 was defined as a significant change.

RESULTS

Seventy-nine percent of patients had elevated baseline serum HER2. Baseline serum HER2 was associated with ORR (P = .043) but not PFS. Patients with a ≥ 20% decrease from baseline of serum HER2 at weeks 4, 8, 12, and 16 had a significantly increased ORR and prolonged PFS. Conversely, those with a ≥ 20% increase from baseline had a significantly lower ORR and shorter PFS.

CONCLUSION

Significant decreases in serum HER2 levels during the first 16 weeks of lapatinib monotherapy were associated with better clinical outcome (longer PFS and increased ORR) in HER2-positive MBC patients.

Evaluation of tumor markers (HER-2/neu oncoprotein, CEA, and CA 15.3) in patients with locoregional breast cancer: prognostic value

Tumor markers were studied in the sera of 883 untreated patients with primary breast cancer diagnosed between 1989 and 2007. Abnormal human epidermal growth factor receptor 2 (HER-2)/neu levels (>15 ng/mL) were found in 9.5%, carcinoembryonic antigen (CEA) in 15.9%, and cancer antigen (CA) 15.3 in 19.7% of the patients. One or more tumor markers were abnormal in 305 (34.5%) of the 883 studied patients. Significantly higher serum HER-2/neu levels were found in patients with tissue overexpression of this oncoprotein (p < 0.0001). CEA, CA 15.3, and HER-2/neu (only in those patients with tissue overexpression) serum levels were related with tumor stage (tumor size and nodal involvement) and steroid receptors (higher values in estrogen receptor-negative (ER-) tumors). Univariate analysis showed that HER-2/neu serum levels were prognostic factors in disease-free survival (DFS) and overall survival (OS) only in patients with tissue overexpression. Multivariate analysis in 834 patients show that nodal involvement, tumor size, ER, CEA, and adjuvant treatment were independent prognostic factors in DFS and OS. When only patients with HER-2/neu overexpression in tissue were studied, tumor size, nodal involvement, and tumor markers (one or another positive) were independent prognostic factors for both DFS and OS. HER-2/neu serum levels were also an independent prognostic factor, with CEA, ER, and nodes in 106 patients treated with neoadjuvant treatment. In summary, serum HER-2/neu, CEA, and CA 15.3 are useful tools in the prognostic evaluation of patients with primary breast cancer.

Serum HER-2/neu conversion to positive at the time of disease progression in patients with breast carcinoma on hormone therapy

BACKGROUND

Prolonged exposure of breast carcinoma cells in vitro to tamoxifen results in tamoxifen resistance. Tamoxifen-resistant cells express increased HER-2/neu mRNA and protein. The objective of this study was to determine whether patients with metastatic or locally advanced breast carcinoma who have negative serum HER-2/neu status at the initiation of first-line hormone therapy with letrozole or tamoxifen convert to positive serum HER-2/neu status at the time of disease progression and to determine whether serum HER-2/neu conversion to positive status is associated with response to therapy and overall survival.

METHODS

Serum samples were obtained at baseline and at the time of disease progression from 240 patients who initially had negative serum HER-2/neu status (< 15 ng/mL). A manual microtiter, enzyme-linked immunosorbent assay that was specific for the extracellular domain of the HER-2/neu (c-erbB-2) oncoprotein product was used to quantitate serum levels.

RESULTS

Among 240 patients, 61 patients (26%) converted from serum HER-2/neu negative to positive (> 15 ng/mL) at the time of disease progression. Thirty-two of 129 patients (25%) who were treated with tamoxifen and 29 of 111 patients (26%) who were treated with letrozole became converted to positive serum HER-2/neu status at the time of disease progression. The response rate and the time to disease progression on first-line hormone therapy were not affected by serum HER-2/neu conversion. The survival of patients who converted to positive serum HER-2/neu status was significantly shorter compared with the survival of patients who remained negative for serum HER-2/neu. A multivariate analysis revealed that conversion to positive serum HER-2/neu status was an independent prognostic variable for survival.

CONCLUSIONS

Conversion to positive serum HER-2/neu status occurred in approximately 25% of patients who received first-line hormone therapy. Conversion to serum HER-2/neu-positive status occurred with equal frequency in antiestrogen and aromatase-inhibitor therapy. The current results showed that serum conversion to HER-2/neu-positive status was an independent risk factor for decreased survival in patients with breast carcinoma.

Monitoring the Circulating Levels of the HER2/neu Oncoprotein in Breast Cancer

The HER2/neu oncoprotein is a major target for the development of new cancer therapies and is similar to the estrogen receptor, which guides hormone therapy. The HER2/neu status is used to guide therapy decisions in patients with HER2/neu-overexpressing breast cancer tumors. The HER2/neu oncogene, or c-erbB-2, encodes a transmembrane receptor protein that is expressed on normal epithelial cells and can be overexpressed in breast cancer cells. Studies have shown that the extracellular domain (ECD) of the HER2/neu oncoprotein is released from the cell and can be measured in the circulation of women with breast cancer. Enzyme-linked immunosorbent assay methods used to measure the circulating HER2/neu ECD have shown that the prevalence of elevated ECD levels is approximately 18.1% in women with primary breast cancer and approximately 45.6% in women with metastatic breast cancer (MBC). Many studies have monitored the circulating ECD levels after surgery and indicate that increasing ECD levels can indicate recurrence of breast cancer earlier than clinical diagnosis. Studies in women with MBC showed that serial changes in circulating HER2/neu ECD levels paralleled the clinical course of disease, regardless of the treatment regimen. Several studies identified a subgroup of patients with MBC who had HER2/neu-negative disease by tissue testing but developed elevated ECD levels with MBC. In contrast to tissue testing, which is a one-time event, monitoring the circulating levels of the HER2/neu ECD in patients with breast cancer provides a real-time assessment of the HER2/neu status and provides important information for managing the therapy of patients with MBC.

Potential clinical utility of serum HER-2/neu oncoprotein concentrations in patients with breast cancer

BACKGROUND

The HER-2/neu oncogene and its p185 receptor protein are indicators of a more aggressive form of breast cancer. HER-2/neu status guides Herceptin therapy, specifically directed to the extracellular domain (ECD) of the HER-2/neu oncoprotein. The HER-2/neu ECD is shed from cancer cells into the circulation and is measurable by immunoassay.

METHODS

We performed a systematic review of the peer-reviewed literature on circulating ECD with respect to prevalence, prognosis, prediction of response to therapy, and monitoring of breast cancer.

RESULTS

The prevalence of increased ECD in patients with primary breast cancer varied between 0% and 38% (mean, 18.5%), whereas in metastatic disease the range was from 23% to 80% (mean, 43%). Some women with HER-2/neu-negative tumors by tissue testing develop increased ECD concentrations in metastatic disease. Increased ECD has been correlated with indicators of poor prognosis, e.g., overall survival and disease-free survival. Increased ECD predicts a poor response to hormone therapy and some chemotherapy regimens but can predict improved response to combinations of Herceptin and chemotherapy. Many studies support the value of monitoring ECD during breast cancer progression because serial increases precede the appearance of metastases and longitudinal ECD changes parallel the clinical course of disease.

CONCLUSIONS

The monitoring of circulating HER-2/neu ECD provides a tool for assessing prognosis, for predicting response to therapy, and for earlier detection of disease progression and timely intervention with appropriate therapy.