MET and ERBB2 are coexpressed in ERBB2+ breast cancer and contribute to innate resistance

Breast cancer displays significant intratumoral heterogeneity, which has been shown to have a substantial impact on both innate and acquired resistance to tyrosine kinase inhibitors. The heterogeneous expression of multiple receptor tyrosine kinases (RTK) in cancers supports tumor signaling robustness and plays a significant role in resistance to targeted inhibition. Recent studies have revealed interactions between the MET receptor and the ERBB receptor family in the therapeutic resistance of several cancers. In this study, the relationship between MET expression/activity and the expression/activity of the ERBB receptor family in human breast cancer was interrogated. Importantly, a significant percentage of ERBB2(+) tumors coexpressing MET and ERBB2 were observed and displayed significant heterogeneity with subpopulations of cells that are MET(-)/ERBB2(+), MET(+)/ERBB2(-), and MET(+)/ERBB2(+). In a MET(+)/ERBB2(+) breast cancer cell line, MET depletion resulted in increased ERBB2 activation, and conversely, ERBB2 depletion resulted in increased MET activation. Neither EGFR nor ERBB3 compensated for MET or ERBB2 knockdown. The loss of either MET or ERBB2 led to a decrease in PI3K/AKT signaling and increased dependency on MAPK. These data show that a subset of ERBB2(+) breast cancers express MET and contain MET(+)/ERBB2(+) subpopulations. Moreover, analysis of RTK activation during ERBB2 knockdown indicated that MET signaling is a compensatory pathway of resistance.

IMPLICATIONS

ERBB2(+) breast cancers with MET(+)/ERBB2(+) subpopulations may have an innate resistance to ERBB2 inhibition and may benefit from combined MET and ERBB2 inhibition.

Adoption of gene expression profile testing and association with use of chemotherapy among women with breast cancer

PURPOSE

Gene expression profile (GEP) testing is a relatively new technology that offers the potential of personalized medicine to patients, yet little is known about its adoption into routine practice. One of the first commercially available GEP tests, a 21-gene profile, was developed to estimate the benefit of adjuvant chemotherapy for hormone receptor-positive breast cancer (HR-positive BC).

PATIENTS AND METHODS

By using a prospective registry data set outlining the routine care provided to women diagnosed from 2006 to 2008 with HR-positive BC at 17 comprehensive and community-based cancer centers, we assessed GEP test adoption and the association between testing and chemotherapy use.

RESULTS

Of 7,375 women, 20.4% had GEP testing and 50.2% received chemotherapy. Over time, testing increased (14.7% in 2006 to 27.5% in 2008; P < .01) and use of chemotherapy decreased (53.9% in 2006 to 47.0% in 2008; P < .01). Characteristics independently associated with lower odds of testing included African American versus white race (odds ratio [OR], 0.70; 95% CI, 0.54 to 0.92) and high school or less versus more than high school education (OR, 0.63; 95% CI, 0.52 to 0.76). Overall, testing was associated with lower odds of chemotherapy use (OR, 0.70; 95% CI, 0.62 to 0.80). Stratified analyses demonstrated that for small, node-negative cancers, testing was associated with higher odds of chemotherapy use (OR, 11.13; 95% CI, 5.39 to 22.99), whereas for node-positive and large node-negative cancers, testing was associated with lower odds of chemotherapy use (OR, 0.11; 95% CI, 0.07 to 0.17).

CONCLUSION

There has been a progressive increase in use of this GEP test and an associated shift in the characteristics of and overall reduction in the proportion of women with HR-positive BC receiving adjuvant chemotherapy.

Estrogen replacement therapy in breast cancer survivors: a matched-controlled series

OBJECTIVE

We prospectively administered estrogen replacement therapy (ERT) to control estrogen deficiency symptoms in breast cancer survivors as part of our clinical practice. We report the consequences of ERT compared with a historical matched-control group.

DESIGN

Two hundred seventy-seven disease-free survivors received ERT. Controls were matched for exact stage, a recurrence-free period similar to the period to ERT initiation in the ERT group, approximate age, and duration of follow-up. The mean time from breast cancer diagnosis to initiation of ERT was 3.61 (+/- 0.25) years, with a median of 1.88 years. The mean duration of ERT was 3.7 (+/- 3.01) years, with a median of 3.05 years.

RESULTS

Hot flashes were relieved in 206 of 223 women (92%), dyspareunia/vaginal dryness in 149 of 167 women (89%), and reactive depression/anxiety/mood change in 111 of 126 women (88%). Univariate analysis demonstrated no statistical differences between the groups for age, stage, pathology at diagnosis, progesterone receptor status, local therapy, breast at risk, prior chemotherapy, and duration of follow-up. The ERT group was more likely to be estrogen receptor negative (P = 0.01), to have received prior ERT (P < 0.001), and to have received no adjuvant tamoxifen (P < 0.001). There was no significant difference between the ERT and control groups in ipsilateral primary/recurrence (5/155 v 5/143; P = 0.85), contralateral breast cancers (10/258 v 9/260; P = 0.99), or systemic metastasis (8/277 v 15/277; P = 0.13). Noncause-specific deaths in the control group numbered 15 (of 277), and in the ERT group, 7 (of 277) (P = 0.03). Overall survival favored the ERT group (P = 0.02).

CONCLUSIONS

In these selected patients, ERT relieved estrogen deficiency symptoms and did not increase the rate or time to an ipsilateral recurrence/new primary, contralateral new primary, local-regional recurrence, or systemic metastases.

Relationship between excision volume, margin status, and tumor size with the development of local recurrence in patients with ductal carcinoma-in-situ treated with breast-conserving therapy

BACKGROUND AND OBJECTIVES

We reviewed our institution's experience treating patients with ductal carcinoma-in-situ (DCIS) with breast-conserving therapy (BCT) to help define the interrelationship between excision volume, margin status, and tumor size with local recurrence.

METHODS

From January 1980 to December 1993, 146 patients received BCT for DCIS. All patients underwent excisional biopsy and 95 cases (64%) underwent re-excision. Each patient received whole breast radiation to a median dose of 45 Gy. An additional 139 cases (94%) received a supplemental boost to the tumor bed (median total dose 60.4 Gy). The median follow-up is 7.2 years.

RESULTS

Seventeen patients developed an ipsilateral breast failure for a 5- and 10-year actuarial rate of 10.2 and 12.4%, respectively. On multivariate analysis, patient age, margin status, the number of slides containing DCIS, the number of DCIS/cancerization of lobules (COL) foci near (< 5 mm) the margin, and a smaller volume of excision (< 60 cm(3)) were all independently associated with outcome. Although the local recurrence rate generally decreased as margin distance increased, these differences did not achieve statistical significance unless the volume of excision was taken into consideration.

CONCLUSIONS

These findings suggest that the success of BCT is directly related to the degree of surgical removal of DCIS and that margin status alone may be suboptimal in defining excision adequacy.

Impact of clinical, pathologic, and treatment-related factors on outcome in patients with locally advanced breast cancer treated with multimodality therapy

The authors reviewed the experience at their institution treating patients with locally advanced breast cancer using multimodality therapy to identify clinical, pathologic, and treatment-related factors affecting outcome. One hundred patients with locally advanced breast cancer were treated with definitive therapy at William Beaumont Hospital. Three patients had stage IIB disease, 45 patients had stage IIIA disease, and 52 patients had IIIB disease. Thirteen patients had inflammatory breast carcinoma. Seventy-four patients (74%) received trimodality therapy consisting of systemic therapy, radiation therapy, and surgery. Systemic therapy was delivered to 90 patients. Eighty-three patients (83%) received adjuvant radiation therapy. Eighty-five patients underwent mastectomy (85%). Multiple clinical, pathologic, and treatment-related factors were analyzed for their impact on outcome. The median follow-up was 47 months. Overall, the 5-year actuarial rates of local control, disease-free survival, overall survival, and cause-specific survival were 81%, 43%, 53%, and 55%, respectively. The 5-year actuarial cause-specific survival rates for patients with inflammatory breast carcinoma, stage IIIA disease, and stage IIIB disease were 25%, 55%, and 53%, respectively. On multivariate analysis, local control was improved with radiation therapy (p = 0.008) and the absence of inflammatory breast carcinoma (p = 0.008). Disease-free survival was improved with the addition of radiation therapy (p = 0.001) and with less than four positive lymph nodes (p = 0.003). Distant metastasis-free survival was improved in patients without inflammatory breast carcinoma (p = 0.0249) and with less than four involved lymph nodes (p = 0.0135). Cause-specific survival and overall survival were adversely affected by the presence of inflammatory breast carcinoma (p = 0.0135 and p = 0.0325, respectively) or four or more involved lymph nodes (p = 0.0082 and p = 0.012, respectively). Radiation therapy appears to be a critical component in the overall treatment of patients with locally advanced breast cancer by improving the rates of local control and disease-free survival. Other adverse factors for survival include four or more positive lymph nodes and inflammatory breast carcinoma.

Treatment outcome with radiation therapy after breast augmentation or reconstruction in patients with primary breast carcinoma

BACKGROUND

Analyses were performed to determine local control and cosmetic outcome of breast carcinoma patients with prosthetically augmented or reconstructed breasts who had received radiation therapy (RT).

METHODS

Twenty-one newly diagnosed breast carcinoma patients with prosthetically augmented or reconstructed breasts were treated with external beam RT. All patients received whole breast RT (median dose, 50.4 gray [Gy]) and 19 were boosted to a median dose of 60.4 Gy. A median dose of 50.4 Gy was delivered to the regional lymph nodes in 12 patients. Tissue equivalent bolus material was used in six patients. Seventeen patients received adjuvant systemic therapy. Cosmetic results were evaluated at 3-6-month intervals.

RESULTS

With a median follow-up of 32 months, good/excellent cosmetic results were observed in 71% of patients (100% in those with augmented breasts and 54% in those with reconstructed breasts). Four patients (19%) with fair/poor cosmetic outcomes required implant removal and/or revision. Multiple clinical and treatment-related factors were analyzed for their impact on cosmetic outcome. A worsened cosmetic result was observed with increasing stage (P = 0.076), breast reconstruction (vs. augmentation) (P = 0.030), and bolus application (P = 0.016). All patients with fair/poor cosmetic outcomes had time intervals from implant insertion to RT ranging from 53-213 days. Two patients developed an isolated local recurrence within the augmented breast.

CONCLUSIONS

Patients with prosthetically augmented breasts can undergo RT and expect good/excellent cosmetic results. Patients with reconstructed breasts are at a significantly greater risk for cosmetic failure. This risk may be related to the higher percentage of patients with advanced disease, those who received bolus application, and those who received earlier delivery of RT (after the cosmetic procedure) in reconstructed breasts.

Immunohistochemical analysis of P-glycoprotein expression in breast cancer: clinical correlations

Paraffin-embedded, formalin-fixed tissue (PEFFT) specimens from a subset of breast cancer patients were analyzed by immunohistochemistry to determine whether or not the presence of P-glycoprotein identified chemotherapy resistance. Two antibodies, C219 (monoclonal) and Ab1 (polyclonal), demonstrated appropriate immunostaining. Retrospectively and prospectively, P-glycoprotein expression was determined from PEFFT of 20 breast cancer biopsies (19 patients with locally advanced or metastatic disease). Immunohistochemical staining was graded for number of positive cells (N0 to N4) and intensity (I0 to I3). The immunostaining N and I of both antibodies were similar. There was no correlation between N, (P = 0.13) or I, (P = 0.67) and chemotherapy response or between N, (P = 0.63) or I, (P = 0.89) and survival. Five patients had residual cancer at repeat biopsy after systemic chemotherapy for locally advanced disease. These specimens had similar N and I as the primary cancer. This assay accurately identifies P-glycoprotein expression in PEFFT and revealed no correlation between expression and chemotherapy response or survival.