In the current genomic era, increasing evidence demonstrates that approximately 2% of HER2-negative breast cancers, by current standard testings, harbor activating mutations of ERBB2. However, whether patients with HER2-negative breast cancer with activating mutations of ERBB2 also experience response to anti-HER2 therapies remains unclear. This case report describes a patient with HER2-nonamplified heavily pretreated breast cancer who experienced prolonged response to trastuzumab in combination with pertuzumab and fulvestrant. Further molecular analysis demonstrated that her tumors had an elevated HER2 dimerization that corresponded to ERBB2 S310F mutation. Located in the extracellular domain of the HER2 protein, this mutation was reported to promote noncovalent dimerization that results in the activation of the downstream signaling pathways. This case highlights the fact that HER2-targeted therapy may be valuable in patients harboring an ERBB2 S310F mutation.
Saranya Chumsri, Jodi Weidler, Siraj Ali, Sohail Balasubramanian, Gerald Wallweber, Lisa DeFazio-Eli, Ahmed Chenna, Weidong Huang, Angela DeRidder, Lindsay Goicocheal and Edith A. Perez
Robert W. Carlson, Susan J. Moench, M. Elizabeth H. Hammond, Edith A. Perez, Harold J. Burstein, D. Craig Allred, Charles L. Vogel, Lori J. Goldstein, George Somlo, William J. Gradishar, Clifford A. Hudis, Mohammad Jahanzeb, Azadeh Stark, Antonio C. Wolff, Michael F. Press, Eric P. Winer, Soonmyung Paik, Britt-Marie Ljung and for the NCCN HER2 Testing in Breast Cancer Task Force
The NCCN HER2 Testing in Breast Cancer Task Force was convened to critically evaluate the ability of the level of HER2 expression or gene amplification in breast cancer tumors to serve as a prognostic and a predictive factor in the metastatic and adjuvant settings, to assess the reliability of the methods of measuring HER2 expression or gene amplification in the laboratory, and to make recommendations regarding the interpretation of test results. The Task Force is a multidisciplinary panel of 24 experts in breast cancer representing the disciplines of medical oncology, pathology, radiation oncology, surgical oncology, epidemiology, and patient advocacy. Invited members included members of the NCCN Breast Cancer Panel and other needed experts selected solely by the NCCN. During a 2-day meeting, individual task force members provided didactic presentations critically evaluating important aspects of HER2 biology and epidemiology: HER2 as a prognostic and predictive factor; results from clinical trials in which trastuzumab was used as a targeted therapy against HER2 in the adjuvant and metastatic settings; the available testing methodologies for HER2, including sensitivity, specificity, and ability to provide prognostic and predictive information; and the principles on which HER2 testing should be based. Each task force member was charged with identifying evidence relevant to their specific expertise and presentation. Following the presentations, an evidence-based consensus approach was used to formulate recommendations relating to the pathologic and clinical application of the evidence to breast cancer patient evaluation and care. In areas of controversy, this process extended beyond the meeting to achieve consensus. The Task Force concluded that accurate assignment of the HER2 status of invasive breast cancer is essential to clinical decision making in the treatment of breast cancer in both adjuvant and metastatic settings. Formal validation and concordance testing should be performed and reported by laboratories performing HER2 testing for clinical purposes. If appropriate quality control/ assurance procedures are in place, either immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) methods may be used. A tumor with an IHC score of 0 or1+, an average HER2 gene/chromosome 17 ratio of less than 1.8, or an average number of HER2 gene copies/cell of 4 or less as determined by FISH is considered to be HER2 negative. A tumor with an IHC score of 3+, an average HER2 gene/chromosome 17 ratio of greater than 2.2 by FISH, or an average number of HER2 gene copies/cell of 6 or greater is considered HER2 positive. A tumor with an IHC score of 2+ should be further tested using FISH, with HER2 status determined by the FISH result. Tumor samples with an average HER2 gene/chromosome ratio of 1.8 to 2.2 or average number of HER2 gene copies/cell in the range of greater than 4 to less than 6 are considered to be borderline, and strategies to assign the HER2 status of such samples are proposed. (JNCCN 2006;4(Suppl 3):S1–S22)
Robert W. Carlson, Elizabeth Brown, Harold J. Burstein, William J. Gradishar, Clifford A. Hudis, Charles Loprinzi, Eleftherios Paul Mamounas, Edith A. Perez, Kathleen Pritchard, Peter Ravdin, Abram Recht, George Somlo, Richard L. Theriault, Eric P. Winer, Antonio C. Wolff and for the NCCN Adjuvant Therapy for Breast Cancer Task Force
The National Comprehensive Cancer Network (NCCN) first published the NCCN Breast Cancer Treatment Guidelines in 1996. The Guidelines address the treatment of all stages of breast cancer across the spectrum of patient care and have been updated yearly. Adjuvant therapy for breast cancer has undergone an especially rapid evolution over the past few years. Therefore, the NCCN Breast Cancer Guidelines Panel was supplemented by additional experts to form the Adjuvant Therapy Task Force to provide a forum for an extended discussion and expanded input to the adjuvant therapy recommendations for the Breast Cancer Treatment Guidelines. Issues discussed included methods of risk-stratification for recurrence; how biologic markers such as HER2 status, quantitative estrogen receptor, or genetic markers can be incorporated as prognostic or predictive factors; and how age, menopausal status, and estrogen receptor levels impact benefits from chemotherapy and endocrine therapy. Additionally, the task force discussed the strategies for use of aromatase inhibitors in postmenopausal women and the potential incorporation of trastuzumab into adjuvant therapy of women with HER2/neu positive breast cancer. This supplement summarizes the background data and ensuing discussion from the Adjvuant Task Force meeting. (JNCCN 2006;4[suppl 1]:S-1–S-26)