HER-3 status by immunohistochemistry in HER-2-positive metastatic breast cancer patients treated with trastuzumab: correlation with clinical outcome

• Published in: Tumori Vol. 98; no. 1; p. 39
• Main Authors: Gori, Stefania, Foglietta, Jennifer, Mameli, Maria Grazia, Stocchi, Lucia, Fenocchio, Daniela, Anastasi, Paola, Iacono, Daniela, Del Sordo, Rachele, Basurto, Carlo, De Angelis, Verena, Sidoni, Angelo
• Format: Journal Article
• Language: English
• Published: United States 01.01.2012
• Subjects: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal, Humanized - therapeutic use; Antineoplastic Agents - therapeutic use; Biomarkers, Tumor - analysis; Breast Neoplasms - chemistry; Breast Neoplasms - drug therapy; Breast Neoplasms - pathology; Disease Progression; Drug Resistance, Neoplasm; Female; Humans; Immunohistochemistry; Kaplan-Meier Estimate; Middle Aged; Neoplasm Grading; Neoplasm Staging; Receptor, ErbB-2 - analysis; Receptor, ErbB-3 - analysis; Time Factors; Trastuzumab; Treatment Outcome
• ISSN: 2038-2529
• DOI: 10.1177/030089161209800105

HER-3 signaling might contribute to resistance to trastuzumab. To clarify the role of HER-3 in HER-2-positive breast cancer, it is important to evaluate the level of HER-3 and its correlations with clinical outcome in metastatic breast cancer patients treated with trastuzumab. HER-3 status by immunohistochemistry was evaluated in HER-2-positive metastatic breast cancer patients treated with trastuzumab-based therapy at our institution. Two scorings were utilized for interpreting staining for HER-3, and the correlation between HER-3 status and clinical outcome was evaluated. We evaluated HER-3 status in 61 of 76 HER-2-positive metastatic breast cancers treated with trastuzumab-based therapy at our institution from 4/1999 to 3/2006. We observed 55.2% objective responses; median time to progression and overall survival from start of trastuzumab therapy were 9.6 months (0.921-78.87) and 29.1 months (1.4-129.5+), respectively. With a cutoff of 50% staining tumor cells, we found 30 HER-3-negative and 31 HER-3-positive tumors. HER-3 status was not significantly associated with clinical outcome, but a shorter time to progression and overall survival were observed in patients with HER-3-positive tumors. HER-3 status by immunohistochemistry was not significantly associated with clinical outcome in HER-2-positive metastatic breast cancer patients. Further studies are necessary to evaluate the prognostic and predictive role of HER-3.