Abstract OT1-1-04: HER2 status of circulating tumor cells in HER2-positive metastatic breast cancer patients: A valuable biomarker in anti-HER2 therapy

Abstract

Abstract Background: In the earlier study which we have conducted, we observed that: among the patients who were histologically positive for HER2 and received anti-HER2 therapy, only those with HER2-positive circulating tumor cells (CTCs) have benefited. We also demonstrated that CTC enumeration with a modified cut-off is a valuable prognostic tool for HER2-positive MBC patients, and formulated the criterion for evaluating CTCs HER2 status. Although the number of cases was not adequate enough so as to make the persuasion of the statistical analysis limited, it was still a valuable innovative study worthy of further exploring. Purpose: we conducted a prospective study in order to find out whether HER2 expression in circulating tumor cells (CTCs) influenced anti-HER2 therapy in those HER2-positive metastatic breast cancer (MBC) patients. Trial design Patients: All the patients randomly enrolled in the trial were diagnosed with metastatic breast cancer, and the metastasis of all eligible subjects can be measured or evaluated, the Eastern Cooperative Oncology Group (ECOG) performance status score is 0 to 3. Each patient had a pathology report confirmed that this was a HER2-positve patient by the means of an immunohistochemistry (IHC) score or a fluorescent in situ hybridization (FISH) ratio, the researcher was also informed of the histological type, nodal status, estrogen receptor (ER), progesterone receptor (PgR) statuses. All of the patients would receive a new line or a new cycle of systematic therapy which must include the anti-HER2 therapy. The blood sample (10 ml) was drawn with an interval of <7days before the initiating of the new treatment. All the therapeutic regimens were made without knowing the CTC results and according to the National Comprehensive Cancer Network (NCCN) clinical practice guidelines (Breast Cancer V.2.2010). Disease status was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST). Detection method: CTC isolation, enumeration and characterization were performed by using the CellSearch technology. HER2 expression intensity in CTC was given a score of 0, 1+, 2+, or 3+, according to the trial we have conducted previously, the CTC HER2 positive criterion was defined as >30% of CTCs over-expressing HER2 (3+). Statistical method: PFS was measured as the time between the baseline CTC assessment and the documentation of disease progression or death. Patients who were alive without progression at the time of analysis, PFS was calculated by the most recent follow-up evaluations. Kaplan-Meier survival curves were generated based on the CTC levels at baseline and the HER2 status of CTC, the curves were compared using the log-rank test. Present accrual and target accrual: 174 eligible patients were enrolled during September 2010 to April 2013, 76 patients were detected with CTC31, 50 patients received a new line or a new cycle of anti-HER2 therapy within 7days. Among the 50 patients, 40 patients received Trastuzumab and others received Lapatinib. With the ongoing of the trial, we’ll continue following up with PFS and other data of the patients. Types of anti-HER2 therapyAnti-HER2 therapyNTrastuzumab40Lapatinib10Total50 Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-1-04.