Activity of trastuzumab-based therapy beyond disease progression in heavily pretreated metastatic breast cancer patients—Single institution experience
13159 Background: Benefits from continuing trastuzumab-based (TZB) therapy beyond disease progression in HER-2-overexpressing metastatic breast cancer (MBC) patients (pts) remain obscure. Methods: A retrospective analysis was undertaken to assess activity of TZB therapy for MBC pts treated in our institution from 2002 to 2005 outside clinical trials. Results: 27 pts were evaluated. Median age: 52 years (range, 33–62). 9 pts (33.3%) were premenopausal. Hormonal receptors status: 9 pts ER(+), 4 pts PgR (+), 2 unknown. HER-2 overexpression was determined by IHC staining (3+ score) in all pts. Metastases location: 18 pts soft tissues/bone, 18 pts visceral disease. Median number of metastatic sites: 2 (range: 1–4). 9 pts (33.3%) had metastases in < 2 locations. 16 pts (59.2%) received neo/adjuvant chemotherapy: 11 pts doxorubicin, 8 pts CMF, 2 pts docetaxel, 4 pts other. Median previous chemotherapy lines for advanced disease: 2 (range: 0–6). 16 pts received doxorubicin/epirubicin, 14 pts docetaxel, 13 pts vinorelbine as a part of advanced disease chemotherapy regimen. Trastuzumab was administered at standard doses and combined with docetaxel, vinorelbine, cisplatin, capecitabine, etoposide, gemcitabine or administered as monotherapy. Response for the first-line TZB therapy was as follows: CR 5/27 pts (18.5%); PR 10/27 pts (37%). Median TTP was 5.8 months (range: 0–22). 14/27 pts (51.8%) received a second-line TZB therapy beyond disease progression. Response for the second-line therapy: CR 2/14 pts (14.3%); PR 5/14 pts (35.7%). Median TTP was 5.1 months (range: 0–24). 6/14 pts received a third-line and subsequent lines (up to five lines) of TZB therapy. PR for subsequent lines of therapy was observed in 4 pts. Median survival has not been reached. Pts who received ≥2 of TZB regimens survived significantly longer than pts who had received only 1 regimen (P = 0,02 logrank). Pts with metastasis in 1 location survived significantly longer than pts with metastasis in ≥2 sites (P = 0,01 logrank). Conclusions: Trastuzumab-based therapy seems to be active in MBC pts beyond disease progression even in heavily pretreated population. Durable responses were observed in some cases. No significant financial relationships to disclose.