Trastuzumab-Based Chemotherapy (CT) for HER2-Positive Metastatic Breast Cancer (MBC): Which Optimal Partner Beyond the First Line? A Single-Centre Retrospective Study

ABSTRACT Background The activity of trastuzumab-based chemotherapy (CT) in HER2+ MBC is well established, but the question of the optimal CT partner remains a relevant issue. We performed a retrospective comparison of the clinical outcomes associated with different trastuzumab-CT regimens. Patients and methods Patients (pts) for this analysis were selected from a monoinstitutional database of HER2+ MBC pts receiving trastuzumab-based CT for the metastatic disease (February 2005-December 2008). Treatment activity and safety were assessed by the WHO criteria, time to progression (TTP) and overall survival (OS) were calculated by the Kaplan Meier method. Results A total of 147 pts with measurable disease were evaluated: 57 received trastuzumab with weekly vinorelbine (T/VNR), 48 weekly or 3–weekly trastuzumab plus docetaxel (T/Doc), 42 a triple combination of 3-weekly trastuzumab plus oral vinorelbine and capecitabine (T/osVNR/Cape) as 1st line therapy. Objective RR was 76% in the T/VNR group, 68% in the T/Doc regimen, and 72% in the T/osVNR/Cape combination. There was no significant difference in median TTP according to treatment type (14, 11 and 12 months, respectively, p = 0.62); median OS was 36 months, 32 and 34 months, respectively (p = 0.48). More treatment-related grade 3-4 toxicities were recorded in the T/Doc population. Following progression, pts received trastuzumab-based subsequent lines of treatment; according to our Institution police, shifting to a different CT partner: all had a 2nd line, 86 a 3rd line, 41 a 4th line, 7 a 5th line. In univariate analysis no visceral involvement, T/Doc 1st line CT, low primary tumor grading were correlated with better PFS and OS; in multivariate analysis the number of trastuzumab-based regimens was the only factor with statistically significant impact on OS (p = 0.02). Conclusions These results confirm the high activity of the tested regimens as 1st line therapy of HER2+ MBC, without significant differences in clinical outcomes, also suggesting the benefit of multiple lines of trastuzumab-based CT in a significant subset of pts, since each subsequent line may contribute to a longer OS. Disclosure All authors have declared no conflicts of interest.