Efficacy of trastuzumab re-therapy in routine treatment of HER2-positive breast cancer patients who relapsed after completed (neo-)adjuvant anti-HER2 therapy.

Abstract

602 Background: Addition of trastuzumab (Roche; T) to chemotherapy (CT) has improved outcomes in patients (pts) with HER2+ breast cancer at all stages, including locally advanced and metastatic disease. Anti-HER2 re-treatment with T is an increasingly used therapy option for the treatment of recurrent/metastatic breast cancer (MBC). However, limited data on T re-treatment is currently available. Methods: Patients with locally recurrent and/or MBC who received T re-therapy were included in this non-interventional study. Among 232 pts enrolled at 121 sites in Germany, 174 pts (33 locally recurrent disease, 141 MBC) were already sufficiently documented to be analyzed for efficacy of T re-therapy in this ongoing study. Progression-free survival (PFS) was assessed by the investigator. Results: The median disease-free interval (calculated from the time of resection of the primary tumor to diagnosis of local recurrence/MBC) was 3.1 years. Median duration of re-therapy with T was 9.3 months. The median PFS of all patients was 10.1 months (95% confidence interval (CI), 8.5 to 13.1). PFS for pts with only locally recurrent disease (n= 33) was 23.6 months. PFS for MBC pts (n=141) was 8.9 months (95% CI, 7.4 to 10.6). For pts with visceral metastases (n=96) a PFS of 8.0 months compared to 10.1 months in patients with only non-visceral (n=45) was recorded. 104 pts were re-treated with T + CT (>70% paclitaxel, vinorelbine, capecitabine or docetaxel alone; PFS= 9.3 months), 26 pts with T + hormonal therapy (HT) (mostly anastrozole, fulvestrant, exemestane, letrozole or tamoxifen; PFS=10.1 months), 24 pts with T+CT+HT (PFS= 19.9 months) and 20 pts with T monotherapy (PFS= 9.4 months). Conclusions: This study provides clinical evidence that re-application of T in combination with either CT, HT or alone is effective in the routine treatment of patients with MBC and/or locally recurrent disease. The benefit observed for pts receiving first-line treatment with T in combination with taxane in pivotal trials as well as recently published data seems comparable to the presented results of pts receiving T re-therapy.