Capecitabine vs. capecitabine + trastuzumab in patients with HER2-positive metastatic breast cancer progressing during trastuzumab treatment: The TBP phase III study (GBG 26/BIG 3-05)

1025 Background: There is uncertainty, if trastuzumab treatment should be continued beyond progression (TBP). Methods: Patients (pts) with HER-2 positive, locally advanced or metastatic breast cancer that progressed during treatment with trastuzumab with or without adjuvant and/or 1st-line metastatic chemotherapy were prospectively randomized to capecitabine (X; 2,500 mg/m² on days 1–14, q21) or X plus continuation of trastuzumab (XH; 6 mg/kg, q3w). The primary end point was TTP. With registration of lapatinib, the slowly accruing trial was closed prematurely. Results: Between 01/04 and 05/07 156 pts (X=78; XH=78) were randomized and stratified according to pre-treatment: taxane/trastuzumab as 1st-line therapy (111 pts), taxanes/trastuzumab as adjuvant therapy (3 pts), trastuzumab alone or without taxanes as 1st-line treatment (42 pts). 75 (48.1%) pts were pre-treated with anthracyclines. 119 (76.3%) showed visceral metastasis. Current analysis (median follow-up 11.8 months) revealed a progression-free su...