Safety and activity of trastuzumab-containing therapies for the treatment of metastatic breast cancer: our long-term clinical experience (GOIM study).

Background: Trastuzumab is widely used as the treatment of choice for HER2-positive metastatic breast cancer (MBC). Patients and methods: Seventy patients, median age 57 years and range 31–81 years, were included in our retrospective analysis with the aim to evaluate safety and activity of trastuzumab-containing therapies. Results: We observed for first-line treatment response rate (RR) 41%, stable disease (SD) 47% and time to progression (TTP) 8 months (range 1–44). Corresponding numbers for second line were RR 23%, SD 62% and (TTP) 9 months (range 3–23) and beyond second line RR 22%, SD 78% and (TTP) 9 months (range 4–19). Overall survival was 19.2 months (3–62 months). The median cumulative dose of trastuzumab administrated was 5286 mg (464–17 940 mg). Trastuzumab was well tolerated. Median left ventricular ejection function (LVEF) at baseline was 62% and at the end of treatment was 59%. The more relevant adverse events consisted of an asymptomatic decrease in LVEF to 40% (baseline 60%) and a grade 3 symptomatic increase in bilirubin. Conclusion: Trastuzumab-containing therapies in MBC show a good safety and toxicity profile and a remarkable activity even in heavily pretreated women. Patients should benefit from continued trastuzumab therapy, as shown by the maintenance of (TTP) even beyond second-line treatment.