Trastuzumab beyond progression in HER2-positive advanced breast cancer: The Royal Marsden experience

BACKGROUND: Recent UK clinical guidance advises against continuing trastuzumab (T) beyond disease progression (PD) in the absence of brain metastases in patients with HER-2 positive (+ve) advanced breast cancer .We have retrospectively evaluated the outcome of patients with HER-2+ve locally advanced (LA) or metastatic breast cancer (MBC) who continued T beyond PD, treated in our unit. METHODS: All HER-2+ve patients on our prospectively maintained database with LA or MBC who received T beyond PD after adjuvant or one line of T for advanced disease were assessed for response and outcome. From the timepoint of T continuation beyond PD, we calculated the overall disease control rate, time to progression (TTP), and overall survival (OS). RESULTS: One hundred and fourteen patients with HER-2+ve LA or MBC treated with T beyond PD were identified. The main site of disease was visceral_in 84 (74%) patients. Seventy-six (66%) had one line of chemotherapy before continuation of T beyond PD and 21 (19%) had two or more. Post-progression, 66 (58%) received T combined with chemotherapy. Of the 93 (82%) patients with documented clinical or radiological response evaluation, 67 (59%) were considered as having stable disease or better. The median TTP was 24 weeks (95% CI: 21–28) and the median OS was 19 months (95% CI: 12–24). CONCLUSION: Our results from an unselected group of patients provide additional evidence that continuation of T beyond PD is of clinical benefit.