Long-term survival in HER2-positive metastatic breast cancer treated with first-line trastuzumab: results from the french real-life curie database.

BACKGROUND

Outcome of HER2-positive metastatic breast cancer (MBC) patients has improved since the use of trastuzumab. However, most HER2-positive MBC patients will progress within 1 year of trastuzumab-based therapy. Only limited data are available concerning long-term responders.

METHODS

The primary objective of this study was to compare overall survival (OS) of HER2+ MBC patients with long-term response to first-line trastuzumab with overall survival of those with non-long-term response, based on two institutional databases: the French Epidemiological Strategy and Medical Economics program and the Breast Database. Long-term responders (LTR) were defined as patients with non-progressive disease for ≥ 2 years on first-line trastuzumab. Secondary objectives included progression-free survival (PFS), and predictive factors for LTR status.

RESULTS

From 2004 to 2014, 422 HER2-positive MBC patients received first-line trastuzumab. With a median follow-up of 48 months, median OS and PFS were 63 months (CI95%, 50-71), and 18 months (CI95%, 15-21) respectively. In 111 patients (26.3%) classified as LTR, median OS was 110 months (CI95%, 95-not reached) versus 56 months in non-LTR patients (CI95%, 47-68). In multivariate logistic regressions, the following factors were independently associated with LTR status: number of metastatic sites (≤ 2 versus > 2, p = 0.01); endocrine therapy for metastatic disease (p = 0.001) and taxane-based first-line chemotherapy (p = 0.003).

CONCLUSION

Several features are associated with long-term response to trastuzumab: few metastatic sites, taxane-based chemotherapy and maintenance endocrine therapy in HR+ patients. Further studies are needed to identify patients in whom trastuzumab can be stopped after several years of sustained response.