Characteristics of Patients With HER2-Positive Metastatic (MBC) or Locally Advanced Breast Cancer (ABC), Treated With Trastuzumab (T) as 1st Line-Therapy and Progression-Free for at Least 3 Years: Interim Analysis of the Lorha Study

ABSTRACT Background For more than ten years, treatment of HER2-positive mBC patients (Pts) is based on T plus taxane in 1st line therapy. So far, in numerous studies, we have observed few subsets of Pts (long-term responders) who have not experienced disease progression for several years after T-based regimen in 1st line treatment. This study aims to characterise these Pts in the daily practice from a clinical and biological perspective. Material and methods This is an ambispective French multicentre non-interventional study. Eligible Pts were women aged ≥18 years with HER2-positive mBC or aBC treated with T as 1st line and who were progression-free for at least 3 years after starting T. The primary objective was to describe the clinical and tumor characteristics of these Pts. Progression Free Survival (PFS), Overall Survival (OS), data on treatment administration and safety were also collected. An exploratory biomarkers analysis is planned on tumor tissue samples. Here we present some preliminary results based on the interim analysis performed at the end of inclusions. Results 159 Pts were enrolled in 2011 and 110 Pts were eligible for data analysis. Median age was 59 years [34-95]. Tumor characteristics were: invasive ductal carcinoma for 96 Pts (88%), positive hormonal receptors in 63 Pts (58%). At initial diagnosis, presenting stages were I-II for 52 Pts (50%). 36 Pts (33%) had a mBC de novo or an aBC. The main metastatic localisations were bone, liver and lung in 51 (47%), 35 (32%) and 22 (20%) Pts respectively. Median T treatment duration was 4.1 years [0.8 - 11.0] in 1st line. T was associated with a taxane-based chemotherapy in 86 Pts (78%). Median PFS was 6.4 years [4.9; - ]. Median OS was not reached. 13 retrospective adverse events related to T (cardiac or leading to discontinuation) were reported. None of these was serious. Conclusions In this long PFS population treated with a T-based treatment in first line for aBC or mBC Pts, no specific profile in terms of clinical or histological characteristics have been observed. Thus, the exploratory biomarkers analysis will be useful to identify such a profile. Disclosure O. Tredan: Roche consultant. P. Beuzeboc: Roche consultant. D. Coeffic: Roche consultant. M. Fellous: Roche employee. L. Arnould: Roche Consultant. All other authors have declared no conflicts of interest.