Metronomic chemotherapy (mCHT) in HER2-ve advanced breast cancer (ABC) patients (pts): What has changed over the time? Preliminary results of the VICTOR-6 study.

Abstract

e12552 Background: mCHT is the minimum biologically effective dose of a chemotherapeutic agent, given at regular dosing regimen with no prolonged drug free interval, that leads to anti-tumor activity. Old regimens included Cyclophosphamide-Methotrexate (CM), whereas in the last years new regimens, such as Vinorelbine (VRL) and Capecitabine (CAPE)-based have been developed. Aim of this observational retrospective ongoing study is to describe the use of mCHT in ABC pts across 5 years and the clinical characteristics of the pts together with efficacy of old (CM-like) vs new (VRL/CAPE-based) metronomic regimens in terms of response and disease control. Methods: We retrospectively identified from clinical records those HER2-ve ABC pts who have received any kind of mCHT in the years 2011-2015, alone, or in combination with a non-metronomic drug. Standard statistical approaches were used for describing the sample characteristics. Logistic and non proportional hazard analysis were used to identify factors associated with response, and time to treatment failure and survival, respectively. This preliminary analysis focuses on Response Rate (RR) and Disease Control Rate (DCR). Results: From June 2011 to December 2015, 267 pts have been identified till now and 233 are fully evaluable. Median age at mCHT start was 67 years. 81% was HR+ and 33% had non-visceral metastatic disease. 22% of the pts received CM, 55% VRL-based and 23% mCAPE-based regimens. mCHT use increased over the time from 15.0% (2011) to 30% (2015). As 1st-line treatment, CM was administered in 27% of compared with more than 48% of patients receiving CAPE/VRL-based regimens. Overall Response Rate (ORR) was 28% and Disease Control Rate (DCR) was 79%. Median duration of mCHT was 6.2 months. New generation metronomic regimens produced higher ORR in comparison to old ones (32% vs 13.5%), with similar duration of treatment (6.4 vs 5.4 months, respectively). Conclusions: The use of mCHT in the treatment of HER2-ve ABC pts has deeply changed across the last 5 years, being new generation regimens used in earlier lines of treatment, producing interesting results in terms of objective response and disease control.