A retrospective study evaluating a fixed low dose capecitabine monotherapy in women with HER-2 negative metastatic breast cancer.

Abstract

To determine if a low fixed dosing strategy of capecitabine would produce comparable clinical activity with less adverse toxicities compared to published data with higher doses in the setting of metastatic breast cancer (mBC). We retrospectively analyzed patients treated with a low fixed dose of capecitabine (CAPE-L) at 1,000mg twice daily for 14days every 21days. Outcomes included clinical benefit rate (CBR), overall response rates (ORR), time to progression (TTP), and overall survival (OS). A historical comparison group of mBC patients treated on 12 prior trials at the package-insert dose of capecitabine (n=1,949) was utilized. Eighty-six patients were analyzed in our cohort. Positive hormone receptor status (79.1 vs. 50.6%), and capecitabine as first-line chemotherapy (44.2 vs. 16.5%) were more frequent in our cohort relative to the historical comparison. The median starting dose in our cohort was 633.5mg/m(2). The CBR was similar between the CAPE-L and the standard dose cohorts (55.8 vs. 49.5%), as was ORR (24.3 vs. 24%), and median TTP (7mo, 95% CI 5.5-8.5 vs. 5.1mo, 95% CI 4.5-5.7). Median OS was longer in our cohort (24mo, 95% CI 16.8-31.2) than the historic standard dose cohort (12.1mo, 95% CI 9.6-14.4), a difference that was likely explained by the higher proportion of patients in the CAPE-L cohort who received capecitabine as first-line chemotherapy and who had hormone receptor positive disease. As expected, adverse events were less frequent with CAPE-L. We found that CAPE-L, which translates into a dose of 600-650mg/m(2), appeared to have good clinical efficacy and acceptable toxicity.