Abstract P1-12-03: Low-dose capecitabine monotherapy in HER-2 negative metastatic breast cancer: a retrospective study.

Abstract

Background: Capecitabine (CAPE) has clinical activity in metastatic breast cancer (MBC) at an FDA approved dose of 1,250mg/m2 twice daily for 14 days every 21 days (BID Q14). This schedule has been adopted by many United States oncologists, although the starting dose is often reduced. To determine if lower doses of CAPE have comparable clinical activity as the FDA approved dose, we performed a retrospective analysis. Methods: A retrospective review of records from a large breast cancer oncology practice and from Sylvester Cancer Center Deerfield Beach from 2000–2008 was performed after approval of the University of Miami IRB. Standard practice was CAPE low dose (CAPE-L) 1,000mg BID Q14. Primary outcome was clinical benefit rate (CBR) defined as complete response (CR), partial response (PR) or stable disease (SD) lasting for ≥ 6 months. Response rates (RR) in patients with measurable disease, progression free survival (PFS), overall survival (OS) defined as time period between beginning of CAPE and death, and adverse events (AE) defined according to the NCI CTCAE version 3.0 were secondary endpoints. A literature review was performed for comparison. Results: Data from 296 patients (pts) with HER-2 negative MBC were reviewed. Of those, 73 received CAPE-L at a starting dose between 303 mg/m2 and 965 mg/m2 (median 614 mg/m2) BID Q14. Median number of prior lines of therapy was 1 (range 0–10); 34/73 (46.6%) of pts received CAPE-L as first line therapy. 23.3% of pts required dose reductions because of palmar-plantar erythrodysesthesia (PPE) (44%), diarrhea (17%), mucositis (11%) or other (28%). RR in 61 patients with measurable disease was 25%. PR occurred in 16/73 (22%), CR (0%), SD ≥ 6 months 21/73 (29%), and PD 31/73 (43%), with a CBR of 37/73 (51%). Median PFS and OS were 6.2 months (95% CI, 4.4 to 8) and 21.4 months (95% CI, 14.4 to 28.6), respectively. AEs are reported in table 2. We recognized 12 trials that used the FDA approved dose in 1,949 patients. Bidimensionally measurable disease was present in 1,630 patients. CBR was reported as 62% in 1,006 patients and RR as 24% in 398. Weighted averages of median PFS and OS were 5.1 months (95% CI, 4.5 to 5.7) and 12 months (95% CI, 9.6 to 14.4), respectively. Detailed toxicity data were available in 11 trials with 1,883 patients. A comparison of current series with literature review at standard dose follows (table 1). Conclusion: Compared with previously published data, CAPE-L appeared more tolerable with comparable clinical efficacy as package insert doses. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-12-03.