Phase I/II study of ixabepilone plus capecitabine in anthracycline-pretreated/resistant and taxane-resistant metastatic breast cancer.
OBJECTIVE
The aim of this study was to determine the safety, maximum tolerated dose (MTD), recommended phase II dose, and efficacy of the epothilone B analogue ixabepilone plus capecitabine in anthracycline-pretreated/ resistant and taxane-resistant metastatic breast cancer (MBC).


METHODS
A total of 106 patients were enrolled. The study consisted of a dose-escalation phase (phase I) and a tumor response rate evaluation phase (phase II). Seventy-four patients were treated in phase I with schedule A (ixabepilone 40 mg/m2 intravenously on day 1 plus capecitabine 1650-2000 mg/m2 on days 1-14 of a 21-day cycle) or schedule B (ixabepilone 8-10 mg/m2 on days 1-3 plus capecitabine 1650 mg/m2 on days 1-14 of a 21- day cycle).


RESULTS
No dose-limiting toxicities (DLTs) were observed in the 8/1650 mg/m2 and 10/1650 mg/m2 cohorts; 1 of 30 patients in the 40/1650 mg/m2 cohort and 2 of 30 patients in the 40/2000 mg/m2 cohort had a DLT consisting of grade 3 plantar-palmar erythrodysesthesia (PPE). The 40/2000 mg/m2 dose was defined as the MTD for schedule A, and a total of 62 patients were treated for the phase II portion of the trial, which examined tumor response. The objective response rate was 30%, median time-to-response was 6 weeks, median duration of response was 6.9 months, and median progression-free survival was 3.8 months. Grade 3/4 treatment-related events in phase II included fatigue (34%), PPE (34%), myalgia (23%), nausea (16%), peripheral neuropathy (19%), and diarrhea/vomiting (10%). Grades 3/4 neutropenia (69%) and leukopenia (55%) were managed primarily by dose reduction/treatment interruption.


CONCLUSIONS
Ixabepilone plus capecitabine demonstrated clinical activity and an acceptable safety profile in patients with anthracycline-pretreated/resistant and taxane-resistant MBC. Ixabepilone was recently approved in the United States for the treatment of resistant/refractory locally advanced or MBC.
Bunnell
Craig
C
Dana-Farber Cancer Institute, Boston, MA 02115, USA. craig_bunnell@dfci.harvard.edu
Vahdat
Linda
L
Schwartzberg
Lee
L
Gralow
Julie
J
Klimovsky
Judith
J
Poulart
Valerie
V
Peck
Ronald
R
Thomas
Eva
E
D000328:Adult; D000368:Aged; D018943:Anthracyclines / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D001952:Bridged-Ring Compounds / Q000627:therapeutic use; D000069287:Capecitabine; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D019008:Drug Resistance, Neoplasm; D034261:Epothilones / Q000008:administration & dosage; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D043823:Taxoids / Q000627:therapeutic use
D018943:Anthracyclines; D001952:Bridged-Ring Compounds; D034261:Epothilones; D043823:Taxoids; D003841:Deoxycytidine; C080625:taxane; D000069287:Capecitabine; C430592:ixabepilone; D005472:Fluorouracil