A phase I study of combination therapy with nanoparticle albumin-bound paclitaxel and cyclophosphamide in patients with metastatic or recurrent breast cancer

The objective of the present clinical study is to determine the maximum tolerated dose (MTD)/recommended dose (RD) of combination therapy with nanoparticle albumin-bound paclitaxel (nab-PTX) and cyclophosphamide (CPA) in patients with metastatic or recurrent breast cancer. nab-PTX and CPA were administered on the first day of each 21-day treatment cycle. The dose of CPA was fixed at 600 mg/m(2), while the dose of nab-PTX was increased from 180 mg/m(2) (Level 1) to 220 mg/m(2) (Level 2) and then to 260 mg/m(2) (Level 3). A total of 11 patients from two institutions were enrolled in the present study. At Level 3, a dose-limiting toxicity (DLT) was observed in 1 patient. Considering treatment continuity and the risk of adverse events in Cycle 2 and thereafter at this level, further subject enrollment at Level 3 was discontinued after two patients had been enrolled. Since the doses used at Level 3 were considered the MTD of nab-PTX and CPA and the doses used at Level 2 were considered the RD of nab-PTX and CPA, three additional subjects were enrolled at Level 2. No DLTs were observed at Level 2. The RD of combination therapy with nab-PTX and CPA was 220 mg/m(2) and 600 mg/m(2), respectively, in patients with metastatic or recurrent breast cancer.