A phase II trial of pemetrexed and gemcitabine in patients with metastatic breast cancer who have received prior taxane therapy.

Purpose: This phase II trial assessed efficacy and safety of pemetrexed plus gemcitabine to treat metastatic or locally advanced breast cancer in patients previously treated with taxanes.

Patients And Methods: Eligible women with advanced breast cancer treated with taxanes in the adjuvant or metastatic setting received pemetrexed 500 mg/m2 on day 1 followed by gemcitabine 1000 mg/m2 on days 1 and 8 of a 21-day cycle. Hematologic toxicities limiting day 8 gemcitabine dosing were observed in the first 20 patients, prompting a protocol amendment to evaluate pemetrexed 500 mg/m2 followed by gemcitabine 1500 mg/m2 on day 1 of a 14-day cycle. Patients received folic acid, vitamin B12, and dexamethasone. The primary endpoint was objective response rate (ORR).

Results: Between July 2003 and September 2006, 73 evaluable women (median age, 52.1 years; range, 28-73 years) were enrolled (21-day schedule: 21 patients, 52% estrogen receptor-positive, 24% HER2-positive; 14-day schedule: 52 patients, 58% ER-positive, 15% HER2-positive). For patients on the 21-day and 14-day schedules, median number of cycles was 4 (range, 1-8 cycles) and 5 (range, 1-38 cycles), respectively. The ORRs were 23.8% and 19.2%, respectively; median survival times were 16.2 months and 13.4 months. The most common grade 3/4 hematologic toxicities were neutropenia (71% vs. 33%) and leukopenia (24% vs. 14%); febrile neutropenia occurred in 10% and 6%. The most common grade 3/4 nonhematologic toxicity was fatigue (29% vs. 10%).

Conclusion: Pemetrexed/gemcitabine given on a 21-day or 14-day schedule is active in patients with advanced breast cancer previously treated with taxanes. A 14-day schedule appears to result in fewer serious toxicities.