A phase II study of pemetrexed and carboplatin in patients with locally advanced or metastatic breast cancer

Pemetrexed and carboplatin have demonstrated activity in breast cancer. Their potential synergism in experimental models and the proven efficacy of pemetrexed/platinum in other indications make pemetrexed/carboplatin an attractive combination in breast cancer. Thus, this two-stage, sequential, open-label, multicenter, phase II study assessed the efficacy and safety of pemetrexed plus carboplatin as first-line therapy in patients with locally advanced breast cancer (LABC) or metastatic breast cancer (MBC).

Patients ≥ 18 years with a histologic/cytologic diagnosis and no prior chemotherapy for LABC or MBC received pemetrexed 600 mg/m² and carboplatin AUC 5.0 on day 1 every 21 days with folic acid and vitamin B₁₂ supplementation.

From June 2003 to April 2005, 50 patients with stage IIIB (30.0%) and stage IV (70.0%) disease were enrolled at 3 study centers. Twenty-eight percent of patients previously received adjuvant chemotherapy, 46.0% had visceral metastases, and 36.0% had ≥3 organs involved. Partial responses (RECIST criteria) were achieved in 27 (54.0%) patients (ORR = 54.0%; 95% CI, 39.3–68.2%). The median response duration was 11.1 months (95% CI, 6.5–14.0 months) and the median time to disease progression was 10.3 months (95% CI, 8.3–14.6 months). CTC hematologic toxicities were grade 3/4 neutropenia (58.0%/28.0%) and grade 3 thrombocytopenia (10.0%) and anemia (18.0%). Two (4.0%) patients had febrile neutropenia, 1 of whom died. No grade 4 non-hematologic toxicities occurred. Grade 3 non-hematologic toxicities were ALT (4.0%) and AST elevation, and edema, fatigue, pruritus, rash/desquamation, and renal toxicity (2.0% each).

Results of this study suggest that the combination of pemetrexed and carboplatin has promising efficacy and an acceptable safety profile. Further assessment of this combination in a randomized trial of various breast cancer patient populations is warranted.