The mTOR Inhibitor Everolimus in Combination with Carboplatin in Metastatic Breast Cancer – a Phase I Trial

Aim: Despite advances in the the first- and second- line treatment of metastatic breast cancer, there remains a large unmet need for additional treatment options. As preclinical studies have suggested that combining everolimus with carboplatin may produce higher activity than each drug by itself, we initiated a phase I study of this combination. Patients and Methods: Patients with pre-treated metastatic breast cancer received weekly carboplatin at AUC2 and daily oral everolimus at different dose-levels (level I: 2.5 mg; II: 5 mg; III: 7.5 mg; IV: 10 mg). Three patients were assigned to dose- levels I to III, and six to dose-level IV. The primary end-point was to determine the maximum tolerated dose (MTD). Results: Fifteen patients were recruited to the study. The median number of previous chemotherapies was four (range: 1-11). No dose-limiting toxicity occurred at levels I-III during the first cycle. Based on the pre-determined definition, the maximum planned dose-level IV was selected as the MTD. Patients received a median of four cycles of treatment (range 1-13). Most frequent grade 3 and 4 toxicities included leukopenia, thrombocytopenia and infection. Response rates were as follows: 21% partial response, 43% stable disease, and 36% progressive disease. Conclusion: Carboplatin and everolimus is a well-tolerated combination for heavily pre-treated metastatic breast cancer. Everolimus (10 mg/d) and carboplatin (AUC2 weekly) were defined as the MTD. This dose is