A phase I trial of pegylated liposomal anthracycline and lapatinib (L) combination in the treatment of metastatic breast cancer (MBC): First evaluation of an anthracycline and lapatinib combination in the treatment of MBC

Abstract

1079 Background: Liposomal formulations such as pegylated liposomal doxorubicin (PLD) were developed to improve the therapeutic index and overall benefit of the anthracyclines (A). L is a selective and highly competitive inhibitor of ErbB1 and ErbB2 tyrosine kinases. The combination of conventional doxorubicin and an ErbB2 targeting agent (trastuzumab), while effective, led in a randomized phase III trial to an unacceptable risk of cardiac toxicity. The combination of PLD and L however may be effective with less cardiac risk Methods: This is an open-label, phase I, dose-escalation trial of PLD at 20, 30, 45 and 60 mg/m2 IV every 4 weeks (maximum of 8 doses) and L, 1,500 mg po daily until progression in patients (pts) with MBC. EGFR and/or ErbB2 positivity was not required. Prior chemotherapy, endocrine therapy and trastuzumab were allowed however prior A use was limited to 240 mg/m2 of doxorubicin or 600 mg/m2 of epirubicin and prior EGFR targeting therapies were not allowed. Concomitant CYP3A4 inducers/ inhibitors were not allowed. A left ventricular ejection fraction (LVEF) of ≥ 50% was required. The primary objective was to evaluate the safety, tolerability and feasibility of the combination of PLD and L, particularly with respect to cardiac safety. MUGAs were performed at entry and every 8 weeks thereafter. Results: 7 patients (PLD: 20 mg/m2 - 3 pts; 30 mg/m2 - 3 pts; and 45 mg/m2 - 1 pt) with a mean age of 43 yrs (range, 33–68) have been treated for a total of 14 treatment cycles. Dose-limiting toxicity (DLT) has not been reached. One pt experienced an LVEF drop to < 50% after 4 cycles however this was accompanied by a pericardial effusion felt to be secondary to progressive disease. Adverse events observed include: grade III/IV- none; grade I/II in ≥2 pts- rash, nausea, and anorexia; grade II leukopenia, fatigue, alopecia, diarrhea, headache were also seen in 1 pt each. Preliminary response data in 4 evaluable pts reveals 1 PR, 1 SD, and 2 PD. Conclusions: In the first 7 pts treated, the combination of PLD and L has been well tolerated. One pt experienced an LVEF drop to < 50%, however this was felt likely to be disease-related. DLT has not yet been reached and accrual is ongoing. No significant financial relationships to disclose.