Cardiac safety of pegylated liposomal doxorubicin (PLD) in combination with trastuzumab (T) in patients with metastatic breast cancer (MBC): Results from a multicenter phase II study

Abstract

1106 Background: Combination therapy of doxorubicin and trastuzumab is highly effective for Her2 positive MBC but characterized by frequent cardiac toxicity (CT). PLD can significantly reduce CT compared to conventional doxorubicin. Patients and Methods: 15 patients were enrolled in a phase II trial to evaluate cardiac safety of T (4 mg/Kg loading dose day 2, followed by weekly 2 mg/Kg) in combination with PLD (40 mg/m2 IV bolus day 1, q 28 d). 75% of pts. presented with more than 1 metastatic site and 40% for second line treatment. PLD was administered for 6 or 9 cycles, respectively, T until disease progression. To assess CT, all pts were evaluated with electrocardiogram (ECG) and echocardiograms (E) for Left Ventricular Ejection Fraction (LVEF) at baseline, every cycle during PLD and T, and every three months during T therapy alone. CT was defined as appearance of signs/ symptoms of congestive heart failure and/or an absolute decrease in LVEF > 10 units (below 50%) or decrease in LVEF > 15 units (above 50%). Results: Four pts. received 6 cycles, 4 pts. received 9 cycles of PLD, 4 pts discontinued treatment due to PD, 3 pts. due to toxicity. After a median follow up time of 15.4 months, 6 pts. (42.9%) demonstrated a clinical benefit and median OS was 16.2 months. Non cardiac side effects were mild with only 3 CTC Grade 3 events of 247 treatment cycles (1.2%). Three pts. developed minor ECG changes without pathological significance and 5 pts. had minor changes in their E with slight diastolic (n=3) or systolic (n=2) dysfunction. During follow-up, 3 pts. were diagnosed with pathological E findings, including 1 slight decrease of LVEF, one diffuse hypokinesia and one strong decrease in LVEF.The median LVEF in the study cohort was 66.1% at baseline, 62.7% after 6 cycles of therapy, 64.4% at the first follow up and did not change significantly until the 5 th examination. Conclusions: This study supports the combination of PLD and H in pts. with HER2 overexpressing metastatic breast cancer as a safe and feasible therapy. Due to the promising clinical response rates in this prognostically unfavorable group, this combination should be evaluated in larger studies as a potential regimen for adjuvant treatment of breast cancer. No significant financial relationships to disclose.