Continuous Trastuzumab Therapy in Breast Cancer Patients With Asymptomatic Left Ventricular Dysfunction.

BACKGROUND: Adjuvant trastuzumab is a highly effective targeted treatment that improves survival for patients with HER2-positive breast cancer. However, trastuzumab interruption is recommended for patients who develop treatment-induced cardiotoxicity (i.e., decline in left ventricular ejection fraction [LVEF], with or without symptoms) and can lead to an incomplete course of treatment. We studied the cardiac safety of continuous trastuzumab therapy among patients with asymptomatic declines in LVEF. METHODS: We retrospectively evaluated patients with HER2-positive breast cancer treated with adjuvant trastuzumab at our institution between 2005 and 2010. Treatment-induced cardiotoxicity was defined by an absolute decrease in LVEF of ≥10% to below 55% or an absolute decrease of ≥16%. Logistic regression was used to determine the association between candidate risk factors and treatment-induced cardiotoxicity. RESULTS: Among 573 patients, 92 (16%) developed treatment-induced cardiotoxicity. Trastuzumab was continued without interruption in 31 of 92 patients with treatment-induced cardiotoxicity­all were asymptomatic with LVEF of ≥50% at cardiotoxicity diagnosis with median LVEF of 53% (range, 50%-63%), and none developed heart failure during follow-up. Risk factors associated with treatment-induced cardiotoxicity included age (p = .011), anthracycline chemotherapy (p = .002), and lower pretrastuzumab LVEF (p < .001). CONCLUSION: Among patients who develop asymptomatic treatment-induced cardiotoxicity with LVEF of ≥50%, continuous trastuzumab therapy appears to be safe.

Trastuzumab interruption and treatment-induced cardiotoxicity in early HER2-positive breast cancer.

Trastuzumab improves outcomes among patients with HER2-positive breast cancer but is associated with a risk of treatment-induced cardiotoxicity (TIC). It is unclear how frequently TIC leads to trastuzumab interruption outside of prospective trials, and how TIC is managed in clinical practice. Patients with HER2-postive breast cancer receiving adjuvant trastuzumab from 2005 to 2010 were identified (n = 608). We evaluated the incidence, risk factors, and management of trastuzumab interruption due to TIC. In total, 488 (80 %) patients were treated with anthracycline prior to trastuzumab. Trastuzumab was interrupted in 108 (18 %) patients. Cumulative trastuzumab dose was lower in the interrupted group (median 86 vs. 108 mg/kg, p < 0.0001). The most common reason for interruption was TIC (66 of 108 patients): 20 had symptomatic heart failure and 46 had asymptomatic left ventricular ejection fraction (LVEF) decline. Patients with trastuzumab interruption for TIC were older (54 vs. 50 years, p = 0.014) with lower LVEF before anthracycline (63 vs. 67 %, p < 0.0001) and trastuzumab (62 vs. 67 %, p < 0.0001) therapy. Mean LVEF at baseline, TIC diagnosis, and follow-up after trastuzumab interruption was 63, 45, and 55 %, respectively. Thirty-three of 66 patients with TIC were re-challenged with trastuzumab, and five patients had recurrent LVEF decline. In clinical practice, trastuzumab interruption is common and most often due to TIC, with most patients receiving anthracycline prior to trastuzumab. Cardiac dysfunction improves after trastuzumab interruption but may not fully recover to baseline. Strategies to minimize cardiotoxicity and treatment interruption should be investigated to prevent persistent left ventricular dysfunction in affected patients.