Combination Therapy of Trastuzumab and Lapatinib in Chemorefractory HER2-Positive Metastatic Colorectal Cancer: An Efficacy and Safety Analysis

Xiaofeng Ma, Zhongsu Yu, Liangping Cheng and Shaoyan Wang

Background and Objective: In patients with colorectal cancer, some genetic abnormalities are identified in the blood, tumors or metastasis. The prognosis of Human Epidermal Growth Factor Receptor 2 (HER2) in colorectal cancer as a biomarker is uncertain. The use of human epidermal growth factor 2 in treating the receptors targeted with epidermal growth factor has shown a negative response. Hence patients who have HER2-positive colorectal cancer may have very few treatment options and also show poor prognosis. The objectives of the study were to evaluate efficacy and safety with 15 months follow-up of the combination of trastuzumab and lapatinib in patients with HER2+ metastatic colorectal cancer. Materials and Methods: A total of 36 patients with HER2+ metastatic colorectal cancer received 4 mg/kg of trastuzumab which is a loading dose and then followed by 2 mg/kg dose once a week and a 1,000 mg/kg dose of oral lapatinib per day until there is evidence of the progressions of the disease (s). Safety parameters evaluated for 15 months follow-up. Results: Out of 36 patients, 3 patients (8.3%) had a complete response, 18 patients (50%) had a partial response and 15 patients (41.6%) had shown to have reached an objective response rate. Among 36 enrolled patients, stable disease was found in 9 patients (25%) and 12 patients had disease for more than 3 months (33.34%). Overall, the disease was controlled in 26 patients. The adverse effects of the patients included gastrointestinal, dermatological, nutritional disorders, paronychia, hand-foot syndrome and very few cases of conjunctivitis, an increase in bilirubin in the blood and a decrease in left ventricular ejection fraction. Conclusion: The combination of trastuzumab and lapatinib is effective against HER2+ positive metastatic colorectal cancer with manageable adverse effects.

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