Efficacy of granulocyte-macrophage colony-stimulating factor combined with metronomic paclitaxel in the treatment of Lewis lung carcinoma transplanted in mice.

Metronomic chemotherapy in combination with immunotherapy is an attractive approach in cancer therapy. The purpose of the present study was to investigate the anti-tumor effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) in combination with metronomic paclitaxel (MET PTX) on Lewis lung carcinoma transplanted in mice. In the present study, tumor-bearing mice survival time and tumor growth were monitored. The day after the end of the treatment, white blood cells were counted, and the number and maturation of dendritic cell were determined by flow cytometry. Besides, microvessel density and tumor cell proliferation were determined by immunohistochemistry, while apoptosis was determined by TUNEL (Terminal deoxynucleotidyl transferase-mediated nick end labeling) assay. Micro F-FDG PET/CT (F-Fluorodeoxyglucose positron emission tomography/computed tomography) was used to obtain SUVmax values. White blood cells reduction was not observed in the mice treated with GM-CSF combined with MET PTX. Moreover, GM-CSF combined with MET PTX further reduced proliferation and microvessel density, promoted tumor apoptosis, increased the dendritic cells number and induced their maturation, with concomitant delay in tumor growth and improved survival. Taken together, GM-CSF combined with MET PTX exerted a synergistic anti-tumor effect against lung cancer in a mouse model through an antiangiogenic activity and inducing dendritic cells maturation without exerting pronounced adverse effects. Hence, combined metronomic chemotherapy and immunotherapy could be a potential strategy for the treatment of patients with advanced lung cancer.