Improved Efficacy of a Microencapsulated Macrophage Colony Stimulating Factor and Methotrexate in Melanoma

Abstract

This study examines the effects of a combination therapy of both methotrexate (MTX) and albumin microspheres containing recombinant human macrophage colony-stimulating factor (rhM-CSF) in melanoma tumors. Melanoma tumors were induced in C57BL/6 male mice with subcutaneous injection of B-16 tumor cells. Therapy started once the tumor size reached 0.5 cm in diameter. Mice were divided into several groups, and dosing was carried out daily until death. Group I received MTX solution (2 mg/kg or 15 mg/kg), group II received rhM-CSF solution (100 μg), group III received albumin rhM-CSF microspheres (100 μg), and groups V–XV received different combinations of both agents daily. The weight, tumor size, and survival time (in days) were recorded. From the results, the control (no rhM-CSF administered) group survived for 11.8 ± 1.92 days, and the group that received MTX solution survived for 19.4 ± 5.03 days. However, the group that received both the MTX solution (15 mg/kg) and albumin rhM-CSF microspheres (100 μg/kg) demonstrated a significant increase (p <. 05) in the survival time (30.4 ± 3.27 days). The concentrations of cytokines (tumor necrosis factor alpha [TNF-α] and interleukin-1 beta [IL-1β]) in the different treatment groups were monitored to determine the effect of rhM-CSF on the immune system. The TNF-α concentration was significantly higher in the group that received the combination therapy (204 ± 54.6 pg/ml) versus the control group (31.5 ± 7.02 pg/ml). The IL-1β concentration was significantly higher (p <. 05) in the rhM-CSF microsphere (100 μg/kg) treated group (62 ± 17.2 pg/ml) versus the rhM-CSF solution (29.1 ± 8.7 pg/cc).