Antitumor effects of different administration sequences of cisplatin and Endostar on Lewis lung carcinoma

Angiogenesis plays an essential role in the growth and metastasis of a number of tumors. Anti-angiogenic drugs are able to normalize tumor vasculature and inhibit tumor growth. Therefore, it has been hypothesized that the combination of cytotoxic chemotherapy drugs and angiogenesis inhibitors may exert complementary therapeutic benefits in the treatment of cancer. In the present study, the effect of the angiogenesis inhibitor, recombinant human endostatin (Endostar), in combination with cisplatin, was evaluated in C57/BL/6 mouse xenografts under different administration sequences. The drug combinations and sequences of administration were analyzed within the cancer xenografts for any inhibitory effects. Changes in the cell cycle distribution of the cells were monitored using flow cytometry. The effects of Endostar, particularly a reduction in the density of microvessels, were assessed using a method that employed anti-cluster of differentiation 31 antibodies. The concentration of cisplatin in the blood and tumor tissue at various time-points following administration was detected by high-performance liquid chromatography. The tumor tissues that received simultaneous Endostar and cisplatin exhibited increased inhibition of tumor growth and improved cell cycle distribution compared with those that received cisplatin alone, or those in which Endostar was administered prior to cisplatin. The simultaneous administration of the drugs resulted in the lowest microvessel density in the xenografts. Under these conditions, the concentration of cisplatin was revealed to be the highest in the grafted tumor tissue. The results of the present study suggest that the co-administration of Endostar and cisplatin may aid in the optimization of the antitumor activity of cisplatin.