Oral pemetrexed facilitates low-dose metronomic therapy and enhances antitumor efficacy in lung cancer

There is a growing interest in preclinical research to consider low-dose metronomic chemotherapy as antiangiogenic cancer treatment. Oral metronomic therapy, in particular, has shown much promise with its ease of daily administration and higher therapeutics window. In that regard, we developed oral pemetrexed using the physical complex with the bile acid enhancers (DCK). In a caco-2 permeability study, the oral pemetrexed/DCK complex had significantly higher drug uptake, and inhibited efflux transporter activity as well. We further observed that the mechanism of oral drug uptake was related to transcellular along with bile acid transporter mediated pathways. The oral administration of drug complex in rats revealed high bioavailability (22.37%) and extended mean residence time. Using SCC7 and A549 xenograft models, we demonstrated that antitumor effects from daily oral metronomic pemetrexed significantly reduced tumor in a dose-dependent manner. The antitumor activity of oral pemetrexed/DCK complex plus cisplatin was superior to both monotherapies. The xenograft study also revealed that oral metronomic therapy markedly reduced microvessel density, proliferation and increased apoptosis in the tumor tissues. Oral metronomic doses were significantly correlated with the elevation of plasma deoxyuridine level, an essential biomarker for pemetrexed therapy. One-month toxicity study confirmed that daily dosing of oral pemetrexed is safe by investigating apoptosis in the gut tissues from mice. Moreover, we analyzed different biochemical parameters and enzymes from the blood to prove that our newly developed oral pemetrexed complex is well tolerated.