HM30181A,a potent P-glycoprotein inhibitor,potentiates the absorption and in vivo antitumor efficacy of paclitaxel in an orthotopic brain tumor model

Objective:Delivery of chemotherapeutic drugs to the brain has remained a major obstacle in the treatment of glioma,owing to the presence of the blood-brain barrier and the activity of P-gp,which pumps its substrate back into the systemic circulation.The aim of the present study was to develop an intravenous formulation of HM30181 A(HM)to inhibit P-gp in the brain to effectively deliver paclitaxel(PTX)for the treatment of malignant glioma.Methods:Two formulations of solubilized HM were designed on the basis of different solid dispersion strategies:i)spray-drying[polyvinlypyrrolidone(PVP)-HM]and ii)solvent evaporation[HP-β-cyclodextrin(cyclodextrin)-HM].The P-gp inhibition of these 2 formulations was assessed on the basis of rhodamine 123 uptake in cancer cells.Blood and brain pharmacokinetic parameters were also determined,and the antitumor effect of cyclodextrin-HM with PTX was evaluated in an orthotopic glioma xenograft mouse model.Results:Although both PVP-HM and cyclodextrin-HM formulations showed promising P-gp inhibition activity in vitro,cyclodextrin-HM had a higher maximum tolerated dose in mice than did PVP-HM.Pharmacokinetic study of cyclodextrin-HM revealed a plasma concentration plateau at 20 mg/kg,and the mice began to lose weight at doses above this level.Cyclodextrin-HM(10 mg/kg)administered with PTX at 10 mg/kg showed optimal antitumor activity in a mouse model,according to both tumor volume measurement and survival time(P<0.05).Conclusions:In a mouse orthotopic brain tumor model,the intravenous co-administration of cyclodextrin-HM with PTX showed potent antitumor effects and therefore may have potential for glioma therapy in humans.

The potential development of drug resistance in rheumatoid arthritis patients identified with p53 mutations

Rheumatoid arthritis(RA)is a chronic inflammatory disease characterized by cartilage and bone damage with the presence of pannus formation which causes uncontrollable proliferation and invasion of fibroblast-like synoviocytes(FLS).Since rheumatoid arthritis is a chronic disorder,the patients normally need to undergo prolonged antirheumatic treatment with the use of disease-modifying antirheumatic drugs(DMARDs),steroids,and nonsteroidal anti-inflammatory drugs(NSAIDs).The efficacy of such long-term pharmaceutical intervention can be significantly affected by the development of drug resistance.The pathological relationship between rheumatoid arthritis and cancer hinted that some chemotherapeutic drugs,such as methotrexate(MTX),could be used for RA treatment.This idea was reinforced by the analysis of mutations in p53 tumor suppressor gene.Around 50%of p53 somatic mutations observed from various cancers are also identified in the synovium of RA patients1(Fig.1A).Of note,the hyperplastic synovium in RA with overexpressed p53 mutants contributed to the destruction of joints in patients with erosive RA.