The Drugability Study Of MDS-11P, A Combretastatin Prodrug Analogue, On Anticancer Effects With Vascular Disrupting Activity

Previous studies have demonstrated the disrupting activity to the tumor vascular vessels in vitro with the tubulin-binding properties of the MDS-11. In the present paper, we further study the prodrug—MDS-11P, its drugability with vascular disrupting and anti-tumor activity.1. The anticancer effects of MDS-11P targeting tumor vascular in vivo(1)Functional vascular volume was assessed 24h, 48h, 72h after 100mg/kg MDS-11P intraperitoneal injection, following that the DNA-binding fluorescent dye Hoechst 33342 (10 mg/kg) was injected via the tail vein into treated and untreated mice. MDS-11P induced significant reduction in perfused vascular volume in H22 liver carcinoma tumors. At 24h after drug administration, the vascular volume in tumor decreased to 30.46%, however, 48h and 72h later, the vascular volume were recovered to 60% of the control level.(2)Tumor vasculature permeability, measured by Evan's blue, increased significantly at 6h after the injection of MDS-11P ( 66.0±12.0μg/g vs. the control value of 33.95±0.96μg/g,P<0.05 by t-test), and reached the peak at 18 h (96.22±9.96μg/g), then dropped sharply to the 51.91±8.90μg/g at 72h.(3) MDS-11P induced massive necrosis in the central region of H22 tumors with only a small rim of viable cells about 30.22% of the control level at 24h. After 48h and 72h, the viable cells were partially recovered to 57.6%,69.7% of the control level.(4) The H22 tumor-bearing mice were treated i.p. with MDS-11P at 100, 50, and 25 mg/kg, CA4P at 50mg/kg twice daily for 8 days. The inhibition rate were 67.65±19.31%, 56.96±16.94%, 29.01±24.21% and 73.73±14.51% respectively, there was no significant differences between MDS-11P (100mg/kg) and CA4P (P=0.23). Compared with the significant body weight loss of the CA4P treated mice, MDS-11P showed better tolerance at the dosage of 50mg/kg. (the mice body weight vs control, P=0.40)(5) MDS-11P repressed the growth of A549 human lung adenocarcinoma xenografted in nude mice with the dosage of 50mg/kg twice daily, the inhibition rates were 59.4% . During the experiment, the body weight of the mice tested showed no significant change in both groups with the xenografts (P>0.05).2. The studies of MDS-11P on safety assessment, pharmacokinetics and drug distribution.(1) The most tolerated dosage (MTD) of MDS-11P was 1000mg/kg. The micronucleus test showed the compound didn't induce any genetic damage.(2)The samples were analyzed by high performance of liquid chromatography with internal standard. Separations were obtained on VenμsiL MP C18 (4.6 mm×250 mm,5μm) using an excitation wavelenth of 288nm. The Gradient system consists of mobile phase A: 50mM KH2PO4 (pH2.2): MeOH = 55: 45; mobile phase B: CH3CN;at a flow rate of 1mL/min. The chromatographic system provides good separation of MDS-11P, MDS-11 with less interference.(3) The main pharmacokinetic parameters of MDS-11P and MDS-11: t1/2β(min): 40.0, 26.7; T peak(min): 6.98, 10.0; Cmax(mg/L): 39.1, 36.3; CL(L·kg-1·min-1): 0.051, 0.067; AUC(mg·min·L-1): 1959.0, 1476.7, respectively. Two-compartment open models were fitted to the plasma-concentration curve of MDS-11P and MDS-11.(4) After MDS-11 incubated with the mouse livermicrosome, we detected a metabolic product of MDS-11 at 8.085 min of retention time by HPLC.(5) The concentrations of MDS-11P and MDS-11 in H22 tumor and the normal tissue were analyzed by HPLC, the results showed MDS-11P distributed much more in kidney, liver, spleen and stomach ; MDS-11 distributed more in kidney, liver and spleen, and less in other tissues.Conclusion: MDS-11P disrupted established tumor blood vessles with decrease of the vascular volume accompanied by increase of tumor blood vessel permeability, resulting in massive tumor cell necrosis. It had antitumor activity in H22 liver carcinoma and A549 human lung adenocarcinoma tumor xenograft models. MDS-11P transformed to MDS-11 quickly in vivo, and distributed to the major tissues with a very short plasma half-life. MDS-11P had a wide therapeutic window, the most tolerated dose was 1000 mg/kg, 10 times larger than 100 mg/kg of therapeutic dose, and without any genotoxicity even at 400mg/kg.After incubation with mouse livermicrosome in vitro, MDS-11 produced a probable metabolites. In general, MDS-11P was a potential antitumor drug targeting established tumor vascular with fine drugability.