Background: PM060184 is new marine derived tubulin-binding agent originally isolated from the sponge Lithoplocamia lithistoides. PM060184 has shown potent antitumor activity in vivo against a panel of different tumor xenografted models such as colon, gastric, NSCLC, prostate and renal. Also, PM060184 has demonstrated to have a potent in vitro and in vivo activity in P-gp overexpressing cells. PM060184 is currently under evaluation in Phase I clinical studies in patients with advanced cancer diseases.
Material and Methods:
Athymic female nu/nu mice were subcutaneously implanted with H460 (NSCLC). Tumor bearing animals were randomly allocated into experimental groups (efficacy or pharmacokinetics -PK-). The animals belonging to the efficacy study received three iv doses in a weekly (q7dx3) schedule of PM060184 at 16 mg/kg or placebo. The antitumor activity was followed by the change in tumor volume for treated and placebo groups. The PK group received a single dose of PM060184 at 16 mg/kg. Then, plasma, tissue (brain, spleen, lung, muscle and heart) and tumor samples (N=3-4/sampling time) were collected at different times and up to 96 h post-administration. Tissue and tumor samples were diluted and homogenized using Precellys®24 bead beating technology. Once homogenized the samples were processed as per plasma. PM060184 was detected in plasma, tissue and tumor extracts by electrospray ionization/tandem mass spectrometry after extraction by supported liquid extraction (SLE).
Results:
The mean maximum plasma concentration (Cmax) was 2,452.5 ng/mL. The area under curve (AUC) was 2,963 ng*hr/mL. The plasma clearance was 5,398.5 mL/hr/kg. The volume of distribution at steady state was 880.7 mL/kg. The terminal half-life was 4.7 hr. The AUC0-tlast values for brain, spleen, lung, muscle and heart were 216.2, 7,402.9, 3,857.7, 2,614.6 and 2,929.5 ng*hr/g, respectively; however the AUC value for H460 xenografted tumors was 51,321.4 ng*hr/g (tlast is 96 hours for tumor, 8 hours for brain and 24 hours for the other tissues).
Conclusion:
PM060184 showed similar plasma and tissue pharmacokinetics properties as well as preferential tumor distribution until 96 h after an iv administration in mice bearing H460 xenografted tumors.