Pharmacology and in vivo efficacy of pyridine-pyrimidine amides that inhibit microtubule polymerization.

Microtubule-targeting agents are important tools in cancer treatment. Generating novel microtubule targeting agents with novel pharmacology could dramatically expand the utility of this class of drugs. Here we characterize the pharmacology of recently described small molecule microtubule polymerization inhibitors. Pharmacokinetic experiments show oral bioavailability through gastric absorption. In vitro assays designed to predict absorption, distribution, metabolism, and excretion (ADME) and safety reveal a scaffold that is metabolically stable, evades P-glycoprotein, does not inhibit CYP enzymes, occurs as a significant free fraction in serum, and has exceptionally high cellular permeability. Together with in vivo efficacy models, pharmacology supports further development as a treatment for solid tumors.