The PTC Therapeutics oral, brain-penetrant tubulin-binding agent, PTC596 , is in Ph. I clinical studies for advanced solid tumors (starting dose of 200 mg PO BIW). We recently highlighted encequidar , a P-gp inhibitor co-dosed with paclitaxel to render paclitaxel orally bioavailable. A directly orally bioavailable tubulin-binder would [...]