Background: A dose limiting toxicity of taxane chemotherapy, including docetaxel and cabazitaxel, is neutropenia. VERU-111 is a novel, oral aand btubulin inhibitor that blocks tubulin polymerization and is not a substrate for multi-drug resistance mechanisms. Nonclinical toxicity studies were recently performed in order to assess the effects of daily, high-dose administration of orally dosed daily VERU-111. Methods: Toxicity of VERU-111 was evaluated in a 28-day oral dosing toxicity study which was conducted in both rats and dogs. These studies were performed at an independent facility under GLP conditions. Results: In both species evaluated, at oral doses of ≤3 mg/kg/day (rat) and ≤8 mg/kg/day (dog) there were no significant observed findings of neutropenia, myelosuppression, or abnormal liver function. Conclusions: In contrast to cabazitaxel and docetaxel, which are given once every 3 weeks IV, VERU-111 given oral, daily for 28 days in toxicity studies in dog and rat did not result in neutropenia, and myelosuppression. Furthermore, VERU-111 orally each day did not affect liver function tests. These nonclinical toxicity studies provide the basis for progressing VERU-111 into a Phase 1b/2 study which targets men with metastatic castration and androgen blocking agent (abiraterone and enzalutamide) resistant prostate cancer.