The maximum tolerated dose of TPI-287 will be determined through a planned dose escalation over 3 sequential cohorts, each comprising of 11 participants randomized to either TPI-287 or placebo. TPI-287 or placebo will be administered as an intravenous infusion once every 3 weeks for 9 weeks, for a total of 4 infusions. Participants who successfully complete this phase will have the option of entering into the open label extension phase during which TPI-287 will be administered once every 3 weeks for an additional 6 weeks, for a total of 3 extra infusions.