To determine the maximum tolerated dose (MTD) and the dose limiting toxicities (DLT) of PRLX 93936 administered IV 3 days a week (Monday, Wednesday and Friday) for 3 weeks followed by a 9 day rest period, as treatment for patients with relapsed or relapsed/refractory multiple myeloma.~To establish the dose of PRLX 93936 recommended for future studies.~To characterize potential toxicities of PRLX 93936.~To assess the pharmacokinetic profile of PRLX 93936.~To evaluate response to treatment, time to response (TTR) and duration of response.~To evaluate time to progression (TTP).
To determine the maximum tolerated dose of, and response to, PRLX 93936 as treatment for patients with relapsed or relapsed/refractory multiple myeloma.