Inclusion Criteria:

- Patient must have a diagnosis of multiple myeloma and have relapsed or
relapsed/refractory disease.

- Patient must have received ≥ 2 prior anti-myeloma regimens including a proteasome
inhibitor and/or immunomodulatory agent.

- Patient currently requires systemic therapy.

- Patient has measurable disease.

- Age ≥ 18 years

- Karnofsky performance status ≥ 60%

- ECOG performance 0, 1 or 2

- Life expectancy of at least three months

- Able to take acetaminophen

- Not pregnant

- Patient must have recovered from toxicities incurred as a result of any previous
anti-myeloma therapy or recovered to baseline.

- Patients who received an autologous stem cell transplant must be ≥ 3 months
post-transplant and all associated toxicities must have resolved to ≤ CTCAE Grade 1.

- QT intervals of QTc ≤ 500 msec

Exclusion Criteria:

- POEMS syndrome

- Plasma cell leukemia

- Primary amyloidosis

- Patient has smoldering multiple myeloma or monoclonal gammopathy of unknown
significance (MGUS).

- Evidence of spinal cord compression or CNS complication unless controlled by
appropriate therapy.

- Patient received chemotherapy or other anti-cancer therapy that may be active against
multiple myeloma within 3 weeks prior to the first dose of PRLX 93936.

- Patient received nitrosureas within 6 weeks prior to the first dose.

- Patient received corticosteroids within 2 weeks prior to the first dose.

- Patient received plasmapheresis within 4 weeks prior to the first dose.

- Patient had major surgery within 4 weeks prior to the first dose.

- Patient had an allogeneic stem cell transplant within 6 months before first dose of
PRLX 93936 or has evidence of graft versus host disease.

- Patient is taking any therapy concomitantly that may be active against multiple
myeloma.

- Patient is currently receiving medication(s) that are principally metabolized
via the cytochrome P450 3A4 enzyme pathway.

- Use of any investigational agents within 28 days or 5 half-lives (whichever is
shorter) of study treatment.

- Patient has peripheral neuropathy of Grade 3 or greater intensity, or painful Grade
2, as defined by the NCI CTC.

- Patient had a myocardial infarction within 6 months of enrollment or has NYHA Class
III or IV heart failure uncontrolled angina, severe uncontrolled ventricular
arrhythmias, or electrocardiographic evidence of acute ischemia or active conduction
system abnormalities.

- Abnormal LVEF (< LLN for the institution for a patient of that age) on echocardiogram

- Patient has poorly controlled hypertension, diabetes mellitus, or other serious
medical or psychiatric illness that could potentially interfere with the completion
of treatment according to protocol.

- Patient had a malignancy other than multiple myeloma within 3 years before
enrollment, with the exception of adequately treated basal cell or squamous cell skin
cancer, in situ cervical cancer, in situ breast cancer, or in situ prostate cancer.

- Patient's clinical laboratory values meet any of the following criteria within the 7
days prior to Study Day 1:

- Bilirubin > 1.5 times ULN

- AST (SGOT), ALT (SGPT) and Alkaline phosphatase > 2.5 times ULN

- Uncontrolled hypercalcemia (defined as serum calcium > 14 mg/dL)

- Serum creatinine > 2.0 mg/dL or creatinine clearance of < 30 mL/min

- ANC < 1000 cells/mm3 or < 750 cells/mm3 due to >50% marrow involvement

- Platelet count < 50,000 cells/mm3

- Hemoglobin < 8.0 g/dL

- Patient is known to be human immunodeficiency virus (HIV)-positive.

- Patient is known to be hepatitis B surface antigen-positive or has known active
hepatitis C infection.

- Patient has an active systemic infection requiring treatment or within 14 days before
first dose of PRLX 93936.

- Pregnant or nursing women