A Study to Determine the Maximum Tolerated Dose of ASG-5ME in Subjects With Castration-Resistant Prostate Cancer

Inclusion Criteria: * Subject has histologically-confirmed castration-resistant prostate cancer and meets at least 1 of the following criteria: * subject's disease has progressed on or after available standard therapy -OR- * there is no effective standard therapy available for treating the subject's disease -OR- * subject or his disease is not suitable for standard therapy -OR- * subject chooses to defer or decline standard therapy (subject is adequately informed of the availability of clinically meaningful therapy and chooses instead to partake in this research using a product with no documented clinical activity) * Testosterone ≤ 50 ng/dL * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Life expectancy of \> 6 months as evaluated and documented by the investigator * Hematologic function, as follows (no red blood cell (RBC) or platelet transfusions are allowed within 4 weeks of the first dose of ASG-5ME): * Absolute neutrophil count (ANC) ≥ 1.5 x 109/L * Platelet count ≥ 100 x 109/L * Hemoglobin ≥ 9 g/dL * Renal function, as follows: creatinine ≤ 1.5 x upper limit of normal (ULN), or creatinine clearance of \> 60 mL/min if serum creatinine is \> 2.0 mg/dL * Total bilirubin \< 1. 5 x ULN * Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT)≤ 1.5 x ULN * International Normalized Ratio (INR) \< 1.3 (or \< 3.0 if on therapeutic anticoagulation) * Serum calcium ≤ ULN * Subjects must be taking and agree to remain on a stable dose of luteinizing hormone-releasing hormone (LHRH) agonist therapy or gonadotropin-releasing hormone (GnRH) antagonist for the duration of the trial if not surgically castrated * Additional Inclusion criteria for Chemotherapy Naïve Cohort: No prior systemic cytotoxic chemotherapies * Additional Inclusion criteria for Chemotherapy Exposed Cohort: * Documented disease progression during or after docetaxel treatment or intolerability to docetaxel treatment * No additional prior chemotherapy for CRPC is allowed Exclusion Criteria: * History of central nervous system metastasis, including incompletely treated epidural disease * History of other primary malignancy (including premalignant myeloid malignancy e.g. myelodysplastic syndrome), unless: * Curatively resected non-melanomatous skin cancer * Other malignancy curatively treated with no known active disease present and no treatment administered for the last 3 years * Active angina or Class III or IV Congestive Heart Failure (CHF) (New York Heart Association CHF Functional Classification System) or clinically significant cardiac disease within 12 months of study enrollment, including myocardial infarction, unstable angina, grade 2 or greater peripheral vascular disease, congestive heart failure, uncontrolled hypertension, or arrhythmias not controlled by outsubject medication * The following treatments are not allowed within 4 weeks of enrollment: cytotoxic chemotherapy, radiation therapy or the dietary supplement PC-SPES * Use of prednisone (or equivalent corticosteroids) \> 20 mg/day are not allowed. Doses \< 20 mg/day are allowed only if they have been at the same dose for \> 4 weeks * Use of anti-androgen therapy (ie, flutamide, bicalutamide and nilutamide) within 6 weeks of study enrollment; non-responders to second-line anti-androgen therapy do not require the 6 week withdrawal period * Monoclonal antibody therapy within 3 months of enrollment with the exception of denosumab (prior or concurrent use of denosumab is allowed) * Peripheral neuropathy of ≥ grade 2 as defined by the CTCAE criteria version 4.0 * Major surgery (that requires general anesthesia) within 4 weeks of study enrollment * Active infection requiring treatment with systemic (intravenous or oral) anti-infectives (antibiotic, antifungal, or antiviral agent) within 72 hours of screening * Use of any investigational drug (including marketed drugs not approved for this indication) within 30 days prior to enrollment * History of thromboembolic events and bleeding disorders ≤ 3 months (e.g., deep vein thrombosis (DVT) or pulmonary embolism (PE)) * Known positive test for human immunodeficiency virus (HIV), hepatitis C, or hepatitis B surface antigen