Inclusion Criteria:

- Signed informed consent

- Age >= 18 years old

- Histologically documented adenocarcinoma of the prostate, clinically refractory or
resistant to hormone therapy, as assessed by progression following at least one
hormonal therapy (orchiectomy or luteinizing hormone-releasing hormone [LHRH]
agonist). Subjects must have documented progression following hormonal therapy
withdrawal of >= 4 weeks duration; nilutamide and bicalutamide require 6 weeks
withdrawal.

- Progression of disease after one prior chemotherapy regimen (which must have been
taxane-based) for CRPC. Progression is defined as at least one of the following: A
minimum of three consecutive serum PSA measurements obtained >= 14 days apart and all
within 3 months, with progressively increasing values for two consecutive
measurements. The latest value must be obtained within the screening period and must
be >= 5 ng/mL; or progression of measurable disease, as defined by RECIST; or
progression of bone disease, as defined by the appearance of one or more new bone
lesions

- Orchiectomy, or castrate levels of testosterone maintained by LHRH agonist <70 ng/mL

- Life expectancy >= 12 weeks

- ECOG performance status of 0 or 1

- Granulocyte count of >= 1500/mL, platelet count of >= 75,000/mL and hemoglobin of >=
9 g/dL (hemoglobin may be supported by transfusion or erythropoietin or other
approved hematopoietic growth factors; darbopoeitin [Aranesp] is permitted)

- Serum bilirubin less than or equal to the upper limit of normal (ULN), unless due to
Gilbert's disease, and alkaline phosphatase, AST, and ALT <= 2.5 x ULN (ALT, AST, and
alkaline phosphatase <= 5 x ULN for subjects with liver metastases; no alkaline
phosphatase upper limit for subjects with bone metastases)

- Serum creatinine <= 1.5 x ULN

- International normalized ratio (INR) <1.5 and activated partial thromboplastin time
(aPTT) <1.5 x ULN (except for subjects receiving warfarin)

- Willing to complete serial PROSQOLI/PPI evaluations and serial diaries of analgesic
use (if necessary)

Exclusion Criteria:

- Prior chemotherapy, radiotherapy, therapeutic radionucleotide or immunotherapy within
4 weeks of Day 1 (the day of the first rhuMAb 2C4 dose). Flutamide therapy, or other
second line hormonal therapies should be withdrawn >= 4 weeks prior to Day 1.
Bicalutamide and nilutamide therapy should be withdrawn >= 6 weeks prior to starting
study medication.

- Prior treatment with HER2 pathway inhibitors (e.g., Herceptin [Trastuzumab], Iressa
[gefitinib], Tarceva [erlotinib hydrochloride], C225, CI1033, and TAK165)

- Treatment with other experimental anticancer agents within 4 weeks prior to Day 1

- Prior history or clinical evidence of central nervous system or brain metastases

- Ejection fraction, determined by ECHO, <50%

- Uncontrolled hypercalcemia (>11.5 mg/dL)

- Prior exposure of >360 mg/m2 doxorubicin, >120 mg/m2 mitoxantrone, or >90 mg/m2
idarubicin

- Ongoing corticosteroid treatment, except for subjects who are on stable doses of <20
mg of prednisone daily (or equivalent), or who are taking corticosteroids for reasons
unrelated to prostate cancer

- History of other malignancies within 5 years prior to Day 1, except for adequately
treated basal or squamous cell skin cancer

- History of serious systemic disease, including active infection, uncontrolled
hypertension (diastolic blood pressure >100 mmHg on two consecutive occasions),
unstable angina, congestive heart failure, or myocardial infarction within 6 months
prior to Day 1, or unstable symptomatic arrhythmia requiring medication (subjects
with chronic atrial arrhythmia, i.e., atrial fibrillation, paroxysmal
supraventricular tachycardia, or controlled hypertension are eligible)

- Ongoing liver disease, including viral or other hepatitis, current alcohol abuse, or
cirrhosis

- Known human immunodeficiency virus infection

- Major surgery or significant traumatic injury within 3 weeks prior to Day 1

- Inability to comply with study and follow-up procedures

- Any other diseases, metabolic dysfunction, physical examination finding, or clinical
laboratory finding giving reasonable suspicion of a disease or condition that
contraindicates the use of an investigational drug or that may affect the
interpretation of the results or render the subject at high risk for treatment
complications