Inclusion Criteria:

- The patient has histologically- or cytologically-confirmed malignant soft tissue
sarcoma (STS), including uterine leiomyosarcoma

- The patient has advanced STS, not amenable to treatment with surgery or radiotherapy

- The patient's Eastern Cooperative Oncology Group (ECOG) performance status is 0-2

- The patient has available tumor tissue from either the primary or metastatic tumor
for determination of PDGFRα expression

- The patient has adequate hematologic function as defined by an absolute neutrophil
count (ANC) ≥ 1500 μL, hemoglobin ≥ 9.0 g/dL, and a platelet count of 100,000/μL
obtained within 2 weeks prior to study entry

- The patient has adequate hepatic function as defined by a total bilirubin ≤ 1.5
mg/dL, and aspartate transaminase (AST) and alanine transaminase (ALT) ≤ 3.0 times
the upper limit of normal (ULN)

- The patient has adequate renal function as defined by serum creatinine ≤ 1.5 × the
institutional ULN. If creatinine is above the ULN, the patient's creatinine clearance
is ≥ 45 mL/min

- The patient has urinary protein ≤ 1+ on dipstick or routine urinalysis; if urine
dipstick or routine analysis is ≥ 2+, a 24-hour urine for protein must demonstrate <
1 g of protein in 24 hours to allow participation

- Because the teratogenicity of IMC-3G3 is not known, women of childbearing potential
(WOCBP) and sexually active males must agree to use adequate contraception (hormonal
or barrier method of birth control; abstinence) prior to study entry and for the
duration of study participation

Exclusion Criteria:

- The patient has histologically- or cytologically-confirmed Kaposi's sarcoma

- The patient has untreated central nervous system metastases

- The patient received prior treatment with doxorubicin, daunorubicin, idarubicin,
and/or other anthracyclines and anthracenediones (ie, mitoxantrone)

- The patient received prior radiation therapy to the mediastinal/pericardial area

- The patient has a history of another primary cancer, with the exception of a)
curatively resected nonmelanomatous skin cancer; b) curatively treated cervical
carcinoma in situ; or c) other primary solid tumor treated with curative intent, no
known active disease present, and no treatment administered during the last 3 years
prior to study entry

- The patient is receiving concurrent treatment with other anticancer therapy,
including other chemotherapy, immunotherapy, hormonal therapy, radiotherapy,
chemo-embolization, targeted therapy, or an investigational agent

- The patient has an elective or a planned major surgery to be performed during the
course of the study

- The patient has an uncontrolled intercurrent illness including, but not limited to,
ongoing or active infection, requiring parenteral antibiotics, symptomatic congestive
heart failure, severe myocardial insufficiency, cardiac arrhythmia, or psychiatric
illness/social situations that would limit compliance with study requirements

- The patient has unstable angina pectoris, angioplasty, cardiac stenting, or
myocardial infarction 6 months prior to study entry

- The patient has known immunodeficiency virus (HIV) infection

- The patient, if female, is pregnant or lactating

- The patient has a known allergy to any of the treatment components