Inclusion:

1. The patient has histologically or cytologically-confirmed sarcoma of one of the following histologies:(1) Ewing's sarcoma / PNET; (2) rhabdomyosarcoma; 3) leiomyosarcoma;(4) adipocytic sarcoma; or (5) synovial sarcoma.
2. The patient has measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded), with minimum lesion size ≥ 2 cm on conventional measurement techniques or ≥ 1 cm on spiral computed tomography (CT) scan.
3. The patient has at least one measurable lesion located outside of a previously irradiated area.
4. The patient has radiographic documentation of disease progression within 6 months prior to study entry (see Section 11.4 for a full definition of disease progression).
5. The patient has relapsed, refractory, and/or metastatic disease, incurable by surgery, radiotherapy, or other conventional systemic therapy.
6. The patient must have either been considered ineligible for systemic chemotherapy or received at least one previous regimen for relapsed, refractory, and/or metastatic disease.
7. The patient is age ≥ 12 years.
8. The patient has a life expectancy of > 3 months.
9. The patient has an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-1.
10. The patient has adequate hematologic function as defined by absolute neutrophil count ≥ 1500/μL, hemoglobin ≥ 9 g/dL, and platelet count ≥ 100,000/μL.
11. The patient has adequate hepatic function as defined by a total bilirubin ≤ 1.5 x the upper limit of normal (ULN), and aspartate transaminase (AST) and alanine transaminase (ALT) ≤ 3 x the ULN (or ≤ 5 x the ULN in the presence of known liver metastases).
12. The patient has adequate coagulation function as defined by international normalized ratio (INR) ≤ 1.5 and partial thromboplastin time (PTT) no more than 5 seconds above the ULN.
13. The patient has adequate renal function as defined by serum creatinine ≤ 1.5 x the institutional ULN or creatinine clearance ≥ 60 mL/min for patients with creatinine levels above 1.5 x the ULN.
14. The patient has fasting serum glucose < 120 mg/dL or below the ULN.
15. Because the teratogenicity of IMC-A12 is not known, women of childbearing potential and men 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.
16. The patient or his or her legal guardian has the ability to understand and the willingness to sign a written informed consent document

Exclusion

1. The patient has uncontrolled brain or leptomeningeal metastases.
2. The patient has not recovered to grade ≤ 1 from adverse events due to agents administered more than 3 weeks prior to study entry.
3. The patient is receiving any other investigational agent(s).
4. The patient has undergone major surgery, hormonal therapy (other than replacement), chemotherapy, radiotherapy, or any form of investigational therapy within 3 weeks prior to enrollment.
5. The patient has a history of treatment with other agents targeting the IGFR.
6. The patient has a history of allergic reactions attributed to compounds of chemical or biologic composition similar to that of IMC-A12.
7. The patient has poorly controlled diabetes mellitus. Patients with a history of diabetes mellitus are allowed to participate, provided that their blood glucose is within normal range (fasting < 120 mg/dL or below ULN) and that they are on a stable dietary or therapeutic regimen for this condition.
8. The patient has an uncontrolled intercurrent illness including, but not limited to, ongoing or active infection requiring parenteral antibiotics, symptomatic congestive heart failure, uncontrolled hypertension, clinically significant cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
9. The patient is receiving therapy with immunosuppressive agents.
10. The patient is pregnant or breastfeeding.
11. The patient is known to be positive for infection with the human immunodeficiency virus.
12. The patient has a history of another primary cancer, with the exception of: a)curatively resected non-melanomatous skin cancer; b) curatively treated cervical carcinoma in-situ; or c) other primary solid tumor curatively resected treated with no known active disease present and no treatment administered for the last 3 years.