Efficacy of Ferric Carboxymaltose in Gastrointestinal Stromal Tumor (GIST) Patients With Iron Deficiency Anemia (IDA) Receiving Systemic Therapy

Inclusion Criteria:

1. GIST patients with IDA planned to start or are receiving systemic therapy with TKIs.
2. Evidence of iron deficiency anemia including, Hgb \< 11 g/dL, but \> 8 g/dL; and transferrin saturation (TSAT) \< 20%.
3. No H/O allergic reaction to iron therapy.
4. No clinical signs active of bleeding.
5. Adequate hematologic (ANC \> 1500/mm\^3, platelet count \> 100,000/mm\^3), renal (serum creatinine \< 1.5mg/dL), and hepatic (serum bilirubin count \< 1.5 x normal and serum glutamic-oxaloacetic transaminase (SGOT) or serum glutamic pyruvic transaminase (SGPT) \< 3 x normal) functions.
6. Patients must have Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 2.
7. Signed informed consent to the study.
8. Male and Females of child bearing potential must use acceptable methods of birth control which include oral contraceptives, spermicide with either a condom, diaphragm or cervical cap, use of an intrauterine device (IUD) or abstinence.
9. Patients are required to read and understand English to comply with protocol requirements.
10. Age \>=18 years old.
11. Life expectancy of at least 6 months.

Exclusion Criteria:

1. Pregnant or lactating women.
2. Patients with any co-morbid condition which renders patients at high risk of treatment complication.
3. Patient has uncontrolled angina, congestive heart failure (New York Heart Association \> class II or known ejection fraction \< 40%), uncontrolled cardiac arrhythmia or hypertension, or acute myocardial infarction within 3 months.
4. Patient has an active seizure disorder. (Patients with a previous history of seizure disorders will be eligible for the study, if they have had no evidence of seizure activity, and they have been free of antiseizure medication for the previous 5 years).
5. Psychological, social, familial, or geographical reasons that would prevent scheduled visits and follow-up.
6. Prior surgery or radiotherapy (RT) within 2 weeks of study entry.
7. Known hypersensitivity reaction to any component of ferric carboxymaltose.
8. Any anemia treatment within 4 weeks before inclusion (oral iron, IV iron, or erythropoiesis-stimulating agents), or transfusion of PRBCs in 2 weeks.
9. Hemochromatosis or other iron storage disorders.
10. Known positive hepatitis with evidence of active disease.
11. Patients with overt bleeding.
12. Ferritin \>/= 800 ng/mL.