Patients are stratified according to histology (uterine leiomyosarcoma vs malignant mixed mullerian tumor/carcinosarcoma). Patients receive ziv-aflibercept over 1 hour on day 1. Treatment repeats every 14 days in the absence of disease progression or unacceptable toxicity. Patients undergo blood collection at baseline, every 8 weeks during treatment, and 60 days after completion of study treatment for population pharmacokinetic analysis using enzyme-linked immunosorbent assay (ELISA).