A Study of NKTR-214 in Combination With Nivolumab in Patients With Metastatic and/or Locally Advanced Sarcoma

Inclusion Criteria: * Male or female age ≥ 12 years at the time of informed consent * Be capable, willing, and able to provide written informed consent/assent. For patients \< 18 years of age, their parents or legal guardians must sign a written informed consent. Assent, when appropriate, will be obtained according to institutional guidelines. * Be willing to comply with clinical trial instructions and requirements. * Patients ≥ 18 years must be willing to comply with the mandatory biopsies. * Patients must have a histologically confirmed metastatic and/or locally advanced sarcoma by the enrolling institution. * For histological specific cohorts, patients must have confirmed metastatic and/or locally advanced osteosarcoma, chondrosarcoma, undifferentiated pleomorphic sarcoma/malignant fibrous histiocytoma high grade myxofibrosarcoma (UPS/MFH/MFS), vascular sarcoma, alveolar soft part sarcoma (ASPS), dedifferentiated/pleomorphic liposarcoma, Small Blue Round CellSynovial, or leiomyosarcoma (LMS) by the enrolling institution. Note: Patients with confirmed sarcoma with histologies not defined by the above cohorts will be enrolled into the "Other" cohort. * Adequate performance status: * Participants ≥16 years ECOG 0 or 1/KPS 100-70% * Participants \<12-15 years Lanksky 100-70% * Patients must have at least one prior line of systemic therapy (e.g.chemotherapy, immunotherapy, targeted or biological therapy) for their sarcoma if standard treatment is appropriate. Treatment …