Study of Cabiralizumab in Patients With Pigmented Villonodular Synovitis / Diffuse Type Tenosynovial Giant Cell Tumor

Inclusion Criteria: * Histologically confirmed diagnosis of inoperable PVNS/ dt-TGCT or potentially resectable tumor that would result in unacceptable functional loss or morbidity as determined by a qualified surgeon or multi-disciplinary tumor board (must be documented in the CRF during screening) * Measurable PVNS/dt-TGCT by RECIST 1.1 on MRI * ECOG performance status \<1 Exclusion Criteria: * Prior therapy with an anti-CSF1R antibody * Prior therapy with PLX3397 unless discontinued for intolerance (i.e., non-progression on prior kinase inhibitor) * Liver function tests (including ALT, AST, and total bilirubin), outside of the range of local laboratory normal at Screening * Inadequate organ or bone marrow function * History of congestive heart failure or myocardial infarction \<1 year prior to first study dose administration * Significant abnormalities on ECG at Screening * Contraindications to MRI and use of intravenous gadolinium-based contrast agents * Creatine Kinase ≥ 1.5x the upper limit of normal * Positive test for latent TB at Screening (Quantiferon test) * Active known or suspected autoimmune disease