Inclusion Criteria:  Conventional chondrosarcoma, unresectable (=inoperable) or metastatic. Measurable disease by RECISTv1.1. Note: Tumor lesions located in a previously irradiated (or other locally treated) area will be considered measurable, provided there has been clear imaging-based progression of the lesions since the time of treatment. Radiologic progression of disease per RECISTv1.1 criteria within 6 months prior to screening for this study. Adequate hematologic, coagulation, hepatic and renal function as defined per protocol. Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1. Estimated life expectancy of at least 12 weeks. Availability of archival tissue or fresh cancer biopsy are mandatory.  Exclusion Criteria:  Any prior exposure to DR5 agonists. Allergy or sensitivity to INBRX-109 or known allergies to CHO-produced antibodies. Non-conventional chondrosarcoma, e.g., clear-cell, mesenchymal, extraskeletal myxoid, myxoid, and dedifferentiated chondrosarcoma. Prior or concurrent malignancies. Exception: Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessments. Chronic liver diseases. Exception: Patients with fatty liver disease are acceptable as long as adequate hepatic function as defined in the inclusion criteria is confirmed. Other exclusion criteria per protocol.