A Study to Assess Safety and Efficacy of SOT106 in Patients With LRRC15-positive Advanced Unresectable or Metastatic Osteosarcoma or Soft Tissue Sarcoma

The trial will consist of the following parts: ‐ Part A: a multinational, multicenter, open‐label, TITE‐BOIN‐guided trial todetermine the MTD and RP2Ds, to evaluate the safety, PK, and preliminary efficacy ofescalating doses of SOT106 in participants with LRRC15‐positive advanced ormetastatic osteosarcoma or soft tissue sarcoma (STS) who have received and/or havebeen determined to be intolerant of all standard of care therapy known to conferclinical benefit. ‐ Part B: This is a randomized, multinational, multicenter, open‐label doseoptimization trial evaluating the two recommended doses for optimization (RDOs)identified in Part A. After the determination of the MTD in Part A andidentification of RDOs, a randomized dose optimization part will be initiated toevaluate the two selected RDOs and to identify the optimal biological dose thatoffers the best balance between benefit and risk and to evaluate safety and efficacyof SOT106 in participants with advanced unresectable or metastatic osteosarcoma orSTS who have no further standard treatment options.