Tegavivint With Gemcitabine in Patients With Relapsed or Refractory Osteosarcoma

Tegavivint will be administered second, IV over 4 hours, on days 1, 8, and 15 at the dose level assigned at study entry Cycle length will be 21 days. A cycle may be repeated for a total of 17 cycles, up to a total duration of therapy of approximately 12 months.

Gemcitabine will be administered first, intravenously (IV) over 60 minutes, on days 1 and 8 at a fixed dose of 1000 mg/m2