2.1 Patient Population
Patients 6-40 years of age with a histologically confirmed diagnosis of relapsed or refractory Ewing sarcoma or high-grade osteosarcoma with evaluable or measurable disease were eligible. Molecular evidence of translocation involving EWSR1 or FUS was required for patients with Ewing sarcoma. A body surface area (BSA) ≥1.25m2 and <2m2 was required due to potential deviations due to rounding given available size of cabozantinib tablets. In addition, Lansky (<16 years of age) or Karnofsky (≥16 years of age) performance score of ≥50 was required. Prior treatment with TKIs other than cabozantinib was allowed. Prior use of topotecan and cyclophosphamide was allowed. If this regimen immediately preceded enrollment to the trial, then no more than two prior cycles were allowed, and the patient must not have progressed on this combination. Patients with unhealed and/or chronic wounds were not eligible, and patients had to be ≥2 weeks from prior major surgical procedures.
The trial was approved by the Dana-Farber/Harvard Cancer Center Institutional Review Board. All patients (or parent/guardian) provided informed consent for participation.