Title
A Feasibility and Randomized Phase 2/3 Study of the VEFGR2/MET Inhibitor Cabozantinib in Combination with Cytotoxic Chemotherapy for Newly Diagnosed Osteosarcoma

Description
This phase II/III trial tests the safety, side effects, and best dose of the drug cabozantinib in combination with standard chemotherapy, and to compare the effect of adding cabozantinib to standard chemotherapy alone in treating patients with newly diagnosed osteosarcoma. Cabozantinib is in a class of medications called kinase inhibitors which block protein signals affecting new blood vessel formation and the ability to activate growth signaling pathways. This may help slow the growth of tumor cells. The drugs used in standard chemotherapy for this trial are methotrexate, doxorubicin, and cisplatin (MAP). Methotrexate stops cells from making DNA and may kill tumor cells. It is a type of antimetabolite. Doxorubicin is in a class of medications called anthracyclines. It works by slowing or stopping the growth of tumor cells in the body. Cisplatin is in a class of medications known as platinum-containing compounds. It works by killing, stopping or slowing the growth of tumor cells. Adding cabozantinib to standard chemotherapy may work better in treating newly diagnosed osteosarcoma.

Objective
PRIMARY OBJECTIVES:

I. To determine the feasibility of adding cabozantinib S-malate (cabozantinib) to standard MAP (high dose methotrexate, doxorubicin hydrochloride [doxorubicin], and cisplatin) chemotherapy in patients with newly diagnosed metastatic osteosarcoma with a resectable primary tumor.

II. To determine whether MAP chemotherapy plus cabozantinib results in more favorable event-free survival (EFS) than MAP chemotherapy alone in patients with localized, resectable osteosarcoma.

III. To determine whether MAP chemotherapy plus cabozantinib results in more favorable event-free survival (EFS) than MAP chemotherapy alone in patients with metastatic, pelvic and unresectable osteosarcoma.

SECONDARY OBJECTIVES:

I. To determine whether MAP chemotherapy plus cabozantinib results in more favorable overall survival (OS) than MAP chemotherapy alone in patients with localized, resectable osteosarcoma.

II. To determine whether MAP chemotherapy plus cabozantinib results in more favorable overall survival (OS) than MAP chemotherapy alone in patients with metastatic, pelvic and unresectable osteosarcoma.

III. To prospectively validate that elevated circulating tumor DNA (ctDNA) levels greater than or equal to 5% at the time of diagnosis are associated with increased risk of EFS-event in patients with localized, resectable osteosarcoma.

IV. To prospectively validate that elevated ctDNA levels greater than or equal to 5% at the time of diagnosis are associated with increased risk of EFS-event in patients with metastatic, pelvic and unresectable osteosarcoma.

V. To prospectively validate that elevated ctDNA levels greater than or equal to 3% after initiation of therapy and prior to definitive surgery are associated with increased risk of EFS-event in patients with localized, resectable osteosarcoma.

VI. To prospectively validate that elevated ctDNA levels greater than or equal to 3% after initiation of therapy and prior to definitive surgery are associated with increased risk of EFS-event in patients with metastatic, pelvic and unresectable osteosarcoma.

VII. To determine whether MAP chemotherapy plus cabozantinib results in increased symptom burden and decreased tolerability to patients as measured by patient reported therapy-specific acute toxicities (Patient-Reported Outcomes-Common Terminology Criteria for Adverse Events [PRO-CTCAE]).

Treatment OUTLINE: This is a dose-escalation study of cabozantinib (Feasibility Phase) followed by a randomized phase II/III study (Efficacy Phase).

FEASIBILITY PHASE (CLOSED TO ACCRUAL 05/09/2025): Patients receive cabozantinib orally (PO), methotrexate intravenously (IV), doxorubicin IV, and cisplatin IV for two 35-day "induction" cycles. Patients are then considered for appropriate local control. Then they receive "consolidation" with methotrexate IV, doxorubicin IV, and cisplatin IV for one 35-day cycle, followed by cabozantinib PO, methotrexate IV, doxorubicin IV, and cisplatin IV for one 35-day cycle, and cabozantinib PO, methotrexate IV, and doxorubicin IV for two 35-day cycles. Patients then receive cabozantinib PO for six 28-day "maintenance" cycles.

EFFICACY PHASE: Patients with standard risk osteosarcoma are randomized to Arm A or Arm B. Patients with high risk osteosarcoma are randomized to Arm C or Arm D.

Key Eligibility Inclusion Criteria:

Patients must be < 40 years of age at the time of enrollment.

Patients must have a body surface area of >= 0.8 m^2 at the time of enrollment.

Patients must have histologic diagnosis (by institutional pathologist) of newly diagnosed high grade osteosarcoma. Primary tumors of all extremity and axial sites are eligible as long as diagnosis of high-grade osteosarcoma is established. Osteosarcoma as a second malignancy is eligible if no prior exposure to systemic chemotherapies.

Feasibility Phase (NOTE: as of Amendment #2B, the feasibility phase has been completed) Patients must have metastatic disease and a resectable primary tumor. Designation of a primary tumor as resectable will be determined at the time of diagnosis by the institutional multidisciplinary team.

Applicable Disease Sites
Sarcoma

Participating Institutions
Gundersen Health System; UW Health University Hospital