(P 261) SUSTAINED RESPONSE WITH RIVOCERANIB AND DENOSUMAB IN RELASPED OSTEOSARCOMA

Objective: Osteosarcoma is a malignancy originating in the mesenchymal cells within the bones. Relapsed osteosarcoma typically has an abysmal prognosis with less than 20% overall survival at 5 years. Targeted therapies have made significant advancements in overall survival for oncology patients in the last two decades, but there have unfortunately been few advancements in treatment of relapsed osteosarcoma. Angiogenesis is an important means for tumor growth in osteosarcoma, and VEGF-2 is a main receptor in the angiogenesis pathway. VEGF overactivation is a poor prognostic indicator in relapsed osteosarcoma with lung metastasis. Rivoceranib is a medication which targets the vascular endothelial growth factor receptor 2 (VEGF-2). Rivocernib’s mechanism of action would indicate it could be a possible targeted treatment option for relapsed osteosarcoma patients.

Methods: Our patient presented in 2015 with osteosarcoma of the left distal femur. She underwent conventional chemotherapy and resection at her original diagnosis. She subsequently relapsed a total of four times, and during this time she underwent five resections and systemic therapy. The patient decided she did not want to undergo conventional chemotherapy after her fourth relapse, and expanded access was obtained for Rivoceranib. The patient was started on Rivoceranib 700mg PO daily with monthly denosumab 120mg SQ injections. On repeat imaging her lesions have continued to show either complete response or partial response with stability in her lung lesions with gradually decreasing SUV.

Results: Imaging shows sustained partial response with Rivoceranib and denosumab therapy for over 1 year since the patient’s fourth relapse. She has mucocutaneous side effects and hypothyroidism secondary to her Rivoceranib, but these have been managed by topical interventions for her rashes and levothyroxine replacement. This therapy was otherwise well tolerated.

Conclusion: Rivoceranib and denosumab combination therapy is a promising treatment option for relapsed osteosarcoma. Further research is needed in the use of Rivoceranib in patients with relapsed osteosarcoma.