Pazopanib as maintenance therapy in pediatric ewing sarcoma: a case series of six patients

Ewing sarcoma (ES) is an aggressive pediatric bone and soft tissue malignancy. Despite advances in multimodal therapy, outcomes remain suboptimal for patients with high-risk features such as large tumor volume, poor histologic response, disseminated disease, or relapse. Maintenance strategies have gained interest in pediatric sarcomas, but evidence in ES is limited. Pazopanib, an oral multi-targeted tyrosine kinase inhibitor, has shown activity in adult soft tissue sarcomas; however, data on its use as maintenance therapy in pediatric ES are scarce. We retrospectively analyzed six pediatric ES patients who received pazopanib as maintenance therapy following consolidation treatment or, when applicable, after high-dose chemotherapy with autologous stem cell transplantation. Indications included poor-risk localized disease, relapse, or stable residual disease after frontline therapy. Pazopanib dosing, duration, toxicity, and clinical outcomes were reviewed. Pazopanib was administered at doses of 400–800 mg in five patients and 200 mg twice daily in one patient. Hair depigmentation occurred in all patients, and one patient developed reversible hepatotoxicity requiring temporary interruption and dose reduction. At a median follow-up of 47 months (range, 18–53 months), five patients remained in complete remission. One patient with disseminated disease at diagnosis developed intracranial relapse 18 months post-transplant while still receiving pazopanib. In this retrospective cohort, pazopanib was generally well tolerated and may have a potential role as maintenance therapy in selected high-risk pediatric ES patients. However, efficacy cannot be determined from this limited series, and prospective studies are needed to better define its clinical utility in ES.