The tyrosine kinase inhibitor regorafenib has demonstrated feasibility and tolerability when combined with standard chemotherapy as first-line treatment for multi-metastatic Ewing sarcoma, according to results from the Rego-Inter-Ewing-1 phase Ib trial presented at the ASCO 2025 Congress by Dr. Pablo Berlanga, a pediatric oncologist at Gustave Roussy.
The international, multicenter study represents a significant shift in treatment strategy for this aggressive bone cancer, testing innovative therapy from the outset rather than reserving it for relapse situations. Ewing sarcoma is the second most common malignant bone tumor in France, primarily affecting children, adolescents, and young adults, with two-thirds of patients aged between 5 and 25 years.
Critical Need for New Treatment Approaches
Patients with multi-metastatic Ewing sarcoma face particularly grim outcomes, with those having extrapulmonary metastases experiencing a three-year progression-free survival rate of just 20%. The presence of metastases represents the most important prognostic factor at diagnosis, highlighting the urgent need for more effective therapeutic interventions.
"The goal is to ensure that young patients benefit from therapeutic innovations at the outset of their care," the researchers noted, contrasting this approach with traditional early-phase clinical trial protocols that typically reserve innovative treatments for relapse situations.
Trial Design and Patient Population
The Rego-Inter-Ewing-1 study enrolled 13 patients aged between 8 and 23 years across seven centers in France, Australia, and the Netherlands. The trial was designed to assess the feasibility of combining regorafenib with standard VDC/IE chemotherapy as first-line treatment for newly diagnosed multi-metastatic Ewing sarcoma patients.
Regorafenib, a tyrosine kinase inhibitor that blocks signals tumor cells need to grow and form new blood vessels, had previously shown limited efficacy as monotherapy in relapsed Ewing sarcoma. The current study aimed to enhance its therapeutic potential by combining it with chemotherapy from treatment initiation.
Safety and Tolerability Results
Early results demonstrated that the combination therapy was well tolerated, with only one dose-limiting toxicity observed throughout the study period. No unexpected adverse events were reported, providing confidence in the safety profile of the combination approach.
The study successfully determined the maximum tolerable dose of regorafenib for young patients, establishing a foundation for future larger-scale trials. The research was supported by the 2021 Fight Kids Cancer call for projects, with regorafenib provided by Bayer.
Future Clinical Development
The positive safety and tolerability findings support the upcoming launch of a European phase III trial, which will compare the regorafenib-chemotherapy combination to chemotherapy alone in all newly diagnosed multi-metastatic Ewing sarcoma patients. Dr. Berlanga indicated that this pivotal trial is expected to open in France by the end of 2025.
The EURO EWING consortium's commitment to developing new therapeutic approaches from first-line treatment represents a paradigm shift that could significantly impact outcomes for high-risk pediatric and young adult cancer patients. This approach ensures that the most vulnerable patients have immediate access to potentially life-saving innovations rather than waiting for disease progression.
