Erdafitinib in pediatric patients with advanced solid tumors with fibroblast growth factor receptor (FGFR) gene alterations: RAGNAR study pediatric cohort.

Abstract

TPS10058 Background: FGFR gene alterations have been observed in pediatric patients with cancers and represent potentially targetable genomic variants. Gliomas (high- and low-grade) and soft tissue sarcomas are among the pediatric solid tumors that may harbor FGFR alterations. Erdafitinib is a selective pan-FGFR inhibitor approved in patients with locally advanced or metastatic urothelial carcinoma with susceptible FGFR2/3 alterations. RAGNAR (NCT04083976) is an ongoing single-arm, open-label, phase 2 histology-agnostic study investigating the efficacy and safety of erdafitinib in patients with advanced solid tumors exhibiting FGFR alterations after failure of standard systemic therapies. Here we describe the pediatric study cohort. Methods: The pediatric cohort (n = 26, planned) includes patients (≥ 6- < 18 y) with advanced solid tumors (measurable disease per RECIST v.1.1 or RANO [brain tumors]) with FGFR mutations, gene fusions, or internal tandem duplication (patients with FGFR amplification are not eligible) identified via local test reports or central molecular testing. Eligible patients will have received ≥ 1 lines of prior systemic therapy, have exhausted or be unable to tolerate standard-of-care therapies, and have documented disease progression and measurable disease. In addition, up to 6 patients in this cohort will be allowed to be treatment naive. Children and adolescents will be treated with oral erdafitinib, allowing pharmacodynamically guided uptitration based on serum phosphate levels to maximize efficacy. Treatment will continue until progressive disease. The primary end point is overall response rate (ORR) assessed by an independent review committee. Secondary efficacy end points include ORR assessed by the investigator, duration of response, disease control rate, clinical benefit rate, progression-free survival, and overall survival. Other secondary end points are pharmacokinetic exposure parameters, incidence/severity of adverse events, and change from baseline in patient-reported health status. End-of-treatment visit will occur 30 days after the last dose of erdafitinib. A follow-up phase will continue until death, withdrawal of consent, loss to follow-up, or end of study. As of January 2022, 3 patients have been enrolled. Clinical trial information: NCT04083976.