RBTT-09. A PHASE 1 STUDY OF CEMIPLIMAB IN PEDIATRIC PATIENTS WITH RELAPSED OR REFRACTORY (R/R) SOLID AND CENTRAL NERVOUS SYSTEM (CNS) TUMORS

Abstract

Abstract DIPG and HGG lead to the majority of pediatric cancer-related deaths. Despite multimodal treatment, the 2-year survival rates for DIPG and HGG are less than 10% and 20%, respectively. Anti-PD-1 therapy combined with radiotherapy has demonstrated synergistic anti-tumor effects. Cemiplimab, a human PD-1 monoclonal antibody, has demonstrated safety and efficacy in patients with advanced malignancies. Combination of cemiplimab with radiation has the potential to be an effective treatment for pediatric patients with DIPG or HGG. This is a multicenter, Phase 1 and early efficacy study (NCT03690869). Phase 1 will enroll pediatric patients with R/R solid or CNS tumors (N≥30) into two age cohorts (0 to < 12 and 12 to < 18 years). Cemiplimab will be administered intravenously every 2 weeks as monotherapy. Primary objectives of Phase 1 are to confirm safety and assess the pharmacokinetics (PK) of cemiplimab to recommend a Phase 2 dose (RP2D) for clinical efficacy assessment. The Efficacy phase will enroll patients with newly diagnosed DIPG or HGG (dose escalation: N≥12 patients each; dose expansion: N≤40 patients each), or recurrent HGG (dose escalation: N≥6 patients; dose expansion: ≤20 patients) into two age cohorts (≥3 to < 12 years and 12 to ≤25 years). There will be two treatment arms for patients with newly diagnosed DIPG or HGG: cemiplimab in combination with conventionally fractionated (Arm 1) or hypofractionated (Arm 2) radiotherapy. Patients with recurrent HGG will receive cemiplimab concomitantly with reirradiation. All patients will continue cemiplimab as monotherapy at completion of combination therapy. Primary objectives of Efficacy Phase are to confirm safety and anticipated RP2D, assess PK, and determine survival and antitumor activity at 12 months (overall survival for newly diagnosed DIPG and recurrent HGG; progression-free survival for newly diagnosed HGG) of cemiplimab when given concomitantly with radiation. This study is currently recruiting patients across multiple sites.