Plus Therapeutics, a clinical-stage pharmaceutical company dedicated to developing targeted radiotherapeutics for challenging central nervous system (CNS) cancers, recently announced a significant advancement: the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for REYOBIQ™ (Rhenium Re186 Obisbemeda). This clearance initiates the ReSPECT-PBC trial, a vital step toward bringing a novel treatment to pediatric patients suffering from highly aggressive brain tumors, specifically recurrent, refractory, or progressive high-grade glioma (HGG) and ependymoma. These pediatric brain cancers are notoriously difficult to treat, with current standard therapies like surgery and external beam radiation offering limited improvements in survival rates, which can be as low as 22% for HGG, emphasizing the critical unmet need REYOBIQ aims to address. Funded by a $3.0 million research grant from the U.S. Department of Defense, the Phase 1/2a ReSPECT-PBC trial is meticulously designed as a two-part, single-arm, prospective study that will first determine the maximum tolerated dose (MTD) and assess the safety and tolerability of REYOBIQ in approximately 24 pediatric patients (aged 6 to 21, with case-by-case consideration up to 25) using a modified 3+3 dose escalation scheme. Subsequently, the Phase 2a portion will enroll around 32 patients (12 with ependymoma and 20 with HGG) at the recommended Phase 2 dose to evaluate efficacy. REYOBIQ has the potential to transform patient outcomes by precisely delivering high doses of beta radiation directly into the tumor via convection enhanced delivery (CED), a method that bypasses the blood-brain barrier and minimizes exposure to surrounding healthy, developing brain tissue. This innovative approach builds upon promising preclinical data and positive efficacy signals observed in adult patients, as evidenced by the successful ReSPECT-GBM trial for recurrent glioblastoma, which showed a doubling of overall survival for patients receiving a therapeutic radiation dose greater than 100 Gy, a finding recently published in Nature Communications. REYOBIQ itself is a unique injectable radiotherapy formulated to deliver a targeted, potent dose of radiation using Rhenium-186, an ideal radioisotope for CNS applications due to its short half-life for targeted destruction and gamma energy for real-time imaging, further solidifying Plus Therapeutics' commitment to developing advanced, image-guided radiotherapeutics for difficult-to-treat CNS cancers.