Cellectar Biosciences Reports Initial Phase 1 Results For Iopofosine I-131 In Relapsed Pediatric High-Grade Glioma, Showing Extended Survival And Disease Control In CLOVER-2 Trial

Cellectar Biosciences, Inc. (NASDAQ:CLRB), a late-stage clinical biopharmaceutical company focused on the discovery and development of drugs for the treatment of cancer, today announced initial results as of June 10, 2025, from the CLOVER-2 Phase 1 clinical trial evaluating iopofosine I 131 in relapsed/refractory pediatric high-grade glioma (pHGG) patients. Rare Pediatric Drug and Orphan Drug Designations for pHGG have previously been granted for iopofosine I 131.

Pediatric high-grade gliomas are a collection of aggressive tumors affecting the brain and central nervous system. The patients enrolled in CLOVER-2 with pHGG (n=14) were diagnosed with diffuse midline gliomas (DMG), ependymomas, diffuse intrinsic pontine gliomas (DIPG), diffuse hemispheric gliomas (DHG) and anaplastic ependymomas. As reported in the literature, median progression free survival (PFS) and overall survival (OS) for patients with relapsed pHGG is poor; approximately 2.25 months and 5.6 months, respectively. While MRI measures of tumor volume change can be helpful and are used as a surrogate in clinical trials, they often fail to predict survival.

All patients receiving a minimum of 55 mCi total administered dose (n=7) experienced an average of 5.4 months of PFS and 8.6 months of OS, ongoing. All patients experienced disease control, which according to the committee for the Response Assessment in Pediatric Neuro-Oncology (RAPNO) does correlate with survival benefit. Three patients who received additional dosing cycles (a minimum of four total infusions) had an average PFS of 8.1 months and an OS of 11.5 months (ranging from 4.9 to 14.9 months), ongoing, with two achieving an objective response (ORR).