Phase 1 dose-escalation trial using convection-enhanced delivery of radio-immunotheranostic 124I-Omburtamab for diffuse intrinsic pontine glioma
Mark M. Souweidane, Evan D. Bander, Pat Zanzonico, Anne S. Reiner, Nicole Manino, Sofia Haque, Jorge A. Carrasquillo, Serge K. Lyashchenko, Sunitha B. Thakur, Jason S. Lewis, Maria Donzelli, Nai‐Kong V. Cheung, Steven M. Larson, Kim Kramer, Neeta Pandit‐Taskar, Ira J. Dunkel
Abstract
BACKGROUND: Median survival for patients with Diffuse Intrinsic Pontine Glioma (DIPG) is 8-12 months. METHODS: A phase 1, open label, 3 + 3 dose-escalation trial delivered radiolabeled 124I-Omburtamab, targeting B7-H3, using MR-guided stereotactic convection-enhanced delivery (CED) into the brainstem of pediatric DIPG patients. CED was performed after completion of standard-of-care external-beam radiation therapy (EBRT). Fifty children were treated and evaluable. 124I-Omburtamab activity was escalated from 0.25 to 10.0 mCi (9.25-370 MBq) and volume escalated from 0.25 mL to 10.0 mL with serial PET/MRI post administration. Safety was the primary outcome. National Cancer Institute Common Terminology Criteria for Adverse Events were assessed for 30 days following CED of 124I-Omburtamab. Secondary outcomes included overall survival and lesion-to-whole-body absorbed dose ratio. RESULTS: The maximum tolerated activity per study protocol was determined to be 6mCi (222 MBq). The overall mean (±SD) total absorbed dose in the lesion per unit injected activity was 35.2 ± 18 cGy/MBq with a high lesion-to-whole-body absorbed dose ratio averaging 816, across all activity levels. Eleven patients had treatment-related grade 3 CNS toxicities with no grade-4 or -5 CNS toxicities. Five dose-limiting toxicity events occurred. Median survival was 15.29 months from diagnosis (95% CI: 12.20-16.83 months). Survival rate estimates at 1, 2, and 3 years were 65.4% (CI 53.3-80.1%), 18.4% (CI: 10.2-33.2%), and 11.7% (CI: 5.3-25.7%), respectively. CONCLUSIONS: Administration of 124I-Omburtamab via CED is a safe treatment option for DIPG, with a maximum tolerated activity level identified. This study represents the first-in-human theranostic use of a 124I radiopharmaceutical, simultaneously, as an imaging and therapeutic agent. TRIAL REGISTRATION: NCT01502917; https://clinicaltrials.gov/study/NCT01502917.