2650 - Integrating Collagen Tile Brachytherapy with External Beam Radiation and Temozolomide for Newly Diagnosed Glioblastoma: A Preliminary Report from a Feasibility Trial
Presenter(s)
M. S. Peach1, K. S. Lee2, L. Sloan3, J. Wanebo4, K. Smith5, A. W. Nowlan6,7, D. J. McCracken7, O. Bloch8, M. Shah9, A. Richardson9, M. H. Khattab10, I. Mohiuddin11, K. Tatebe12, E. L. Chang13, J. J. Dombrowski14, M. A. Garcia15, D. G. Brachman15, A. C. Turner15, S. Patel15, and C. Chen16; 1Department of Radiation Oncology, Brody School of Medicine, East Carolina University, Greenville, NC, 2ECU Health Medical Center, Greenville, NC, 3University of Minnesota: Department of Radiation Oncology, Minneapolis, MN, 4Ivy Brain Tumor Center, Barrow Neurological Institute, Phoenix, AZ, 5Barrow Neurological Institute, Phoenix, AZ, 6Peachtree Radiation Oncology, Atlanta, GA, 7Piedmont Healthcare, Atlanta, GA, 8UC Davis Brain Tumor Program, Sacramento, CA, 9Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 10Tampa General Hospital, Tampa, FL, 11AdventHealth Medical Group, Orlando, FL, 12Rush University Medical Center, Chicago, IL, 13Department of Radiation Oncology, University of Southern California Keck School of Medicine, Los Angeles, CA, 14Saint Louis University School of Medicine, St. Louis, MO, 15GT Medical Technologies, Tempe, AZ, 16Department of Neurosurgery at the Warren Alpert Medical School of Brown University, Providence, RI
Purpose/Objective(s): Glioblastoma (GBM) commonly undergoes rapid early progression (REP) after resection and prior to initiation of external beam radiation therapy (EBRT). A proposed strategy to forestall REP is by starting radiation at time of GBM resection using intracavitary collagen tile brachytherapy (CTBT). NCT05342883 (“GESTALT”) is a feasibility study of implanting CTBT at surgery followed by EBRT and temozolomide (TMZ) for patients with newly diagnosed GBM. The GESTALT protocol includes a novel EBRT planning methodology that accounts for dose from CTBT that results in a cumulative dose distribution similar to the standard of care, avoiding possible confounding effects from dose escalation. The primary study aim is to determine the proportion of patients initiating the EBRT within 21-35 days of surgery as a way of ensuring the novel EBRT planning does not introduce treatment delay.
Materials/Methods: In this single-arm, open-label, multi-center prospective trial NCT05342883, eligible patients received implantation of cesium-131 CTBT (GammaTile, GT Medical Technologies, Tempe AZ USA), and subsequent EBRT+ TMZ. The primary feasibility aim assesses the percentage of patients in the intent-to-treat (ITT) population who commenced EBRT within the 21–35-day postoperative window. Central review was required for EBRT plans. Data were analyzed using descriptive statistics, and confidence intervals were calculated to estimate the precision of the primary outcome measure.
Results: From 8/2022 - 12/2024, 46 patients with IDH wild type GBM were enrolled. Of 46 patients who completed the screening visit, 41 underwent surgery (IIT population) and 30 proceeded to EBRT as of the date of this report. Among these 30 patients, the median time from surgery to EBRT initiation was 29 days (range: 23–70 days, mean: 32 days, 95% CI: 26–36 days). There were 3 patients that started EBRT after 35 days. These three patients started on day 45, 65, and 70 due to fever, deep vein thrombosis, and wound infection, respectively. None of these three patients were delayed due to radiation planning time requirements.
Conclusion: These findings support the feasibility of planning and starting EBRT in a timely manner after CTBT. A high proportion of patients initiated EBRT within the desired postoperative timeframe, which is the primary study aim of NCT05342883. The safety aim will be reported separately with longer follow up. From a feasibility perspective, these preliminary findings support the conception of a phase 3 randomized trial to further evaluate the efficacy and safety of this novel combined therapeutic approach.