GammaTile, a radiation-emitting implant, has shown promising results in reducing early tumor regrowth in glioblastoma patients, according to new data from the GESTALT phase 1 feasibility trial. The trial, which tested the safety and practicality of incorporating GammaTile into standard treatment for newly diagnosed glioblastoma, found that only 6% of patients experienced rapid early progression, compared to historical rates of 50% to 70%.
Background on Glioblastoma Treatment
Standard treatment for glioblastoma typically involves surgical resection followed by external beam radiation therapy and chemotherapy. However, radiation is often delayed 3 to 6 weeks after surgery to allow the brain and incision to heal, during which time residual microscopic tumor cells can continue to proliferate.
This delay leads to rapid early progression, a phenomenon where tumor cells grow quickly enough to become visible on MRI scans before standard radiation treatment can begin. Rapid early progression is associated with poorer survival rates and sometimes requires a second surgery.
Trial Design and Results
The GESTALT trial enrolled 67 patients with newly diagnosed glioblastoma across 15 US hospitals. Patients underwent surgical resection with concurrent GammaTile placement in the resection cavity, followed by a shortened course of external beam radiation therapy and standard temozolomide-based chemotherapy.
The trial’s primary goal was to determine the safety and practicality of this combined approach, rather than to formally test efficacy against a control arm. The results showed that patients receiving GammaTile did not experience more serious side effects than those typically associated with standard treatment alone.
Clark Chen, MD, PhD, principal investigator of the trial, states that even after a successful surgery, microscopic glioblastoma cells remain in the brain. In 50 to 70 percent of patients, these cells grow quickly enough to become visible on MRI scans before standard radiation treatment can begin. This early regrowth is associated with poorer survival, creating an urgent need for treatments that can target cancer cells without affecting wound healing.
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GammaTile and Future Trials
GammaTile consists of cesium-131 radiation sources embedded in a bioresorbable collagen tile, placed directly into the surgical cavity at the time of tumor removal. The FDA first cleared GammaTile in 2018 for recurrent brain tumors and expanded that clearance in 2020 to include upfront treatment of any malignant brain tumor.
Based on the GESTALT findings, GT Medical Technologies has launched the BRIDGES phase 3 trial, which will compare standard resection plus external beam radiation therapy and temozolomide against resection with GammaTile placement followed by abbreviated external beam radiation therapy and the same chemotherapy regimen, in patients with newly diagnosed glioblastoma.
Michael Garcia, MD, MS, chief medical officer of GT Medical Technologies, notes that GammaTile was built to close the gap in glioblastoma care created by the wait for traditional external beam radiation to begin after surgery. These results show what’s possible when residual cancer cells are not given time to regrow between surgery and radiation.
The use of GammaTile could become a standard part of glioblastoma treatment, potentially improving patient outcomes by reducing the risk of early tumor regrowth. The ongoing BRIDGES trial will provide more insight into the efficacy of GammaTile in this context.
The GESTALT trial’s findings have significant implications for the treatment of glioblastoma, and the use of GammaTile may offer a new approach to addressing the challenges of this disease. For patients with glioblastoma, learning about stroke rehabilitation is also important, as it can help them understand the importance of rehabilitation in their treatment plan.