PROVIDENCE, R.I., August 18, 2026
GT Medical Technologies, Inc. announced new clinical findings suggesting that its GammaTile® targeted radiation therapy may help address early tumor regrowth in patients with newly diagnosed glioblastoma. Presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, results from the multicenter GESTALT feasibility study evaluated the integration of GammaTile with surgery, followed by a shortened course of external beam radiation therapy (EBRT) and standard chemotherapy. The findings provide the foundation for an ongoing Phase III randomized clinical trial evaluating the approach in frontline glioblastoma treatment.
Immediate Radiation Targets Residual Tumor Cells
Glioblastoma is an aggressive brain cancer that remains difficult to treat despite advances in surgery, radiation and chemotherapy. Standard care generally involves maximal surgical removal followed by radiation and chemotherapy, but these treatments are typically delayed for several weeks after surgery to allow the brain and surgical site to heal. During this interval, microscopic tumor cells remaining after surgery can continue to proliferate, creating a critical window for early disease progression. The GESTALT investigators evaluated GammaTile, a cesium-131-based radiation therapy device implanted directly into the surgical cavity immediately after tumor removal. Unlike conventional EBRT, which begins after postoperative recovery, GammaTile is designed to deliver localized radiation immediately at the site where the tumor was removed. The company states that the short radiation range allows treatment to remain concentrated around the surgical cavity while minimizing exposure to surrounding healthy tissue. GammaTile also delivers a higher localized radiation dose than conventional external radiation can safely provide. The multicenter Phase I GESTALT study, led by Clark Chen, M.D., Ph.D., involved 67 patients across 15 U.S. institutions. Investigators assessed whether GammaTile could be incorporated safely and practically into the treatment pathway for newly diagnosed glioblastoma. Patients received surgery with concurrent GammaTile placement, followed by a shortened EBRT course and standard chemotherapy.
GESTALT Reports Lower Early Tumor Regrowth
A key observation from the feasibility study was the rate of rapid early tumor regrowth following surgery. According to GT Medical Technologies, only 6% of patients experienced rapid early tumor regrowth, compared with the 50% to 70% rates cited in the release for patients whose radiation and chemotherapy are delayed for several weeks after surgery. The findings suggest that immediate localized radiation may help target residual glioblastoma cells during the postoperative period, potentially reducing the opportunity for microscopic disease to progress before conventional treatment begins. Importantly, the study also found that the combined treatment approach was safe and feasible, with patients not experiencing more serious adverse effects than would typically be expected with standard treatment. The results should nevertheless be interpreted in the context of the study design. GESTALT was a Phase I feasibility study, rather than a definitive randomized efficacy trial. The reported findings provide an important clinical signal but do not establish that GammaTile improves overall survival or other long-term outcomes. A larger randomized study is needed to determine its potential clinical benefit.
Advertisement
Phase III BRIDGES Trial Advances Clinical Evaluation
Building on the GESTALT findings, GT Medical Technologies has launched the Phase III BRIDGES trial, designed to further evaluate GammaTile as part of frontline treatment for newly diagnosed glioblastoma. The randomized study will provide an opportunity to assess whether the immediate radiation strategy can translate the encouraging feasibility findings into measurable improvements in patient outcomes. The development program reflects a broader effort to improve localized cancer treatment by delivering radiation closer to the time of tumor removal. GammaTile is already authorized for commercial distribution in the United States for patients with newly diagnosed malignant intracranial neoplasms and recurrent intracranial neoplasms. The company is now investigating whether its targeted approach can play a larger role in the initial treatment of glioblastoma. For patients facing this highly aggressive disease, the central scientific question is whether treating residual tumor cells immediately during surgery can prevent early progression while maintaining an acceptable safety profile. Results from the ongoing Phase III BRIDGES study are expected to provide more definitive evidence regarding the potential role of GammaTile in the frontline glioblastoma treatment paradigm.
Source: GT Medical Technologies press relese
