The US Food and Drug Administration (FDA) has approved floretyrosine F 18 (¹⁸F-FET) from Telix Pharmaceuticals for positron emission tomography (PET) imaging in patients with glioma, marking the first FDA approval of an FET-PET imaging agent for glioma in the United States.
The approval, announced by Telix on September 14, 2026, covers the use of floretyrosine F 18 to help differentiate recurrent or progressive glioma from treatment-related changes, alongside other diagnostic evaluations. The agent is approved for use in adults and pediatric patients aged 1 month and older.
This distinction can be clinically important after glioma treatment, when imaging abnormalities may represent either active tumor or treatment-related effects. MRI remains central to glioma follow-up, but post-treatment changes can sometimes be difficult to distinguish from recurrent disease.
What Is Floretyrosine F 18?
Floretyrosine F 18, also known as ¹⁸F-FET, is a radioactive diagnostic imaging agent used with PET.
Following intravenous administration, the agent is transported through amino acid transport systems, including L-type amino acid transporters LAT1 and LAT2. The fluorine-18 radioisotope then enables areas of increased tracer uptake to be visualized on PET imaging.
Unlike conventional anatomical imaging, amino acid PET provides functional information related to amino acid transport and tumor activity, potentially complementing MRI in the assessment of glioma.
Floretyrosine F 18 is a diagnostic imaging agent, not an anticancer treatment, and its FDA indication specifies that findings should be interpreted together with other diagnostic evaluations.
Addressing a Diagnostic Challenge in Glioma
A major challenge in the follow-up of patients with glioma is determining whether new or increasing abnormalities after treatment represent recurrent or progressive tumor or changes caused by prior therapy.
Treatment-related effects, including radiation-associated changes, can resemble tumor progression on conventional imaging.
Amino acid PET has therefore been investigated as a complementary imaging approach that may provide additional information when MRI findings are equivocal.
According to Telix, the FDA approval makes floretyrosine F 18 the first FDA-approved FET-PET imaging agent specifically indicated for glioma in the United States.
Experts Comment on the Approval
Kevin Richardson, Chief Executive Officer of Telix Precision Medicine, commenting on how the approval could affect clinical decision-making for patients with glioma, said:
“As the first FDA-approved PET imaging drug for glioma, Pixclara will provide physicians in the U.S. with more certainty in their diagnoses and greater confidence in their treatment planning for patients.”
Kelly Sitkin, President and CEO of the American Brain Tumor Association, commenting on the potential role of the imaging approach in glioma follow-up, said:
“We welcome the FDA’s decision, which provides a pathway to access this technology in the U.S. and helps address a critical unmet need in brain cancer diagnostics.”
Patrick Wen, MD, E. Antonio Chiocca, MD, PhD, Family Endowed Chair in Neuro-Oncology at Mass General Brigham Cancer Institute, commenting on the significance of having an FDA-approved FET-PET imaging option, said:
“This is a very positive step forward for brain cancer imaging and treatment planning.”
Wen highlighted the potential of FET-PET to contribute to the management of patients with glioma and to support treatment planning when conventional imaging does not provide sufficient diagnostic certainty.
Approval Follows Previous FDA Complete Response Letter
The approval follows a longer regulatory pathway for floretyrosine F 18.
In April 2025, the FDA issued Telix a Complete Response Letter for its original New Drug Application. The agency determined that the submitted evidence did not, at that stage, provide substantial evidence of effectiveness and requested additional confirmatory evidence.
Following subsequent discussions with the FDA, Telix developed a resubmission package incorporating additional analyses of existing clinical data.
The company resubmitted the application in March 2026, and the FDA accepted the application for review the following month.
The September 2026 approval therefore follows the completion of that regulatory resubmission process.
Further Development in Neuro-Oncology
Telix is also investigating floretyrosine F 18 in a Phase 3 study evaluating its potential use in the diagnosis of brain metastases.
That indication remains investigational and is not included in the current FDA approval.
The company is separately developing iodofalan I 131 as an investigational targeted radiopharmaceutical therapy for recurrent glioblastoma. The therapeutic candidate has not received marketing authorization.
The approval of floretyrosine F 18 introduces an FDA-approved amino acid PET imaging option for glioma in the United States. It may expand the role of FET-PET as a complementary tool when clinicians need to distinguish suspected tumor progression from treatment-related changes.
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