TLX101 Demonstrated Efficacy in Recurrent High-Grade Glioma

According to preliminary results from the phase 2 IPAX-Linz study, TLX101 therapy was efficacious in recurrent high-grade glioma, a type of brain cancer.

Treatment with TLX101 (131I-iodofalan1) elicited efficacy in recurrent high-grade glioma, a type of brain cancer, according to preliminary results from the phase 2 IPAX-Linz study which were shared in a press release from Telix Pharmaceuticals Limited.

TLX101 treatment was well tolerated with no serious side effects reported in patients and indicated a median overall survival of 12.4 months from the initiation of treatment with TLX101, or 32.2 months from initial diagnosis. The press release notes that this is consistent with previous data observed in the IPAX-1 study in patients at first recurrence, with only one prior resection and treatment with standard chemoradiotherapy.

The median overall survival reported in the IPAX-1 trial was 13 months from the initiation of treatment with TLX101, or 23 months from initial diagnosis. Comparatively, recurrent glioblastoma treated with external beam radiation therapy alone have a reported median survival of 9.9 months from treatment.

“These preliminary results in relapsed patients showed that TLX101 treatment was very well tolerated, with no serious adverse events, at a higher dose than in previous studies,” said principal investigator of the IPAX-Linz, IPAX-1 and IPAX-2 studies, Professor Josef Pichler, of Kepler University Hospital, in Austria.

“Early efficacy from IPAX-1 was corroborated, despite the poor prognostic parameters with MGMT unmethylated tumors and multiple relapses before commencing experimental therapy in this IPAX-Linz study. TLX101 continues to show significant potential to improve outcomes for patients living with high-grade glioma. These results also potentially support higher therapeutic doses in subsequent prospective controlled studies,” Pichler continued.

The press release went on to highlight that Pichler will share preliminary results from IPAX-Linz at the Nuclear Medicine and Neuro-oncology Symposium taking place in Vienna, Austria, from May 9th to 10th, 2025.

TLX101 is a targeted radiation treatment that is given through the bloodstream and is designed to attach to a specific protein called LAT1, which is found in high amounts on glioblastoma cells. Because the brain is protected by a natural barrier — called the blood-brain barrier — TLX101 was developed as a small molecule that can pass through this barrier to reach the tumor.

TLX101 has been granted orphan drug status in both the United States and Europe, which means it is recognized as a potential treatment for a rare disease like glioma. However, TLX101 and its companion imaging agent, TLX101-CDx, are still being studied in clinical trials and have not yet been approved for use by health authorities in any country.

More Information on the Phase 2 Trial

The phase 2 IPAX-Linz study is a clinical trial designed to evaluate the safety, tolerability and efficacy of TLX101 treatment when combined with external beam radiation therapy. This study particularly focuses on patients with high-grade gliomas, including glioblastoma, who are experiencing either their first or second recurrence of the disease. Eight patients were included in the study and received intravenous doses of TLX101 that were adjusted based on patient responses. TLX101 was given in multiple sequential doses — up to 4 gigabecquerels (GBq) before and up to 2 GBq after a second course of external beam radiation therapy.

To be eligible for the trial, participants needed to have glioblastoma that had recurred following completion of standard treatment with radiation and chemotherapy. Additionally, at least six months must have passed since their initial course of radiation. Patients also had to undergo an imaging scan using the investigational PET6 agent, TLX101-CDx (Pixclara®7; 18F-floretyrosine; 18F-FET), which helps identify tumors with unusually high amino acid activity.

Moreover, surgery was permitted for patients whose tumors had returned. Notably, among the eight participants, five had tumors with an unmethylated MGMT gene, a feature often linked to poorer treatment outcomes.

“These are encouraging results, offering new options for patients with historically poor outcomes. We are grateful to Dr. Pichler and his team for building on the IPAX-1 study in a more advanced and complex study cohort that is also representative of a real-world patient population,” Dr. David Cade, chief medical officer at Telix, concluded.

The Company continues to investigate TLX101 in the front-line and recurrent treatment settings, and the phase 1/2 IPAX-2 clinical trial investigating standard of care and TLX101-CDx as a companion diagnostic, continues to recruit patients with front-line glioblastoma.

For more news on cancer updates, research and education, don’t forget to subscribe to CURE®’s newsletters here.