EJNMMI Research: TLX400-Tx Shows Encouraging Disease Control in Medullary Thyroid Cancer
Melbourne (Australia) and Indianapolis, IN (United States) | July 24, 2026
Telix today announces publication of long‑term clinical outcomes from an investigator‑led study evaluating TLX400‑Tx, its lead fibroblast activation protein (FAP)-targeted therapy candidate, in patients with advanced or metastatic medullary thyroid carcinoma (MTC)[1].
Published in the European Journal of Nuclear Medicine and Molecular Imaging (EJNMMI) Research, TLX400-Tx (177Lu-DOTAGA.Glu.(FAPi)2) demonstrated encouraging disease control, an acceptable safety profile, and preliminary efficacy signals in this rare, difficult‑to‑treat thyroid cancer. The peer-reviewed results further support the clinical potential of Telix’s lead FAP therapeutic candidate in solid tumors.
In this retrospective analysis of data from patients treated in a real-world compassionate use setting, Dr. Sanjana Ballal and colleagues report outcomes from 17 evaluable patients with progressive, locally advanced or metastatic MTC, most of whom had received prior systemic therapies and had limited remaining treatment options[2]. Patients received a median of five cycles of TLX400-Tx, with a subset also receiving tandem 177Lu/225Ac-DOTAGA.Glu.FAPi dimer therapy[3].
The analysis demonstrated a disease control rate of 80% according to RECIST 1.1 criteria[4], with a partial response rate of 33%, and stable disease in 47% of patients. The median progression-free survival (PFS) was 26 months, and the median overall survival (OS) was 42 months. The overall hematologic and hepatic safety profile was acceptable in this advanced patient population, with no dose-limiting toxicities detected. The authors concluded that this supports the tolerability of the treatment or intervention administered during the study period.
Dr. Sanjana Ballal, Senior Researcher at the All India Institute of Medical Sciences (AIIMS, New Delhi), investigator and lead author, said, “This study highlights the potential of TLX400‑Tx for patients with advanced MTC, particularly those who have exhausted standard therapies and/or have limited treatment options remaining. The favorable safety profile and encouraging preliminary efficacy signals warrant further validation in larger prospective studies.”
Dr. David N. Cade, Group Chief Medical Officer, Telix, added, “These real‑world data in medullary thyroid cancer further reinforce the scientific potential and versatility of Telix’s FAP-targeting platform. TLX400-Tx continues to demonstrate a favorable safety profile and potential efficacy across multiple tumor types, supporting a broad clinical development strategy.”
About medullary thyroid carcinoma (MTC)
Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignancy originating from C-cells of the thyroid, accounting for approximately 1% to 5% of all thyroid cancers[5]. The 10-year-survival rate exceeds 95% for intrathyroidal disease but drops to ~40% in the presence of distant metastases. For localized MTC, complete surgical resection of the tumor and affected lymph nodes remains the cornerstone of curative treatment. However, in patients with distant metastases, therapeutic options are limited. MTC is typically resistant to chemotherapy and radiotherapy and does not take up radioiodine, making treatment challenging. Currently, first-line systemic therapies include tyrosine kinase inhibitors (TKIs) such as vandetanib and cabozantinib, and selective RET inhibitors like selpercatinib. While these agents can lead to objective tumor reduction, complete responses are rare, and off-target toxicities often impair quality of life[6].
About TLX400-Tx
FAP-targeted radiopharmaceutical therapy has the potential to disrupt the tumor microenvironment and target both stromal and tumor cells. TLX400-Tx is a next generation FAP-targeting therapeutic candidate, differentiated by a novel structure that aims to drive prolonged tumor retention while minimizing off-target uptake. TLX400-Tx was designed to overcome the limitations seen with first-generation FAP compounds and has extensive pre-clinical and clinical data covering a range of tumors[7].
TLX400-Tx has not received a marketing authorization in any jurisdiction.
[1] Ballal et al. EJNMMI Res. 2026.
[2] Data were collected as part of a compassionate use program covered by an overarching protocol, approved by the institutional ethics board.
[3] In the tandem dimer therapy regimen, treatment allocation (177Lu-only vs tandem therapy) was not protocol-driven and was influenced by availability and clinical considerations, reflecting real-world practice.
[4] Response Evaluation Criteria in Solid Tumors (RECIST 1.1).
[5] Kaliszewski et al. Cancers. 2022.
[6] Wells et al. Thyroid. 2015; Kim et al. Endocrinol Metab. 2021. Koehler et al. Thyroid. 2021.
[7] See Telix investor presentation lodged with the ASX on November 19, 2024; Ballal et al. Thyroid. 2025; Ballal et al. J Nucl Med. 2025.