Lu-177-DOTATATE peptide therapy achieved tumor control in most patients with radioiodine-resistant thyroid cancer, remained effective after treatment breaks, and caused no severe side effects.
60% tumor controlPeptide radiation therapy achieved stable or shrinking tumors in most patients with radioiodine-resistant thyroid cancer
What the researchers found
Lu-177-DOTATATE peptide receptor radionuclide therapy (PRRT) — normally used for neuroendocrine tumors — showed promising results in 7 patients with advanced thyroid cancer that no longer responded to radioiodine. SSTR PET scans confirmed high somatostatin receptor uptake in metastases (SUVmax 10.4 ± 8.6), particularly in bone.
Among 5 patients receiving continuous PRRT, 60% achieved tumor control by volume and RECIST criteria. The 2 patients who had treatment breaks still showed stable disease at follow-up, and when PRRT was restarted, their tumors responded again — suggesting the treatment remains effective even after interruption. No severe adverse events (Grade 3-5) occurred in either group.
Why it matters
When thyroid cancer stops responding to radioiodine — the standard targeted therapy — treatment options become limited. This small study suggests that peptide-based radiation therapy, already proven in neuroendocrine tumors, may offer a new option for these patients. The finding that PRRT can be stopped and restarted while maintaining effectiveness is particularly encouraging for long-term management.
The numbers in context
n=7 patients · ≥2 PRRT cycles each · SUVmax 10.4 ± 8.6 · 60% tumor control (continuous group) · 100% stable disease at first follow-up (discontinuous group) · 0 Grade 3-5 adverse events
How the study worked
Retrospective analysis of 7 patients with radioiodine-refractory differentiated thyroid carcinoma who received at least 2 cycles of Lu-177-DOTATATE PRRT. Patients were subdivided into continuous treatment (5 patients) and discontinuous treatment with at least a one-year gap (2 patients). Tumor response was assessed using PET-derived total tumor volume, thyroglobulin levels, and RECIST 1.1 criteria. Adverse events were graded using CTCAE.
Who was studied
Patients with advanced radioiodine-refractory differentiated thyroid carcinoma
What this study cannot tell us
With only 7 patients, this is a very small case series — the smallest meaningful cohort to report. The retrospective design limits causal conclusions. There was no control group for comparison. The variable treatment schedules make it difficult to determine optimal PRRT protocols for thyroid cancer. Longer follow-up is needed to assess durability of responses.
How to read the evidence
This is preliminary evidence from a very small retrospective case series of 7 patients. While the results are encouraging and adverse events were minimal, the tiny sample size and lack of controls severely limit the strength of conclusions.
When this study was published
Published in 2025, this is among the first studies to report PRRT outcomes specifically in radioiodine-refractory thyroid cancer, representing a new frontier for peptide-based therapy.
The bigger picture
PRRT's success in neuroendocrine tumors has prompted researchers to test it in other cancers that express somatostatin receptors. Thyroid cancer is a natural candidate. This study, while tiny, provides the first evidence that peptide-targeted radiation may work in radioiodine-refractory thyroid cancer — potentially opening a new treatment avenue for patients who have run out of options.
Questions still open
- What percentage of radioiodine-refractory thyroid cancers express sufficient somatostatin receptors to be eligible for PRRT?
- What is the optimal number of PRRT cycles and interval for thyroid cancer specifically?
- Could combining PRRT with thyroid-targeted therapies like lenvatinib improve outcomes?
Common questions
What does it mean when thyroid cancer becomes 'radioiodine-refractory'?
How does PRRT differ from radioactive iodine therapy?
Read the original research
Peptide Receptor Radionuclide Therapy with Lu-177-DOTATATE and Monitoring with Somatostatin Receptor PET/CT in Patients with Advanced Differentiated Thyroid Carcinoma.
Molecular imaging and biology, 27(6), 954-965
Citation
Kunte, Sophie Carina; Wenter, Vera U; Holzgreve, Adrien; Sheikh, Gabriel T; Widjaja, Liam; Gildehaus, Franz Josef; Lindner, Simon; Schirrmacher, Ralf; Spitzweg, Christine; Auernhammer, Christoph J; Werner, Rudolf A; Zacherl, Mathias J. (2025). Peptide Receptor Radionuclide Therapy with Lu-177-DOTATATE and Monitoring with Somatostatin Receptor PET/CT in Patients with Advanced Differentiated Thyroid Carcinoma.. Molecular imaging and biology, 27(6), 954-965. https://doi.org/10.1007/s11307-025-02053-w