Phase I testing of Af-001 (At-211) for differentiated thyroid cancer
Official title: A Phase I Trial of the Alpha Particle-emitting Radiopharmaceutical, Af-001, in Patients With Differentiated Thyroid Cancer
Run by Alpha Fusion Inc. · NCT07287748 · Data updated 2026-11-12
This trial will test Af-001, an experimental At-211 alpha-particle radiopharmaceutical given intravenously, in adults with unresectable, recurrent, or metastatic differentiated thyroid cancer after total thyroidectomy.
Quick facts
| Phase | Phase 1 |
|---|---|
| Study type | Interventional |
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 38 (estimated) |
| Sponsor | Alpha Fusion Inc. Industry-sponsored |
| Locations | 1 site (Kashiwa) |
| Status | Recruiting |
| Started | January 1, 2026 |
| Main results expected | July 31, 2028 |
| Study ends | July 31, 2028 |
| Registry record updated | December 31, 2025 |
| Trial ID | NCT07287748 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are adults with papillary or follicular thyroid cancer who have had total thyroidectomy and have radically unresectable, recurrent, or metastatic disease, with ECOG performance status 0–2 and expected survival of at least six months; Part Ia requires patients refractory to or intolerant of standard therapy, while Part Ib requires RAI‑naive status.
✕Probably not a fit
Patients who are pregnant, breastfeeding, wish to preserve fertility, have non-differentiated thyroid cancers (such as anaplastic or medullary), have poor performance status, or have resectable disease are unlikely to benefit or be eligible.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
The study has two parts: Part Ia is a single-dose dose-escalation phase to determine the maximum tolerated dose (MTD) and assess safety in patients with unresectable, recurrent, or metastatic differentiated thyroid cancer who are refractory to or intolerant of standard therapies. Part Ib randomizes RAI‑naive patients into two parallel arms at the MTD or MTD‑1 (about 10 patients per arm) to study multiple-dose safety, preliminary efficacy, and to select a recommended Phase II dose (RP2D), with randomization stratified by sites of metastases. Af-001 ([211At]NaAt) is administered intravenously and delivers alpha-particle radiation to thyroid cancer lesions. Patients will have clinical, laboratory, and imaging follow-up to monitor response and toxicity at a single study center.
Why it matters
Potential benefit: If successful, Af-001 could offer a highly targeted radiation treatment that shrinks or controls metastatic differentiated thyroid cancer while limiting exposure to surrounding tissues.
How similar studies have gone: Targeted alpha-particle therapies including At-211 have shown promising early activity in other cancers, but Af-001 for differentiated thyroid cancer is a novel approach with limited prior clinical data.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: \<Ia part\> * Patients with differentiated thyroid cancer (papillary carcinoma, follicular carcinoma) after total thyroidectomy. * Patients with radically unresectable, recurrent, metastatic disease who are judged by the principal investigator or sub-investigator (hereinafter, "principal/sub-investigators") to be refractory to or intolerant of standard-of-care therapy. \<Ib part\> * Patients with radically unresectable, recurrent, metastatic disease who are RAI naive * Patients with measurable lesions. \<Ia/Ib part\> * Patients with an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 to 2 and stable general condition. * Patients expected to survive for at least 6 additional months based on clinical symptoms and physical examination findings. Exclusion Criteria: \<Ia/Ib part\> * Patients who need to preserve fertility. * Females who are pregnant or may be pregnant, breastfeeding patients, or patients or their partners who cannot agree to appropriate contraception. * Patients with active multiple cancers (synchronous multiple cancers and ectopic double cancers with a disease-free period of \<=3 years). * Patients with uncontrolled active infections. * Patients who are positive for hepatitis B virus surface (HBs) antigen, hepatitis C virus (HCV) antibodies, or human immunodeficiency virus (HIV) antibodies.
Where it's running
-
National Cancer Center Hospital East
Kashiwa, Japan Recruiting
Study contacts
- Principal investigator: Tahara, Chief — National Cancer Center Hospital East
- Study coordinator: Alpha Fusion Clinical Development
- Email: development@alpha-fusion.com
- Phone: +81335185330
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.