Researchers tested a new type of radioactive treatment called astatine-211 on 11 patients with thyroid cancer that had stopped responding to standard radioactive iodine therapy. This first-time-ever human study gave patients a single injection of this new treatment and carefully watched for side effects and how well it worked. Most patients tolerated the treatment reasonably well, and some showed signs of cancer improvement. While the results are early and the sample is small, this research suggests the new treatment might be a helpful option for people with this difficult-to-treat type of cancer.
The Quick Take
- What they studied: Whether a new radioactive treatment called astatine-211 is safe and effective for patients with thyroid cancer that no longer responds to standard radioactive iodine treatment
- Who participated: 11 patients with advanced thyroid cancer that had spread to other parts of their body and stopped responding to the usual radioactive iodine therapy
- Key finding: The treatment was generally tolerable, though higher doses caused blood cell problems in about half the patients who received them. Between 33-40% of patients showed significant reduction in cancer markers, and 90% had stable disease (cancer didn’t grow) at 6-month follow-up
- What it means for you: If you have thyroid cancer that doesn’t respond to standard treatment, this research suggests a potential new option may be available in the future. However, this is very early research with a small group of patients, so much more testing is needed before it becomes widely available
The Research Details
This was the first time doctors tested this new radioactive treatment in humans. Eleven patients with advanced thyroid cancer that had stopped responding to standard treatment received a single injection of astatine-211. The researchers started with the lowest dose in a few patients, then gradually increased the dose in new groups of patients to find the safest and most effective amount. This careful approach, called dose escalation, is standard practice when testing new treatments for the first time in people.
Before receiving the treatment, patients followed a special diet low in iodine and received a hormone injection to prepare their bodies. Doctors then tracked side effects, measured how the treatment moved through the body, and checked whether the cancer improved using blood tests and imaging scans over a 6-month period.
The study used strict guidelines to define and measure side effects, ensuring consistent reporting. Researchers looked at both safety (what went wrong) and effectiveness (whether the cancer improved) as their main goals.
This research approach is important because it’s the first time this particular treatment has been tested in humans, so safety is the top priority. By starting with low doses and gradually increasing them, researchers can identify the highest dose that patients can tolerate without serious harm. This information is crucial for planning future studies and eventually offering the treatment to more patients. The combination of safety monitoring and effectiveness measures helps doctors understand whether this new approach is worth pursuing further.
Strengths of this study include its careful dose-escalation design, strict safety monitoring using standard medical guidelines, and 6-month follow-up imaging to assess cancer response. The study was published in a respected medical journal focused on nuclear medicine. Limitations include the very small number of patients (11 total), which means results may not apply to everyone with this type of cancer. This is intentionally a small study because it’s the first human test of this treatment. Results are preliminary and need confirmation in larger studies before doctors can confidently recommend this treatment to most patients.
What the Results Show
The treatment was generally well-tolerated by most patients. At the lowest dose (1.25 MBq/kg), given to 2 patients, there were no serious side effects. At the middle dose (2.5 MBq/kg), given to 3 patients, side effects were mild to moderate. At the highest dose (3.5 MBq/kg), given to 6 patients, 3 patients experienced significant blood cell problems (low white blood cells or lymphocytes) that lasted more than a week, which is considered a dose-limiting toxicity—meaning this dose caused too much harm.
Common side effects across all dose levels included swelling of salivary glands (the glands that make saliva in your mouth), dry mouth, nausea, decreased appetite, and vomiting. Most of these side effects were mild to moderate in severity. The salivary gland swelling was the most frequent major side effect, occurring in multiple patients.
Regarding cancer response, 90% of patients (9 out of 10 with imaging follow-up) had stable disease at 6 months, meaning their cancer didn’t grow. One patient showed progressive disease (cancer growth). Some patients showed improvement in blood markers of cancer: 33% at the middle dose and 40% at the highest dose showed greater than 50% reduction in thyroglobulin levels, a protein that indicates thyroid cancer activity.
Imaging scans at 6 months showed varied responses: one patient achieved complete response (cancer disappeared), two patients showed partial response (cancer shrank), two patients had progressive disease (cancer grew), and five patients had stable disease (cancer stayed the same size). The pharmacokinetic data (how the treatment moved through the body) showed the treatment concentrated in areas with cancer, which is the desired behavior. The absorbed dose calculations helped researchers understand how much radiation different organs received, which is important for understanding long-term safety.
This is the first human study of astatine-211 for thyroid cancer, so there are no direct human comparisons. However, astatine-211 is theoretically superior to standard radioactive iodine because it delivers more intense, localized damage to cancer cells. Previous laboratory studies suggested this treatment might work better than iodine for cancers that have become resistant to iodine therapy. This first human study confirms that the treatment can be given safely at certain doses and shows early signs of effectiveness, supporting the theoretical predictions from earlier research.
The most important limitation is the very small number of patients (11 total), which means results may not apply to all people with this type of cancer. This is intentional for a first-in-human study, but it means we can’t be confident about how common side effects will be in larger populations. The study only followed patients for 6 months, so we don’t know about long-term effects or whether benefits last longer. The study didn’t compare this treatment to other options, so we can’t say whether it’s better or worse than alternatives. Finally, because this is a very new treatment, we don’t yet know how it will work in different types of patients or whether certain groups might benefit more than others.
The Bottom Line
This research is too early to make specific recommendations for patients. However, it suggests that astatine-211 may be worth further investigation as a treatment option for thyroid cancer that doesn’t respond to standard radioactive iodine. Patients with radioiodine-refractory thyroid cancer should discuss this research with their oncologist to understand whether participation in future clinical trials might be appropriate. The evidence is preliminary (early-stage research), so confidence in recommendations is low at this time.
This research is most relevant to people with differentiated thyroid cancer that has spread to other parts of the body and stopped responding to standard radioactive iodine treatment. It may also interest oncologists and nuclear medicine specialists who treat thyroid cancer. People with other types of thyroid cancer or those whose cancer still responds to standard treatment should not assume this applies to them. Family members of people with this type of cancer may find this information helpful for understanding new treatment options.
This is very early research, so realistic timelines are uncertain. If this treatment continues to show promise in larger studies (which typically take 2-5 years), it could potentially become available through clinical trials within 3-5 years. Approval for wider use would require even more testing and could take 5-10 years or longer. Patients interested in this treatment should ask their doctors about clinical trial opportunities rather than expecting it to be available immediately.
Want to Apply This Research?
- If enrolled in a future trial, track weekly blood work results (white blood cell count, lymphocyte count) and monthly thyroglobulin levels to monitor both side effects and cancer response. Use the app to log dates of blood draws and results to identify patterns in how your body responds.
- Users interested in this treatment should use the app to: (1) document all current thyroid cancer treatments and their effectiveness, (2) record questions to ask their oncologist about clinical trial eligibility, (3) track symptoms like dry mouth or nausea that might occur with new treatments, and (4) maintain a log of imaging results and cancer marker levels to share with their medical team.
- Set up monthly reminders to review thyroglobulin levels and imaging results with your healthcare provider. Create a symptom log to track side effects if you participate in a trial. Use the app to maintain a timeline of your cancer progression and treatment responses, which helps your medical team make informed decisions about your care.
This research describes a first-in-human clinical trial of an experimental treatment and should not be interpreted as medical advice or a recommendation for treatment. Astatine-211 is not yet approved by the FDA or other regulatory agencies for treating thyroid cancer. If you have thyroid cancer, especially cancer that has not responded to standard treatment, discuss this research with your oncologist or endocrinologist to understand whether you might be eligible for clinical trials or other treatment options. Do not delay or avoid standard medical care based on this information. This summary is for educational purposes only and does not replace professional medical consultation.