Trial results for a Phase 2 study (NCT03109847) investigating metformin hydrochloride to mitigate sequelae of radioactive iodine treatment for thyroid cancers were posted on ClinicalTrials.gov on 2025-12-11. The trial was terminated and showed no statistically significant difference in red blood cell count change between the metformin hydrochloride arm and placebo, with a mean difference of 0.52 million cells per microliter (p=0.404).
Background
Metformin hydrochloride was investigated in this pilot clinical trial for its potential role in mitigating the side effects of radioactive iodine treatment in patients with differentiated thyroid cancer. The hypothesis was that metformin hydrochloride might reduce the metabolic activity of cancer cells and surrounding supportive tissues, thereby lessening sequelae.
Trial design
The study (NCT03109847), titled "Metformin to Mitigate Sequelae of Radioactive Iodine Treatment for Thyroid Cancers," was a Phase 2 clinical trial. It was designed to evaluate metformin hydrochloride in patients with Thyroid cancer. The trial enrolled 13 participants and included two arms: Arm I (metformin hydrochloride) and Arm II (placebo). The overall status of the trial was TERMINATED.
Key results
The trial evaluated the change in red blood cell count from pre-resection to post-resection. For this outcome:
- The Arm I (metformin hydrochloride) group showed a mean change of -0.11 million cells per microliter.
- The Arm II (placebo) group showed a mean change of -0.63 million cells per microliter.
A t-test (2-sided) for the mean difference (net) between the groups yielded a value of 0.52 million cells per microliter, with a 95.0% Confidence Interval ranging from -1.26 to 2.29. The p-value for this analysis was 0.404, indicating no statistically significant difference.
Regarding safety, the number of adverse events reported was higher in the active treatment arm:
- Arm I (metformin hydrochloride) reported 32 Adverse Events.
- Arm II (placebo) reported 11 Adverse Events.
What this means
The results from this Phase 2 trial indicate that metformin hydrochloride did not demonstrate a statistically significant benefit in mitigating the change in red blood cell count following radioactive iodine treatment for thyroid cancers compared to placebo. The trial's termination and the observed p-value of 0.404 suggest that the study did not meet its intended efficacy endpoint for this measure. Additionally, the higher number of adverse events reported in the metformin hydrochloride arm compared to placebo warrants consideration for future research into this application.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03109847, titled "Metformin to Mitigate Sequelae of Radioactive Iodine Treatment for Thyroid Cancers," were posted on 2025-12-11 on clinicaltrials.gov.