Last updated on June 2019

Efficacy of Radium 223 in Radioactive Iodine Refractory Bone Metastases From Differentiated Thyroid Cancer

Brief description of study

The purpose of this Phase II single-arm study is to evaluate the efficacy of Radium-223 in treating bone lesions from differentiated thyroid cancer that are I-131 refractory. Based on the results of the phase III trial, the protocol using an injection of Radium-223 activity of 50 kBq/kg b.w. given 6 times at 4 weeks interval will be applied. The end point of this study will be the evaluation of Radium-223 efficacy one month after 3 administrations, i.e. at 3 months after the first injection. If disease progression at that time is excluded, patients will be treated with 3 further injections for a total of 6 administrations of Radium-223. The principal response criterion at 3 and 6 months will be the metabolic response on FDG PET/CT, but other imaging techniques will also be performed: axial skeleton MRI, 99mTc-HMDP bone scan and FNa PET/CT. Axial skeleton MRI is the reference for soft tissue study. 99mTc- HMDP bone scan is the most used and available routine tool to detect bone metastases in cancer patients, but its sensitivity in patients with bone metastases from thyroid cancer is low, because most lesions are lytic [23]. 18FNa PET/CT shows higher sensitivity than 99mTc-HMDP bone scan to detect bone lesions in cancer patients and is able to detect micrometastases that are not seen on bone scan [24] [25]. Preliminary results show some interest of using this tracer to evaluate the sclerotic component of bone metastases from thyroid cancer [26]. Furthermore preliminary data show that FNa PET/CT can be useful to quantify response to Radium-223 in prostate cancer. In only five patients evaluated by FNa PET/CT at baseline, 6 weeks and 12 weeks after 100 KBq/Kg of Radium-223, semiquantitative analysis by SUV max showed a relationship between PSA and SUV max level decrease in 3 patients (-44%, -31%, -27% vs -52%, -75, and -49% respectively) [27].

Finally bone metastases that are visible on morphological imaging (CT scan or on RI) are frequently submitted to local treatment modalities, and this may induce fibrosis and recalcification. Therefore, already treated metastases and not treated metastases will be studied separately as two separate subgroups of target lesions.

Clinical Study Identifier: NCT02390934

Recruitment Status: Closed

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