Radium 223 in bone metastases from radioactive iodine refractory thyroid cancer: single arm Phase II trial preliminary results

  • Purpose: to evaluate the efficacy of Radium 223 in patients with bone metastases from radioactive iodine (RAI) refractory thyroid cancer (DTC).

    Methods: This is a multicenter single arm two-stage Simon Phase II trial (NCT02390934). Primary objective was to establish the efficacy of 3 monthly Radium-223 administrations (3M) by FDG PET/CT. Main secondary objectives were: to establish the efficacy of 6 monthly administrations of Radium-223 (6M) by FDG PET/CT, 3M and 6M response on bone scan and 18 NaF PET/CT and safety .

    Results: 10 patients were prospectively enrolled between July 2015 and December 2017 (4 M; 6F; Median Age 74 y, range 62-76). Patients presented with Papillary (n=5), Follicular (n=3), Poorly differentiated TC (n=2). Median number of RAI treatments received before Radium 223 was 4 (3-6). Patients received previously external radiation therapy (n=9), thermal ablation (n=3) and bone surgery (n=8). 9/10 patients received 6 cycles of radium 223, 1 patient stopped after 3 cycles because of bone skeletal event. 3M response at FDG PET was Stable Disease (SD) in 6/10 and progressive disease (PD) in 4/10 cases. In 9 evaluable patients 6M response at FDG PET was SD in 5 cases and PD in 4 cases. 6M response at bone scan was SD in 9/9 cases and at 18NaF PET/CT was SD in 8 cases and Partial Response (PR) in 1 case. 2 patients developed acute myeloid and promyelocitic leukemia  during follow up.

    Conclusions: Trial was stopped for absence of response to Radium 223 at FDG PET and severe hematological events.


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