Study of 68Ga-NODAGA-RGD PET/CT in predicting short-term efficacy of tyrosine kinase inhibitor in the treatment of distant metastatic differentiated thyroid cancer

Jun WANG; Jingjing FU; Xiaowei TANG; Xiaochen YAO; Liang SHI; Shaohua LI; Feng WANG

ABSTRACT

Objective:

To investigate the clinical application of 68Ga-cyclo( L-arginylglycyl- L-α-aspartyl- D-tyrosyl-N6-(((4, 7-bis(carboxymethyl)-1, 4, 7-triazonan-1-yl)acetyl))- L-lysyl) (NODAGA-RGD) PET/CT to evaluate short-term efficacy of tyrosine kinase inhibitor (TKI) in distant metastatic differentiated thyroid cancer (dmDTC).

Methods:

From October 2019 to March 2023, 13 dmDTC patients (5 males, 8 females; age 68(65, 69) years) from Nanjing First Hospital were retrospectively enrolled, of which 9 were clinically confirmed as radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) and 4 were dmDTC without radioactive iodine treatment. All patients underwent 68Ga-NODAGA-RGD PET/CT to assess neovascularization of the target lesions (TL), and the SUV max and target background ratio (T/B) were recorded. After 3 months of TKI treatment (anrotinib ( n=9) or apatinib ( n=4)), change rates of the maximum diameter of TL and thyroglobulin (Tg) were measured. The correlation of SUV max, T/B and the change rate of the maximum diameter of TL were analyzed by Spearman rank correlation analysis. ROC curve analysis was performed for the effectiveness of the T/B and TKI therapy, and the difference of the remission rate of lesions was analyzed by Fisher exact test.

Results:

In 13 patients, 36 TL were measured by 68Ga-NODAGA-RGD PET/CT with SUV max of 5.44(3.43, 7.56) and T/B of 5.25(4.50, 7.23). The change rate of the maximum diameter of TL was -30%(-39%, -21%) and the change rate of Tg was -68%(-96%, -52%). T/B was negatively correlated with the change rate of the maximum diameter of TL after TKI therapy ( rs=-0.46, P=0.005), while SUV max was not correlated with the change rate of the maximum diameter of TL ( rs=0.03, P=0.883). ROC curve analysis showed that the optimal cut-off value for T/B was 4.95, with the AUC of 0.698, the sensitivity of 87.5%, and the specificity of 60.0%. Compared to lesions with T/B<4.95, those with T/B≥4.95 showed higher remission rate (2/14 vs 63.6%(14/22); P=0.006). After 3 months of TKI treatment, the disease control rate was 12/13.

Conclusion:

68Ga-NODAGA-RGD PET/CT can effectively reflect tumor neovascularization, predict efficacy of TKI therapy, and provide powerful imaging evidence for TKI therapy in dmDTC.