Anlotinib in progressive RAI-refractory differentiated thyroid cancer: long-term results and PET/CT prognostic markers

The efficacy and tolerability of anlotinib in patients with progressive radioactive iodine refractory differentiated thyroid cancer (RAIR-DTC), especially those with prior VEGFR-targeted therapies, are not fully understood. This study reported the long-term outcomes of anlotinib-treated progressive RAIR-DTC patients and evaluated the prognostic value of 68Ga-NOTA-3PRGD2 and 18F-FDG PET/CT parameters. In this open-label, single-arm, single-center, prospective trial, 20 progressive RAIR-DTC patients were enrolled to receive anlotinib (orally once daily on days 1-14 every 3 weeks). The study endpoints included long-term efficacy and safety. The association between PET/CT parameters at baseline and 6-week assessments and progression-free survival (PFS) was also investigated. The median PFS was 22.5 (95% CI, 16.8-27.9) months, the estimated median overall survival was 38.4 (95% CI, 20.4-56.4) months, the overall response rate was 47.4% (95% CI, 24.4-71.1), the disease control rate was 89.5% (95% CI, 66.9-98.7), and the median time to response was 4.1 (range, 1.3-8.4) months. There were no significant differences in clinicopathological, efficacy, and safety markers between patients with prior VEGFR-targeted agents (treated group, n = 10) or those without (naïve group, n = 10) (P > 0.05). Higher baseline integrin-expressing tumor burden on 68Ga-NOTA-3PRGD2 PET/CT and glucose metabolic progression on 18F-FDG PET/CT 6 weeks after anlotinib treatment were both associated with shorter PFS. Anlotinib showed promise as an effective treatment option for both initial and salvage therapy in progressive RAIR-DTC patients. Integrin- and glucose metabolic-based PET/CT parameters showed predictive potential in anlotinib-treated patients and warrant further study.