Redifferentiation Strategies in Refractory Thyroid Cancer: First Insights from Taiwan

He-Jiun JiangTaiwan Speaker Redifferentiation Strategies in Refractory Thyroid Cancer: First Insights from TaiwanBackground: Patients with BRAF p.V600E-mutated radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) face a poor prognosis. While MAPK pathway inhibition can restore radioiodine (RAI) avidity, standard full-dose protocols (e.g., MERAIODE) are often associated with significant toxicity (Grade 3/4 adverse events >20%). This study investigates the efficacy and safety of a novel low-dose, pulsed redifferentiation strategy in a real-world Asian cohort. Methods: We conducted a retrospective cohort study of 24 patients with metastatic BRAF p.V600E RAIR-PTC. Patients received a 60-day induction regimen of Dabrafenib (75 mg BID) and Trametinib (2 mg QOD, every other day). A "Treat-All" strategy was employed, omitting diagnostic scanning to avoid stunning effects, followed by a fixed therapeutic dose of 131-I (150-200 mCi). Primary endpoints included RAI uptake restoration, objective response rate (ORR), disease control rate (DCR), and safety profile. Results: RAI avidity was restored in 83.3% of patients. The regimen demonstrated an exceptional safety profile without Grade 3/4 adverse events. While the ORR was 16.7%, the DCR reached 83.3% at 6 months. Age <55 years was identified as the most significant predictor for objective tumor regression (p=0.007). Furthermore, the study highlights the clinical value of "TKI-Free Survival," with 88.9% of prior TKI users achieving a sustained drug holiday. Conclusion: The low-dose, pulsed BRAF/MEK inhibition protocol offers a highly tolerable and effective redifferentiation strategy. While tumor shrinkage is less pronounced than with full-dose regimens, the high rate of disease control and excellent safety profile make it a viable option for stabilizing disease and improving quality of life, particularly for younger patients (<55) or those intolerant to standard TKI therapy.