Larotrectinib Followed by Radioactive Iodine Therapy for Patients with Differentiated Thyroid Cancer Having NTRK Gene Fusions

What this Trial Is About

Papillary thyroid cancer PTC is the most common type of differentiated thyroid cancer DTC. Traditional treatment after surgery includes radioactive iodine RAI therapy, but it is effective in less than 25% of patients with lung metastases and carries risks such as lung scarring and secondary cancers. This study evaluates the combination of larotrectinib followed by RAI therapy in patients with differentiated thyroid cancer that has a specific NTRK gene fusion. Participants will receive larotrectinib alone for 6 months at the FDA-approved dose. After this period, they will undergo 131I radioactive iodine therapy while continuing larotrectinib for 5 more days. Those who experience disease progression during larotrectinib treatment will stop it and proceed directly to 131I therapy. Following treatment, patients will enter a monitoring phase without active therapy. During the study, patients will have chest CT scans to assess lung disease and other evaluations to monitor safety and treatment response. The primary outcome is the number of patients achieving a complete structural response in the lungs at 18 months. Participants will be followed throughout treatment and observation periods, with assessments including performance status and organ function tests to ensure safety and measure outcomes.

Larotrectinib to Enhance RAI Avidity in Differentiated Thyroid Cancer