Donafenib Combined With Anti-PD-1 Antibody for Neoadjuvant Therapy in Locally Advanced Thyroid Cancer

This study is testing a combination of two drugs — donafenib (a targeted therapy) and an anti-PD-1 immunotherapy drug — given before surgery to shrink locally advanced thyroid cancer that cannot be easily removed with an operation. The goal is to see if this treatment can make the cancer small enough to be fully removed. **You may be eligible if...** - You are between 18 and 80 years old - You have been diagnosed with locally advanced differentiated thyroid cancer (a type that originates from normal thyroid cells) confirmed by a tissue test - Your cancer is considered hard to remove completely with surgery, or has invaded nearby structures like the windpipe, esophagus, or major blood vessels - You have not received any cancer treatment before - You are reasonably fit (ECOG score 0-2) and your organs are functioning adequately - You are willing to have a biopsy at the start and end of the study **You may NOT be eligible if...** - Your thyroid cancer is an undifferentiated (anaplastic), medullary, lymphoma, or sarcoma type - You have cancer spread to the brain or lining of the brain - You have active autoimmune disease or have previously taken immune checkpoint drugs (anti-PD-1, anti-CTLA-4) - You have had major surgery within the past 4 weeks - You have serious heart conditions, active infections (HIV, hepatitis B/C, tuberculosis), or uncontrolled bleeding - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.