Immunotherapy for patients with thyroid cancer: a comprehensive appraisal

Thyroid cancer is the most common endocrine malignancy. It presents a significant challenge despite advances in treatment. Immunotherapy, which harnesses the body's immune system to fight cancer, has emerged as a potential solution. The immune system's interaction with cancer cells follows a complex process involving immune surveillance, equilibrium, and escape. On the other hand, cancer cells develop mechanisms, such as loss of antigenicity and immunogenicity, as well as creating an immunosuppressed tumor microenvironment, to evade immune response. Immunotherapy modalities, including immune checkpoint inhibitors like anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and anti-programmed cell death protein 1/programmed cell death protein-ligand 1 (PD-1/PD-L1), have shown promising results in various cancers. In the context of thyroid cancer, immunotherapy, particularly PD-1/PD-L1 blockade, has been explored in patients with follicular cell-derived thyroid carcinomas and medullary thyroid carcinomas (MTCs). Clinical trials using PD-1/PD-L1 inhibitors, such as pembrolizumab and nivolumab, have been conducted for these cases, with varying degrees of success. Although preclinical studies have suggested the potential benefit of immunotherapy modalities for patients with follicular cell-derived thyroid carcinoma, to date, clinical studies have failed to demonstrate clear clinical benefits in patients with advanced thyroid cancer. Additionally, other approaches like dendritic cell vaccination and radioimmunotherapy have been explored mainly for MTC, showing potential but requiring further investigation. While immunotherapy holds promise, especially in combination with other treatments, further research, and high-quality clinical trials are necessary to establish its effectiveness in treating advanced thyroid cancers.