Complete radiographic response to immunotherapy in a patient with metastatic anaplastic thyroid cancer – a case report and review of the literature

Here we present the case of a 76-year-old female with anaplastic thyroid cancer (ATC), stage pT3bN0, who was initially treated with total thyroidectomy followed by adjuvant radiotherapy after non-radical (R1) surgery. Three months after initial treatment, the disease rapidly progressed and disseminated to the lungs, causing significant pulmonary insufficiency. Due to high PD-L1 expression of the tumor, the patient was offered off-label immunotherapy with an immune checkpoint inhibitor (ICI) (nivolumab monotherapy) and demonstrated a remarkable radiographic and clinical response, achieving prolonged progression-free survival (12 months) and overall survival (18 months). ICIs may represent a valuable therapeutic option for patients with metastatic ATC exhibiting high PD-L1 expression. The presented case report and literature review underscore the need for clinical trials to confirm the efficacy of immunotherapy in ATC.