Effectiveness of immune checkpoint inhibitor therapy in thyroid cancer: A systematic review

Thyroid cancer incidence has risen in recent years, with high mortality rates in aggressive subtypes. Clinical trials of immune checkpoint inhibitors (ICIs), indicate efficacy against a range of solid tumours. However, their role in the thyroid remains to be established. This systematic review (PROSPERO: CRD420250634944) assesses the effectiveness and safety of ICIs in thyroid cancer, reported following PRISMA guidelines.

Searches were performed in 6 databases (EMBASE, PubMed, CENTRAL, Scopus, Web of Science and Clinicaltrials.gov) from inception to 10th January 2025. All studies reporting efficacy outcomes for ICIs in thyroid cancer were included. Clinical trials databases were searched for the most recent results and ongoing trials. Study quality was assessed using the CASP checklist.

Of 1,207 studies retrieved, 33 met the inclusion criteria. Of these trials, 14 investigated ICI plus tyrosine kinase inhibitors, and 5 studies each evaluated dual ICI combinations, ICI monotherapy, or ICIs plus chemotherapy or radiotherapy. Included studies reported variable efficacy and safety. Studies in anaplastic thyroid cancer (ATC) using biomarker-stratified ICI combinations demonstrated the greatest effectiveness. The safety profiles were generally manageable, with common adverse events including fatigue, anorexia, and increased lipase levels.

ICIs show promising responses in thyroid cancer, particularly in ATC. However, the current evidence is limited to non-randomised phase I-II studies, and no phase III trials have been conducted to date. Further investigation in larger, placebo-controlled trials is required to assess efficacy in clinical practice. Predictive biomarkers can help identify patients who may experience the greatest clinical benefit, maximising cost-effectiveness.