Pralsetinib as neoadjuvant therapy for RET-Altered differentiated thyroid cancer: Two case reports.

Background: 5-10% of thyroid cancers are at locally advanced stage. Neoadjuvant targeted therapy will likely create surgical opportunities for these patients with unresectable or borderline resectable tumors. Pralsetinib, a RET inhibitor, has been approved for advanced or metastatic RET-altered thyroid cancer. However, there is no evidence on the efficacy of pralsetinib as neoadjuvant therapy in locally advanced RET-altered thyroid cancer.

Case Report: Two patients with locally advanced pappilary thyroid carcinoma (PTC) were treated with pralsetinib (400 mg daily) to reduce tumor size and increase the chance of R0 resection. Both PTCs, characterized by RET-fusion, underwent successful R0 resection without major surgical complications after 4-months neoadjuvant pralsetinib.

Conclusion: There is a potential for pralsetinib as a neoadjuvant treatment in PTC with RET-fusion.