TRK Fusions Help to Fulfill Unmet Need in Thyroid Cancer Treatment Landscape

Maria E. Cabanillas, MD, an oncologic endocrinologist, professor, and faculty director in the Department of Endocrine Neoplasia at The University of Texas MD Anderson Cancer Center, discusses the treatment landscape for patients with thyroid cancers harboring a TRK fusion.

TRK fusions occur specifically in differentiated thyroid cancer (DTC) and anaplastic thyroid cancer (ATC), as well as poorly DTC which is classified as another type of thyroid cancer, Cabanillas says. TRK fusions have not been observed in medullary thyroid cancer, however, limiting use of larotrectinib (Vitrakvi), a TRK inhibitor, to patients with DTC and ATC who harbor the TRK fusion.

For the treatment of patients with DTC, particularly those with advanced progressive disease, the options include 2 VGEF receptor inhibitors, sorafenib (Nexavar) and lenvatinib (Lenvima), Cabanillas says. The only effective therapy in ATC, however, is for patients harboring a BRAF mutation, which is the FDA-approved combination of dabrafenib (Tafinlar) and trametinib (Mekinist). For patients with ATC who are not BRAF-mutated, there are no good therapies available at this time, according to Cabanillas.

It is important to recognize that although TRK fusions are rare in DTC and ATC, physicians should be checking for these rare fusions considering there are now selective therapies available for the population.