Larotrectinib Shows Efficacy in TRK Fusion Thyroid Cancer

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 pooled results of 2 larotrectinib (Vitrakvi) trials (NCT02122913 and NCT02576431) for patients with advanced or metastatic TRK fusion-positive thyroid cancer.

The overall response rate (ORR) was 75% for the overall cohort, which included 19 patients with papillary thyroid cancer, 7 with anaplastic thyroid cancer, and 2 with follicular. Cabanillas says there were good results in these patients with differentiated thyroid cancers, where the ORR was 90%, including 2 patients with complete response (CR) 17 patients with a partial response (PR), and no patients with progressive disease (PD).

Patients with anaplastic thyroid cancer had an ORR of 29%, which is good for this population, according to Cabanillas. None of these patients had CR, 2 had PR, 1 had stable disease, and 3 patients had PD as their best response.

The analysis showed that the median duration of response in the overall cohort was not reached, which was impressive, Cabanillas says. The median time to response was 1.9 months. Treatment was ongoing in 68% of patients at the time of the data cutoff. For the overall cohort, the median progression-free survival was not met, and the median overall survival was 27.8 months.