Larotrectinib Delivers 79% ORR and 71% Six-Year OS in NTRK-Fusion Differentiated Thyroid Cancer

Larotrectinib, a highly selective CNS-penetrant TRK inhibitor, was pooled across three trials (n=31; NCT02576431, NCT02122913, NCT02637687). In advanced TRK-fusion thyroid carcinoma, adults received 100 mg BID. Among 24 differentiated cases (DTC) and seven anaplastic (ATC), the RECIST-assessed overall response rate was 65% overall – 79% in DTC (3 CR, 16 PR) vs. 14% in ATC. Median PFS across both DTC and ATC was 39 months with a median duration of response of 35 months. Median OS was not reached for DTC (six-year OS 71%) and was 9 months for ATC. Safety remained largely grade 1–2; grade 3/4 TRAEs occurred in 16% with no treatment discontinuations.