Durability of Response With Selpercatinib in Patients With -Activated Thyroid Cancer: Long-Term Safety and Efficacy From LIBRETTO-001

JCO LIBRETTO-001 is a registrational phase I/II, single-arm, open-label study of selpercatinib in patients with (REarranged during Transfection)-activated cancers (ClinicalTrials.gov identifier: NCT03157128). We present long-term safety and efficacy from LIBRETTO-001 in patients with -mutant medullary thyroid cancer (MTC; n = 324) and fusion-positive thyroid cancer encompassing different histological subtypes (TC; n = 66). At the data cutoff of January 2023, the objective response rate was 82.5% among patients with cabozantinib/vandetanib-naïve MTC and 95.8% among patients with treatment-naïve TC. At a median follow-up time of 42.4 and 44.0 months in patients with cabozantinib/vandetanib-naïve and pretreated MTC, the median progression-free survival (PFS) was not reached and 41.4 months, respectively. At a median follow-up time of 24.9 and 30.4 months in patients with treatment-naïve and pretreated TC, the median PFS was not reached and 27.4 months, respectively. Three-year PFS rates were 75.2% and 87.3% among patients with cabozantinib/vandetanib-naïve MTC and treatment-naïve TC, respectively. Median PFS was similar to median duration of response for each patient group. The safety profile of selpercatinib was consistent with previous reports. With an additional follow-up of 37 months and 228 more patients from the last disclosure, selpercatinib continued to provide durable and robust responses in treatment-naïve and previously treated patients with -mutant MTC and fusion-positive TC.