Clinical Data As of the data cut-off date of June 17, 2019, median duration of response (DOR) was 20.3 months (95% CI: 13.8-24.0) and median progression-free survival (PFS) was 18.4 months (95% CI: 12.9-24.9). Since the majority of patients remain in response or progression-free as of the data cut-off date, these medians will continue to mature over time. In a safety analysis of all 531 patients enrolled to LIBRETTO-001, selpercatinib was well-tolerated, with only 9 patients (1.7%) discontinuing therapy due to treatment-related toxicity.