Real-world treatment patterns and clinical outcomes in patients with radioiodine-refractory differentiated thyroid cancer (RAI-R DTC) treated with first line lenvatinib monotherapy in the United States.

[PURPOSE] Lenvatinib was approved for the treatment of patients with radioiodine-refractory differentiated thyroid cancer (RAI-R DTC) in the United States (US) in 2015. The main objective of the current study was to assess real-world clinical effectiveness in RAI-R DTC patients treated with first line lenvatinib monotherapy in the US.

[METHODS] A retrospective chart review was conducted in RAI-R DTC patients who initiated lenvatinib monotherapy as first line treatment between February 2015 and September 2020. Anonymized data were abstracted by prescribing physicians from individual patient's electronic health records. Clinical outcomes included provider-reported real-world best overall response (rwBOR), real-world progression-free survival (rwPFS), and overall survival (OS). Time-to-event endpoints were assessed using Kaplan-Meier methods.

[RESULTS] Our study included 308 RAI-R DTC patients treated with first line lenvatinib. At lenvatinib initiation, patients' median age was 60 years, 51.6% were female, and 26.0% of patients had an ECOG performance score of ≥2. Over the follow-up period, 32.5% of patients discontinued first line lenvatinib permanently, with others remaining on treatment. The median duration of lenvatinib therapy was 17.5 months overall. Provider-reported rwBOR (complete or partial response) to lenvatinib was 72.4%. Median rwPFS was 49.0 months. Estimated rwPFS rates at 24 and 48 months were 68.5% and 55.0%, respectively. Estimated OS rates at 24 and 72 months were 78.4% and 57.0%, respectively; median OS was not reached.

[CONCLUSION] The current study reinforces the clinical effectiveness of first line lenvatinib as standard of care in patients with RAI-R DTC in real-world clinical practice in the US.