SAT518 Real World Use of Systemic Therapy for Treatment of Advanced Thyroid Cancer

Disclosure: D. Chen: None. M. Banerjee: None. T. Xu: None. F.P. Worden: None. M.R. Haymart: None. Background. Since 2011, the United States Food and Drug Administration (FDA) has approved eight small-molecule kinase inhibitors (SMKIs) for the treatment of advanced thyroid cancer (i.e., radioiodine-refractory metastatic differentiated thyroid cancer, metastatic medullary thyroid cancer, and anaplastic thyroid cancer). The National Comprehensive Cancer Network (NCCN) clinical practice guidelines recommend use of 15 SMKIs, of which eight are FDA-approved and seven are commercially available, for the treatment of advanced thyroid cancer. However, little is known about how these medications are used in the real-world setting for treatment of patients with advanced thyroid cancer. Methods. This descriptive study used data from Optum Clinformatics Data Mart, a de-identified commercial claims database of a large national health insurance provider. We identified patients with thyroid cancer who had prescription claims for at least one of the 15 SMKIs of interest (axitinib, cabozantinib, dabrafenib, entrectinib, everolimus, larotrectinib, lenvatinib, pazopanib, pralsetinib, selpercatinib, sorafenib, sunitinib, trametinib, vandetanib, and vemurafenib). Lines of therapy were defined by the date of SMKI claims. We describe changes in usage patterns over time with a focus on the demographics of patients who were newly initiated on treatment of advanced thyroid cancer, and on the medications used for each line of therapy. Results. Between 2013-2021, 886 patients were treated for advanced thyroid cancer with at least one of the 15 SMKIs of interest. Median age was 65.1 years. Most patients were female (54.6%), non-Hispanic White (62.1%), and had supplementary Medicare insurance (60.6%). Between 2013 and 2016, there was an increase in the proportion of Hispanic patients and a corresponding decrease in the proportion of non-Hispanic White patients treated for advanced thyroid cancer. Although most patients were initiated on an FDA-approved SMKI as first line therapy, 23.1% (N=205) were initiated on a commercially available SMKI. Sorafenib was the most prescribed first-line therapy in 2013 (24.4%) and 2014 (48.3%). Lenvatinib was the most prescribed first-line therapy between 2015-2021 when prescriptions for lenvatinib constituted 38.3-55.6% of all SMKIs prescribed for the treatment of advanced thyroid cancer. Between 2017-2021, a minority of patients were treated with up to a fifth line of therapy although the majority (81.8%) were treated with only a first line agent. Conclusions. Since 2015 when lenvatinib was approved by the FDA for treatment of advanced differentiated thyroid cancer, it has become the most commonly prescribed SMKI for treatment of advanced thyroid cancer. However, variation exists in which SMKIs are used to treat patients with advanced thyroid cancer, with almost one-quarter of patients initiated on commercially available SMKIs. Presentation Date: Saturday, June 17, 2023