e19578 Background: Sézary syndrome (SS) is an aggressive type of cutaneous T-cell lymphomas (CTCL). Due to its low prevalence, there are limited data on real-world treatment patterns of currently available SS therapies. Furthermore, recent approvals of new agents for patients with CTCL as well as COVID-19 likely impacted real-world treatment patterns. Objective: To examine real-world treatment patterns and the impact of COVID-19 among SS patients treated in 2018-2020 in the US. Methods: Patients with public or private insurance in the 2018-2020 Symphony Health Solutions database were classified into 3 groups: ≥1 diagnosis of SS (ICD-10-CM code: C84.1x) in 2018, 2019, and 2020, respectively. Patient characteristics and treatment patterns for all therapies recommended by the National Comprehensive Cancer Network guidelines version 2.2021 were examined: systemic therapy (e.g., extracorporeal photopheresis (ECP), parenteral, or oral agents), skin-directed therapy (SDT, e.g., topical, local radiation, total skin electron beam therapy, or phototherapy) and bone marrow transplant. The impact of COVID-19 was assessed via quarterly analysis. National drug codes, current procedural terminology and healthcare common procedure coding system codes were used to identify all treatments. Results: The analyses included 869, 882, and 853 SS patients in 2018, 2019, and 2020, respectively (mean age: 66.3, 66.9 and 67.3 years; male: 54.4%, 54.8%, and 55.6%). Overall, systemic therapy increased from 2018 to 2020 (41.8% to 46.5%), with increased parenteral (20.7% to 28.7%) but decreased ECP (17.0% to 13.5%) usage. SDT increased from 2018 to 2020 (48.9% to 52.9%), with increased topical (42.3% to 48.3%) but decreased phototherapy (6.3% to 4.1%) usage. ECP, mogamulizumab, and bexarotene were the most prescribed systemic therapies in 2019-2020, with mogamulizumab being the only one with increased usage over time. Quarterly analysis showed a decreasing ECP from Q1 to Q4 within each year, with a notable drop in Q2 2020. For parental systemics, there was an increasing trend in 2019 and 2020, but utilization in Q4 2020 was lower than that of Q3 2020. For oral systemic, there was a notable drop in Q2 2020 but an increased trend in Q3-Q4 2020. Conclusions: This claims analysis indicated increased use in systemic and SDT among SS patients in 2018-2020. The quarterly analysis indicated that the drop in ECP and oral systemic usage in Q2 2020 coincided with the onset of the pandemic, but there was a stable use of parenteral systemic during 2020.