Real-world treatment patterns among patients with metastatic castration-resistant prostate cancer (mCRPC) in the US

49 Background: mCRPC is an incurable disease with poor prognosis. Though multiple treatments such as novel hormonal therapies (NHT: abiraterone [abi], enzalutamide [enza], docetaxel [doce], cabazitaxel [caba], sipuleucel-T [Sip-T] etc.) are approved, real-world data regarding treatment sequencing are lacking. This study assesses the real-world treatment patterns within the context of FDA-approved life-prolonging treatments for mCRPC. Methods: The IBM MarketScan database was used to identify newly diagnosed (incident) mCRPC patients from 1/1/2014-5/31/2020. Adult males were required to have a diagnosis of PC, and subsequently evidence of metastasis and castration (medical or surgical). Incident mCRPC status (index) was determined 3 ways: 1) treatment with an NHT within 3 months after castration and an FDA-approved mCRPC treatment ≥3 months after NHT; 2) first FDA-approved treatment ≥6 months after castration; 3) first FDA-approved treatment 3-6 months after castration and a second FDA-approved treatment ≥3 months after treatment. Lines of therapy (LOT) were measured in the variable-length follow-up of ≥1 month and consisted of all drugs observed within 28 days of first observed treatment. Duration of therapy was measured as start of line to start of next line or end of enrollment. Results: A total of 2,912 mCRPC patients met all study criteria and received ≥1 LOT. Among those, 48.7% had ≥2 LOT, and 21.8% had ≥3 LOT. Patients were an average age of 71 years at index and used leuprolide (87%), abi (10%), doce (9%) and enza (8%) prior to index. In mCRPC the most common observed first line (1L) monotherapy regimens were abi (35%), enza (34%), and doce (14%). The most common observed second-line (2L) treatments were enza (36%), abi (27%), and doce (14%). Mean duration of 1L was 292 days compared to 245 days in 2L. The most frequently observed treatment sequences (1L to 2L) are reported in the table. Opioids (62%) and denosumab (47%) use was common in mCRPC patients. Conclusions: Among mCRPC patients, NHTs were the most common 1st and 2nd LOTs and alternate NHT after a first NHT was the most common sequence. With rapidly evolving treatment options in metastatic prostate cancer, these data can help guide estimation of eligible patients for different clinical trials. Further studies are needed to understand the high attrition from 1L to subsequent lines of therapy, the reasons for treatment preference and impact on clinical outcomes with different treatment sequencings.[Table: see text]