P161 | EVALUATION OF ATTRITION RATES IN REAL-LIFE SETTING: A SINGLE-CENTER SURVEY IN THE LAST 12 YEARS (2012-2024)

For multiple myeloma (MM), the proportions of patients reaching the subsequent line of therapy (LOT) decline gradually and real-world data describing the attrition rates of LOT in real-life in Italy are limited. To this end, we retrospectively evaluated 707 newly diagnosed MM, with 421 (59.5%) patients receiving only the first LOT. The combination of bortezomib, thalidomide with dexamethasone/prednisone was the most common frontline treatment before 2017, while daratumumab-based regimens constituted most frontline treatment in 2020 and beyond. The attrition rates from the first to the fourth LOT exhibited a gradual upward trend (61%, 32%, 17% and 5%, respectively in 2012-2017 versus 44%, 33%, 24% and 4% in 2018-2024). MM who underwent autologous stem cell transplantation (ASCT) and received lenalidomide-based maintenance showed lower attrition rates across all LOTs (range 19–27%) than MM without ASCT (range 35-65%) in 2012-2017, but not in 2018-2024 where attrition rates were comparable among patients treated with ASCT+lena maintenance (range 2-16%) or front-line continuous therapy based on daratumumab and/or lenalidomide (range 3-20%). Median overall survival in the 2012-2017 cohort was 57.4%, significantly lower than 2018-2024 cohort (67.0%), mainly due to the wide use of daratumumab-based first line regimens. The multivariate Cox regression model revealed that ISS stage III (HR 2.17, p <0.001), aggressive clinical presentation with elevated LDH or extra-medullary disease (HR 3.15, p<0.001), Hb<10 g/dL (HR 3.15, p<0.001) comorbidities such as amyloidosis (HR 1.62, p = 0.02) and any-grade infections in the first year (HR 3.62, p = 0.001) were independent risk factors for MM patients attritted from the frontline treatment in 2018-2024 cohort. In both cohorts we found increased gradually across all LOTs, with no significant differences in attrition rates between 2012-2017 and 2018-2024 cohorts. Lower attrition rate were found after first line in patients receiving daratumumab and continuous lenalidomide Acknowledgments: this work is funded by the European Union - Next Generation EU - PNRR M6C2 Investimento 2.1 “Valorizzazione e potenziamento della ricerca biomedica del SSN" - Grant n. PNRR- MCNT1-2023-12377893– CUP Master: I63C23000410006