Real-world data from a multi-center study: Insights to the efficacy and safety in patients with ovarian cancer (OC) received niraparib as first-line (1st-L) maintenance therapy (MT)

5551 Background: Niraparib has significantly extended PFS as 1st-L MT OC in PRIMA/PRIME. Due to the more complex in treatment and status of the patients (pts) in clinal practice, more real-world data is needed to verify the efficacy and safety of Niraparib. Meanwhile, exploring the link between clinical characters and PFS, may to establish a clinical model to predict Niraparib benefits. Methods: This is a retrospective multicentric study recruiting OC pts received Niraparib as 1st-L MT from fourteen hospitals throughout China from Jan. 2019 to Dec. 2021. The database lock-time was on Dec. 31st, 2022. The pts’ basic characters, especially biomarkers, KELIM scores, etc. were recorded. Survival analyses were conducted using the Kaplan-Meier method and log-rank test, and 95% CI were calculated. The primary endpoint was PFS, and secondary endpoints included time to treatment discontinuation (TTD), time to first subsequent therapy (TFST) and safety. The exploratory endpoint was to establish a clinical prediction model of Niraparib benefits. Results: 199 pts’ data were analyzed. The median(m) follow-up at the time of the data cutoff was 14.93 months (mos) (12.17, 39.47). Baseline characteristics were shown in Table. MPFS was not reached (NR) (29.80 to not be estimated, NE), with maturity 29.64%, and PFS rate at 6, 12, 18, 24mos was 89.4%, 79.5%, 68.3%, 64.5% respectively, showing the efficacy of Niraparib. MPFS (95% CI) in subgroups were as follows: BRCAwt 23.83mos (23.83 to NE); HRD negative 15.63mos (12.6 to NE); KELIM＜1 NR (15.33 to NE); BRCA1/2m, HRD positive and KEILM≥1 subgroups were all NR yet, due to the no longer enough follow-up time and low data maturity. Multivariate analysis found that pts with <65 years, BRCA1/2m, HRD positive, KELIM＞1, and R0 after primary cytoreductive surgery were likely to have longer PFS. The rate of grade ≥3 thrombocytopenia was 19.1%. Treatment discontinuation occurred in 11 (5.5%) pts due to TEAEs. The clinical prediction model for probability of progression was established from 149 pts (training dataset): Score = 0.612 Age ＞65 + 0.3889 BMI ≤23.90 + 0.097 FIGO IV + 0.191Chronic N +1.398 Surgery result R1/R2 +2.552 BRCA wt . The probability of disease progression received Niraparib in 6, 12 and 18m can be obtained by mapping the score to the nomogram. Conclusions: The efficacy and safety of Niraparib in this study are consistent with the results in PRIME. The clinical predictive model established in this database needs more data to be matured and verified. [Table: see text]