Background: In the RW CHAR1ZMA study, 414 pts with EOC treated with 1L platinum-based CT (pbCT) and receiving 1L maintenance (1LM) nir mono had a median time to next treatment (TTNT) from end of 1L, a proxy for RW progression-free survival, of 13.3 mo (95% CI, 12.0–15.8 mo).¹ Limited data exist on RW outcomes in pts with EOC who receive nir mono as 1LSM after 1L pbCT + bev treatment. The SW1TCH study describes nir mono use and outcomes as 1LSM therapy after 1L pbCT + bev treatment in a US RW setting. Methods: Using the nationwide Flatiron Health electronic health record–derived deidentified database, this retrospective observational study included pts ≥18 y of age at initial EOC diagnosis who received 1L pbCT + bev treatment followed by nir 1LM mono, initiated between Jan 1, 2017, and Sep 2, 2022. The index date was the initiation of nir 1LM. Pts were followed until the earliest of date of death, last activity, or end of study (Nov 30, 2022). Time to treatment discontinuation (TTD) and TTNT were estimated with Kaplan-Meier methods. Results: Of 93 pts selected, median age at index was 67 y (IQR, 60–72 y). Most pts had an Eastern Cooperative Oncology Group performance score of 0–1 (75.3%) and stage III/IV disease at diagnosis (89.2%). Overall, 86.0% of pts had BRCA wild-type EOC. 19.4% and 22.6% of pts had evidence of homologous recombination (HR)-deficient and HR-proficient EOC, respectively, whereas HR deficiency status was unknown for 58.1%. Median duration of 1L therapy was 4.8 mo (IQR, 3.6–6.0 mo), and median time from end of 1L pbCT to start of 1LM was 1.2 mo (IQR, 0.8–1.8 mo). Reasons for nir discontinuation are shown in the Table. Median TTD from index was 9.3 mo (95% CI, 6.0–11.3 mo). Median TTNT from end of 1L was 12.9 mo (95% CI, 11.5–19.0 mo). Conclusions: Observed results are consistent with CHAR1ZMA,¹ suggesting the RW benefit of nir mono in 1LM regardless of bev use with1L pbCT. This RW study demonstrates that nir mono as 1LSM therapy is a viable treatment option for pts with advanced EOC. References: 1. Coleman RL, et al. ESMO Open. 2023;8(1):100823. doi: https://doi.org/10.1016/j.esmoop.2023.100823.

^aEstimated using Kaplan-Meier curves. ^bAmong 61 pts who discontinued nir; pts may have ≥1 reason for discontinuation. ^cOther may include financial reasons, pt request, disease-related symptom not specific to therapy, other (including death), no evidence of disease, unknown, and completed treatment.