e17606 Background: The phase 3 MIRASOL trial showed that MIRV significantly improved median PFS (5.62 mo) and OS (16.46 mo) vs CTx (PFS: 3.98 mo; OS: 12.75 mo) in adult patients (pts) with FRα positive PROC after 1-3 prior systemic lines of therapy (LOT). Given potential differences between pts treated in routine clinical practice and those enrolled in trials, this study evaluated patient characteristics and outcomes of MIRV monotherapy and single-agent CTx in a RW setting. Methods: This retrospective cohort study used the US-based electronic health record-derived deidentified Flatiron Health Research Database (2011–2025) to identify PROC patients who received either MIRV monotherapy after Nov. 2022 or single-agent CTx (topotecan, paclitaxel, or doxorubicin) after Jan. 2020 (index therapy). Baseline clinicodemographic and biomarker data were recorded for all pts. RW median PFS (mPFS) and OS (mOS) were evaluated for the index therapy using Kaplan–Meier estimates. Scaled RW adverse event (AE) data were described for MIRV pts. Results: There were 129 pts included in the MIRV and 342 pts in the CTx cohorts. While baseline characteristics were largely comparable between groups (Table 1), our study cohort was more clinically diverse than MIRASOL, including primary platinum-refractory pts and a wider range of prior LOT (1-11 vs 1-3). The RW mPFS (95% CI) for MIRV- and CTx-treated pts was 5.65 (4.30–6.21) mo and 3.38 (3.02–3.94) mo, respectively. RW mOS for CTx-treated pts was 7.59 (6.08–8.56) mo. RW mOS data for MIRV-treated pts were not yet mature. In a subgroup of pts with 1-3 prior LOT and no primary platinum refractory disease, the RW mPFS was 5.33 (4.00–7.31) mo and 3.09 (2.76–3.84) mo for MIRV- (n=76) and CTx-treated (n=194) pts, respectively. Scaled RW AE data remain consistent with the previously established safety profile of MIRV. Conclusions: In the RW setting, MIRV monotherapy in PROC patients showed comparable PFS to MIRASOL. These results support the generalizability of trial findings to routine clinical practice and potentially to a broader patient spectrum, as well as demonstrate a consistent MIRV safety profile in RW patients beyond the MIRASOL trial population. Patient Characteristics MIRV Pts (N=129) CTx Pts (N=342) Age, median, y 68 68 Race, White, % 65.9 67.8 Community setting, % 73.6 72.8 Serous Histology, % 88.4 72.2 Stage III/IV at diagnosis, % 78.3 76.6 1-3 prior LOT, % 66.7 67.8 Primary platinum-refractory a , % 10.1 14.3 Prior bevacizumab, % 82.9 72.5 Prior PARPi, % 61.2 48.0 Abbreviations: CTx, single-agent chemotherapy; LOT, lines of therapy; MIRV, mirvetuximab soravtansine; PARPi, poly (ADP-ribose) polymerase inhibitor. a Defined as disease that progressed during a platinum-based regimen or has progressed within 4 weeks of the last dose of first-line platinum-containing CTx.
Chan et al. (Thu,) studied this question.