55P Long-term responders (LTR) with niraparib maintenance in platinum-sensitive recurrent high-grade serous ovarian cancer (PSROC) focusing on subsequent therapies and post-progression outcomes (GEICO-88R study)

The GEICO-88R study evaluated the real-world use of niraparib (NIR) as maintenance treatment in patients (pts) with PSROC (Cueva et al, EJC 2023). A subanalysis of the LTR subgroup (NIR exposure ≥12 mo) was also communicated (Cueva et al, ESMO 2023,795-P). In this study across 57 Spanish sites, pts received NIR at fixed 300 mg/day or individualized starting dose. Now, an extended follow-up (FU) analysis of LTR has been performed, focused on subsequent systemic lines. The characteristics of 107 LTR were previously reported describing a high-risk population, mostly BRCAwt (81.3%), with a median of 2 prior treatment lines and significant concomitant comorbidities (46.7%). Of note, 58.3% ORR was observed in the 48 pts with pre-NIR measurable disease. 61 pts (62.8%) had at least 1 post-NIR systemic line, with 53 pts (86.9%) having a platinum-based treatment (PBT). The proportion of pts receiving subsequent lines was: 1-2L, 55.7%; 3-4L, 24.6%; ≥5L, 19.7%. 31 (29%) pts remained on NIR therapy upon analysis. 61 pts (57%) had very long maintenance (>24 mo) and 68.9% of them remained alive. With a median FU of 49.1 mo, the median PFS, PFS2 and OS were 26.4 (95% CI 21.3-28.8), 33.5 (95% CI 28.5-NA) and 56.9 mo (95% CI 48.2-NA) respectively. Median PFS of first and second post-NIR lines were 8.2 (95% CI 6-12) and 7 mo (95% CI 4.7-10.4) respectively. The ORR with the first subsequent line was 34.9%. 2 pts had AML (1.8%) and 1 MDS (0.9%).Table: 55PFirst and second lines after niraparib (NIR)LTR (N = 97)N (%)N (%)First-line after NIR61 (62.8)Second-line after NIR45 (46.4)PBT + bev12 (19.7)PBT + bev1 (2.2)PBT w/o bev31 (50.8)PBT w/o bev11 (24.4)Pac + bev1 (1.6)Pac + bev4 (8.9)PARPi2 (3.3)Pac w/o bev6 (13.3)Other15 (24.6)PRS + bev1 (2.2)None36 (37.1)PRS w/o bev5 (11.1)PARPi2 (4.4)Other15 (33.3)None52 (53.6)PBT: Platinum-based treatment. PRS: Platinum-resistant scheme (other than paclitaxel). Bev: Bevacizumab. Pac: Paclitaxel. Open table in a new tab PBT: Platinum-based treatment. PRS: Platinum-resistant scheme (other than paclitaxel). Bev: Bevacizumab. Pac: Paclitaxel. This subanalysis of LTR to NIR maintenance in real life focusing on post-NIR treatment shows a significant proportion of pts with NIR therapy >24 mo; that most pts received a PBT as next line; and a remarkable median OS (56.9 mo).