Introduction/Background A significant proportion of OC patients eventually progress during or following PARPi exposure. Progression under PARPi may undermine sensitivity to chemotherapy.

Methodology We retrospectively identified patients treated with a PARPi as maintenance in the 4 participating centers and who received subsequent CT. We evaluated progression-free survival (PFS) calculated from the start of the subsequent CT to the next progression/death.

Results 291 patients were identified (2003–2021). PARPi exposure was as maintenance in adjuvant (n=41) or relapsed setting (n=250) with a median number of previous lines of chemotherapy of 1 (range: 1.0–7.0). Progression under PARPi exposure was predominant (n=253/291; 87%). BRCA mutation was identified in 129 pts and negative/unknown in 162 pts. Median duration of PARPi exposure was 6.5 months (range: 0.2–54.3). Subsequent treatment included platinum-based CT (PBC) for 182 (62.5%) pts and non-platinum-based CT (nPBC) for 109 (37.5%) pts. With a median follow-up of 25.3 months (95% CI [23.0; 31.7]), median PFS was 6.7 m (95% CI [5.7; 7.6]) and 3.5 m (95% CI [2.8; 4.6]) with PBC and nPBC respectively. In BRCA mutated pts, median PFS was 6.7 [5.2; 8.3] and 2.7 [2.4; 4.3] with subsequent PBC (n=99) and nPBC (n=30) based CT respectively. Platinum free interval (PFI) under PARPi was associated with numerically longer PFS with subsequent CT: PFI ≤ 6m (PFS =3.0m [2.7;4.1]) ; PFI ]6 ;12] (PFS=6.5m [4.7 ;7.6]) and PFI> 12 m (PFS= 6.9m [5.9 ;8.0]). Subsequent treatment for adjuvant PARPi exposure included PBC for 35 (85.4%) pts. With a median follow-up of 16.8m (95% CI [9.3;-]), median PFS was 6.8m (95% CI [5.1;10.3]) with PBC for these patients.

Conclusion This is the largest series of RWE on the efficacy of chemotherapy after progression under PARPi maintenance. Outcomes appear poor when pts progress under the pressure of PARPi whether received in 1st or subsequent lines.

Disclosures See online