Correlation of longtime efficacy maintenance PARP inhibitor therapy with pre-treatment in a single-institution experience.

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e18084 Background: The use of PARP inhibitors (Olaparib-Niraparib) has shown an important benefit in PFS in patients with relapsed ovarian cancer both with gBRCA and non-BRCA mutation. Methods: This was a single-institution, retrospective cohort study of 93 patients. Clinical data were obtained by the review of the electronic medical report. The 93 patients were treated with PARP Inhibitors(PARP-I) between Apr 2014 and Dic 2019. The patients were evaluated according to age, BRCA mutation, pretreatment with Trabectedin, Bevacizumab, last line of pretreatment with Platinum-Gemcitabine+Paclitaxel versus Caelyx-Oxaliplatin, number of previous lines of chemotherapy, residual disease before PARP-I. Statistical analysis of survival was performed with Kaplan-Meyer, univariate and multivariate analysis with Cox regression. Disease Free Survival (DFS) was evaluated from the start of PARP-I therapy while Overall Survival (OS) from the diagnosis. Results: Median age was 64 (42-90), patients with germinal mutation BRCA were 34 (36.6%), 58 without mutation and 1 patient without genetical analysis. 20 (21,5%) patients were pretreated with Trabectedin plus Pegylated Liposomal Doxorubicine (PLD), while 8 (8,6%) with Trabectedin-Bevacizumab, 26 (28%) patients were pretreated with Bevacizumab +/- Trabectedin. Before PARP-I patients more frequently were pretreated with 2-3 line 60, 64.5%): in the last line of pretreatment chemotherapy 47 (50,4%) patients received PLD+-Oxaliplatin versus Carboplatin-Taxol or Carboplatin-Gemcitabine. In 64% of the patients CTscan or ecography showed residual disease > 1 cm before starting PARP-I treatment . Median follow-up was 17 months: 54 (58.1%) patients in PARP-I treatment relapsed, while 32 (34.1%) patients died. Multivariate analysis showed a significant association in the number of lines pretreatment: in more than 3 lines HR was 2.00 (CI 1.2-3.4, p = 0.012), according to residuum less or more 1 cm prior to start PARP therapy (logrank p = 0,0286). Conclusions: The administration of PARP is important for OS immediately after 2° line chemotherapy in platinum sensitive patients Logrank p = 0.0065, with higher response not significant, about OS specially if following non-anemic PLD-Oxaliplatin therapy (p = 0,0849 Logrank) Also significant is OS according to residuum less or more 1 cm prior to start PARP therapy (logrank p = 0,0286) The doses and relative reductions in PARP-I did not change efficacy.