Prognostic nomogram for progression-free survival in patients with BRCA mutations and platinum-sensitive recurrent ovarian cancer on maintenance olaparib therapy following response to chemotherapy

Abstract

BackgroundThe impact of maintenance therapy with PARP inhibitors (PARPi) on progression-free survival (PFS) in patients with BRCA mutations and platinum-sensitive recurrent ovarian cancer (PSROC) varies widely. Individual prognostic factors do not reliably distinguish patients who progress early from those who have durable benefit. We developed and validated a prognostic nomogram to predict PFS in these patients. MethodsThe nomogram was developed using data from a training patient cohort with BRCA mutations and high-grade serous PSROC on the placebo arm of two maintenance therapy trials, Study 19 and SOLO2/ENGOT-ov21. We performed multivariable Cox regression analysis based on pre-treatment characteristics to develop a nomogram that predicts PFS. We assessed the discrimination and validation of the nomogram in independent validation patient cohorts treated with maintenance olaparib. ResultsThe nomogram includes four PFS predictors: CA-125 at randomisation, platinum-free interval, presence of measurable disease and number of prior lines of platinum therapy. In the training (placebo) cohort (internal validation C-index 0.64), median PFS in the model-predicted good, intermediate and poor-risk groups was: 7.7 (95% CI 5.3–11.3), 5.4 (4.8–5.8) and 2.9 (2.8–4.4) months, respectively. In the validation (olaparib) cohort (C-index 0.71), median PFS in the model-predicted good, intermediate and poor-risk groups was: not reached, 16.6 (13.1–22.4) and 8.3 (7.1–10.8) months, respectively. The nomogram showed good calibration in the validation cohort (calibration plot). ConclusionsThis nomogram can be used to predict PFS and counsel patients with BRCA mutations and PSROC prior to maintenance olaparib and for stratification of patients in trials of maintenance therapies.