Using quality-adjusted progression-free survival as an outcome measure to assess the benefits of cancer drugs in randomized-controlled trials: case of the BOLERO-2 trial

The aim of this study is to estimate the quality-adjusted progression-free survival (QAPFS) as an effectiveness measure for the treatment arms of the BOLERO-2 trial. For each treatment arm of the trial, QAPFS was estimated by multiplying the overall health utility weights associated with progression-free survival (PFS) (accounting for utility decrements associated with the adverse events of treatments) by the corresponding mean PFS time. Health utility data were obtained from the literature, while mean PFS times were estimated through a survival analysis of the reconstructed individual patient data of the BOLERO-2 trial. PFS (robust mean, (95 % robust confidence interval)) was 44.73 weeks (41.03; 48.43) for Everolimus + Exemestane and 22.98 weeks (19.88; 26.08) for Placebo + Exemestane. The QAPFS (robust mean, (95 % robust confidence interval)) for the treatment arms of the trial was 30.09 (27.60; 32.58) for Everolimus + Exemestane and 16.27 (14.07; 18.46) for Placebo + Exemestane, respectively. Using QAPFS as an outcome measure provides a complete picture of the benefit induced by the treatment arms of the BOLERO-2 trial. The benefit of Everolimus + Exemestane over Placebo + Exemestane observed in the trial is maintained in this analysis. The approach and estimates obtained as part of our analysis can serve as a basis for cost effectiveness analyses of the treatment arms of the BOLERO-2 trial.