A novel approach to visualize clinical benefit of therapies for chronic graft versus host disease (cGvHD): the probability of being in response (PBR) applied to the REACH3 study

Overall response rate (ORR) is commonly used as key endpoint to assess treatment efficacy of chronic graft versus host disease (cGvHD), either as ORR at week 24 or as best overall response rate (BOR) at any time point up to week 24 or beyond. Both endpoints as well as duration of response (DOR) were previously reported for the REACH3 study, a phase 3 open-label, randomized study comparing ruxolitinib (RUX) versus best available therapy (BAT). The comparison between RUX and BAT was performed on ORR and BOR using all randomized patients, while DOR was derived for the subgroup of responders only. Here we illustrate the application of the probability of being in response (PBR), a graphical method presenting simultaneously the time to first response and subsequent failure using all randomized patients. In REACH3, PBR showed an earlier time to first response, a higher probability of being in response and a longer duration of response for RUX compared to BAT. PBR is a clinically easily interpretable measurement and can serve as a novel efficacy endpoint to assess treatments for chronic graft versus host disease.