Abstract

Background: The prespecified on-treatment analysis of ASCEND-ND (NCT02876835) raised concerns about a higher relative risk of cancer-related adverse events (AEs) with daprodustat vs darbepoetin in patients with anaemia of CKD. This concern was not observed in dialysis patients in ASCEND-D (NCT02879305). Methods: ASCEND-ND randomized 3872 patients to daprodustat or darbepoetin. ASCEND-D randomized 2964 patients to daprodustat or conventional erythropoiesis-stimulating agents (ESAs). In both studies ESA comparators used different dosing intervals (3/week, 1/week, every 2 or every 4 weeks). The prespecified on-treatment approach examined relative risks for cancer AEs up to the last dose date + 1 day. In these analyses, owing to different dosing intervals between arms, Cox models were used to estimate the daprodustat effect by various follow-up periods (censoring at last dose date, last dose date + dosing intervals, or end of study). Results: In ASCEND-ND, the safety of daprodustat vs darbepoetin on cancer-related AEs depended on the duration of follow-up after last dose date: hazard ratio (HR) 1.04 [95% confidence interval (CI) 0.77, 1.40] at end of study [HR 1.12 (95% CI 0.81, 1.56) for last dose date + dosing interval; HR 1.50 (95% CI 1.04, 2.15) for last dose date + 1 day]. In ASCEND-D, no excess risk of cancer-related AEs was observed with any model examined. Conclusions: Prespecified on-treatment analyses for cancer-related AEs appeared to result in biased risk estimates in ASCEND-ND by preferentially under-counting events from patients assigned to darbepoetin. Analyses accounting for longer darbepoetin dosing intervals, or extending follow-up, resulted in attenuation of effect estimates towards neutrality, similar to ASCEND-D, where ESA comparator dosing intervals are closer to daprodustat. Trial registration: The ASCEND-ND trial is registered with ClinicalTrials.gov (NCT02876835); the ASCEND-D trial is registered with ClinicalTrials.gov (NCT02879305).