MO541HEMATOLOGIC EFFICACY OF VADADUSTAT FOR ANEMIA IN PATIENTS WITH NON--DIALYSIS-DEPENDENT CHRONIC KIDNEY DISEASE
Authors: Koury Mark , Pergola Pablo E , Roy-Chaudhury Prabir , Farag Youssef , Vargo Dennis , Luo Wenli , Winkelmayer Wolfgang 
Published: May 2021

Abstract

Background and Aims
Vadadustat is a small-molecule inhibitor of hypoxia-inducible factor prolyl hydroxylases under development to treat anemia associated with chronic kidney disease (CKD). The vadadustat phase 3 program includes four efficacy and cardiovascular safety outcome trials of vadadustat versus the erythropoiesis-stimulating agent (ESA) darbepoetin alfa. Here we describe detailed results on hematologic efficacy in two phase 3, randomized trials (the PRO2TECT trials) in adult patients with non–dialysis-dependent (NDD) CKD and anemia, in which vadadustat met prespecified noninferiority criteria compared to darbepoetin alfa, with respect to hematologic efficacy (correction/maintenance of hemoglobin [Hb] target concentrations).

Method
The mean screening Hb level for the ESA-untreated NDD-CKD trial (NCT02648347) had to be &lt;10.0 g/dL, and for the ESA-treated NDD-CKD trial (NCT02680574), the range had to be from 8.0-11.0 g/dL in the United States (US) and from 9.0-12.0 g/dL non-US. In the ESA-untreated trial, patients received no ESA within 8 weeks before randomization; in the ESA-treated trial, patients were maintained on ESA therapy, with ≥1 dose received within 6 weeks prior to or during screening. The vadadustat starting dose was 300 mg/day for all patients, whereas the initial darbepoetin alfa dose depended on each patient’s prior dose or the product label. Both vadadustat and darbepoetin alfa doses were titrated according to prespecified dosing algorithms to achieve target Hb concentrations (US: 10-11 g/dL; non-US: 10-12 g/dL) both during the primary (PEP; weeks 24-36) and secondary (SEP; weeks 40-52) evaluation periods. Herein, we present topline results from the PEP and SEP endpoints, in addition to more detailed erythrocyte parameters.

Results
A total of 3,476 patients (1751 ESA-untreated and 1725 ESA-treated) were randomized 1:1 to vadadustat or darbepoetin alfa. In both trials, vadadustat was noninferior to darbepoetin alfa with regard to the difference of mean change in Hb concentrations between baseline and PEP, as well as between baseline and SEP. The respective proportions of patients (vadadustat vs. darbepoetin alfa) with an average Hb value within the geography-specific target range in the PEP and SEP were 50.4% versus 50.2% and 43.1% versus 43.5% in the ESA-untreated trial and 60.1% versus 60.7% and 50.7% versus 49.0% in the ESA-treated trial. The proportion of patients (vadadustat vs darbepoetin alfa) who achieved an Hb increase &gt;1.0 g/dL from baseline to week 52 was assessed only for the ESA-untreated trial and was 87.7% (95% CI: 85.4%, 89.8%) for vadadustat versus 88.0% (95% CI: 85.6%, 90.0%) for darbepoetin alfa.
Hematologic parameters at time points within the PEP and SEP are presented in Table 1. In both the ESA-untreated and ESA-treated trials, the reticulocyte count trended up from baseline through week 52 for vadadustat and trended down from baseline for darbepoetin alfa. Trends in erythrocyte mean corpuscular volume and erythrocyte mean corpuscular Hb were largely unremarkable by week 52 in both treatment groups.

Conclusion
Vadadustat demonstrated similar profiles across erythrocyte parameters compared with darbepoetin alfa in the treatment of adults with anemia in CKD not on dialysis, whether ESA-untreated or ESA-treated at study entry.