Safety Endpoints With Vadadustat Versus Darbepoetin Alfa in Patients With Non-Dialysis-Dependent CKD: A Post Hoc Regional Analysis of the PRO2TECT Randomized Clinical Trial of ESA-Naïve Patients

Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors as a New Treatment Option for Anemia in Chronic Kidney Disease

Anemia plays an important role in chronic kidney disease (CKD) progression because it worsens the quality of life and increases the risk of cardiovascular complications in CKD patients. In such cases, anemia is mainly caused by endogenous erythropoietin (EPO) and iron deficiencies. Therefore, KDIGO and ERBP guidelines for anemia treatment in CKD patients focus on recombinant EPO and iron supplementation. A recent new treatment option for anemia in CKD patients involves blocking the hypoxia-inducible factor (HIF) system with prolyl hydroxylase inhibitors (PHIs), what causes increasing endogenous EPO production and optimizing the use of iron. Clinical studies have shown that the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) covered in this manuscript-roxadustat, vadadustat, daprodustat, and molidustat-effectively increase hemoglobin (Hb) levels in both non-dialyzed and dialyzed CKD patients. Moreover, these medicines reduce blood lipid levels and do not accelerate CKD progression. However, blockage of the HIF system by HIF-PHIs may be associated with adverse effects such as cardiovascular complications, tumorogenesis, hyperkalemia. and retinopathy. More extensive and long-term clinical trials of HIF-PHIs-based anemia treatment in CKD patients are needed, and their results will indicate whether HIF-PHIs represent an effective and safe alternative to EPO and iron supplementation for anemia treatment in CKD patients.

A spotlight on using HIF-PH inhibitors in renal anemia

INTRODUCTION

Erythropoiesis-stimulating agents (ESAs) together with iron supplementation had been the standard treatment for anemia in chronic kidney disease (CKD) for the past decades. Recently, hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) have attracted attention as a novel treatment option.

AREAS COVERED

This review summarizes the effectiveness and the safety of HIF-PHIs based on previous clinical trials and discusses points to consider for their clinical use.

EXPERT OPINION

The results from clinical trials demonstrate that HIF-PHIs are non-inferior to ESAs in terms of the efficacy to maintain or improve blood hemoglobin levels. However, concerns about adverse events including cardiovascular outcomes, thrombotic events, and tumor progression have prevented HIF-PHIs from being widely approved for clinical use. Also, long-term safety has not been demonstrated yet. Practically, HIF-PHIs should be used with caution in patients with a history of thrombosis or active malignancy. Patients without them may be preferable for HIF-PHIs if those are bothered with regular injections of ESAs or are hyporesponsive to ESAs without obvious reasons, provided that the drugs were approved in the country. Even so, clinicians must take caution for signs of adverse events such as heart failure after prescribing the drugs.

Evaluating the safety and efficacy of vadadustat for the treatment of anemia associated with chronic kidney disease

INTRODUCTION

The breakthrough in erythropoietin-stimulating agents in the 1990s improved the prognosis and treatment of complications in chronic kidney disease patients and renal anemia. Discovery of the novel molecular mechanisms for hypoxia-inducible factor (HIF) transcription factor under hypoxic conditions has led to the development of oral drugs, HIF-Prolyl Hydroxylase inhibitors (HIF-PHIs), that constantly activate erythropoietin by inhibiting prolyl hydroxylase. HIF-PHIs have gained rapid approval in Asian countries, including Japan, with six distinct types entering clinical application.

AREAS COVERED

This article provides a comprehensive review of the latest literature, with a particular focus on the effectiveness and safety of vadadustat.

EXPERT OPINION

A phase 3, randomized, open-label, clinical trial (PRO2TECT) demonstrated that vadadustat had the prespecified non-inferiority for hematologic efficacy as compared with darbepoetin alfa in non-dialysis-dependent patients not previously treated with ESA. However, vadadustat did not show non-inferiority in major adverse cardiovascular events in the non-US/non-Europe patients. It may partly because of imbalances of the baseline eGFR level in those countries. In dialysis-dependent patients, a phase 3 clinical trial (INNO2VATE) showed vadadustat was non-inferior to darbepoetin alfa in cardiovascular safety and maintenance of hemoglobin levels. Adverse events including cancer, retinopathy, thrombosis, and vascular calcification should be evaluated in future clinical studies.

Consensus commentary and position of the Italian Society of Nephrology on KDIGO controversies conference on novel anemia therapies in chronic kidney disease

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are new drugs developed for the treatment of anemia associated with chronic kidney disease (CKD). This class of drugs stimulates endogenous erythropoietin production and, at the same time, improves iron absorption and mobilization of iron stores (less evident with daprodustat, vadadustat and enarodustat). Several studies have been published in the last few years showing that these agents are not inferior to standard therapy in correcting anemia associated with CKD. The efficacy of HIF-PHIs is coupled with a safety profile comparable to that of standard erythropoiesis stimulating agent (ESA) treatment. However, studies with HIF-PHIs were not long enough to definitively exclude the impact of new drugs on adverse events, such as cancer, death and possibly cardiovascular events, that usually occur after a long follow-up period. Kidney Disease: Improving Global Outcomes (KDIGO) recently reported the conclusions of the Controversies Conference on HIF-PHIs held in 2021. The goal of the present position paper endorsed by the Italian Society of Nephrology is to better adapt the conclusions of the latest KDIGO Conference on HIF-PHIs to the Italian context by reviewing the efficacy and safety of HIF-PHIs as well as their use in subpopulations of interest as emerged from more recent publications not discussed during the KDIGO Conference.

Safety Endpoints With Vadadustat Versus Darbepoetin Alfa in Patients With NonDialysis-Dependent CKD: A Post Hoc Regional Analysis of the PRO2TECT Randomized Clinical Trial of ESA-Treated Patients

Rationale & Objective

In the PRO2TECT trials, vadadustat was found to be noninferior to darbepoetin alfa in hematologic efficacy but not for major adverse cardiovascular events (MACE; all-cause death or nonfatal myocardial infarction or stroke) in patients with non-dialysis-dependent chronic kidney disease (NDD-CKD). We investigated the regional differences in MACE in the PRO2TECT trials.

Study Design

Phase 3, global, open-label, randomized, active-controlled clinical trial.

Setting & Participants

A total of 1,725 erythropoiesis-stimulating agent (ESA)-treated patients with anemia and NDD-CKD.

Intervention

1:1 randomization to receive vadadustat or darbepoetin alfa.

Outcomes

The primary safety end point was the time to first MACE.

Results

At baseline, patients in Europe (n=444) were primarily treated with darbepoetin alfa, showed higher proportions on low ESA doses (<90 U/kg/wk epoetin alfa equivalents) with a hemoglobin concentration of ≥10 g/dL compared with patients in the US (n=665) and non-US/non-Europe (n=614) regions. The MACE rates per 100 person-years in the 3 vadadustat groups across regions were 14.5 in the US, 11.6 in Europe, and 10.0 in the non-US/non-Europe groups, whereas event rates in the darbepoetin alfa group were considerably lower in Europe than in the US and non-US/non-Europe groups (6.7 vs 13.3 and 10.5, respectively). The overall hazard ratio for MACE for vadadustat vs darbepoetin alpha was 1.16; 95% CI, 0.93-1.45, but varied by geographical region, with a greater hazard ratio seen in Europe (US, 1.07; 95% CI, 0.78-1.46; Europe, 2.05; 95% CI, 1.24-3.39; non-US/non-Europe, 0.91; 95% CI, 0.60-1.37); interaction between study treatment and geographical region, P = 0.07). In Europe, ESA rescue was associated with a higher risk of MACE in both groups.

Limitations

Several analyses are exploratory.

Conclusions

In this trial, there was a low risk of MACE in the darbepoetin alfa group in Europe. Patients in Europe were generally on low doses of ESA, with hemoglobin already within target range. The low risk of MACE may have been related to a limited need to switch and titrate darbepoetin alfa compared with the non-US/non-Europe group.

Funding

Akebia Therapeutics, Inc.

Trial Registration

ClinicalTrials.gov identifier: NCT02680574.