Cardiovascular and renal safety outcomes of hypoxia-inducible factor prolyl-hydroxylase inhibitor roxadustat for anemia patients with chronic kidney disease: a systematic review and meta-analysis

Abstract

This systematic review and meta-analysis were conducted to evaluate the cardiac and kidney-related adverse effects of roxadustat for the treatment of anemia in CKD patients. 18 trials with a total of 8806 participants were identified for analysis. We employed a fixed-effects model for analysis. The pooled result revealed no significant difference in the risk of occurrence of cardiac disorders when comparing CKD patients receiving roxadustat with the placebo (RR = 1.049; CI [0.918 to 1.200]) or ESA (RR = 1.066; CI [0.919 to 1.235]), in both dialysis-dependent (DD) (RR = 1.094; CI [0.925 to 1.293]) or non-dialysis-dependent (NDD) (RR = 1.036; CI [0.916 to 1.171]) CKD patients. No significant difference was observed in the risk of kidney-related adverse events when comparing roxadustat with the placebo (RR = 1.088; CI [0.980 to 1.209]) or ESA (RR = 0.968; CI [0.831 to 1.152]), in DD (RR = 2.649; CI [0.201 to 34.981]) or NDD (RR = 1.053; CI [0.965 to 1.149]) CKD patients. A high risk of hyperkalemia was observed in the roxadustat group in DD (RR = 0.939; CI [0.898 to 0.981]). Incidence of hypertension was higher in the roxadustat for NDD patients (RR = 1.198; CI [1.042 to 1.377]), or compared to the placebo (RR = 1.374; CI [1.153 to 1.638]). In summary, the risk of cardiac or kidney-related events observed in the roxadustat was not significantly increase whether in DD or NDD patients. However, attention must be paid to the occurrence of hyperkalemia for DD patients and hypertension in NDD patients using roxadustat.

Keywords:

• Cardiovascular-related events
• kidney-related events
• roxadustat
• chronic kidney disease
• anemia

Introduction

Chronic kidney disease (CKD) is an epidemic with global prevalence which can be attributed to the rising incidence of diabetes, hypertension, and obesity, as well as an aging population. Regardless of the underlying etiology, CKD poses a serious threat to human health because of its slow progress that leads to an irreversible loss of kidney units. Globally, over 30,000 deaths annually are attributed to CKD [1]. Anemia, which is a major and clinically significant complication in patients with CKD is associated with a variety of adverse clinical outcomes such as increased risk of cardiovascular disease (CVD), hospitalization, and mortality [2, 3].

Currently, the main approach for correcting CKD associated anemia is the use of injectable erythropoiesis-stimulating agents (ESAs), administered either intravenously (IV) or subcutaneously (SC), as well as oral or IV supplemental iron therapy [4]. We have henceforth used the term ESA to encompass short-acting recombinant human erythropoietin (rhEPO; epoetin), intermediate-acting darbepoetin alfa, and long-acting epoetin beta pegol. ESA is effective for most patients, however, anemia continues to afflict CKD patients. This is partly attributed to limited response to ESA observed in some CKD patients. The most common causes of ESA hyporesponsiveness include iron deficiency and inflammation, as well as secondary hyperparathyroidism, inadequate dialysis, and malnutrition [5]. ESA treatment does not enhance clinical outcomes in CKD patients with systolic heart failure or in patients with mild to moderate anemia. Moreover, a previously conducted study has reported that higher doses of ESA are associated with an enhanced risk of all-cause mortality and hypertension, independent of Hb levels [6]. In unadjusted analyses, failure to achieve target Hb and the use of high-dose darbepoetin were also observed to be significantly associated with increased risks of major endpoints, composite death, cardiovascular events (myocardial infarction, congestive heart failure), or stroke [7]. Recognizing this risk, the U.S. Food and Drug Administration updated ESA product labels in 2011, including a black box warning to flag the risk of death, serious adverse cardiovascular effects, and stroke when hemoglobin levels reached 11 g/dL added [8–12]. The high cost of recombinant ESA is also an issue in addition to its safety problems [13, 14], although concomitant iron supplementation may prove cost effective in reducing ESA dosage. However, excessive iron supplementation can cause an iron overload and can increase the risk of incidence of CVD and mortality in hemodialysis patients [15]. Hence, there is an urgent need to develop a safe and effective drug for correcting renal anemia, which can be used long-term without enhancing the risk of cardiovascular events in CKD patients.

Roxadustat is a novel orally administered, small molecule hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor that is used to treat anemia in patients with in dialysis-dependent (DD) and not dialysis-dependent (NDD) CKD. This drug works by reversibly binding and inhibiting HIF-prolyl hydroxylase, an enzyme responsible for degrading transcription factors in the HIF family under normal oxygen conditions. Inhibition of these enzymes may cause a reduction in HIF degradation, thereby promoting HIF activity and resulting in enhanced endogenous erythropoietin production and increased erythropoiesis. For NDD CKD anemia patients, roxadustat dose-dependently elevates hemoglobin (Hb) levels, significantly decreases ferritin levels, and briefly increases endogenous EPO levels within or near the physiological range compared with placebo at high doses. Additionally, the orally administered roxadustat reduces iron metabolism disorders in DD and NDD CKD-related anemia patients by elevating serum transferrin, enhancing intestinal iron absorption, as well as releasing stored iron [16, 17]. In a Phase three study, the efficacy and safety of roxadustat was favorable when compared to that of the placebo and ESA, leading to its approval for the treatment of NDD and DD CKD in Chile, China, the European Union (EU), Japan and South Korea [18–21]. Therefore, we conducted this systematic review and meta-analysis to summarize and assess the effects of oral roxadustat on the incidence of cardiac and renal-related advance events (AEs) in anemia of CKD in patients for further evidence.

Methods

This systematic review and meta-analysis were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. The review protocol has been registered on the International Prospective Register of Systematic Reviews (www.crd.york.ac.uk/PROSPERO; registration no. CRD42023387347).

Data sources and search strategies

Two independent investigators conducted a comprehensive assessment followed by literature selection of relevant studies on roxadustat for cardiovascular and renal outcome events in patients with CKD published before October 11, 2023 using the search engines PubMed, Embase database and Cochrane Central Register of Controlled Trials, with the search limited to English-language trials. Moreover, references of selected trials as well as relevant previous meta-analyses were screened to identify eligible trials that had not been identified by the database searches. All articles identified by electronic and manual selects were entered into EndNote X9. Duplicates were extracted and a database was eventually prepared for further screening. Supplemental Table S1 provides details for Search strategy.

Inclusion criteria and data extraction

The trials which met the following criteria were included in this systematic review and meta-analysis:1) the trial population comprised of CKD patients either receiving dialysis or not receiving dialysis, and who had anemia (age > 18years);2) oral roxadustat was used as intervention 3) comprised of a control group which received either placebo or ESA 4) included assessment of cardiac disorders and kidney-related AEs as primary outcomes. Cardiac disorders mainly consisted of cardiovascular death, myocardial infarction, ischemic stroke as well as other cardiac diseases and major adverse cardiovascular events. Renal-related AEs included worsening of CKD or reduced estimated glomerular filtration rate (eGFR), renal failure or acute kidney injury, or ‘renal disorders’ or ‘kidney-related adverse events’ reported in the included trials. Secondary outcomes comprised of the incidence of hypertension and hyperkalemia. Finally, 18 trials met the inclusion criteria though full-text screening, and were included in our systematic review and meta-analysis. Each search result was independently reviewed for eligibility by two authors (L.T. and M.D.W.) and any discrepancies in opinion were settled by discussion and consensus. When consensus was not reached, a third reviewer corresponding author (W.J.L.) acted as an arbitrator.

Quality assessment

The Cochrane Collaboration’s risk of bias tool was utilized to assess the methodological quality of the included trials. Two investigators separately conducted the quality assessment. In the event of disagreements during the screening and evaluation process, the issue was discussed, mediated upon and resolved with the help of a third party. The risk of bias for every item was classified as low, high, and unclear in accordance with the Cochrane Handbook for systematic Reviews.

Statistical analysis

We pooled risk ratios (RRs) with 95% confidence interval (CI) to determine the treatment effect of roxadustat on cardiac and renal disorders. All statistical analyses were performed using the Stata MP Software (version 14). In the statistical analysis of the effect of roxadustat on cardiac and renal disorders, p < 0.05 was deemed as a significant statistical difference. Heterogeneity between trials was evaluated by employing Cochrane’s Q test and reported as I-squared (I²). Heterogeneity was categorized as low (I² ≤ 40%), moderate (I² ≤ 70%) or high (I²>70%). I² ≤ 40% and p < 0.1 indicated that there was a lack of homogeneity among the trials, and the fixed-effects model was employed in the result analysis. The source of heterogeneity was explored by the following methods: (A) through sensitivity analysis, each trial was eliminated one by one to identify the trial that caused the heterogeneity. (B) subgroup analysis was conducted based on type of control, continents and types of study populations (C) Meta-regression analyses conducted based on continents, types of study populations, and type of control. Furthermore, the potential publication bias in each analysis was evaluated quantitatively by Begg’s test in which p > 0.05 was deemed as significant.

Results

Characteristics of included trials

The trial selection was done in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement flowchart demonstrated in Figure 1. To begin with, initial literature searches from PubMed, Embase and the Cochrane library helped us identify 1200 articles, 398 of which were duplicates. Of the remaining 802 articles, 754 articles were excluded after reviewing their titles and/or abstract, leaving 48 articles to be further assessed via detailed full-article screening, following which, 18 trials [1, 16–20, 22–32] were found to satisfy our inclusion criteria and were included in this systematic review and meta-analysis.

Figure 1. (A) PRISMA flow diagram of study selection process.

The characteristics of the included trials are depicted in Table 1. A total of 8806 patients were enrolled in the 18 trials and thus were a part of our study. The included trials were published from 2015 to 2022, with the sample size in each trial ranging from 91 to 2133. All 18 trials were published in English. The patients’ ages ranged from 18 to 80 years.

Table 1. Study participant characteristics.

Studies	Years	Country	ClinicalTrials.gov number	Participants(n)	Gender	Age	does	Patient disease	Control	Iron supplementation
Besarab et al. [16]	2015	USA	NCT00761657	117	Both sexes	18 − 80 years old	1.5,2.0 or 0.7 mg/kg	anemia and Stage 3 or 4 CKD	Placebo - controlled	Yes (IV iron)
Chen et al. [17]	2017	China	NCT01599507	91	Both sexes	18 − 80 years old	Low (1.1–1.75 mg/kg) or high (1.50–2.25 mg/kg)	Chronic Kidney Disease Not Receiving Dialysis	Placebo -controlled	Yes (IV iron)
Chen et al. [17]	2017	China	NCT01596855	96	Both sexes	18 − 80 years old	low (1.1–1.8 mg/kg), medium (1.5–2.3 mg/kg)	Chronic Kidney Disease patinets undergoing dialysis	ESA- controlled	Yes (IV iron)
Chen et al. [20]	2019	China	NCT02652806	1043	Both sexes	18 to 75 years old	70 mg (in patients weighing40 to < 60 kg) or 100 mg (in patients weighing ≥ 60 kg)	end-stage kidney disease, had Chronic Kidney Disease patinets received dialysis for at least 16 weeks	Epoetin Alfa active- controlled	Yes (intravenous iron)
Chen et al. [19]	2019	China	NCT02652819	152	Both sexes	18 and 75 years old	According to a weight based starting dose of 70 mg (in patients weighing 40 to < 60kg)or 100 (in patients weighing ≥ 60kg)	Anemia in Patients with Kidney Disease Not Receiving Dialysis	Placebo - controlled	Yes (intravenous iron)
Akizawa et al. [24]	2019	Japan	NCT01964196	107	Both sexes	20–74 years old	(50, 70, or 100 mg) TIW	Japanese patients with anemia associated with NDD-CKD	Placebo- controlled	Yes (oral iron)
Akizawa et al. [20]	2020	Japan	NCT02952092.	303	Both sexes	≥20 years old	Initial dose of roxadustat (70 mg or 100 mg) TIW	CKD Patients with Anemia on Hemodialysis in Japan	ESA- controlled	Yes (oral and IV iron)
Coyne et al. [30]	2020	USA	NCT01750190	616	Both sexes	≥ 18 years old	Patients weighing 45 to <70 kg received 70 mg roxadustat or placebo, and those weighing ≥70 kg received 100 mg TIW	Stage 3–5 CKD and not on dialysis	Placebo - controlled	Yes(i.v. iron. Oral iron)
Akizawa et al. [25]	2021	Japan	NCT02988973	334	Both sexes	≥20 years old	Initial Dose Conversion to Roxadustat, Based on ESA Use	Anemia in NDD CKD	ESA- controlled	Yes (ferric citrate hydrat)
Hou et al. [26]	2021	China	ChiCTR2000035054	129	Both sexes	18–75 years old	The initial dose of roxadustat was given according to weight: 100 mg for patients weighing 45 to <60 kg and 120 mg for patients weighing 60 kg	CKD and renal anemia who received peritoneal dialysis	ESA- controlled	Yes (oral iron)
Shotov et al. [27]	2021	Russia	NCT01887600	597	Both sexes	≥ 18 years old	weight 45 to 70 kg = 70 mg; weight >70 to 160 kg= 100 mg	Anemia in chronic kidney	Placebo - controlled	Yes (oral iron)
Fishbane et al. [28]	2021	USA	NCT02174627	922	Both sexes	≥ 18 years old	The starting dose of roxadustat and placebo was 70 mg TIW The maximum dose was capped at the lower of 3.0 mg/kg or 300 mg per dose administration.	Anemia in chronic kidney disease patients not on dialysis	Placebo - controlled	Yes(iv iron or oral iron)
Barratt et al. [22]	2021	UK	NCT02021318	305	Both sexes	≥ 18 years old	weight-based dose weight 45.0 to 70.0 kg, roxadustat 70 mg; weight >70.0 to 160.0 kg, roxadustat 100 mg)	Stages 3–5 CKD who were not receiving dialysis	ESA- controlled	Yes (oral iron)
Provenzanoet al. [31]	2021	Russia	NCT02052310	741	Both sexes	≥18 years old	roxadustat was 70 mg (patients weighing	Chronic Kidney Disease patinets on hemodial dialysis or peritoneal dialysis for ESRD	Placebo- controlled	Yes(intravenous iron)
Charytan et al. [32]	2021	USA	NCT02273726	834	Both sexes	≥18 years old	Roxadustat starting doses were 70, 100, 150, or 200 mg TIW based on the patient’s prescribed prestudy ESA dose.	ESKD and were on dialysis for ≥3 months	ESA- controlled	Yes(i.v. iron or Oral iron)
Csiky et al. [23]	2021	Hungary	number 2013-001497-16	143	Both sexes	at least 18 years old	Roxadustat was supplied as 20-mg, 50-mg, and 100-mg tablets for oral administration TIW	Anemia in Patients with End-Stage Kidney Disease on Stable Dialysis	ESA- controlled	Yes(i.v. iron or Oral iron)
Wu et al. [33]	2022	China	2021-KY-0271	143	Both sexes	18–75 years old	Roxadustat was 100 mg (in patients weighing between 45 and <60 kg) or 120 mg (in patients weighing ≥60 kg) three times a week orally	anemia and residual renal function in patients new to peritoneal dialysis	ESA- controlled	Yes (oral iron)
Fishbane et al. [29]	2022	USA	NCT02174731	2133	Both sexes	≥18 years	roxadustat who were receiving an ESA at entry, starting doses were 70–200 mg TIW, based on prior ESA dose; ESAnaive patients at entry started roxadustat on either 70 mg (patients with dry weights 45–70 kg) or 100 mg (dry weights 70–160 kg) TIW	CKD on hemodialysis or peritoneal dialysis	ESA- controlled	Yes (oral iron)

The table represents data from studies stratified by the intervention and comparator.

Risk of bias and quality evaluation of individual trials

Based on the Cochrane Collaboration tool for assessing different domains of study quality, the risk of bias was evaluated and the results are depicted in Figure 2. Among the 18 trials, 88.88% (16/18) of the trials demonstrated adequate random sequence generation, while one study had unclear reporting. In addition, 83.33% (15/18) of the trials demonstrated allocation concealment, with two trial exhibiting unclear concealment status. 44.44% (8/18) of the trials were blinded trials. Appropriate methods were used to handle incomplete outcome data and the attrition and exclusion cases were also described in 88.88% (16/18) of the trials. However, in two trials, the handling of incomplete outcome data was not elaborately explained. In terms of selective outcome reporting, 88.88% (16/18) of the trials demonstrated a low risk of reporting bias (Figure 2A, B).

Figure 2. Risk of bias graph. (A) Risk of bias summary, (B) risk for each included study.

Effect of roxadustat on cardiovascular-related events

Seventeen trials that reported cardiovascular-related events after the use of roxadustat were eventually included in the study. Nine of these trials were conducted with NDD patients and eight with DD patients. Meta-analysis indicated that oral roxadustat did not cause serious adverse effects or cardiovascular-related events in anemic patients with CKD, irrespective of whether the patients received dialysis (RR = 1.094; CI [0.925 to 1.293]; p = 0.294, I² = 0.0%) or did not receive dialysis (RR = 1.036; CI [0.916 to 1.171]; p = 0.576, I² = 0.0%) (Figure 3A). Moreover, subgroup analysis also suggested that oral roxadustat did not cause a significant difference in the risk of cardiovascular events in anemic patients with CKD when compared with placebo (RR = 1.049; CI [0.918 to 1.200]; p = 0.479, I² = 10.8%) or ESA (RR = 1.066; CI [0.919 to 1.235]; p = 0.398, I² = 0.0%) (Figure 3B). Subgroup analysis manifested that there was a low degree of heterogeneity between the included trials on cardiovascular adverse events with roxadustat compared to placebo. Meta-regression analyses conducted based on continents, types of study populations, and type of control revealed that each variable did not affect the risk of cardiovascular events with oral roxadustat and could not eliminate the heterogeneity within groups (Supplementary Table S3). Ultimately, by continents, our subgroup analysis results suggested that no increased risk of cardiovascular-related events with oral roxadustat, whether in Asia (RR = 0.882; CI [0.437 to 1.782]; p = 0.727, I² = 0.0%), the America (RR = 1.086; CI [0.971 to 1.213]; p = 0.148, I² = 29.3%), or Europe(RR = 0.971; CI [0.771 to 1.222]; p = 0.803, I² = 0.0%) (Figure 3C). No evidence of publication bias was observed (for Egger’s test, p = 0.416) (Supplementary Figure S1A).

Figure 3. Forest Plots of the effect of roxadustat on cardiovascular-related events. (A) Forest Plots of the effect of roxadustat on cardiovascular-related events based on NDD or DD patients. (B) Forest Plots of the effect of roxadustat on cardiovascular-related events compared with placebo or ESA. (C) Forest Plots of the effect of roxadustat on cardiovascular-related events based on continent. All outcomes are reported in risk ratios (RRs) for treatment vs the comparator and 95% credible intervals (95%-CI).

Effect of roxadustat on renal adverse events

Eleven trials reported the risk of renal adverse events associated with oral roxadustat in the treatment of anemia in CKD. Nine of these trials included NDD patients and two included DD patients. The pooled results demonstrated that there is no tangible risk of renal adverse events with oral roxadustat in both NDD (RR = 1.053; CI [0.965 to 1.149]; p = 0.244, I² = 0.0%) and DD (RR = 2.649; CI [0.201 to 34.981]; p = 0.459, I² = 41.8%) (Figure 4A) patients. However, moderate between-trial heterogeneity (I² = 41.8%, p = 0.190) was observed in the DD group. Meta-regression analyses according to continent, type of subject, and type of control suggested that type of control did affect the risk of oral roxadustat on renal adverse events and could eliminate the heterogeneity within groups (Supplementary Table S4). Furthermore, subgroup analysis also suggested that oral roxadustat did not demonstrate a significant difference in the risk of renal adverse events in anemic patients with CKD when compared with placebo (RR = 1.088; CI [0.980 to 1.209]; p = 0.115, I² = 0.0%) or ESA (RR = 0.968; CI [0.831 to 1.152]; p = 0.670, I² = 0.0%) (Figure 4B). Finally, in terms of continent, our subgroup analysis results indicated that no increased risk of renal related events with oral roxadustat, whether in Asia (RR = 1.193; CI [0.674 to 2.113]; p = 0.545, I² = 0.0%), America (RR = 1.101; CI [0.987 to 1.229]; p = 0.084, I² = 0.0%), or Europe(RR = 0.946; CI [0.818 to 1.094]; p = 0.453, I² = 0.0%) (Figure 4C). No evidence of publication bias was observed (for Egger’s test, p = 0.793) (Supplementary Figure S1B).

Figure 4. Forest Plots of the effect of roxadustat on renal adverse events. (A) Forest Plots of the effect of roxadustat on renal adverse events based on NDD or DD patients. (B) Forest Plots of the effect of roxadustat on renal adverse events compared with placebo or ESA. (C) Forest Plots of the effect of roxadustat on renal adverse events based on continent. All outcomes are reported in risk ratios (RRs) for treatment vs the comparator and 95% credible intervals (95%-CI).

Seven trials evaluated the risk of progression to ESKD associated with treatment of anemia in CKD patients with oral roxadustat. The results of pooled analysis indicated that the risk of ESKD progression in patients with CKD anemia of NDD patients treated with oral roxadustat did not significantly increase, when compared with placebo (RR = 1.062; CI [0.939 to 1.201]; p = 0.339, I² = 0.0%) or EAS (RR = 0.931; CI [0.750 to 1.156]; p = 0.517, I² = 0.0%) (Figure 5A). Considering continent, our subgroup analysis results manifested that no increased risk of progression to ESKD with oral roxadustat in patients, whether in America (RR = 1.035; CI [0.898 to 1.192]; p = 0.637, I² = 0.0%), or Europe (RR = 1.012; CI [0.859 to 1.191]; p = 0.890 I² = 30.5%) (Figure 5B). No evidence of publication bias was observed (for Egger’s test, p = 0.225) (Supplementary Figure S1C).

Figure 5. Forest Plots of the effect of roxadustat on the risk of progression to ESKD. (A) Forest Plots of the effect of roxadustat in NDD patients on progression to ESKD compared with placebo or ESA. (B) Forest Plots of the effect of roxadustat on progression to ESKD based on continent. All outcomes are reported in risk ratios (RRs) for treatment vs the comparator and 95% credible intervals (95%-CI).

Effect of roxadustat on hyperkalemia

Sixteen trials reporting the risk of hyperkalemia associated with oral roxadustat therapy for anemia in CKD patients were enrolled in this study, of which nine trials included NDD patients and seven trials had included DD patients. The pooled analysis demonstrated no statistically significant difference in the risk of hyperkalemia in the oral roxadustat therapy group in NDD patients (RR = 1.130; CI [0.943 to 1.355]; p = 0.186, I² = 0.0%). However, a higher risk of hyperkalemia in the oral roxadustat therapy group in DD patients (RR = 0.939; CI [0.898 to 0.981]; p = 0.005, I² = 15.8%) (Figure 6A). Meta-regression analyses performed according to continents, types of study populations, and type of control intervention indicated that each variable did not remarkable affect the risk of hyperkalemia with oral roxadustat and could not eliminate the heterogeneity within groups (Supplementary Table S5). Subgroup analysis based on the type of control intervention further demonstrated no significant difference in risk of hyperkalemia associated with the use of oral roxadustat for treatment of anemia in CKD patients when compared to placebo group (RR = 1.219; CI [0.991 to 1.499]; p = 0.061, I² = 0.0%), but a higher risk of hyperkalemia related to the use of oral roxadustat for the treatment of anemia in CKD patients, when compared to the ESA group (RR = 0.935; CI [0.893 to 0.979]; p = 0.004, I² = 0.0%) (Figure 6B). Furthermore, subgroup analysis based on continent suggested that increase risk of hyperkalemia with oral roxadustat in patients from Asia (RR = 1.700; CI [1.063 to 2.720]; p = 0.027, I² = 0.0%), but not remarkable increase risk of hyperkalemia with oral roxadustat in patients from America (RR = 0.960; CI [0.915 to 1.007]; p = 0.095, I² = 43.9%), or Europe (RR = 0.833; CI [0.560 to 1.240]; p = 0.368 I² = 0.0%) (Figure 6C). No evidence of publication bias was observed (for Egger’s test, p = 0.331) (Supplementary Figure S1D).

Figure 6. Forest Plots of the effect of roxadustat on hyperkalemia. (A) Forest Plots of the effect of roxadustat on hyperkalemia based on NDD or DD patients. (B) Forest Plots of the effect of roxadustat on hyperkalemia compared with placebo or ESA. (C) Forest Plots of the effect of roxadustat on hyperkalemia based on continent. All outcomes are reported in risk ratios (RRs) for treatment vs the comparator and 95% credible intervals (95%-CI).

Effect of roxadustat on hypertension

Sixteen trials reporting the risk of hypertension related to oral roxadustat therapy for anemia in CKD patients were enrolled in our study. Eight of these trials had recruited NDD patients and eight had recruited DD patients. The pooled results indicated that a higher risk of hypertension was observed in NDD (RR = 1.198; CI [1.042 to 1.377]; p = 0.011, I² = 36.0%) patients, but no significant statistical difference was observed in the risk of hypertension in the oral roxadustat therapy group for DD patients (RR = 1.036; CI [0.887to 1.209]; p = 0.657, I² = 0.0%) (Figure 7A). Meta-regression analyses performed according to continents, types of study populations, and type of control intervention manifested that each variable did not remarkable affect the risk of hypertension with oral roxadustat and could not eliminate the heterogeneity within groups (Supplementary Table S6). Moreover, subgroup analysis based on the type of control intervention further demonstrated a higher risk of hypertension associated with the use of oral roxadustat for the treatment of anemia in CKD patients, when compared to the placebo (RR = 1.374; CI [1.153 to 1.638]; p = 0.000, I² = 0%), but there was no statistically significant difference in the risk of hypertension in the oral roxadustat therapy group when compared with ESA group (RR = 0.990; CI [0.871 to 1.126]; p = 0.881, I² = 0.0%)(Figure 7B). In addition, subgroup analysis according to continent suggested that increase risk of hypertension with oral roxadustat in patients from America (RR = 1.287; CI [1.087 to 1.524]; p = 0.003, I² = 0.0%), but not remarkable increase risk of hypertension with oral roxadustat in patients from Asia (RR = 0.818; CI [0.546 to 1.225]; p = 0.330, I² = 0.0%), or Europe (RR =1.053; CI [0.917 to 1.210]; p = 0.465 I²= 60.3%) (Figure 7C). No evidence of publication bias was observed (for Egger’s test, p = 0.838) (Supplementary Figure S1E).

Figure 7. ­Forest Plots of the effect of roxadustat on hypertension. (A) Forest Plots of the effect of roxadustat on hypertension based on NDD or DD patients. (B) Forest Plots of the effect of roxadustat on hypertension compared with placebo or ESA. (C) Forest Plots of the effect of roxadustat on hyperkalemia based on continent. All outcomes are reported in risk ratios (RRs) for treatment vs the comparator and 95% credible intervals (95%-CI).

Discussion

This study conducted a systematic review and meta-analysis of previous clinical studies on roxadustat to evaluate its impact on cardiovascular and renal adverse events in CKD anemic patients either requiring or not requiring dialysis. The meta-analysis of the 18 trials included in this study revealed that there were no significant differences in terms of cardiovascular events, renal-related adverse events, the risk of progression to ESKD between the roxadustat group and the placebo group or ESA group. However, a higher risk of hyperkalemia in the oral roxadustat therapy group in DD patients. In addition, a higher risk of hypertension was identified in NDD patients who received oral roxadustat, whereas no significant risk of hypertension risk was detected in DD patients treated with oral roxadustat. A higher risk of hypertension in CKD patients with anemia treated with oral roxadustat compared to those receiving placebo, but no significant hypertension risk was observed in the roxadustat treatment group compared to the ESA group. The results obtained in the aforementioned study indicated that although treatment with oral roxadustat is associated with an increased risk of hypertension in NDD patients, these risks do not seem to translate into clinical outcomes related to cardiovascular or renal risk events.

CVD is the primary cause of death in CKD patients [33], and anemia is an independent risk factor for developing CVD in CKD patients [34]. Although the management of anemia is crucial for CKD patients, the current treatment regime comprising of the use of ESA and iron supplements is far from satisfactory [35]. Hence, we evaluated a novel drug called roxadustat for the correction of renal anemia. As a hypoxia-inducible factor-prolyl hydroxylase inhibitor (HIF-PHI), roxadustat promotes the production of endogenous EPO (erythropoietin), increases sensitivity to EPO receptors, and improves iron homeostasis in CKD patients [36]. In terms of cardiovascular outcomes, our analysis suggests that there is no correlation between intake of oral roxadustat and adverse reactions related to cardiovascular events in CKD anemia patients, regardless of whether the patients are undergoing dialysis treatment or not. Previous studies have also demonstrated roxadustat to be relatively safe [37, 38]. Furthermore, compared to participants receiving ESA treatment, patients treated with roxadustat exhibit a lower incidence of composite cardiovascular safety endpoints. First, this may be attributed to the fact that roxadustat, as described above, can generate endogenous EPO levels close to the physiological range, fully stimulating red blood cell production without exposing the patients to excessively concentrated EPO levels that could potentially exert a negative impact on vascular biology [39]. Second, the potential improvement brought about by roxadustat or its neutral effect on certain traditional cardiovascular risk factors may be attributed to its ability to lower serum cholesterol. Studies have confirmed the total cholesterol and LDL cholesterol reducing effect exerted by roxadustat [27, 40, 41]. Its mechanism of action involves inhibition of cholesterol synthesis and promoting its intestinal excretion [42]. Roxadustat is not only involved in regulating lipid metabolism, but may plays a part in adapting to acute and chronic ischemia, atherosclerosis, and vascular calcification [43, 44]. However, the current results have not been proven to be conclusive or consistent. Third, the protective myocardial cell effect exerted by roxadustat against ischemic injury to cardiac cells can be attributed to its ability to enhance anaerobic respiration and promote the production of oxygen-independent ATP, thereby maintaining energy supply to the myocardial cells [45]. Finally, previous studies have indicated that roxadustat stabilizes the expression of HIF-1α and enhances GLUT1 and GLUT4, thereby promoting glycolysis in cardiac myocytes and partially improving myocardial cell death caused by elevated β-oHb levels [46]. However, current summary data from three Phase 3 studies indicate that in NDD CKD patients with concomitant anemia, roxadustat’s cardiovascular safety is similar to that of placebo, and there is no evidence suggesting that HIF-PHIs confer significant cardiovascular protective advantages [47]. This is consistent with our conclusion. While HIF-1α promotes glycolysis during hypoxia, it also affects metabolism under normoxic conditions. Deletion of HIF-1α in cardiac myocytes leads to reduced levels of ATP, as well as impaired myocardial contractility [48]. Paradoxically, overexpression of cardiac HIF-1α has also been observed to cause contractile dysfunction [49]. In summary, HIF-PHIs may exert cardioprotective effects under low-level inhibition/stabilization, and further research is needed to investigate the dose and duration of HIF-PHI use.

In terms of renal endpoints, our analysis indicates that oral roxadustat does not elevate the risk of progression to ESKD in patients with chronic kidney disease-associated anemia, regardless of whether they are on dialysis or not. Currently, some studies have partially supported this conclusion by conducting in-depth investigations into the mechanisms of roxadustat. One study has demonstrated that roxadustat can protect against renal ischemia/reperfusion injury by regulating inflammatory responses [50]. In addition, a self-controlled, single-center study, included 30 maintenance hemodialysis patients resistant to ESA, shown that after 3 months of using roxadustat, the levels of inflammatory cytokines interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α, interferon-γ, and endotoxin in patients’ serum gradually decreased. Based on acute kidney injury (AKI) patients as well as animal and cell experiments, previous research have confirmed that roxadustat (FG-4592) protects against ischemia-induced acute kidney injury by improving CD73 and reducing AIM2 inflammasome activation [51]. Moreover, the non-inferior efficacy of roxadustat in ESKD might be because of its ability to regulate oxidative stress [52]. According to reports, activation of HIF can prevent the enhanced occurrence of kidney oxidative stress induced by diabetes mellitus and also prevent and ameliorate the progression of DN [53].

Roxadustat does not increase the risk of hyperkalemia in patients with CKD in NDD patients, but increase the risk of hyperkalemia in patients with CKD in DD patients. Currently, there is a lack of in-depth research on the effects of roxadustat on blood potassium levels. The impact of roxadustat on blood potassium levels may vary among individuals. Roxadustat is primarily metabolized in the liver and is mainly excreted through the bile, with a small portion being eliminated by the kidneys [54]. In certain cases, roxadustat may interfere with the renal excretion of potassium, which could result in elevated potassium levels in the blood. However, there is currently no reliable evidence available.

Regarding the effect of roxadustat on hypertension, our results indicated that a higher risk of hypertension was observed in NDD patients. Additionally, subgroup analysis based on the type of control intervention further revealed a higher risk of hypertension associated with oral roxadustat treatment of anemia in CKD patients when compared to the placebo group, but no statistically significant difference was observed when compared with ESA group. HIF transcription factors are also known to contribute to the development of pulmonary hypertension, suggesting that HIF-PHIs have a complex effect on vasculature [55]. This is supported by our finding of an inconsistent risk of hypertension in the roxadustat group relay on whether it was compared with the placebo or ESA group. Moreover, previous basic research evidence that roxadustat have a minor blood pressure–lowering effect. For example, Previous animal studies have indicated that roxadustat, in Angiotensin II (Ang II)-induced hypertension models, prevented vascular thickening and myocardial hypertrophy by downregulating AGTR1 expression. It also enhanced AGTR2 and endothelial nitric oxide synthase (eNOS) protein levels in the mouse aorta, thereby mitigating the hypertensive response [52]. Current research on roxadustat’s effects on blood pressure and its potential mechanisms has not yet yielded consistent results. Further studies with larger sample sizes are needed to conduct in-depth and systematic research in the future.

Limitations and strengths

Our meta-analysis has several limitations. First, this study did not evaluate specific laboratory indicators related to cardiac and renal function outcomes in the included trials. Second, since the evaluation of roxadustat is currently ongoing in Phase II or III clinical trials, there were inconsistencies in the dosages and observation periods of roxadustat among the included studies. Different doses and durations of roxadustat may affect the regulation of HIF-α on multiple target genes to varying degrees, potentially impacting the results of the analysis. Additionally, our meta-analysis included 18 studies that met the inclusion criteria, and every included trial being industry-sponsored, could influence the results of the analysis. Meta-analysis cannot substitute for adequately powered randomized controlled trials. In spite of these limitations, this is a systematic review and meta-analysis of clinical studies on cardiovascular and renal adverse events of roxadustat in anemic DD and NDD CKD patients. The meta-analysis revealed that there were no significant differences in terms of cardiovascular events, renal-related adverse events, or the risk of progression to ESKD between the roxadustat group and the placebo group or ESA group, regardless of whether dialysis was received or not. However, a higher risk of hyperkalemia in the oral roxadustat therapy group in DD patients, or compared to the ESA group. In addition, a higher risk of hypertension was identified in NDD patients who received oral roxadustat, whereas no significant risk of hypertension risk was detected in DD patients treated with oral roxadustat.

Conclusion

To conclude, roxadustat as a novel orally administered for the treatment of anemia for CKD. This meta-analysis of the 18 trials with a total of 8806 patients revealed that there were no significant differences in terms of cardiovascular events, renal-related adverse events, the risk of progression to ESKD, using roxadustat for treating anemia in CKD, regardless of whether dialysis was received or not. However, attention must be paid to the occurrence of hyperkalemia for DD patients and hypertension in NDD patients using roxadustat.

Authors’ contributions

L.T: Conceptualization, Methodology and Assessed the risk of bias. M.D.W: Methodology, Software and Assessed the risk of bias. M.C.L and Y.Y.P: Data curation, J.W.Z: Software. B.J.Z: Supervision. Y.T.W: Validation. W.J.Z: Conceived and designed the experiments. All authors reviewed the manuscript.

Availability of data and material

All data generated or analyzed during this study are included in this published article.

Consent for publication

Manuscript is approved by all authors for publication.

Abbreviations
CKD	=	Chronic kidney disease
ESRD	=	End-stage renal disease
CVD	=	cardiovascular disease
ESA	=	erythropoiesis-stimulating agent
IV	=	intravenously
SC	=	subcutaneously
PRISMA	=	Preferred reporting items for systematic reviews and meta-analyses
FDA	=	Food and Drug Administration
RhEPO	=	recombinant human erythropoietin
HIF	=	hypoxia-inducible factor
HIF-PHI	=	hypoxia-inducible factor-prolyl hydroxylase inhibitor
Hb	=	hemoglobin
NDD	=	non- dialysis dependence
DD	=	dialysis dependence
AE	=	advance events
MACE	=	Major adverse cardiovascular events
RR	=	risk ration
CI	=	Confidence interval
Egfr	=	Estimated glomerular filtration rate
DN	=	Diabetic Nephropathy
BP	=	Blood pressure
HIF-1α	=	hypoxia-inducible factor 1α
DM	=	diabetes mellitus
eNOS	=	endothelial nitric oxide synthase
AKI	=	acute kidney injury

Acknowledgments

A previous version of this manuscript was published as a preprint: https://www.authorea.com/ Doi:10.22541/au.169117207.72929950/v1.

Disclosure statement

The authors have no relevant financial or non-financial interests to disclose.

Additional information

Funding

This study was supported by and The National Natural Youth Science Foundation of China (no. 82104847) and The National Natural Science Foundation of China (no. 82374366), and Beijing Municipal Cultivation Program (PZ2022022)