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Lamy A, Chertow GM, Jessen M, Collar A, Brown CD, Mack CA, Marzouk M, Scavo V, Washburn TB, Savage D, Smith J, Bennetts J, Assi R, Shults C, Arghami A, Butler J, Devereaux P, Zager R, Wang C, Snapinn S, Browne A, Rodriguez J, Ruiz S, Singh B. Effects of RBT-1 on preconditioning response biomarkers in patients undergoing coronary artery bypass graft or heart valve surgery: a multicentre, double-blind, randomised, placebo-controlled phase 2 trial. EClinicalMedicine 2024; 68:102364. [PMID: 38586479 PMCID: PMC10994969 DOI: 10.1016/j.eclinm.2023.102364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 04/09/2024] Open
Abstract
Background RBT-1 is a combination drug of stannic protoporfin (SnPP) and iron sucrose (FeS) that elicits a preconditioning response through activation of antioxidant, anti-inflammatory, and iron-scavenging pathways, as measured by heme oxygenase-1 (HO-1), interleukin-10 (IL-10), and ferritin, respectively. Our primary aim was to determine whether RBT-1 administered before surgery would safely and effectively elicit a preconditioning response in patients undergoing cardiac surgery. Methods This phase 2, double-blind, randomised, placebo-controlled, parallel-group, adaptive trial, conducted in 19 centres across the USA, Canada, and Australia, enrolled patients scheduled to undergo non-emergent coronary artery bypass graft (CABG) and/or heart valve surgery with cardiopulmonary bypass. Patients were randomised (1:1:1) to receive either a single intravenous infusion of high-dose RBT-1 (90 mg SnPP/240 mg FeS), low-dose RBT-1 (45 mg SnPP/240 mg FeS), or placebo within 24-48 h before surgery. The primary outcome was a preoperative preconditioning response, measured by a composite of plasma HO-1, IL-10, and ferritin. Safety was assessed by adverse events and laboratory parameters. Prespecified adaptive criteria permitted early stopping and enrichment. This trial is registered with ClinicalTrials.gov, NCT04564833. Findings Between Aug 4, 2021, and Nov 9, 2022, of 135 patients who were enrolled and randomly allocated to a study group (46 high-dose, 45 low-dose, 44 placebo), 132 (98%) were included in the primary analysis (46 high-dose, 42 low-dose, 44 placebo). At interim, the trial proceeded to full enrollment without enrichment. RBT-1 led to a greater preconditioning response than did placebo at high-dose (geometric least squares mean [GLSM] ratio, 3.58; 95% CI, 2.91-4.41; p < 0.0001) and low-dose (GLSM ratio, 2.62; 95% CI, 2.11-3.24; p < 0.0001). RBT-1 was generally well tolerated by patients. The primary drug-related adverse event was dose-dependent photosensitivity, observed in 12 (26%) of 46 patients treated with high-dose RBT-1 and in six (13%) of 45 patients treated with low-dose RBT-1 (safety population). Interpretation RBT-1 demonstrated a statistically significant cytoprotective preconditioning response and a manageable safety profile. Further research is needed. A phase 3 trial is planned. Funding Renibus Therapeutics, Inc.
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Affiliation(s)
- Andre Lamy
- Department of Perioperative Medicine and Surgery, Population Health Research Institute, Hamilton, Ontario, Canada
| | - Glenn M. Chertow
- Departments of Medicine and Epidemiology and Population Health, Stanford University School of Medicine, Stanford, CA, USA
| | - Michael Jessen
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alonso Collar
- Department of Thoracic Surgery and Vascular Surgery, MyMichigan Health, Midland, MI, USA
| | - Craig D. Brown
- Department of Cardiac Surgery, New Brunswick Heart Centre, Saint John, New Brunswick, Canada
| | - Charles A. Mack
- Department of Cardiothoracic Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Mohamed Marzouk
- Department of Cardiac Surgery, Québec Heart and Lung Institute, Québec, Québec, Canada
| | - Vincent Scavo
- Department of Cardiovascular and Thoracic Surgery, Lutheran Medical Group, Fort Wayne, Indiana, USA
| | - T Benton Washburn
- Department of Cardiothoracic Surgery, Huntsville Hospital Heart Center, Huntsville, AL, USA
| | - David Savage
- Department of Cardiothoracic Surgery, Indiana University Health, Bloomington, IN, USA
| | - Julian Smith
- Department of Surgery (School of Clinical Sciences at Monash Health), Monash University and Department of Cardiothoracic Surgery, Monash Health, Melbourne, Victoria, Australia
| | - Jayme Bennetts
- Department of Cardiothoracic Surgery, Flinders Medical Centre, Southern Adelaide Local Health Network, Adelaide, Australia
- Department of Surgery, College of Medicine and Public Health, Flinders University, Adelaide, Australia
| | - Roland Assi
- Department of Cardiac Surgery, Yale University School of Medicine, New Haven, CT, USA
| | - Christian Shults
- Department of Cardiac Surgery, MedStar Heart and Vascular Institute, Washington, DC, USA
| | - Arman Arghami
- Department of Cardiovascular Surgery, Mayo Clinic, Rochester, MN, USA
| | - Javed Butler
- Department of Medicine, University of Mississippi, Jackson, MS, USA
- Baylor Scott and White Research Institute, Dallas, TX, USA
| | - P.J. Devereaux
- Department of Perioperative Medicine and Surgery, Population Health Research Institute, Hamilton, Ontario, Canada
| | - Richard Zager
- Department of Drug Development & Medical Affairs, Renibus Therapeutics Inc, Southlake, TX, USA
| | - Chao Wang
- Pharma Data Associates LLC, Piscataway, NJ, USA
| | - Steve Snapinn
- Seattle-Quilcene Biostatistics LLC, Seattle, WA, USA
| | - Austin Browne
- Department of Perioperative Medicine and Surgery, Population Health Research Institute, Hamilton, Ontario, Canada
| | - Jeannette Rodriguez
- Department of Drug Development & Medical Affairs, Renibus Therapeutics Inc, Southlake, TX, USA
| | - Stacey Ruiz
- Department of Drug Development & Medical Affairs, Renibus Therapeutics Inc, Southlake, TX, USA
| | - Bhupinder Singh
- Department of Drug Development & Medical Affairs, Renibus Therapeutics Inc, Southlake, TX, USA
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Zager RA. Oxidant- induced preconditioning: A pharmacologic approach for triggering renal 'self defense'. Physiol Rep 2022; 10:e15507. [PMID: 36305701 PMCID: PMC9615572 DOI: 10.14814/phy2.15507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 05/07/2023] Open
Abstract
Acute kidney injury (AKI) is a common event, occurring in ~5% and ~35% of hospitalized and ICU patients, respectively. The development of AKI portends an increased risk of morbidity, mortality, prolonged hospitalization, and subsequent development of chronic kidney disease (CKD). Given these facts, a multitude of experimental studies have addressed potential methods for inducing AKI prevention in high-risk patients. However, successful clinical translation of promising experimental data has remained elusive. Over the past decade, our laboratory has focused on developing a method for safely triggering AKI protection by inducing "kidney preconditioning" in mice by the intravenous administration of a combination of Fe sucrose (FeS) + tin protoporphyrin (SnPP). These agents induce mild, but short lived, 'oxidant stress' which synergistically activate a number of kidney 'self-defense' pathways (e.g., Nrf2, ferritin, IL-10). Within 18-24 h of Fe/SnPP administration, marked protection against diverse forms of experimental toxic and ischemic AKI results. FeS/SnPP-mediated reductions in kidney injury can also indirectly decrease injury in other organs by mitigating the so called "organ cross talk" phenomenon. Given these promising experimental data, three phase 1b clinical trials were undertaken in healthy subjects and patients with stage 3 or 4 CKD. These studies demonstrated that FeS/SnPP were well tolerated and that they up-regulated the cytoprotective Nrf2, ferritin, and IL-10 pathways. Two subsequent phase 2 trials, conducted in patients undergoing 'on-pump' cardiovascular surgery or in patients hospitalized with COVID 19, confirmed FeS/SnPP safety. Furthermore, interim data analyses revealed statistically significant improvements in several clinical parameters. The goals of this review are to: (i) briefly discuss the historical background of renal "preconditioning"; (ii) present the experimental data that support the concept of FeS/SnPP- induced organ protection; and (iii) discuss the initial results of clinical trials that suggest the potential clinical utility of an 'oxidant preconditioning' strategy.
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Affiliation(s)
- Richard A. Zager
- Department of MedicineUniversity of WashingtonSeattleWashingtonUSA
- Fred Hutchinson Cancer CenterSeattleWashingtonUSA
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Zager RA, Johnson ACM. The NRF2 stimulating agent, tin protoporphyrin, activates protective cytokine pathways in healthy human subjects and in patients with chronic kidney disease. Physiol Rep 2021; 8:e14566. [PMID: 32940965 PMCID: PMC7507518 DOI: 10.14814/phy2.14566] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Tin protoporphyrin (SnPP), a heme oxygenase 1 (HO-1) inhibitor, triggers adaptive tissue responses that confer potent protection against acute renal- and extra-renal tissue injuries. This effect is mediated, in part, via SnPP-induced activation of the cytoprotective Nrf2 pathway. However, it remains unclear as to whether SnPP can also upregulate humoral cytokine defenses, either in healthy human subjects or in patients with CKD. If so, then systemically derived cytokines could contribute SnPP-induced tissue protection. METHODS SnPP (90 mg IV) was administered over 2 hr to six healthy human volunteers (HVs) and 12 subjects with stage 3-4 CKD. Plasma samples were obtained from baseline upto 72 hr post injection. Two representative anti-inflammatory cytokines (IL-10, TGFβ1), and a pro-inflammatory cytokine (TNF-α), were assayed. Because IL-6 has been shown to induce tissue preconditioning, its plasma concentrations were also assessed. In complementary mouse experiments, SnPP effects on renal, splenic, and hepatic IL-10, IL-6, TGFβ1, and TNF-α production (as gauged by their mRNAs) were tested. Tissue HO-1 mRNA served as an Nrf2 activation marker. RESULTS SnPP induced marked (~5-7x) increases in plasma IL-10 and IL-6 concentrations within 24-48 hr, and to equal degrees in HVs and CKD patients. SnPP modestly raised plasma TGFβ1 without impacting plasma TNF-α levels. In mouse experiments, SnPP did not affect IL-6, IL-10, TNF-α, or TGFβ1 mRNAs in kidney despite marked renal Nrf2 activation. Conversely, SnPP increased splenic IL-10 and hepatic IL-6/TGFβ1 mRNA levels, suggesting these organs as sites of extra-renal cytokine generation. CONCLUSIONS SnPP can trigger cytoprotective cytokine production, most likely in extra-renal tissues. With ready glomerular cytokine filtration, extra-renal/renal "organ cross talk" can result. Thus, humoral factors seemingly can contribute to SnPP's cytoprotective effects.
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Affiliation(s)
- Richard A Zager
- Department of Medicine, University of Washington, Seattle, WA, USA.,Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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Zager RA, Johnson ACM, Guillem A, Keyser J, Singh B. A Pharmacologic "Stress Test" for Assessing Select Antioxidant Defenses in Patients with CKD. Clin J Am Soc Nephrol 2020; 15:633-642. [PMID: 32291269 PMCID: PMC7269210 DOI: 10.2215/cjn.15951219] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 03/20/2020] [Indexed: 12/30/2022]
Abstract
BACKGROUND AND OBJECTIVES Oxidative stress is a hallmark and mediator of CKD. Diminished antioxidant defenses are thought to be partly responsible. However, there is currently no way to prospectively assess antioxidant defenses in humans. Tin protoporphyrin (SnPP) induces mild, transient oxidant stress in mice, triggering increased expression of select antioxidant proteins (e.g., heme oxygenase 1 [HO-1], NAD[P]H dehydrogenase [quinone] 1 [NQO1], ferritin, p21). Hence, we tested the hypothesis that SnPP can also variably increase these proteins in humans and can thus serve as a pharmacologic "stress test" for gauging gene responsiveness and antioxidant reserves. DESIGN , setting, participants, & measurementsA total of 18 healthy volunteers and 24 participants with stage 3 CKD (n=12; eGFR 30-59 ml/min per 1.73 m2) or stage 4 CKD (n=12; eGFR 15-29 ml/min per 1.73 m2) were injected once with SnPP (9, 27, or 90 mg). Plasma and/or urinary antioxidant proteins were measured at baseline and for up to 4 days post-SnPP dosing. Kidney safety was gauged by serial measurements of BUN, creatinine, eGFR, albuminuria, and four urinary AKI biomarkers (kidney injury molecule 1, neutrophil gelatinase-associated lipocalin, cystatin C, and N-acetyl glucosaminidase). RESULTS Plasma HO-1, ferritin, p21, and NQO1 were all elevated at baseline in CKD participants. Plasma HO-1 and urine NQO1 levels each inversely correlated with eGFR (r=-0.85 to -0.95). All four proteins manifested statistically significant dose- and time-dependent elevations after SnPP injection. However, marked intersubject differences were observed. p21 responses to high-dose SnPP and HO-1 responses to low-dose SnPP were significantly suppressed in participants with CKD versus healthy volunteers. SnPP was well tolerated by all participants, and no evidence of nephrotoxicity was observed. CONCLUSIONS SnPP can be safely administered and, after its injection, the resulting changes in plasma HO-1, NQO1, ferritin, and p21 concentrations can provide information as to antioxidant gene responsiveness/reserves in subjects with and without kidney disease. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER A Study with RBT-1, in Healthy Volunteers and Subjects with Stage 3-4 Chronic Kidney Disease, NCT0363002 and NCT03893799.
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Affiliation(s)
- Richard A Zager
- Clinical Research Division, The Fred Hutchinson Cancer Research Center, Seattle, Washington .,Department of Medicine, The University of Washington, Seattle, Washington
| | - Ali C M Johnson
- Clinical Research Division, The Fred Hutchinson Cancer Research Center, Seattle, Washington
| | | | | | - Bhupinder Singh
- Renibus Therapeutics, Southlake, Texas.,Department of Medicine, The University of California, Irvine, California
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Johnson ACM, Delrow JJ, Zager RA. Tin protoporphyrin activates the oxidant-dependent NRF2-cytoprotective pathway and mitigates acute kidney injury. Transl Res 2017; 186:1-18. [PMID: 28586635 DOI: 10.1016/j.trsl.2017.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/30/2017] [Accepted: 05/12/2017] [Indexed: 10/19/2022]
Abstract
Tin protoporphyrin (SnPP), a heme oxygenase (HO) inhibitor, can paradoxically protect against diverse forms of acute kidney injury (AKI). This study sought potential underlying mechanisms. CD-1 mice received intravenous SnPP, followed 4-18 hours later by a variety of renal biochemical, histologic, and genomic assessments. Renal resistance to ischemic-reperfusion injury (IRI) was also sought. SnPP was rapidly taken up by kidney and was confined to proximal tubules. Transient suppression of renal heme synthesis (decreased δ aminolevulinic acid synthase expression), a 2.5-fold increase in "catalytic" Fe levels and oxidant stress resulted (decreased glutathione; increased malondialdehyde, and protein carbonyl content). Nrf2 nuclear translocation (∼2x Nrf2 increase; detected by enzyme-linked immunosorbent assay, Western blotting), with corresponding activation of ∼20 Nrf2-sensitive genes (RNA-Seq) were observed. By 18 hours after SnPP injection, marked protection against IRI emerged. This represented "preconditioning", not a direct SnPP effect, given that SnPP administered at the time of IRI exerted no protective effect. The importance of transient oxidant stress in SnPP "preconditioning" was exemplified by the following: (1) oxidant stress induced by a different mechanism (myoglobin injection) recapitulated SnPP's protective action; (2) GSH treatment blunted SnPP's protective influence; (3) SnPP raised cytoprotective heavy chain ferritin (Fhc), a response enhanced by exogenous Fe injection; and (4) SnCl2, a ∼35- to 50-fold HO-1 inducer (not inhibitor) evoked neither oxidant stress nor mitigated IRI (seemingly excluding HO-1 activity in SnPP's protective effect). SnPP specifically accumulates within proximal tubule cells; transient "catalytic" Fe overload and oxidative stress result; Nrf2-cytoprotective pathways are upregulated; and these changes help protect against ischemic AKI.
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Affiliation(s)
| | - Jeff J Delrow
- The Fred Hutchinson Cancer Research Center, Seattle, Wash
| | - Richard A Zager
- The Fred Hutchinson Cancer Research Center, Seattle, Wash; The University of Washington, Seattle, Wash.
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