Renibus Therapeutics Announces Publication of a Novel Stress Test for Assessing Antioxidant Defenses in Chronic Kidney Disease

--In a phase 1 study, RBT-6 was administered to study participants with moderate to severe chronic kidney disease (CKD) and showed an increase in expression of antioxidant proteins. These findings may help develop a pharmacologic stress test for determining antioxidant reserves in CKD and other medical conditions.

Southlake, Texas, UNITED STATES

DALLAS, Texas, June 16, 2020 (GLOBE NEWSWIRE) -- Renibus Therapeutics, Inc., a clinical stage biotechnology company developing novel therapies for prevention and treatment of kidney diseases, today reported the publication of results from a Phase 1 study evaluating the safety and efficacy of RBT-6 (stannous protoporphyrin) for assessing select antioxidant defenses in patients with CKD. The results were published in the prestigious Clinical Journal of American Society of Nephrology (Zager, R et al. CJASN April 2020, CJN.15951219; DOI:

Oxidative Stress in CKD

Oxidative stress is a hallmark of CKD. However, currently there is no way to assess a patient’s antioxidant defense mechanisms and reserves, which may help from a prognostic or therapeutic standpoint. The study team identified four antioxidant proteins (heme oxygenase 1 [HO-1], NAD[P]H dehydrogenase [quinone] 1 [NQO1], ferritin and p21] for which levels could be measured at baseline and in response to a pharmacologic stress. Since RBT-6 triggers increased expression of the aforementioned proteins, its administration could determine antioxidant reserves that may guide therapy of patients with medical conditions causing oxidative stress including, but not limited to, CKD.

Phase 1 Study Design

A total of 24 participants with moderate to severe CKD were enrolled and given a single dose of RBT-6. Plasma and urinary antioxidant proteins were measured at baseline and for up to 4 days post-RBT-6 dosing. Kidney safety was assessed by serial measurements of BUN, creatinine, eGFR, albuminuria and biomarkers of renal tubular injury.

Study 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 the infusion. Marked inter-subject differences were observed. RBT-6 was well tolerated by all participants, and no evidence of nephrotoxicity was observed.

“These results suggest that RBT-6 when administered as a single dose may provide insights into the ability of the body to respond to oxidative stress and the state of antioxidant reserves. For example, were a patient with CKD to demonstrate severely decreased antioxidant reserves, he or she may have a high risk of disease progression and may need more aggressive management of their disease”, said Dr. Richard Zager, Professor of Medicine at University of Washington and lead author of the study. 

Renibus is planning to develop this pharmacologic stress test for clinical use and is assessing next steps towards obtaining regulatory approval.

About Renibus

Renibus Therapeutics is a clinical stage biotechnology company developing novel therapies for kidney diseases. The Company’s portfolio includes RBT-1 for prevention of acute kidney injury, RBT-2 for delaying progression of CKD, RBT-3 for the treatment of iron deficiency anemia, RBT-6 for pharmacologic stress testing in CKD, and RBT-9 for other conditions associated with oxidative stress, including COVID-19. Taken together, these assets potentially represent significant market opportunities for the company. 


This article contains information regarding our future discovery, development efforts, business strategy, and market opportunities. This information constitutes a forward-looking statement. There are a number of risks and uncertainties that could cause our actual results to differ materially from those indicated by such forward-looking statements. These risks and uncertainties include those inherent in pharmaceutical research, such as adverse results in our drug discovery and clinical development processes, decisions made by the FDA and other regulatory authorities, market conditions, our ability to obtain, maintain and enforce proprietary rights and our ability to obtain any necessary financing to conduct our planned activities.

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