siRNA Targeted to p53 Attenuates Ischemic and Cisplatin-Induced Acute Kidney Injury

Proximal tubule cells (PTCs), which are the primary site of kidney injury associated with ischemia or nephrotoxicity, are the site of oligonucleotide reabsorption within the kidney. We exploited this property to test the efficacy of siRNA targeted to p53, a pivotal protein in the apoptotic pathway, to prevent kidney injury. Naked synthetic siRNA to p53 injected intravenously 4 h after ischemic injury maximally protected both PTCs and kidney function. PTCs were the primary site for siRNA uptake within the kidney and body. Following glomerular filtration, endocytic uptake of Cy3-siRNA by PTCs was rapid and extensive, and significantly reduced ischemia-induced p53 upregulation. The duration of the siRNA effect in PTCs was 24 to 48 h, determined by levels of p53 mRNA and protein expression. Both Cy3 fluorescence and in situ hybridization of siRNA corroborated a short t½ for siRNA. The extent of renoprotection, decrease in cellular p53 and attenuation of p53-mediated apoptosis by siRNA were dose- and time-dependent. Analysis of renal histology and apoptosis revealed improved injury scores in both cortical and corticomedullary regions. siRNA to p53 was also effective in a model of cisplatin-induced kidney injury. Taken together, these data indicate that rapid delivery of siRNA to proximal tubule cells follows intravenous administration. Targeting siRNA to p53 leads to a dose-dependent attenuation of apoptotic signaling, suggesting potential therapeutic benefit for ischemic and nephrotoxic kidney injury

Teprasiran, a Small Interfering RNA, for the Prevention of Acute Kidney Injury in High-Risk Patients Undergoing Cardiac Surgery

Background: Acute kidney injury (AKI) affects up to 30% of patients undergoing cardiac surgery, leading to increased in-hospital and long-term morbidity and mortality. Teprasiran is a novel small interfering RNA that temporarily inhibits p53-mediated cell death that underlies AKI. Methods: This prospective, multicenter, double-blind, randomized, controlled phase 2 trial evaluated the efficacy and safety of a single 10 mg/kg dose of teprasiran versus placebo (1:1), in reducing the incidence, severity, and duration of AKI after cardiac surgery in high-risk patients. The primary end point was the proportion of patients who developed AKI determined by serum creatinine by postoperative day 5. Other end points included AKI severity and duration using various prespecified criteria. To inform future clinical development, a composite end point of major adverse kidney events at day 90, including death, renal replacement therapy, and ≥25% reduction of estimated glomerular filtration rate was assessed. Both serum creatinine and serum cystatin-C were used for estimated glomerular filtration rate assessments. Results: A total of 360 patients were randomly assigned in 41 centers; 341 dosed patients were 73±7.5 years of age (mean±SD), 72% were men, and median European System for Cardiac Operative Risk Evaluation score was 2.6%. Demographics and surgical parameters were similar between groups. AKI incidence was 37% for teprasiran- versus 50% for placebo-treated patients, a 12.8% absolute risk reduction, P=0.02; odds ratio, 0.58 (95% CI, 0.37-0.92). AKI severity and duration were also improved with teprasiran: 2.5% of teprasiran- versus 6.7% of placebo-treated patients had grade 3 AKI; 7% teprasiran- versus 13% placebo-treated patients had AKI lasting for 5 days. No significant difference was observed for the major adverse kidney events at day 90 composite in the overall population. No safety issues were identified with teprasiran treatment. Conclusions: The incidence, severity, and duration of early AKI in high-risk patients undergoing cardiac surgery were significantly reduced after teprasiran administration. A phase 3 study with a major adverse kidney event at day 90 primary outcome that has recently completed enrollment was designed on the basis of these findings (NCT03510897)

Neuregulin Promotes Incomplete Autophagy of Prostate Cancer Cells That Is Independent of mTOR Pathway Inhibition

Growth factors activating the ErbB receptors have been described in prostate tumors. The androgen dependent prostate cancer cell line, LNCaP, expresses the ErbB-1, ErbB-2 and ErbB-3 receptor tyrosine kinases. Previously, it was demonstrated that NRG activates ErbB-2/ErbB-3 heterodimers to induce LNCaP cell death, whereas, EGF activates ErbB-1/ErbB-1 or ErbB-1/ErbB-2 dimers to induce cell growth and survival. It was also demonstrated that PI3K inhibitors repressed this cell death suggesting that in androgen deprived LNCaP cells, NRG activates a PI3K-dependent pathway associated with cell death.In the present study we demonstrate that NRG induces autophagy in LNCaP cells, using LC3 as a marker. However, the autophagy induced by NRG may be incomplete since p62 levels elevate. We also demonstrated that NRG- induced autophagy is independent of mammalian target of rapamycin (mTOR) inhibition since NRG induces Akt and S6K activation. Interestingly, inhibition of reactive oxygen species (ROS) by N-acetylcysteine (NAC), inhibited NRG-induced autophagy and cell death. Our study also identified JNK and Beclin 1 as important components in NRG-induced autophagy and cell death. NRG induced elevation in JNK phosphorylation that was inhibited by NAC. Moreover, inhibitor of JNK inhibited NRG-induced autophagy and cell death. Also, in cells overexpressing Bcl-2 or cells expressing sh-RNA against Beclin 1, the effects of NRG, namely induction of autophagy and cell death, were inhibited.Thus, in LNCaP cells, NRG-induces incomplete autophagy and cell death that depend on ROS levels. These effects of NRG are mediated by signaling pathway that activates JNK and Beclin 1, but is independent of mTOR inhibition

Teprasiran, A Small Interfering RNA, for the Prevention of Acute Kidney Injury in High-Risk Patients Undergoing Cardiac Surgery: A Randomized Clinical Study

Acute kidney injury (AKI) affects up to 30% of cardiac surgery patients, leading to increased in-hospital and long-term morbidity and mortality. Teprasiran is a novel small interfering RNA (siRNA) that temporarily inhibits p53-mediated cell death, which underlies AKI. This prospective, multicenter, double-blind, randomized, controlled Phase 2 trial evaluated the efficacy and safety of a single 10 mg/kg dose of teprasiran vs. placebo (1:1), in reducing the incidence, severity, and duration of AKI following cardiac surgery in high-risk patients. The primary endpoint was proportion of patients who developed AKI determined by serum creatinine (sCr) by post-operative day 5. Other endpoints included AKI severity and duration using various prespecified criteria. To inform future clinical development, a composite endpoint of major adverse kidney events at day 90 (MAKE90), including death, renal replacement therapy (RRT) and ≥25% reduction of estimated glomerular filtration rate (eGFR) was assessed. Both sCr and serum cystatin-C (sCys) were used for eGFR assessments. A total of 360 patients were randomized in 41 centers. 341 dosed patients were 73±7.5 years old (mean±SD), 72% were male, and median Euroscore-II (European System for Cardiac Operative Risk Evaluation) was 2.6%. Demographics and surgical parameters were similar between groups. AKI incidence was 37% for teprasiran vs. 50% for placebo-treated patients, a 12.8% absolute risk reduction (ARR), p=0.02; OR=0.58 (95% CI 0.37 to 0.92). AKI severity and duration were also improved with teprasiran: 2.5% of teprasiran vs. 6.7% of placebo-treated patients had Grade 3 AKI; 7% teprasiran vs. 13% placebo-treated patients had AKI lasting for 5 days. No significant difference was observed for the MAKE90 composite in the overall population. No safety issues were identified with teprasiran treatment. The incidence, severity, and duration of early AKI in high-risk patients undergoing cardiac surgery were significantly reduced following teprasiran administration. A Phase 3 study with a MAKE90 primary outcome which has recently completed enrollment was designed based on these findings (NCT03510897). URL: https://clinicaltrials.gov/ Unique Identifier: NCT02610283