Platelet inhibitory effects of the Phase 3 anticancer and normal tissue cytoprotective agent, RRx-001

RRx-001: a chimeric triple action NLRP3 inhibitor, Nrf2 inducer, and nitric oxide superagonist

RRx-001 is a shape shifting small molecule with Fast Track designation for the prevention/amelioration of chemoradiation-induced severe oral mucositis (SOM) in newly diagnosed Head and Neck cancer. It has been intentionally developed or "engineered" as a chimeric single molecular entity that targets multiple redox-based mechanisms. Like an antibody drug conjugate (ADC), RRx-001 contains, at one end a "targeting" moiety, which binds to the NLRP3 inflammasome and inhibits it as well as Kelch-like ECH-associated protein 1 (KEAP1), the negative regulator of Nrf2, and, at the other end, a conformationally constrained, dinitro containing 4 membered ring, which fragments under conditions of hypoxia and reduction to release therapeutically active metabolites i.e., the payload. This "payload", which is delivered specifically to hypoperfused and inflamed areas, includes nitric oxide, nitric oxide related species and carbon-centered radicals. As observed with ADCs, RRx-001 contains a backbone amide "linker" attached to a binding site, which correlates with the F_ab region of an antibody, and to the dinitroazetidine payload, which is microenvironmentally activated. However, unlike ADCs, whose large size impacts their pharmacokinetic properties, RRx-001 is a nonpolar small molecule that easily crosses cell membranes and the blood brain barrier (BBB) and distributes systemically. This short review is organized around the de novo design and in vivo pro-oxidant/pro-inflammatory and antioxidant/anti-inflammatory activity of RRx-001, which, in turn, depends on the reduced to oxidized glutathione ratio and the oxygenation status of tissues.

Intravascularly infused extracellular matrix as a biomaterial for targeting and treating inflamed tissues

Decellularized extracellular matrix in the form of patches and locally injected hydrogels has long been used as therapies in animal models of disease. Here we report the safety and feasibility of an intravascularly infused extracellular matrix as a biomaterial for the repair of tissue in animal models of acute myocardial infarction, traumatic brain injury and pulmonary arterial hypertension. The biomaterial consists of decellularized, enzymatically digested and fractionated ventricular myocardium, localizes to injured tissues by binding to leaky microvasculature, and is largely degraded in about 3 d. In rats and pigs with induced acute myocardial infarction followed by intracoronary infusion of the biomaterial, we observed substantially reduced left ventricular volumes and improved wall-motion scores, as well as differential expression of genes associated with tissue repair and inflammation. Delivering pro-healing extracellular matrix by intravascular infusion post injury may provide translational advantages for the healing of inflamed tissues 'from the inside out'.

Clinical Course of Two Patients with COVID-19 Respiratory Failure After Administration of the Anticancer Small Molecule, RRx-001

Two critically ill COVID-19 infected patients, who had exhausted all available treatment options, were treated with the small-molecule RRx-001 with subsequent improvement. RRx-001, a first-in-class small molecule with anti-inflammatory, vascular normalizing and macrophage-repolarizing properties, has been safely administered 300+ patients in clinical trials. This is the first report of RRx-001 treatment of COVID-19.

Early Fresh Frozen Plasma Transfusion: Is It Associated With Improved Outcomes of Patients With Sepsis?

Background: So far, no study has investigated the effects of plasma transfusion in the patients with sepsis, especially in the terms of prognosis. Therefore, we aimed to explore the association of early fresh frozen plasma (FFP) transfusion with the outcomes of patients with sepsis.

Methods: We performed a cohort study using data extracted from the Medical Information Mart for Intensive Care III database (v1.4). External validation was obtained from the First Affiliated Hospital of Wenzhou Medical University, China. We adopted the Sepsis-3 criteria to extract the patients with sepsis and septic shock. The occurrence of transfusion during the first 3-days of intensive care unit (ICU) stay was regarded as early FFP transfusion. The primary outcome was 28-day mortality. We assessed the association of early FFP transfusion with the patient outcomes using a Cox regression analysis. Furthermore, we performed the sensitivity analysis, subset analysis, and external validation to verify the true strength of the results.

Results: After adjusting for the covariates in the three models, respectively, the significantly higher risk of death in the FFP transfusion group at 28-days [e.g., Model 2: hazard ratio (HR) = 1.361, P = 0.018, 95% CI = 1.054–1.756] and 90-days (e.g., Model 2: HR = 1.368, P = 0.005, 95% CI = 1.099–1.704) remained distinct. Contrarily, the mortality increased significantly with the increase of FFP transfusion volume. The outcomes of the patients with sepsis with hypocoagulable state after early FFP transfusion were not significantly improved. Similar results can also be found in the subset analysis of the septic shock cohort. The results of external validation exhibited good consistency.

Conclusions: Our study provides a new understanding of the rationale and effectiveness of FFP transfusion for the patients with sepsis. After recognizing the evidence of risk-benefit and cost-benefit, it is important to reduce the inappropriate use of FFP and avoid unnecessary adverse transfusion reactions.

Discovery of RRx-001, a Myc and CD47 Downregulating Small Molecule with Tumor Targeted Cytotoxicity and Healthy Tissue Cytoprotective Properties in Clinical Development

After extensive screening of aerospace compounds in an effort to source a novel anticancer agent, RRx-001, a first-in-class dinitroazetidine small molecule, was selected for advancement into preclinical and clinical development. RRx-001 is a minimally toxic small molecule with a distinct chemical structure and mechanism of action. The paradox of RRx-001 is that it mediates both antitumor cytotoxicity and normal tissue protection. The question of exactly how RRx-001 does this, and by means of what mechanism(s), depending on the route of delivery, intravenous or intratumoral, are explored. RRx-001 is currently in phase 2 and 3 clinical trials for the treatment of multiple solid tumor malignancies and as a supportive care drug.

Purification and analysis of a protein cocktail capable of scavenging cell-free hemoglobin, heme, and iron

BACKGROUND

Hemolysis releases toxic cell-free hemoglobin (Hb), heme, and iron, which overwhelm their natural scavenging mechanisms during acute or chronic hemolytic conditions. This study describes a novel strategy to purify a protein cocktail containing a comprehensive set of scavenger proteins for potential treatment of hemolysis byproducts.

STUDY DESIGN AND METHODS

Tangential flow filtration was used to purify a protein cocktail from Human Cohn Fraction IV (FIV). A series of in vitro assays were performed to characterize composition and biocompatibility. The in vivo potential for hemolysis byproduct mitigation was assessed in a hamster exchange transfusion model using mechanically hemolyzed blood plasma mixed with the protein cocktail or a control colloid (dextran 70 kDa).

RESULTS

A basis of 500 g of FIV yielded 62 ± 9 g of a protein mixture at 170 g/L, which bound to approximately 0.6 mM Hb, 1.2 mM heme, and 1.2 mM iron. This protein cocktail was shown to be biocompatible in vitro with red blood cells and platelets and exhibits nonlinear concentration dependence with respect to viscosity and colloidal osmotic pressure. In vivo assessment of the protein cocktail demonstrated higher iron transport to the liver and spleen and less to the kidney and heart with significantly reduced renal and cardiac inflammation markers and lower kidney and hepatic damage compared to a control colloid.

DISCUSSION

Taken together, this study provides an effective method for large-scale production of a protein cocktail suitable for comprehensive reduction of hemolysis-induced toxicity.

Platelet inhibitory effects of the Phase 3 anticancer and normal tissue cytoprotective agent, RRx-001

The platelet inhibitory effects of the Phase 3 anticancer agent and nitric oxide (NO) donor, RRx-001, (1-bromoacetyl-3,3-dinitroazetidine) were examined ex vivo and compared with the diazeniumdiolate NO donor, diethylenetriamine NONOate (DETA-NONOate), which spontaneously releases nitric oxide in aqueous solution. In the absence of red blood cells and in a dose-dependent manner, DETA-NONOate strongly inhibited platelet aggregation induced by several stimuli (ADP, epinephrine and collagen) whereas RRx-001 only slightly inhibited platelet aggregation under the same conditions in a dose-dependent manner; these antiaggregant effects were blocked when both DETA-NONOate and RRx-001 were co-incubated with carboxy-PTIO (CPTIO 0.01-100 micromol), a widely accepted NO scavenger. However, in the presence of red blood cells from healthy human donors, RRx-001, which binds covalently to haemoglobin (Hb) and catalyses the production of NO from endogenous nitrite, more strongly inhibited the aggregation of platelets than DETA-NONOate in a dose-dependent manner likely because haemoglobin avidly scavenges nitric oxide and reduces its half-life; the RRx-001-mediated platelet inhibitory effect was increased in the presence of nitrite. The results of this study suggest that RRx-001-bound Hb (within RBCs) plays an important role in the bioconversion of NO2- to NO^. , which makes RRx-001 a more physiologically relevant inhibitor of platelet aggregation than other nitric oxide donors, whose effects are attenuated in the presence of red blood cells. Therefore, RRx-001-mediated platelet inhibition is a potentially useful therapeutic property, especially in hypercoagulable cancer patients that are at an increased risk of thrombotic complications.