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A Review of RRx-001: A Late-Stage Multi-Indication Inhibitor of NLRP3 Activation and Chronic Inflammation. Drugs 2023; 83:389-402. [PMID: 36920652 PMCID: PMC10015535 DOI: 10.1007/s40265-023-01838-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2023] [Indexed: 03/16/2023]
Abstract
Chronic unresolving inflammation is emerging as a key underlying pathological feature of many if not most diseases ranging from autoimmune conditions to cardiometabolic and neurological disorders. Dysregulated immune and inflammasome activation is thought to be the central driver of unresolving inflammation, which in some ways provides a unified theory of disease pathology and progression. Inflammasomes are a group of large cytosolic protein complexes that, in response to infection- or stress-associated stimuli, oligomerize and assemble to generate a platform for driving inflammation. This occurs through proteolytic activation of caspase-1-mediated inflammatory responses, including cleavage and secretion of the proinflammatory cytokines interleukin (IL)-1β and IL-18, and initiation of pyroptosis, an inflammatory form of cell death. Several inflammasomes have been characterized. The most well-studied is the nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome, so named because the NLRP3 protein in the complex, which is primarily present in immune and inflammatory cells following activation by inflammatory stimuli, belongs to the family of nucleotide-binding and oligomerization domain (Nod) receptor proteins. Several NLRP3 inflammasome inhibitors are in development, all with multi-indication activity. This review discusses the current status, known mechanisms of action, and disease-modifying therapeutic potential of RRx-001, a direct NLRP3 inflammasome inhibitor under investigation in several late-stage anticancer clinical trials, including a phase 3 trial for the treatment of third-line and beyond small cell lung cancer (SCLC), an indication with no treatment, in which RRx-001 is combined with reintroduced chemotherapy from the first line, carboplatin/cisplatin and etoposide (ClinicalTrials.gov Identifier: NCT03699956). Studies from multiple independent groups have now confirmed that RRx-001 is safe and well tolerated in humans. Additionally, emerging evidence in preclinical animal models suggests that RRx-001 could be effective in a wide range of diseases where immune and inflammasome activation drives disease pathology.
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Oronsky B, Guo X, Wang X, Cabrales P, Sher D, Cannizzo L, Wardle B, Abrouk N, Lybeck M, Caroen S, Oronsky A, Reid TR. Discovery of RRx-001, a Myc and CD47 Downregulating Small Molecule with Tumor Targeted Cytotoxicity and Healthy Tissue Cytoprotective Properties in Clinical Development. J Med Chem 2021; 64:7261-7271. [PMID: 34043360 DOI: 10.1021/acs.jmedchem.1c00599] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
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.
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Affiliation(s)
- Bryan Oronsky
- EpicentRx Inc., 11099 North Torrey Pines Road, Suite 160, La Jolla, California 92037, United States
| | - XiaoNing Guo
- SciClone Pharmaceuticals Co., Ltd., 22 Floor, Shanghai Central Plaza, No. 381 Middle Huaihai Road, Huangpu, Shanghai 200020, China
| | - XiaoHui Wang
- SciClone Pharmaceuticals Co., Ltd., 22 Floor, Shanghai Central Plaza, No. 381 Middle Huaihai Road, Huangpu, Shanghai 200020, China
| | - Pedro Cabrales
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - David Sher
- Department of Radiation Oncology, UT Southwestern Medical Center, 2280 Inwood Road, Dallas, Texas 75390, United States
| | - Lou Cannizzo
- Department of Space Systems, Northrop Grumman Corporation, 2980 Fairview Park Drive, Falls Church, Virginia 22042, United States
| | - Bob Wardle
- Department of Space Systems, Northrop Grumman Corporation, 2980 Fairview Park Drive, Falls Church, Virginia 22042, United States
| | - Nacer Abrouk
- EpicentRx Inc., 11099 North Torrey Pines Road, Suite 160, La Jolla, California 92037, United States
| | - Michelle Lybeck
- EpicentRx Inc., 11099 North Torrey Pines Road, Suite 160, La Jolla, California 92037, United States
| | - Scott Caroen
- EpicentRx Inc., 11099 North Torrey Pines Road, Suite 160, La Jolla, California 92037, United States
| | - Arnold Oronsky
- InterWest Partners, 467 First Street, Suite 201, Los Altos, California 94022, United States
| | - Tony R Reid
- EpicentRx Inc., 11099 North Torrey Pines Road, Suite 160, La Jolla, California 92037, United States
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Jani VP, Asaro R, Oronsky B, Cabrales P. RRx-001 Increases Erythrocyte Preferential Adhesion to the Tumor Vasculature. Int J Mol Sci 2021; 22:ijms22094713. [PMID: 33946824 PMCID: PMC8124275 DOI: 10.3390/ijms22094713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 11/16/2022] Open
Abstract
Red blood cells (RBCs) serve a variety of functions beyond mere oxygen transport both in health and pathology. Notably, RRx-001, a minimally toxic pleiotropic anticancer agent with macrophage activating and vascular normalization properties currently in Phase III trials, induces modification to RBCs which could promote vascular adhesion similar to sickle cells. This study assessed whether RBCs exposed to RRx-001 adhere to the tumor microvasculature and whether this adhesion alters tumor viability. We next investigated the biomechanics of RBC adhesion in the context of local inflammatory cytokines after treatment with RRx-001 as a potential mechanism for preferential tumor aggregation. Human HEP-G2 and HT-29 tumor cells were subcutaneously implanted into nu/nu mice and were infused with RRx-001-treated and Technetium-99m (99mTc)-labeled blood. RBC adhesion was quantified in an in vitro human umbilical vein endothelial cell (HUVEC) assay under both normoxic and hypoxic conditions with administration of either lipopolysaccharide (LPS) or Tumor necrosis alpha (TNFα) to mimic the known inflammation in the tumor microenvironment. One hour following administration of 99mTc labeled RBCs treated with 10 mg/kg RRx-001, we observed an approximate 2.0-fold and 1.5-fold increase in 99mTc-labeled RBCs compared to vehicle control in HEPG2 and HT-29 tumor models, respectively. Furthermore, we observed an approximate 40% and 36% decrease in HEP-G2 and HT-29 tumor weight, respectively, following treatment with RRx-001. To quantify RBC adhesive potential, we determined τ50, or the shear stress required for 50% disassociation of RBCs from HUVECs. After administration of TNF-α under normoxia, τ50 was determined to be 4.5 dynes/cm2 (95% CI: 4.3-4.7 dynes/cm2) for RBCs treated with 10 μM RRx-001, which was significantly different (p < 0.05) from τ50 in the absence of treatment. Under hypoxic conditions, the difference of τ50 with (4.8 dynes/cm2; 95% CI: 4.6-5.1 dynes/cm2) and without (2.6 dynes/cm2; 95% CI: 2.4-2.8 dynes/cm2) 10 μM RRx-001 treatment was exacerbated (p = 0.05). In conclusion, we demonstrated that RBCs treated with RRx-001 preferentially aggregate in HEP-G2 and HT-29 tumors, likely due to interactions between RRx-001 and cysteine residues within RBCs. Furthermore, RRx-001 treated RBCs demonstrated increased adhesive potential to endothelial cells upon introduction of TNF-α and hypoxia suggesting that RRx-001 may induce preferential adhesion in the tumor but not in other tissues with endothelial dysfunction due to conditions prevalent in older cancer patients such as heart disease or diabetic vasculopathy.
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Affiliation(s)
- Vinay P. Jani
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA;
| | - Robert Asaro
- Department of Structural Engineering, University of California, San Diego, La Jolla, CA 92093, USA;
| | - Bryan Oronsky
- EpicentRx Inc., 4445 Eastgate Mall, Suite 200, San Diego, CA 92121, USA;
| | - Pedro Cabrales
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA;
- Correspondence: ; Tel.: +1-858-534-5847
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Raghunand N, Gatenby RA. Bridging Spatial Scales From Radiographic Images to Cellular and Molecular Properties in Cancers. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00053-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Oronsky B, Carter CA, Caroen S, Scribner C, Oronsky A, Reid TR. RRx-001, a first-in-class small molecule inhibitor of MYC and a downregulator of CD47, is an "erythrophagoimmunotherapeutic". Oncoimmunology 2020; 9:1746172. [PMID: 33457091 PMCID: PMC7790525 DOI: 10.1080/2162402x.2020.1746172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The main mechanism of action of RRx-001, a pharmaceutically unprecedented sui generis Phase 3 small molecule that is derived from the aerospace industry, is clarified. RRx-001 has demonstrated anticancer activity through antiangiogenic, immune, epigenetic, antioxidant, apoptotic and nitric oxide (NO) pathways, resulting in its pleiomorphic description as an antiangiogenic/vascular normalizer.
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Affiliation(s)
- Bryan Oronsky
- Clinical and Scientific Department, EpicentRx, Inc, La Jolla, CA, USA
| | - Corey A Carter
- Clinical and Scientific Department, EpicentRx, Inc, La Jolla, CA, USA
| | - Scott Caroen
- Clinical and Scientific Department, EpicentRx, Inc, La Jolla, CA, USA
| | - Curtis Scribner
- Clinical and Scientific Department, EpicentRx, Inc, La Jolla, CA, USA
| | - Arnold Oronsky
- Clinical and Scientific Department, InterWest Partners, Menlo Park, CA, USA
| | - Tony R Reid
- Clinical and Scientific Department, EpicentRx, Inc, La Jolla, CA, USA
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Oronsky B, Scribner C, Aggarwal R, Cabrales P. RRx-001 protects normal tissues but not tumors via Nrf2 induction and Bcl-2 inhibition. J Cancer Res Clin Oncol 2019; 145:2045-2050. [PMID: 31250159 DOI: 10.1007/s00432-019-02958-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/19/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND RRx-001, a minimally toxic next-generation checkpoint inhibitor that targets myeloid suppressor cells in the tumor microenvironment, has also been shown to protect normal tissues from the cytotoxic effects of chemotherapy and radiation. The following experiments were carried out to determine whether the cytoprotective functions of RRx-001 in normal cells were operative in tumor cells. DESIGN The effects of RRx-001 on normal cells, and ovarian cancer A2780 and UWB1 cells were evaluated with a colony-forming assay. Western blot densitometry was used to measure Nrf2 nuclear translocation in Caco2 cells after exposure to RRx-001. Following incubation with RRx-001, levels of the antioxidant, NQO1, were determined in Caco2 cells by measuring absorbance over 300 min at 440 nm. RRx-001-mediated cytotoxicity in HCT-116 colorectal cancer cells was evaluated with an MTT assay. In addition, the effect of RRx-001 incubation on the protein expression of Nrf2, PARP, cleaved PARP, procaspases 3, 8, and 9, Bcl-2, and Bax in HCT-116 colorectal cells was determined by western blot analysis. RESULTS RRx-001 is demonstrated to induce Nrf2 in normal tissues, mediating protection, and to downregulate the Nrf2-controlled antiapoptotic target gene, B-cell lymphoma 2 (Bcl-2) in tumors, mediating cytotoxicity. CONCLUSION Through Nrf2 induction in normal cells and inhibition of Bcl-2 in tumor cells, RRx-001 selectively protects normal cells against lethality in normal cells, but induces apoptosis in tumor cells.
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Affiliation(s)
- Bryan Oronsky
- EpicentRx Inc, 4445 Eastgate Mall, Suite 200, San Diego, CA, 92121, USA.
| | - Curtis Scribner
- EpicentRx Inc, 4445 Eastgate Mall, Suite 200, San Diego, CA, 92121, USA
| | - Rahul Aggarwal
- Helen Diller Comprehensive Cancer Center, University of California San Francisco, UCSF, Box 1711, San Francisco, CA, 94143, USA
| | - Pedro Cabrales
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, San Diego, CA, 92093, USA
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Hu RX, Yang J, Chen X, Zhang X, Zhang MB. Monomer, chain, layer and 3-D framework constructed by linear 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Oronsky B, Oronsky N, Cabrales P. Platelet inhibitory effects of the Phase 3 anticancer and normal tissue cytoprotective agent, RRx-001. J Cell Mol Med 2018; 22:5076-5082. [PMID: 30010241 PMCID: PMC6156345 DOI: 10.1111/jcmm.13791] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/12/2018] [Indexed: 01/02/2023] Open
Abstract
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.
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Affiliation(s)
| | | | - Pedro Cabrales
- Department of Bioengineering, University of California San Diego, La Jolla, California
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