Patent Highlight Cite This: ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX
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Modulators of Proteolysis for the Treatment of Carcinomas Robert B. Kargbo* Usona Institute, 277 Granada Drive, San Luis Obispo, California 93401-7337, United States
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Important Compound Classes.
and a number of disease-causing proteins have been investigated. The MDM2 protein, which is also known as E3 ubiquitin-protein ligase MDM2, functions as E3 ubiquitin ligase of the p53 tumor suppressor and as an inhibitor of p53 transcriptional activation. In normal cell function without oncogenic stress signal, MDM2 keeps the p53 level at low concentration. However, in response to DNA cellular stress or DNA damage, the p53 level increases and consequently leads to an increase in MDM2. As a result, p53 regulates MDM2 both at the transcription and activity levels. In cancer patients, however, 50% are found with p53 mutation and patients with wild type p53 were often found to have p53 down regulation by MDM2 via the interaction of p53 and MDM2. The function of MDM2 as E3 ligase has allowed the recruiting of MDM2 as a disease-causing protein, its ubiquitination, and degradation in drug discovery. The VHL tumor suppressor is the substrate recognition subunit of the E3 ligase complex VCB, which consists of elongins B and C, Cullin 2, and ring box protein 1 (Rbx1) and has been used as an E3 ligase with exciting therapeutic potential. VHL disease is characterized by an increased risk of clear cell renal carcinoma, hemangioblastoma of the nervous system, and adrenal pheochromocytoma. The primary substrate of VHL is the Hypoxia Inducible Factor 1α (HIF1α), which upregulates genes such as the pro-angiogenic growth factor, vascular endothelial growth factor (VEGF), GLUT1, glucose transport, and red blood cell inducing cytokine, erythropoietin, in response to low oxygen levels. Many tumors have been shown to have mutations in the VHL, the targeting subunit of VCB, which supports the clinical significance of the HIF pathway. In addition, a subset of the observed mutations of VHL may cause weak binding to the HIF-1α and is associated with cancer and cardiovascular diseases. Cereblon (CRBN) is a substrate receptor for the CRL4 (CUL4−RBX1−DDB1) ubiquitin ligase complex. Bound substrates are ubiquitinated by the cereblon−CRL4 complex, leading to their degradation by the 26S proteasome. A number of CRBN substrates have been identified and have demonstrated that the addition of CRBN modulating ligands triggers their recruitment and degradation. CRBN forms an E3 ubiquitin ligase complex with damaged DNA binding protein 1 (DDB1), Cullin-4A (CUL4A), and regulator of cullins 1 (ROC1). This complex ubiquitinates a number of proteins but the mechanism has not been completely elucidated. However, CRBN ubiquitination of target proteins result in increased levels of fibroblast growth factor 8 (FGF8) and fibroblast growth factor 10 (FGF10). Consequently, ubiquitin ligase
Title. Modulators of Proteolysis and Associated Methods of Use Patent Application Number. WO 2018/226542 A1 Publication Date. December 13, 2018 Priority Application. US 62/517,581 US 62/563,612 Priority Date. June 09, 2017 September 26, 2017 Inventors. Crew, A. P.; Dong, H.; Wang, J.; Crews, C. M.; Jaime-Figueroa, S. Assignee Company. Arvinas, Inc. and Yale University. Disease Area. Cancers Biological Target. cMet and p 38 protein targets Summary. PROTACs (PROteolysis TArgeting Chimeras) are new generation heterobifunctional small molecules, which target proteins for degradation via recruitment to ubiquitinprotein ligase (E3). PROTAC degradation compounds have shown therapeutic advantages, including improved potency, specificity, catalytic activity, and prolonged pharmacodynamics and present a potential orthogonal therapeutic strategy which expands the druggable target space. PROTACs consist of small molecule target inhibitor or binder on one side that is chemically linked to an E3 ligase recruiter compound on the other side. PROTACs enable degradation by simultaneous binding of the target protein and the E3 ligase complex proteins, which brings the target protein into close proximity for ubiquitination, consequently targeting it for degradation through the ubiquitin proteasomal system (UPS). There are hundreds of E3 ligases in eukaryotes, and many more proteins are involved in active E3 ligase complexes; however, very few binding compounds which could be used as recruiter molecules for PROTAC design are known. The von Hippel Lindau (VHL) and Cereblon (CRBN) are substrate adaptor components of larger E3 Cullin-RING complexes that have been extensively used for PROTAC-mediated protein degradation and have shown significant success against diverse set of targets. Nutlins are the first small molecule E3 ligase mouse double minute 2 homologue (MDM2) inhibitors. The PROTAC approach allows deliberate degradation of target proteins using the cells’ own degradation machinery (of which over 600 E3 ubiquitin ligases are known in humans), © XXXX American Chemical Society
Received: January 6, 2019
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DOI: 10.1021/acsmedchemlett.9b00006 ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX
ACS Medicinal Chemistry Letters
Patent Highlight
Key Structures.
complex is important for limb outgrowth in embryos, the absence of which will cause DDB1 to form a complex with DDB2 that functions as a DNA damage-binding protein. CRBN modulators have provided important proof-of-principle for the development of compounds targeting specific proteins for destruction that previously had been considered undruggable. Apoptosis is a critical cell process in normal development and homeostasis of multicellular organisms. The dysfunction of apoptosis is a hallmark of human cancers and plays a major role in the failure of current anticancer drugs. Inhibitors of apoptosis proteins (IAPs) are protein family, which are involved in suppressing apoptosis. IAPs contain an E3 ligase specific domain and baculoviral IAP repeat (BIR) domains which recognize substrates and promote their ubiquitination. In addition, IAPs promote ubiquitination and can directly bind and inhibit caspases such as caspase-3, caspase-7, and caspase-9 which activate apoptosis. The activities of IAPs are regulated by intracellular protein known as pro-apoptotic protein Second Mitochondria-Derived Activator of Caspases (SMAC), also known as Direct IAP Binding Protein (DIABLO) with low isoelectric point. In normal healthy cells, IAPs and SMAC function to maintain healthy cells. However, in cancers and other proliferative disorders, the activities of IAPs are not adequately modulated and would cause or exacerbate abnormal proliferation and survival. There exists an ongoing need for effective treatment for disease associated with overexpression or aggregation of cMet, and disease associated with overexpression or aggregation of p38. Consequently, small-molecule therapeutic agents that target cMet and p38 could leverage or potentiate VHL’s, cereblon’s, MDM2’s, and IAPs’, which may provide specificity for compounds in this Patent Highlight. In addition, compounds of this Patent Highlight provide a broad range of pharmacological activities consisting with the degradation/ inhibition of targeted polypeptides from wide protein class or family. These bifunctional or PROTAC compounds could provide an effective treatment or amelioration of disease condition such as cancer (gastric, nonsmall cell lung cancer, advanced hepatocellular carcinoma, and papillary renal cell cancer). PROTAC of this Patent Highlight comprise target protein (protein/polypeptide targeting ligand or PTM group) and ubiquitination ligase modulator (ULM), which can be VHL binding moiety (VLM) or a cereblon E3 ubiquitin ligase binding moiety (CLM) or a MDM2 E3 ubiquitin ligase binding moiety (MLB), or an IAP E3 ubiquitin ligase binding moiety (ILM). Definitions. X = Cl, F, Br, H, CN, Me, OMe, OCF3 W5 = ULM selected from a group of phenyls or 5−10 membered hetereoayl R15 = R16 = ULM selected from a group of halo, substituted alkyl, substituted haloalkyl and so forth. o = 0, 1, 2, 3, or 4.
Biological Assay. AlphaLISA ternary complex assay, Cellular thermal shift assay (CETSA), PROTAC washout assay, ubiquitination assay, cycloheximide chase assay, and so forth. Biological Data. The table below shows DC50 at the concentration at which 50% degradation was observed at Dmax maximal degradation observed.
Recent Review Articles. 1. Churcher, I. J. Med. Chem. 2018, 61, 444. 2. Walczak, M. J.; Petzold, G.; Thoma, N. H. Nat. Chem. Biol. 2017, 13, 452. 3. Ottis, P.; Crews, C. M. ACS Chem. Biol. 2017, 12, 892. 4. Neklessa, T. K.; Winkler, J. D.; Crews, C. M. Pharmacol. Ther. 2017, 174, 138.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Robert B. Kargbo: 0000-0002-5539-6343 Notes
The author declares no competing financial interest.
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DOI: 10.1021/acsmedchemlett.9b00006 ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX
