1
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Park JC, Shin D. Current Landscape of Antibody-Drug Conjugate Development in Head and Neck Cancer. JCO Precis Oncol 2024; 8:e2400179. [PMID: 39151109 DOI: 10.1200/po.24.00179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 06/14/2024] [Accepted: 07/22/2024] [Indexed: 08/18/2024] Open
Abstract
Antibody-drug conjugates (ADCs) are fusions of therapeutic drugs and antibodies conjugated by a linker, designed to deliver a therapeutic payload to cells expressing the target antigen. By delivering the highly cytotoxic agent directly to cancer cells, ADCs are designed to enhance safety and broaden the therapeutic window. Recently, ADCs have demonstrated promising efficacy in various solid tumors and are rapidly expanding their indications. The prognosis of patients with advanced head and neck squamous cell carcinoma (HNSCC) remains poor, with no new therapeutics since the advent of anti-PD-1 antibodies in 2016, highlighting a critical need for innovative therapies. Recent preliminary results suggest that ADCs could be promising treatment options for HNSCC as they explore a variety of target antigens, payloads, and linkers. However, for successful adaptation of ADCs in the treatment of HNSCC, addressing key challenges such as payload toxicities, antigen heterogeneity, and adaptive resistance will be essential. Current research focused on new ADC structures, including multispecific antibodies and noncytotoxic payloads, and diverse combination approaches, show promise for future advancements.
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Affiliation(s)
- Jong Chul Park
- Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | - Donghoon Shin
- MetroWest Medical Center, Tufts University School of Medicine, Framingham, MA
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2
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Xi J, Liu K, Peng Z, Dai X, Wang Y, Cai C, Yang D, Yan C, Li X. Toxic warhead-armed antibody for targeted treatment of glioblastoma. Crit Rev Oncol Hematol 2024; 193:104205. [PMID: 38036153 DOI: 10.1016/j.critrevonc.2023.104205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 10/31/2023] [Accepted: 11/16/2023] [Indexed: 12/02/2023] Open
Abstract
Glioblastoma is a fatal intracranial tumor with a poor prognosis, exhibiting uninterrupted malignant progression, widespread invasion throughout the brain leading to the destruction of normal brain tissue and inevitable death. Monoclonal antibodies alone or conjugated with cytotoxic payloads to treat patients with different solid tumors showed effective. This treatment strategy is being explored for patients with glioblastoma (GBM) to obtain meaningful clinical responses and offer new drug options for the treatment of this devastating disease. In this review, we summarize clinical data (from pubmed.gov database and clinicaltrial.gov database) on the efficacy and toxicity of naked antibodies and antibody-drug conjugates (ADCs) against multiple targets on GBM, elucidate the mechanisms that ADCs act at the site of GBM lesions. Finally, we discuss the potential strategies for ADC therapies currently used to treat GBM patients.
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Affiliation(s)
- Jingjing Xi
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Kai Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Zhaolei Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Xiaolin Dai
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Yulin Wang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Chunyan Cai
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Dejun Yang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Chunmei Yan
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Xiaofang Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
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3
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Joseph AM, Nahar K, Daw S, Hasan MM, Lo R, Le TBK, Rahman KM, Badrinarayanan A. Mechanistic insight into the repair of C8-linked pyrrolobenzodiazepine monomer-mediated DNA damage. RSC Med Chem 2022; 13:1621-1633. [PMID: 36561066 PMCID: PMC9749960 DOI: 10.1039/d2md00194b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/18/2022] [Indexed: 11/07/2022] Open
Abstract
Pyrrolobenzodiazepines (PBDs) are naturally occurring DNA binding compounds that possess anti-tumor and anti-bacterial activity. Chemical modifications of PBDs can result in improved DNA binding, sequence specificity and enhanced efficacy. More recently, synthetic PBD monomers have shown promise as payloads for antibody drug conjugates and anti-bacterial agents. The precise mechanism of action of these PBD monomers and their role in causing DNA damage remains to be elucidated. Here we characterized the damage-inducing potential of two C8-linked PBD bi-aryl monomers in Caulobacter crescentus and investigated the strategies employed by cells to repair the same. We show that these compounds cause DNA damage and efficiently kill bacteria, in a manner comparable to the extensively used DNA cross-linking agent mitomycin-C (MMC). However, in stark contrast to MMC which employs a mutagenic lesion tolerance pathway, we implicate essential functions for error-free mechanisms in repairing PBD monomer-mediated damage. We find that survival is severely compromised in cells lacking nucleotide excision repair and to a lesser extent, in cells with impaired recombination-based repair. Loss of nucleotide excision repair leads to significant increase in double-strand breaks, underscoring the critical role of this pathway in mediating repair of PBD-induced DNA lesions. Together, our study provides comprehensive insights into how mono-alkylating DNA-targeting therapeutic compounds like PBD monomers challenge cell growth, and identifies the specific mechanisms employed by the cell to counter the same.
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Affiliation(s)
- Asha Mary Joseph
- National Centre for Biological Sciences (Tata Institute of Fundamental Research) Bangalore India
| | - Kazi Nahar
- School of Cancer & Pharmaceutical Sciences, Faculty of Life Sciences & Medicine, King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Saheli Daw
- National Centre for Biological Sciences (Tata Institute of Fundamental Research) Bangalore India
| | - Md Mahbub Hasan
- School of Cancer & Pharmaceutical Sciences, Faculty of Life Sciences & Medicine, King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Rebecca Lo
- John Innes Centre, Department of Molecular Microbiology Colney Lane Norwich NR4 7UH UK
| | - Tung B K Le
- John Innes Centre, Department of Molecular Microbiology Colney Lane Norwich NR4 7UH UK
| | - Khondaker Miraz Rahman
- School of Cancer & Pharmaceutical Sciences, Faculty of Life Sciences & Medicine, King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Anjana Badrinarayanan
- National Centre for Biological Sciences (Tata Institute of Fundamental Research) Bangalore India
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4
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Gregson SJ, Pugh K, Patel N, Afif-Rider S, Vijayakrishnan B, Santos K, Riedl J, Hutchinson I, Kang GD, Chooi KP, Beard R, Adams L, Barry CS, Ball K, Masterson LA, McFarlane M, Hartley JA, Howard PW. Efficacy, Tolerability, and Pharmacokinetic Studies of Antibody-Drug Conjugates Containing a Low-Potency Pyrrolobenzodiazepine Dimer. Mol Cancer Ther 2022; 21:1439-1448. [PMID: 35793464 DOI: 10.1158/1535-7163.mct-22-0145] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/27/2022] [Accepted: 06/28/2022] [Indexed: 11/16/2022]
Abstract
Antibody-drug conjugate (ADC) research has typically focused on the release of highly potent cytotoxic agents to achieve antitumor efficacy. However, recently approved ADCs trastuzumab deruxtecan and sacituzumab govitecan release lower-potency topoisomerase inhibitors. This has prompted interest in ADCs that release lower-potency cytotoxic drugs to potentially enhance therapeutic index and reduce unwanted toxicity. Pyrrolobenzodiazepine (PBD) dimer ADCs have been widely investigated in human clinical trials, which have focused on high-potency PBDs. In this study, we evaluated five ADCs that release the low-potency PBD dimer SG3650. The relatively low cLogD for this agent facilitated higher drug-to-antibody ratio (DAR) conjugation without the need for antibody engineering or functionalization of the drug. The rank order of potency for DAR 2 site-specific ADCs (conjugated at the C239i position) matched the order for the corresponding free drugs in vitro. Despite free drug SG3650 being inactive in vivo, the DAR 2 ADCs derived from the corresponding drug-linker SG3584 showed antitumor efficacy in solid (anti-HER2) and hematological (anti-CD22) xenograft models. Antitumor activity could be enhanced by conjugating SG3584 to trastuzumab at higher DARs of 4 and 8 and by adjusting dosing and schedule. Higher-DAR conjugates were stable and displayed good rat pharmacokinetic profiles as measured by ELISA and LC-MS/MS. A single intravenous dose of isotype control SG3584 DAR 2 ADC resulted in no mortality in rats or monkeys at doses of up to 25 and 30 mg/kg, respectively. These findings suggest that further investigations of low-potency PBD dimers in ADCs that target hematological and solid tumors are warranted.
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Affiliation(s)
- Stephen J Gregson
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Kathryn Pugh
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Neki Patel
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | | | | | - Kathleen Santos
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Jitka Riedl
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Ian Hutchinson
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Gyoung-Dong Kang
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - K Phin Chooi
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Rhiannon Beard
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Lauren Adams
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Conor S Barry
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Kathryn Ball
- AstraZeneca, Granta Park, Cambridge, United Kingdom
| | - Luke A Masterson
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | | | - John A Hartley
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
| | - Philip W Howard
- TTD Chemistry, AstraZeneca, QMB Innovation Centre, 42 New Road, London, United Kingdom
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5
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Nguyen GTH, Leung WY, Tran TN, Wang H, Murray V, Donald WA. Mechanism for the Binding of Netropsin to Hairpin DNA Revealed Using Nanoscale Ion Emitters in Native Mass Spectrometry. Anal Chem 2019; 92:1130-1137. [PMID: 31778608 DOI: 10.1021/acs.analchem.9b04209] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Netropsin is one of the first ligands to be discovered that selectively binds to the minor groove of DNA and is actively used as a scaffold for developing potential anticancer and antibiotic agents. The mechanism by which netropsin binds to hairpin DNA remains controversial with two competing mechanisms having been proposed. In one mechanism, netropsin binding induces a hairpin-to-duplex DNA transition. Alternatively, netropsin binds in two thermodynamically different modes at a single duplexed AATT site. Here, results from native mass spectrometry (MS) with nanoscale ion emitters indicate that netropsin can simultaneously and sequentially bind to both hairpin and duplex DNA. Duplex DNA was not detected using conventional MS with larger emitters because nanoscale emitters significantly reduce the extent of salt adduction to ligand-DNA complex ions, including in the presence of relatively high concentrations of nonvolatile salts. Based on native MS and polyacrylamide gel electrophoresis results, the abundances of hairpin and duplex DNA are unaffected by the addition of netropsin. By native MS, the binding affinities for five ligand-DNA and DNA-DNA interactions can be rapidly obtained simultaneously. This research indicates a "simultaneous binding mechanism" for the interactions of netropsin with DNA.
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Affiliation(s)
- Giang T H Nguyen
- School of Chemistry , University of New South Wales , Sydney New South Wales 2052 , Australia
| | - Wai Yu Leung
- School of Biotechnology and Biomolecular Sciences , University of New South Wales , Sydney New South Wales 2052 , Australia
| | - Thinh N Tran
- School of Chemistry , University of New South Wales , Sydney New South Wales 2052 , Australia
| | - Huixin Wang
- School of Chemistry , University of New South Wales , Sydney New South Wales 2052 , Australia.,Mark Wainwright Analytical Centre , University of New South Wales , Sydney New South Wales 2052 , Australia
| | - Vincent Murray
- School of Biotechnology and Biomolecular Sciences , University of New South Wales , Sydney New South Wales 2052 , Australia
| | - William A Donald
- School of Chemistry , University of New South Wales , Sydney New South Wales 2052 , Australia
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6
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Singh R, Reid EE, Harris L, Salomon PL, Miller ML, Chari RVJ, Keating TA. Antibody-Drug Conjugates with Indolinobenzodiazepine Dimer Payloads: DNA-Binding Mechanism of Indolinobenzodiazepine Dimer Catabolites in Target Cancer Cells. Mol Pharm 2019; 17:50-58. [PMID: 31742408 DOI: 10.1021/acs.molpharmaceut.9b00675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
DNA-targeting indolinobenzodiazepine dimer (IGN) payloads are used in several clinical-stage antibody-drug conjugates. IGN drugs alkylate DNA through the single imine moiety present in the dimer in contrast to the pyrrolobenzodiazepine dimer drugs, such as talirine and tesirine, which contain two imine moieties per dimer and cross-link DNA. This study explored the mechanism of binding of IGN to DNA in cells and to synthetic duplex and hairpin oligonucleotides. New, highly sensitive IGN-DNA binding enzyme-linked immunosorbent assay methods were developed using biotinylated IGN analogues (monoimine, diimine, and diamine IGNs) and digoxigenin-labeled duplex oligonucleotides, which allowed the measurement of drug-DNA adducts in viable cells at concentrations below IC50. Furthermore, the release of free drug from the IGN-DNA adduct upon treatment with nuclease ex vivo was tested under physiological conditions. The monoimine IGN drug formed a highly stable adduct with DNA in cells, with stability similar to that of the diimine drug analogue. Both monoimine and diimine IGN-DNA adducts released free drugs upon DNA cleavage by nuclease at 37 °C, although more free drug was released from the monoimine compared to the diimine adduct, which presumably was partly cross-linked. The strong binding of the monoimine IGN drug to duplex DNA results from both the noncovalent IGN-DNA interaction and the covalent bond formation between the 2-amino group of a guanine residue and the imine moiety in IGN.
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Affiliation(s)
- Rajeeva Singh
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
| | - Emily E Reid
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
| | - Luke Harris
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
| | - Paulin L Salomon
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
| | - Michael L Miller
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
| | - Ravi V J Chari
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
| | - Thomas A Keating
- ImmunoGen, Inc. , 830 Winter Street , Waltham , Massachusetts 02451 , United States
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7
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Archer KE, Reid EE, Shizuka M, Woods J, Harris L, Maloney EK, Bartle LM, Ab O, Wilhelm A, Setiady Y, Ponte JF, Singh R, Keating TA, Chari RVJ, Miller ML. Synthesis of Highly Potent N-10 Amino-Linked DNA-Alkylating Indolinobenzodiazepine Antibody-Drug Conjugates (ADCs). ACS Med Chem Lett 2019; 10:1211-1215. [PMID: 31413807 DOI: 10.1021/acsmedchemlett.9b00254] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/22/2019] [Indexed: 12/14/2022] Open
Abstract
Indolinobenzodiazepine DNA alkylators (IGNs) are the cytotoxic payloads in antibody-drug conjugates (ADCs) currently undergoing Phase I clinical evaluation (IMGN779, IMGN632, and TAK164). These ADCs possess linkers that have been incorporated into a central substituted phenyl spacer. Here, we present an alternative strategy for the IGNs, linking through a carbamate at the readily available N-10 amine present in the monoimine containing dimer. As a result, we have designed a series of N-10 linked IGN ADCs with a wide range of in vitro potency and tolerability, which may allow us to better match an IGN with a particular target based on the potential dosing needs.
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Affiliation(s)
- Katie E. Archer
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Emily E. Reid
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Manami Shizuka
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - James Woods
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Luke Harris
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Erin K. Maloney
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Laura M. Bartle
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Olga Ab
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Alan Wilhelm
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Yulius Setiady
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Jose F. Ponte
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Rajeeva Singh
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Thomas A. Keating
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Ravi V. J. Chari
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
| | - Michael L. Miller
- ImmunoGen, Inc., 830 Winter Street, Waltham, Massachusetts 02451, United States
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8
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Gregson SJ, Tiberghien AC, Masterson LA, Howard PW. Pyrrolobenzodiazepine Dimers as Antibody–Drug Conjugate (ADC) Payloads. CYTOTOXIC PAYLOADS FOR ANTIBODY – DRUG CONJUGATES 2019. [DOI: 10.1039/9781788012898-00296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The pyrrolobenzodiazepine (PBD) ring system was first discovered in the 1960s and is found in several naturally occurring potent anti-tumour antibiotics. The mode of action of PBDs involves sequence-selective [purine–guanine–purine (PuGPu)] alkylation in the minor groove of DNA through covalent binding from guanine N2 to the PBD C11-position. Dimerization of the PBD ring system gives molecules that can cross-link DNA, which leads to a substantial increase in potency and DNA binding affinity and an extension of sequence-selectivity compared with monomers. PBD dimers feature as the cytotoxic component of numerous ADCs being evaluated in clinical trials. PBD-ADC clinical candidates loncastuximab tesirine, camidanlumab tesirine and rovalpituzumab tesirine employ a PBD N10 linkage while vadastuximab talirine uses a C2-linkage. The PBD dimer scaffold is versatile and offers many opportunities to diversify the ADC platform, with extensive research being performed worldwide to develop the next generation of PBD payload–linker molecules. The search for new PBD payload–linker molecules has mainly focused on changes in payload structure (e.g. PBD C2 modification and macrocyclisation), alternative conjugation strategies (e.g. haloacetamides, ‘click’ approaches and pyridyl disulphides), non-peptide triggers in the linker (e.g. disulphides) and non-cleavable derivatives (i.e. payload release through antibody degradation).
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9
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Yaghoubi S, Karimi MH, Lotfinia M, Gharibi T, Mahi-Birjand M, Kavi E, Hosseini F, Sineh Sepehr K, Khatami M, Bagheri N, Abdollahpour-Alitappeh M. Potential drugs used in the antibody-drug conjugate (ADC) architecture for cancer therapy. J Cell Physiol 2019; 235:31-64. [PMID: 31215038 DOI: 10.1002/jcp.28967] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 05/20/2019] [Indexed: 01/04/2023]
Abstract
Cytotoxic small-molecule drugs have a major influence on the fate of antibody-drug conjugates (ADCs). An ideal cytotoxic agent should be highly potent, remain stable while linked to ADCs, kill the targeted tumor cell upon internalization and release from the ADCs, and maintain its activity in multidrug-resistant tumor cells. Lessons learned from successful and failed experiences in ADC development resulted in remarkable progress in the discovery and development of novel highly potent small molecules. A better understanding of such small-molecule drugs is important for development of effective ADCs. The present review discusses requirements making a payload appropriate for antitumor ADCs and focuses on the main characteristics of commonly-used cytotoxic payloads that showed acceptable results in clinical trials. In addition, the present study represents emerging trends and recent advances of payloads used in ADCs currently under clinical trials.
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Affiliation(s)
- Sajad Yaghoubi
- Department of Clinical Microbiology, Iranshahr University of Medical Sciences, Iranshahr, Iran
| | | | - Majid Lotfinia
- Physiology Research Center, Kashan University of Medical Sciences, Kashan, Iran.,Core Research Lab, Kashan University of Medical Sciences, Kashan, Iran
| | - Tohid Gharibi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Immunology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Motahare Mahi-Birjand
- Infectious Disease Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Esmaeil Kavi
- Department of Nursing, School of Nursing, Larestan University of Medical Sciences, Larestan, Iran
| | - Fahimeh Hosseini
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Koushan Sineh Sepehr
- Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Mehrdad Khatami
- NanoBioelectrochemistry Research Center, Bam University of Medical Sciences, Bam, Iran
| | - Nader Bagheri
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
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10
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Duerr C, Friess W. Antibody-drug conjugates- stability and formulation. Eur J Pharm Biopharm 2019; 139:168-176. [DOI: 10.1016/j.ejpb.2019.03.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 03/28/2019] [Accepted: 03/29/2019] [Indexed: 01/01/2023]
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11
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Li Q, Barrett A, Vijayakrishnan B, Tiberghien A, Beard R, Rickert KW, Allen KL, Christie RJ, Marelli M, Harper J, Howard P, Wu H, Dall'Acqua WF, Tsui P, Gao C, Borrok MJ. Improved Inhibition of Tumor Growth by Diabody-Drug Conjugates via Half-Life Extension. Bioconjug Chem 2019; 30:1232-1243. [PMID: 30912649 DOI: 10.1021/acs.bioconjchem.9b00170] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Despite some clinical success with antibody-drug conjugates (ADCs) in patients with solid tumors and hematological malignancies, improvements in ADC design are still desirable due to the narrow therapeutic window of these compounds. Tumor-targeting antibody fragments have distinct advantages over monoclonal antibodies, including more rapid tumor accumulation and enhanced penetration, but are subject to rapid clearance. Half-life extension technologies such as PEGylation and albumin-binding domains (ABDs) have been widely used to improve the pharmacokinetics of many different types of biologics. PEGylation improves pharmacokinetics by increasing hydrodynamic size to reduce renal clearance, whereas ABDs extend half-life via FcRn-mediated recycling. In this study, we used an anti-oncofetal antigen 5T4 diabody conjugated with a highly potent cytotoxic pyrrolobenzodiazepine (PBD) warhead to assess and compare the effects of PEGylation and albumin binding on the in vivo efficacy of antibody fragment drug conjugates. Conjugation of 2× PEG20K to a diabody improved half-life from 40 min to 33 h, and an ABD-diabody fusion protein exhibited a half-life of 45 h in mice. In a xenograft model of breast cancer MDA-MB-436, the ABD-diabody-PBD showed greater tumor growth suppression and better tolerability than either PEG-diabody-PBD or diabody-PBD. These results suggest that the mechanism of half-life extension is an important consideration for designing cytotoxic antitumor agents.
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Affiliation(s)
| | | | | | | | - Rhiannon Beard
- Spirogen , 42 New Road , E1 2AX , London , United Kingdom
| | | | | | | | | | | | - Philip Howard
- Spirogen , 42 New Road , E1 2AX , London , United Kingdom
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12
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Jackson PJM, Kay S, Pysz I, Thurston DE. Use of pyrrolobenzodiazepines and related covalent-binding DNA-interactive molecules as ADC payloads: Is mechanism related to systemic toxicity? DRUG DISCOVERY TODAY. TECHNOLOGIES 2018; 30:71-83. [PMID: 30553523 DOI: 10.1016/j.ddtec.2018.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/12/2018] [Accepted: 10/15/2018] [Indexed: 06/09/2023]
Abstract
Antibody-drug conjugates (ADCs) consist of monoclonal antibodies (mAbs) or antibody fragments conjugated to biologically active molecules (usually highly cytotoxic small molecules) through chemical linkers. Although no ADCs containing covalent-binding DNA-interactive payloads have yet been approved (although two containing the DNA-cleaving payload calicheamicin have), of those in clinical trials systemic toxicities are beginning to emerge. This article discusses the observed toxicities in relation to the structures and mechanisms of action of payload type.
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Affiliation(s)
- Paul J M Jackson
- Femtogenix Ltd., Biopark, Broadwater Road, Welwyn Garden City AL7 3AX, United Kingdom
| | - Syafiq Kay
- Femtogenix Ltd., Biopark, Broadwater Road, Welwyn Garden City AL7 3AX, United Kingdom; Institute for Pharmaceutical Science, King's College London, Faculty of Life Sciences and Medicine, Franklin Wilkins Building, London SE1 9NH, United Kingdom
| | - Ilona Pysz
- Femtogenix Ltd., Biopark, Broadwater Road, Welwyn Garden City AL7 3AX, United Kingdom; Institute for Pharmaceutical Science, King's College London, Faculty of Life Sciences and Medicine, Franklin Wilkins Building, London SE1 9NH, United Kingdom
| | - David E Thurston
- Femtogenix Ltd., Biopark, Broadwater Road, Welwyn Garden City AL7 3AX, United Kingdom; Institute for Pharmaceutical Science, King's College London, Faculty of Life Sciences and Medicine, Franklin Wilkins Building, London SE1 9NH, United Kingdom.
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13
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Angelbello AJ, Chen JL, Childs-Disney JL, Zhang P, Wang ZF, Disney MD. Using Genome Sequence to Enable the Design of Medicines and Chemical Probes. Chem Rev 2018; 118:1599-1663. [PMID: 29322778 DOI: 10.1021/acs.chemrev.7b00504] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.
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Affiliation(s)
- Alicia J Angelbello
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jonathan L Chen
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jessica L Childs-Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Peiyuan Zhang
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Zi-Fu Wang
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Matthew D Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
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14
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Christie RJ, Tiberghien AC, Du Q, Bezabeh B, Fleming R, Shannon A, Mao S, Breen S, Zhang J, Zhong H, Harper J, Wu H, Howard PW, Gao C. Pyrrolobenzodiazepine Antibody-Drug Conjugates Designed for Stable Thiol Conjugation. Antibodies (Basel) 2017; 6:antib6040020. [PMID: 31548535 PMCID: PMC6698857 DOI: 10.3390/antib6040020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 12/24/2022] Open
Abstract
Thiosuccinimide-linked antibody-drug conjugates (ADCs) are susceptible to drug loss over time due to a retro-Michael reaction, which can be prevented by selecting stable conjugation positions or hydrolysis of the thiosuccinimide. Here, we investigate pyrrolobenzodiazepine (PBD) ADC drug-linkers equipped with N-phenyl maleimide functionality for stable thiol conjugation via thiosuccinimide hydrolysis. Two PBD drug-linker formats (enzyme-cleavable and non-cleavable) were evaluated following site-specific conjugation to an engineered cysteine incorporated at position T289, which is known to be unstable for N-alkyl maleimide conjugates. N-phenyl maleimide PBDs conjugated to antibodies with similar efficiencies as N-alkyl maleimide PBDs and enhanced thiosuccinimide hydrolysis for N-phenyl maleimide PBDs was confirmed by mass spectrometry, capillary isoelectric focusing, and a SYPRO Orange dye binding assay. All of the PBD ADCs were highly potent in vitro regardless of maleimide- or linker-type, exhibiting low pM EC50 values. Thiol conjugation to N-phenyl maleimide PBD minimized the retro-Michael reaction in both rat and mouse serum. However, cleavage of the valine-alanine dipeptide in mouse serum for ADCs containing cleavable drug-linker led to drug loss regardless of maleimide type, which impacted ADC potency in tumor growth inhibition studies that were conducted in mouse models. Therapeutic improvement in mouse tumor models was realized for ADCs prepared with non-cleavable PBD drug-linkers that were conjugated through N-phenyl maleimide, where a stronger tumor growth inhibition (TGI) response was achieved when compared to the analogous N-alkyl maleimide drug-linker ADC. Altogether, our findings highlight the stability and efficacy benefits of N-phenyl maleimide functionality for ADCs that are produced with thiol-maleimide conjugation chemistry.
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Affiliation(s)
- R James Christie
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
| | | | - Qun Du
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
| | - Binyam Bezabeh
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
| | - Ryan Fleming
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
| | - Amanda Shannon
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
| | - Shenlan Mao
- Oncology Research, MedImmune, Gaithersburg, MD 20878, USA.
| | - Shannon Breen
- Oncology Research, MedImmune, Gaithersburg, MD 20878, USA.
| | - Jing Zhang
- Oncology Research, MedImmune, Gaithersburg, MD 20878, USA.
| | - Haihong Zhong
- Oncology Research, MedImmune, Gaithersburg, MD 20878, USA.
| | - Jay Harper
- Oncology Research, MedImmune, Gaithersburg, MD 20878, USA.
| | - Herren Wu
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
| | | | - Changshou Gao
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD 20878, USA.
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15
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Mantaj J, Jackson PJM, Rahman KM, Thurston DE. From Anthramycin to Pyrrolobenzodiazepine (PBD)-Containing Antibody-Drug Conjugates (ADCs). Angew Chem Int Ed Engl 2017; 56:462-488. [PMID: 27862776 PMCID: PMC5215561 DOI: 10.1002/anie.201510610] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 04/11/2016] [Indexed: 12/15/2022]
Abstract
The pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are a family of sequence-selective DNA minor-groove binding agents that form a covalent aminal bond between their C11-position and the C2-NH2 groups of guanine bases. The first example of a PBD monomer, the natural product anthramycin, was discovered in the 1960s, and the best known PBD dimer, SJG-136 (also known as SG2000, NSC 694501 or BN2629), was synthesized in the 1990s and has recently completed Phase II clinical trials in patients with leukaemia and ovarian cancer. More recently, PBD dimer analogues are being attached to tumor-targeting antibodies to create antibody-drug conjugates (ADCs), a number of which are now in clinical trials, with many others in pre-clinical development. This Review maps the development from anthramycin to the first PBD dimers, and then to PBD-containing ADCs, and explores both structure-activity relationships (SARs) and the biology of PBDs, and the strategies for their use as payloads for ADCs.
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Affiliation(s)
- Julia Mantaj
- Institute of Pharmaceutical ScienceKing's College LondonBritannia House, 7 Trinity Street, London SE1 1DB, and Femtogenix Ltd, Britannia House, 7 Trinity StreetLondonSE1 1DBUK
| | - Paul J. M. Jackson
- Institute of Pharmaceutical ScienceKing's College LondonBritannia House, 7 Trinity Street, London SE1 1DB, and Femtogenix Ltd, Britannia House, 7 Trinity StreetLondonSE1 1DBUK
| | - Khondaker M. Rahman
- Institute of Pharmaceutical ScienceKing's College LondonBritannia House, 7 Trinity Street, London SE1 1DB, and Femtogenix Ltd, Britannia House, 7 Trinity StreetLondonSE1 1DBUK
| | - David E. Thurston
- Professor of Drug Discovery, King's College London, Faculty of Life Sciences & MedicineInstitute of Pharmaceutical ScienceBritannia House, 7 Trinity StreetLondonSE1 1DBUK
- Femtogenix LtdBritannia House, 7 Trinity StreetLondonSE1 1DBUK
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16
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Jackson PJ, Rahman KM, Thurston DE. The use of molecular dynamics simulations to evaluate the DNA sequence-selectivity of G–A cross-linking PBD–duocarmycin dimers. Bioorg Med Chem Lett 2017; 27:102-108. [DOI: 10.1016/j.bmcl.2016.10.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 10/06/2016] [Accepted: 10/09/2016] [Indexed: 10/20/2022]
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17
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Mantaj J, Jackson PJM, Rahman KM, Thurston DE. Entwicklung Pyrrolobenzodiazepin(PBD)-haltiger Antikörper-Wirkstoff-Konjugate (ADCs) ausgehend von Anthramycin. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510610] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Julia Mantaj
- Institute of Pharmaceutical Science; King's College London
- Femtogenix Ltd; London Großbritannien
| | - Paul J. M. Jackson
- Institute of Pharmaceutical Science; King's College London
- Femtogenix Ltd; London Großbritannien
| | - Khondaker M. Rahman
- Institute of Pharmaceutical Science; King's College London
- Femtogenix Ltd; London Großbritannien
| | - David E. Thurston
- Institute of Pharmaceutical Science; Faculty of Life Sciences & Medicine; King's College London; Britannia House, 7 Trinity Street London SE1 1DB Großbritannien
- Femtogenix Ltd; Britannia House; London 7 Trinity Street SE1 1DB Großbritannien
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18
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Zhang D, Pillow TH, Ma Y, Cruz-Chuh JD, Kozak KR, Sadowsky JD, Lewis Phillips GD, Guo J, Darwish M, Fan P, Chen J, He C, Wang T, Yao H, Xu Z, Chen J, Wai J, Pei Z, Hop CECA, Khojasteh SC, Dragovich PS. Linker Immolation Determines Cell Killing Activity of Disulfide-Linked Pyrrolobenzodiazepine Antibody-Drug Conjugates. ACS Med Chem Lett 2016; 7:988-993. [PMID: 27882196 DOI: 10.1021/acsmedchemlett.6b00233] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/22/2016] [Indexed: 11/29/2022] Open
Abstract
Disulfide bonds could be valuable linkers for a variety of therapeutic applications requiring tunable cleavage between two parts of a molecule (e.g., antibody-drug conjugates). The in vitro linker immolation of β-mercaptoethyl-carbamate disulfides and DNA alkylation properties of associated payloads were investigated to understand the determinant of cell killing potency of anti-CD22 linked pyrrolobenzodiazepine (PBD-dimer) conjugates. Efficient immolation and release of a PBD-dimer with strong DNA alkylation properties were observed following disulfide cleavage of methyl- and cyclobutyl-substituted disulfide linkers. However, the analogous cyclopropyl-containing linker did not immolate, and the associated thiol-containing product was a poor DNA alkylator. As predicted from these in vitro assessments, the related anti-CD22 ADCs showed different target-dependent cell killing activities in WSU-DLCL2 and BJAB cell lines. These results demonstrate how the in vitro immolation models can be used to help design efficacious ADCs.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Jingtian Chen
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - Changrong He
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - Tao Wang
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - Hui Yao
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - Zijin Xu
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - Jinhua Chen
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - John Wai
- Wuxi Apptec, 288 Fute Zhong
Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
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19
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Mantaj J, Jackson PJM, Karu K, Rahman KM, Thurston DE. Covalent Bonding of Pyrrolobenzodiazepines (PBDs) to Terminal Guanine Residues within Duplex and Hairpin DNA Fragments. PLoS One 2016; 11:e0152303. [PMID: 27055050 PMCID: PMC4824457 DOI: 10.1371/journal.pone.0152303] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 03/11/2016] [Indexed: 01/02/2023] Open
Abstract
Pyrrolobenzodiazepines (PBDs) are covalent-binding DNA-interactive agents with growing importance as payloads in Antibody Drug Conjugates (ADCs). Until now, PBDs were thought to covalently bond to C2-NH2 groups of guanines in the DNA-minor groove across a three-base-pair recognition sequence. Using HPLC/MS methodology with designed hairpin and duplex oligonucleotides, we have now demonstrated that the PBD Dimer SJG-136 and the C8-conjugated PBD Monomer GWL-78 can covalently bond to a terminal guanine of DNA, with the PBD skeleton spanning only two base pairs. Control experiments with the non-C8-conjugated anthramycin along with molecular dynamics simulations suggest that the C8-substituent of a PBD Monomer, or one-half of a PBD Dimer, may provide stability for the adduct. This observation highlights the importance of PBD C8-substituents, and also suggests that PBDs may bind to terminal guanines within stretches of DNA in cells, thus representing a potentially novel mechanism of action at the end of DNA strand breaks.
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Affiliation(s)
- Julia Mantaj
- Institute of Pharmaceutical Science, King’s College London, 7 Trinity Street, London, SE1 1DB, United Kingdom
| | - Paul J. M. Jackson
- Femtogenix Limited, Britannia House, 7 Trinity Street, London, SE1 1DB, United Kingdom
| | - Kersti Karu
- UCL Chemistry Mass Spectrometry Facility, Christopher Ingold Building, Chemistry Department, 20 Gordon Street, London, WC1H 0AJ, United Kingdom
| | - Khondaker M. Rahman
- Institute of Pharmaceutical Science, King’s College London, 7 Trinity Street, London, SE1 1DB, United Kingdom
- Femtogenix Limited, Britannia House, 7 Trinity Street, London, SE1 1DB, United Kingdom
- * E-mail: (DET); (KMR)
| | - David E. Thurston
- Institute of Pharmaceutical Science, King’s College London, 7 Trinity Street, London, SE1 1DB, United Kingdom
- Femtogenix Limited, Britannia House, 7 Trinity Street, London, SE1 1DB, United Kingdom
- * E-mail: (DET); (KMR)
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20
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Varvounis G. An Update on the Synthesis of Pyrrolo[1,4]benzodiazepines. Molecules 2016; 21:154. [PMID: 26828475 PMCID: PMC6273195 DOI: 10.3390/molecules21020154] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/23/2015] [Accepted: 01/05/2016] [Indexed: 01/12/2023] Open
Abstract
Pyrrolo[1,4]benzodiazepines are tricyclic compounds that are considered “privileged structures” since they possess a wide range of biological activities. The first encounter with these molecules was the isolation of anthramycin from cultures of Streptomyces, followed by determination of the X-ray crystal structure of the molecule and a study of its interaction with DNA. This opened up an intensive synthetic and biological study of the pyrrolo[2,1-c][1,4]benzodiazepines that has culminated in the development of the dimer SJG-136, at present in Phase II clinical trials. The synthetic efforts have brought to light some new synthetic methodology, while the contemporary work is focused on building trimeric pyrrolo[2,1-c][1,4]benzodiazepines linked together by various heterocyclic and aliphatic chains. It is the broad spectrum of biological activities of pyrrolo[1,2-a][1,4]benzodiazepines that has maintained the interest of researchers to date whereas several derivatives of the even less studied pyrrolo[1,2-d][1,4]benzodiazepines were found to be potent non-nucleoside HIV-1 reverse transcriptase inhibitors. The present review is an update on the synthesis of pyrrolo[2,1-c][1,4]benzodiazepines since the last major review of 2011, while the overview of the synthesis of the other two tricyclic isomers is comprehensive.
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Affiliation(s)
- George Varvounis
- Department of Chemistry, Section of Organic Chemistry and Biochemistry, University of Ioannina, 451 10 Ioannina, Greece.
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21
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Mellinas-Gomez M, Spanswick VJ, Paredes-Moscosso SR, Robson M, Pedley RB, Thurston DE, Baines SJ, Stell A, Hartley JA. Activity of the DNA minor groove cross-linking agent SG2000 (SJG-136) against canine tumours. BMC Vet Res 2015; 11:215. [PMID: 26282406 PMCID: PMC4539724 DOI: 10.1186/s12917-015-0534-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 08/06/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cancer is the leading cause of death in older dogs and its prevalence is increasing. There is clearly a need to develop more effective anti-cancer drugs in dogs. SG2000 (SJG-136) is a sequence selective DNA minor groove cross-linking agent. Based on its in vitro potency, the spectrum of in vivo and clinical activity against human tumours, and its tolerability in human patients, SG2000 has potential as a novel therapeutic against spontaneously occurring canine malignancies. RESULTS In vitro cytotoxicity was assessed using SRB and MTT assays, and in vivo activity was assessed using canine tumour xenografts. DNA interstrand cross-linking (ICL) was determined using a modification of the single cell gel electrophoresis (comet) assay. Effects on cell cycle distribution were assessed by flow cytometry and measurement of γ-H2AX by immunofluorescence and immunohistochemistry. SG2000 had a multi-log differential cytotoxic profile against a panel of 12 canine tumour cell lines representing a range of common tumour types in dogs. In the CMeC-1 melanoma cell line, DNA ICLs increased linearly with dose following a 1 h treatment. Peak ICL was achieved within 1 h and no removal was observed over 48 h. A relationship between DNA ICL formation and cytotoxicity was observed across cell lines. The formation of γ-H2AX foci was slow, becoming evident after 4 h and reaching a peak at 24 h. SG2000 exhibited significant anti-tumour activity against two canine melanoma tumour models in vivo. Anti-tumour activity was observed at 0.15 and 0.3 mg/kg given i.v. either once, or weekly x 3. Dose-dependent DNA ICL was observed in tumours (and to a lower level in peripheral blood mononuclear cells) at 2 h and persisted at 24 h. ICL increased following the second and third doses in a repeated dose schedule. At 24 h, dose dependent γ-H2AX foci were more numerous than at 2 h, and greater in tumours than in peripheral blood mononuclear cells. SG2000-induced H2AX phosphorylation measured by immunohistochemistry showed good correspondence, but less sensitivity, than measurement of foci. CONCLUSIONS SG2000 displayed potent activity in vitro against canine cancer cell lines as a result of the formation and persistence of DNA ICLs. SG2000 also had significant in vivo antitumour activity against canine melanoma xenografts, and the comet and γ-H2AX foci methods were relevant pharmacodynamic assays. The clinical testing of SG2000 against spontaneous canine cancer is warranted.
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Affiliation(s)
- Maria Mellinas-Gomez
- CR-UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA, UK.
| | - Victoria J Spanswick
- CR-UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
| | - Solange R Paredes-Moscosso
- CR-UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
| | - Matthew Robson
- UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6BT, UK.
| | - R Barbara Pedley
- UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6BT, UK.
| | - David E Thurston
- The School of Pharmacy, University College London, Brunswick Square, London, WC1E 6BT, UK.
- Present address: Institute of Pharmaceutical Science, King's College London, Britannia House, 7 Trinity Street, London, SE1 1DB, UK.
| | - Stephen J Baines
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA, UK.
- Present address: Willows Referral Service, Highlands Road, Shirley, Solihull, West Midlands, B90 4NH, UK.
| | - Anneliese Stell
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA, UK.
| | - John A Hartley
- CR-UK Drug-DNA Interactions Research Group, UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
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22
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Thurston DE, Vassoler H, Jackson PJM, James CH, Rahman KM. Effect of hairpin loop structure on reactivity, sequence preference and adduct orientation of a DNA-interactive pyrrolo[2,1-c][1,4]benzodiazepine (PBD) antitumour agent. Org Biomol Chem 2015; 13:4031-40. [DOI: 10.1039/c4ob02405b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Pyrrolobenzodiazepine (PBD) monomer GWL-78 reacts faster with DNA hairpins containing a hexaethylene glycol (HEG) loop compared to hairpins containing a TTT loop due to the greater structural flexibility of the HEG.
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Affiliation(s)
| | - Higia Vassoler
- UCL School of Pharmacy
- University College London
- London WC1N 1AX
- UK
| | | | - Colin H. James
- UCL School of Pharmacy
- University College London
- London WC1N 1AX
- UK
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23
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Hemming K, Chambers CS, Jamshaid F, O'Gorman PA. Intramolecular azide to alkene cycloadditions for the construction of pyrrolobenzodiazepines and azetidino-benzodiazepines. Molecules 2014; 19:16737-56. [PMID: 25329868 PMCID: PMC6271382 DOI: 10.3390/molecules191016737] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/26/2014] [Accepted: 10/13/2014] [Indexed: 11/22/2022] Open
Abstract
The coupling of proline- and azetidinone-substituted alkenes to 2-azidobenzoic and 2-azidobenzenesulfonic acid gives precursors that undergo intramolecular azide to alkene 1,3-dipolar cycloadditions to give imine-, triazoline- or aziridine-containing pyrrolo[1,4]benzodiazepines (PBDs), pyrrolo[1,2,5]benzothiadiazepines (PBTDs), and azetidino[1,4]benzodiazepines. The imines and aziridines are formed after loss of nitrogen from a triazoline cycloadduct. The PBDs are a potent class of antitumour antibiotics.
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Affiliation(s)
- Karl Hemming
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield, West Yorkshire HD1 3DH, UK.
| | - Christopher S Chambers
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield, West Yorkshire HD1 3DH, UK
| | - Faisal Jamshaid
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield, West Yorkshire HD1 3DH, UK
| | - Paul A O'Gorman
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield, West Yorkshire HD1 3DH, UK
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24
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Rahman KM, Corcoran DB, Bui TTT, Jackson PJM, Thurston DE. Pyrrolobenzodiazepines (PBDs) do not bind to DNA G-quadruplexes. PLoS One 2014; 9:e105021. [PMID: 25133504 PMCID: PMC4136862 DOI: 10.1371/journal.pone.0105021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 07/15/2014] [Indexed: 12/11/2022] Open
Abstract
The pyrrolo[2,1-c][1,4] benzodiazepines (PBDs) are a family of sequence-selective, minor-groove binding DNA-interactive agents that covalently attach to guanine residues. A recent publication in this journal (Raju et al, PloS One, 2012, 7, 4, e35920) reported that two PBD molecules were observed to bind with high affinity to the telomeric quadruplex of Tetrahymena glaucoma based on Electrospray Ionisation Mass Spectrometry (ESI-MS), Circular Dichroism, UV-Visible and Fluorescence spectroscopy data. This was a surprising result given the close 3-dimensional shape match between the structure of all PBD molecules and the minor groove of duplex DNA, and the completely different 3-dimensional structure of quadruplex DNA. Therefore, we evaluated the interaction of eight PBD molecules of diverse structure with a range of parallel, antiparallel and mixed DNA quadruplexes using DNA Thermal Denaturation, Circular Dichroism and Molecular Dynamics Simulations. Those PBD molecules without large C8-substitutents had an insignificant affinity for the eight quadruplex types, although those with large π-system-containing C8-substituents (as with the compounds evaluated by Raju and co-workers) were found to interact to some extent. Our molecular dynamics simulations support the likelihood that molecules of this type, including those examined by Raju and co-workers, interact with quadruplex DNA through their C8-substituents rather than the PBD moiety itself. It is important for the literature to be clear on this matter, as the mechanism of action of these agents will be under close scrutiny in the near future due to the growing number of PBD-based agents entering the clinic as both single-agents and as components of antibody-drug conjugates (ADCs).
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Affiliation(s)
- Khondaker M. Rahman
- Department of Pharmacy, Institute of Pharmaceutical Science, King's College London, London, United Kingdom
- * E-mail: (KMR); (DET)
| | - David B. Corcoran
- Department of Pharmacy, Institute of Pharmaceutical Science, King's College London, London, United Kingdom
| | - Tam T. T. Bui
- Department of Pharmacy, Institute of Pharmaceutical Science, King's College London, London, United Kingdom
| | - Paul J. M. Jackson
- Department of Pharmacy, Institute of Pharmaceutical Science, King's College London, London, United Kingdom
| | - David E. Thurston
- Department of Pharmacy, Institute of Pharmaceutical Science, King's College London, London, United Kingdom
- * E-mail: (KMR); (DET)
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25
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Abstract
Antibody-drug conjugates (ADCs) represent a promising therapeutic modality for the clinical management of cancer. The recent approvals of brentuximab vedotin and ado-trastuzumab emtansine plus emerging data for many molecules in clinical trials highlight the potential for ADCs to offer new therapeutic options for patients. Currently, more than 30 ADCs are being evaluated in early- or late-stage clinical trials. Accordingly, much has been done to refine and transform the early-generation ADCs to the highly effective products that we now have in clinical development. These changes include a better understanding of optimal target selection, advances in antibody engineering, improvements in linker/payload conjugation strategies, and the generation of highly potent ADC payloads. In this review, we detail the current status of ADCs in both preclinical and clinical development, highlight technological advancements in ADC development, and speculate towards the future of this targeted therapeutic platform.
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Affiliation(s)
- Fiona Mack
- Oncology Research Unit, World Wide Research and Development, Pfizer Inc, Pearl River, NY
| | - Michael Ritchie
- Oncology Research Unit, World Wide Research and Development, Pfizer Inc, Pearl River, NY
| | - Puja Sapra
- Oncology Research Unit, World Wide Research and Development, Pfizer Inc, Pearl River, NY.
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26
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Jeffrey SC, Burke PJ, Lyon RP, Meyer DW, Sussman D, Anderson M, Hunter JH, Leiske CI, Miyamoto JB, Nicholas ND, Okeley NM, Sanderson RJ, Stone IJ, Zeng W, Gregson SJ, Masterson L, Tiberghien AC, Howard PW, Thurston DE, Law CL, Senter PD. A potent anti-CD70 antibody-drug conjugate combining a dimeric pyrrolobenzodiazepine drug with site-specific conjugation technology. Bioconjug Chem 2013; 24:1256-63. [PMID: 23808985 DOI: 10.1021/bc400217g] [Citation(s) in RCA: 194] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A highly cytotoxic DNA cross-linking pyrrolobenzodiazepine (PBD) dimer with a valine-alanine dipeptide linker was conjugated to the anti-CD70 h1F6 mAb either through endogenous interchain cysteines or, site-specifically, through engineered cysteines at position 239 of the heavy chains. The h1F6239C-PBD conjugation strategy proved to be superior to interchain cysteine conjugation, affording an antibody-drug conjugate (ADC) with high uniformity in drug-loading and low levels of aggregation. In vitro cytotoxicity experiments demonstrated that the h1F6239C-PBD was potent and immunologically specific on CD70-positive renal cell carcinoma (RCC) and non-Hodgkin lymphoma (NHL) cell lines. The conjugate was resistant to drug loss in plasma and in circulation, and had a pharmacokinetic profile closely matching that of the parental h1F6239C antibody capped with N-ethylmaleimide (NEM). Evaluation in CD70-positive RCC and NHL mouse xenograft models showed pronounced antitumor activities at single or weekly doses as low as 0.1 mg/kg of ADC. The ADC was tolerated at 2.5 mg/kg. These results demonstrate that PBDs can be effectively used for antibody-targeted therapy.
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Affiliation(s)
- Scott C Jeffrey
- Department of Research & Translational Medicine, Seattle Genetics, Inc., Bothell, WA 98021, USA.
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27
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Rahman KM, Jackson PJM, James CH, Basu BP, Hartley JA, de la Fuente M, Schatzlein A, Robson M, Pedley RB, Pepper C, Fox KR, Howard PW, Thurston DE. GC-targeted C8-linked pyrrolobenzodiazepine-biaryl conjugates with femtomolar in vitro cytotoxicity and in vivo antitumor activity in mouse models. J Med Chem 2013; 56:2911-35. [PMID: 23514599 DOI: 10.1021/jm301882a] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DNA binding 4-(1-methyl-1H-pyrrol-3-yl)benzenamine (MPB) building blocks have been developed that span two DNA base pairs with a strong preference for GC-rich DNA. They have been conjugated to a pyrrolo[2,1-c][1,4]benzodiazepine (PBD) molecule to produce C8-linked PBD-MPB hybrids that can stabilize GC-rich DNA by up to 13-fold compared to AT-rich DNA. Some have subpicomolar IC50 values in human tumor cell lines and in primary chronic lymphocytic leukemia cells, while being up to 6 orders less cytotoxic in the non-tumor cell line WI38, suggesting that key DNA sequences may be relevant targets in these ultrasensitive cancer cell lines. One conjugate, 7h (KMR-28-39), which has femtomolar activity in the breast cancer cell line MDA-MB-231, has significant dose-dependent antitumor activity in MDA-MB-231 (breast) and MIA PaCa-2 (pancreatic) human tumor xenograft mouse models with insignificant toxicity at therapeutic doses. Preliminary studies suggest that 7h may sterically inhibit interaction of the transcription factor NF-κB with its cognate DNA binding sequence.
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Affiliation(s)
- Khondaker M Rahman
- Department of Pharmacy, Institute of Pharmaceutical Sciences, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
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28
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Rahman KM, Rosado H, Moreira JB, Feuerbaum EA, Fox KR, Stecher E, Howard PW, Gregson SJ, James CH, de la Fuente M, Waldron DE, Thurston DE, Taylor PW. Antistaphylococcal activity of DNA-interactive pyrrolobenzodiazepine (PBD) dimers and PBD-biaryl conjugates. J Antimicrob Chemother 2012; 67:1683-96. [PMID: 22547662 PMCID: PMC3370821 DOI: 10.1093/jac/dks127] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Objectives Pyrrolobenzodiazepine (PBD) dimers, tethered through inert propyldioxy or pentyldioxy linkers, possess potent bactericidal activity against a range of Gram-positive bacteria by virtue of their capacity to cross-link duplex DNA in sequence-selective fashion. Here we attempt to improve the antibacterial activity and cytotoxicity profile of PBD-containing conjugates by extension of dimer linkers and replacement of one PBD unit with phenyl-substituted or benzo-fused heterocycles that facilitate non-covalent interactions with duplex DNA. Methods DNase I footprinting was used to identify high-affinity DNA binding sites. A staphylococcal gene microarray was used to assess epidemic methicillin-resistant Staphylococcus aureus 16 phenotypes induced by PBD conjugates. Molecular dynamics simulations were employed to investigate the accommodation of compounds within the DNA helix. Results Increasing the length of the linker in PBD dimers led to a progressive reduction in antibacterial activity, but not in their cytotoxic capacity. Complex patterns of DNA binding were noted for extended PBD dimers. Modelling of DNA strand cross-linking by PBD dimers indicated distortion of the helix. A majority (26 of 43) of PBD-biaryl conjugates possessed potent antibacterial activity with little or no helical distortion and a more favourable cytotoxicity profile. Bactericidal activity of PBD-biaryl conjugates was determined by inability to excise covalently bound drug molecules from bacterial duplex DNA. Conclusions PBD-biaryl conjugates have a superior antibacterial profile compared with PBD dimers such as ELB-21. We have identified six PBD-biaryl conjugates as potential drug development candidates.
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29
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Liu Y, Chai Y, Kumar A, Tidwell RR, Boykin DW, Wilson WD. Designed compounds for recognition of 10 base pairs of DNA with two at binding sites. J Am Chem Soc 2012; 134:5290-9. [PMID: 22369366 DOI: 10.1021/ja211628j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Short AT base pair sequences that are separated by a small number of GCs are common in eukaryotic parasite genomes. Cell-permeable compounds that bind effectively and selectively to such sequences present an attractive therapeutic approach. Compounds with linked, one or two amidine-benzimidazole-phenyl (ABP) motifs were designed, synthesized, and evaluated for binding to adjacent AT sites by biosensor-surface plasmon resonance (SPR). A surprising feature of the linked ABP motifs is that a set of six similar compounds has three different minor groove binding modes with the target sequences. Compounds with one ABP bind independently to two separated AT sites. Unexpectedly, compounds with two ABP motifs can bind strongly either as monomers or as cooperative dimers to the full site. The results are supported by mass spectrometry and circular dichroism, and models to explain the different binding modes are presented.
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Affiliation(s)
- Yang Liu
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302-4098, United States
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30
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Seifert J, Pezeshki S, Kamal A, Weisz K. Inter- and intrastrand DNA crosslinks by 2-fluoro-substituted pyrrolobenzodiazepine dimers: stability, stereochemistry and drug orientation. Org Biomol Chem 2012; 10:6850-60. [DOI: 10.1039/c2ob25654a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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31
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Rahman KM, James CH, Bui TTT, Drake AF, Thurston DE. Observation of a Single-Stranded DNA/Pyrrolobenzodiazepine Adduct. J Am Chem Soc 2011; 133:19376-85. [DOI: 10.1021/ja205395r] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Khondaker M. Rahman
- Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, U.K
| | - Colin H. James
- Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, U.K
| | - Tam T. T. Bui
- Biomolecular Spectroscopy Centre, Kings College London, Guy’s Campus, London SE1 1UL, U.K
| | - Alex F. Drake
- Biomolecular Spectroscopy Centre, Kings College London, Guy’s Campus, London SE1 1UL, U.K
| | - David E. Thurston
- Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, U.K
- Spirogen Ltd., The School of Pharmacy, University of London, London WC1N 1AX, U.K
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32
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Lewis EA, Munde M, Wang S, Rettig M, Le V, Machha V, Wilson WD. Complexity in the binding of minor groove agents: netropsin has two thermodynamically different DNA binding modes at a single site. Nucleic Acids Res 2011; 39:9649-58. [PMID: 21890907 PMCID: PMC3239193 DOI: 10.1093/nar/gkr699] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Structural results with minor groove binding agents, such as netropsin, have provided detailed, atomic level views of DNA molecular recognition. Solution studies, however, indicate that there is complexity in the binding of minor groove agents to a single site. Netropsin, for example, has two DNA binding enthalpies in isothermal titration calorimetry (ITC) experiments that indicate the compound simultaneously forms two thermodynamically different complexes at a single AATT site. Two proposals for the origin of this unusual observation have been developed: (i) two different bound species of netropsin at single binding sites and (ii) a netropsin induced DNA hairpin to duplex transition. To develop a better understanding of DNA recognition complexity, the two proposals have been tested with several DNAs and the methods of mass spectrometry (MS), polyacrylamide gel electrophoresis (PAGE) and nuclear magnetic resonance spectroscopy in addition to ITC. All of the methods with all of the DNAs investigated clearly shows that netropsin forms two different complexes at AATT sites, and that the proposal for an induced hairpin to duplex transition in this system is incorrect.
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Affiliation(s)
- Edwin A Lewis
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA
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Hartley JA, Hamaguchi A, Suggitt M, Gregson SJ, Thurston DE, Howard PW. DNA interstrand cross-linking and in vivo antitumor activity of the extended pyrrolo[2,1-c][1,4]benzodiazepine dimer SG2057. Invest New Drugs 2011; 30:950-8. [PMID: 21384134 DOI: 10.1007/s10637-011-9647-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 02/11/2011] [Indexed: 10/18/2022]
Abstract
The pyrrolobenzodiazepines (PBDs) are naturally occurring antitumor antibiotics and a PBD dimer (SJG-136, SG2000) is in Phase II trials. SG2000 is a propyldioxy linked PBD dimer which binds sequence selectively in the minor groove of DNA forming DNA interstrand and intrastrand cross-linked adducts, and also mono-adducts depending on sequence. SG2057 is the corresponding dimer containing a pentyldioxy linkage. SG2057 has multilog differential in vitro cytotoxicity against a panel of human tumour cell lines with a mean GI(50) of 212 pM. The agent is highly efficient at producing DNA interstrand cross-links in cells which form rapidly and persist over a 48 h period. Significant antitumor activity was demonstrated in several human tumor xenograft models. Cures were obtained in a LOX-IMVI melanoma model following a single administration and dose-dependent activity, including regression responses, observed in SKOV-3 ovarian and HL-60 promyelocytic leukemia models following repeat dose schedules. In the advanced stage LS174T model, SG2057 administered either as a single dose, or in two repeat dose schedules, was superior to irinotecan. SG2057 is therefore a highly active antitumor agent, with more potent in vitro activity and superior in vivo activity to SG2000, warranting further development.
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Affiliation(s)
- John A Hartley
- Spirogen Ltd, UCL Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6BT, UK.
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