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Teicher BA, Morris J. Antibody-Drug Conjugate Targets, Drugs and Linkers. Curr Cancer Drug Targets 2022; 22:463-529. [PMID: 35209819 DOI: 10.2174/1568009622666220224110538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/22/2021] [Accepted: 11/09/2021] [Indexed: 11/22/2022]
Abstract
Antibody-drug conjugates offer the possibility of directing powerful cytotoxic agents to a malignant tumor while sparing normal tissue. The challenge is to select an antibody target expressed exclusively or at highly elevated levels on the surface of tumor cells and either not all or at low levels on normal cells. The current review explores 78 targets that have been explored as antibody-drug conjugate targets. Some of these targets have been abandoned, 9 or more are the targets of FDA-approved drugs, and most remain active clinical interest. Antibody-drug conjugates require potent cytotoxic drug payloads, several of these small molecules are discussed, as are the linkers between the protein component and small molecule components of the conjugates. Finally, conclusions regarding the elements for the successful antibody-drug conjugate are discussed.
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Affiliation(s)
- Beverly A Teicher
- Developmental Therapeutics Program, DCTD, National Cancer Institute, Bethesda, MD 20892,United States
| | - Joel Morris
- Developmental Therapeutics Program, DCTD, National Cancer Institute, Bethesda, MD 20892,United States
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2
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Coumans RGE, Ariaans GJA, Spijker HJ, Renart Verkerk P, Beusker PH, Kokke BPA, Schouten J, Blomenröhr M, van der Lee MMC, Groothuis PG, Ubink R, Dokter WHA, Timmers CM. A Platform for the Generation of Site-Specific Antibody-Drug Conjugates That Allows for Selective Reduction of Engineered Cysteines. Bioconjug Chem 2020; 31:2136-2146. [PMID: 32697078 DOI: 10.1021/acs.bioconjchem.0c00337] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Engineering cysteines at specific sites in antibodies to create well-defined ADCs for the treatment of cancer is a promising approach to increase the therapeutic index and helps to streamline the manufacturing process. Here, we report the development of an in silico screening procedure to select for optimal sites in an antibody to which a hydrophobic linker-drug can be conjugated. Sites were identified inside the cavity that is naturally present in the Fab part of the antibody. Conjugating a linker-drug to these sites demonstrated the ability of the antibody to shield the hydrophobic character of the linker-drug while resulting ADCs maintained their cytotoxic potency in vitro. Comparison of site-specific ADCs versus randomly conjugated ADCs in an in vivo xenograft model revealed improved efficacy and exposure. We also report a selective reducing agent that is able to reduce the engineered cysteines while leaving the interchain disulfides in the oxidized state. This enables us to manufacture site-specific ADCs without introducing impurities associated with the conventional reduction/oxidation procedure for site-specific conjugation.
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Affiliation(s)
| | | | - Henri J Spijker
- Byondis B.V., Microweg 22, 6545 CM Nijmegen, The Netherlands
| | | | | | - Bas P A Kokke
- Byondis B.V., Microweg 22, 6545 CM Nijmegen, The Netherlands
| | - Jan Schouten
- Byondis B.V., Microweg 22, 6545 CM Nijmegen, The Netherlands
| | | | | | | | - Ruud Ubink
- Byondis B.V., Microweg 22, 6545 CM Nijmegen, The Netherlands
| | - Wim H A Dokter
- Byondis B.V., Microweg 22, 6545 CM Nijmegen, The Netherlands
| | - C Marco Timmers
- Byondis B.V., Microweg 22, 6545 CM Nijmegen, The Netherlands
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3
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Shi B, Wu M, Li Z, Xie Z, Wei X, Fan J, Xu Y, Ding D, Akash SH, Chen S, Cao S. Antitumor activity of a 5T4 targeting antibody drug conjugate with a novel payload derived from MMAF via C-Lock linker. Cancer Med 2019; 8:1793-1805. [PMID: 30843650 PMCID: PMC6488119 DOI: 10.1002/cam4.2066] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 01/15/2019] [Accepted: 02/12/2019] [Indexed: 12/19/2022] Open
Abstract
Antibody-drug conjugates (ADCs) belong to a promising class of biopharmaceuticals in which target-killing of tumor cells was achieved by marrying the potency of the cytotoxic payload with the tumor specificity of the antibody. Here we developed a novel ADC (ZV0508) that targets 5T4 oncofetal antigen, which is overexpressed in many carcinomas on both bulk tumor cells and cancer stem cells. A novel cytotoxic payload called Duostatin-5 (Duo-5) which was derived from monomethyl auristatin F (MMAF) was attached to a 5T4 targeting antibody (ZV05) by interchain cysteine cross-linking conjugation via a disubstituted C-Lock linker. We have investigated the antitumor efficacy of ZV0508 by in vitro and in vivo studies, and compared its antitumor activity with ZV05-mcMMAF (ZV0501), in which MMAF was linked via a conventional noncleavable maleimidocaproyl linker. As results, ZV0508 exhibited ideal antiproliferative effects through blocking cell cycle and inducing cell apoptosis. The in vivo studies revealed that both ZV0501 and ZV0508 exhibited excellent antitumor activities even at a single dose. Although ZV0508 was inferior to ZV0501 in vitro, it elicited more durable antitumor responses than ZV0501 in vivo. The superior in vivo activity of ZV0508 may be due to the combined use of the disubstituted C-Lock linker and the novel payload Duo-5, resulting in a more stable and potent ADC. Taken together, these data suggest ZV0508 is a worthy candidate for the treatment of 5T4 positive cancers.
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MESH Headings
- Animals
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/therapeutic use
- Antigens, Neoplasm/metabolism
- Antineoplastic Agents/pharmacokinetics
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Apoptosis/drug effects
- Cell Cycle Checkpoints/drug effects
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cross-Linking Reagents
- Female
- Humans
- Immunoconjugates/pharmacokinetics
- Immunoconjugates/pharmacology
- Immunoconjugates/therapeutic use
- Male
- Mammary Neoplasms, Experimental/drug therapy
- Mammary Neoplasms, Experimental/metabolism
- Mammary Neoplasms, Experimental/pathology
- Mice, Inbred BALB C
- Mice, Nude
- Molecular Targeted Therapy/methods
- Neoplasms/drug therapy
- Neoplasms/metabolism
- Neoplasms/pathology
- Oligopeptides/pharmacology
- Tumor Cells, Cultured/drug effects
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Baoying Shi
- College of Pharmaceutical Sciences, Institute of Drug Metabolism and Pharmaceutical Analysis and Zhejiang Provincial Key Laboratory of Anti‐Cancer Drug ResearchZhejiang UniversityHangzhouChina
| | - Min Wu
- Zova Biotherapeutics IncFuyang, HangzhouChina
| | - Zhaohui Li
- Zova Biotherapeutics IncFuyang, HangzhouChina
| | | | - Xiaoyue Wei
- College of Pharmaceutical Sciences, Institute of Drug Metabolism and Pharmaceutical Analysis and Zhejiang Provincial Key Laboratory of Anti‐Cancer Drug ResearchZhejiang UniversityHangzhouChina
| | - Jiansheng Fan
- College of Pharmaceutical Sciences, Institute of Drug Metabolism and Pharmaceutical Analysis and Zhejiang Provincial Key Laboratory of Anti‐Cancer Drug ResearchZhejiang UniversityHangzhouChina
| | - Yingchun Xu
- College of Pharmaceutical Sciences, Institute of Drug Metabolism and Pharmaceutical Analysis and Zhejiang Provincial Key Laboratory of Anti‐Cancer Drug ResearchZhejiang UniversityHangzhouChina
| | - Ding Ding
- Noeantigen Therapeutics (HangZhou) Co., LtdHangzhouChina
| | - Sajid Hamid Akash
- College of Pharmaceutical Sciences, Institute of Drug Metabolism and Pharmaceutical Analysis and Zhejiang Provincial Key Laboratory of Anti‐Cancer Drug ResearchZhejiang UniversityHangzhouChina
| | - Shuqing Chen
- College of Pharmaceutical Sciences, Institute of Drug Metabolism and Pharmaceutical Analysis and Zhejiang Provincial Key Laboratory of Anti‐Cancer Drug ResearchZhejiang UniversityHangzhouChina
| | - Sheldon Cao
- Zova Biotherapeutics IncFuyang, HangzhouChina
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4
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Shapiro GI, Vaishampayan UN, LoRusso P, Barton J, Hua S, Reich SD, Shazer R, Taylor CT, Xuan D, Borghaei H. First-in-human trial of an anti-5T4 antibody-monomethylauristatin conjugate, PF-06263507, in patients with advanced solid tumors. Invest New Drugs 2017; 35:315-323. [PMID: 28070718 PMCID: PMC5418317 DOI: 10.1007/s10637-016-0419-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/22/2016] [Indexed: 12/20/2022]
Abstract
Background The antibody-drug conjugate PF-06263507 targets the cell-surface, tumor-associated antigen 5T4 and consists of a humanized IgG1 conjugated to the microtubule-disrupting agent monomethylauristatin-F by a non-cleavable maleimidocaproyl linker. In this first-in-human, dose-finding trial (NCT01891669), we evaluated safety, pharmacokinetics, and preliminary antitumor activity of PF-06263507 in pretreated patients with advanced solid tumors, unselected for 5T4 expression. starting at 0.05 mg/kg, with 25, 56, and 95% dose increments, depending on observed dose-limiting toxicities (DLTs), applying a modified continual reassessment method. Results Twenty-six patients received PF-06263507 at 0.05 to 6.5 mg/kg. The first DLT, grade 3 photophobia, occurred at 4.34 mg/kg and two additional DLTs, grade 2 keratitis and grade 1 limbal stem cell deficiency (> 2-week dosing delay), at 6.5 mg/kg. The most common adverse events (AEs) were fatigue (38.5%), photophobia (26.9%), and decreased appetite, dry eye, nausea, and thrombocytopenia (23.1% each). No treatment-related grade 4-5 AEs were reported. Systemic exposure of PF-06263507 increased in a dose-related manner. At the maximum tolerated dose (MTD, 4.34 mg/kg), mean terminal half-life for PF-06263507 and unconjugated payload were ~6 and 3 days, respectively. Payload serum concentrations were substantially lower compared with PF-06263507. No objective responses were observed. Conclusions The MTD and recommended phase II dose were determined to be 4.34 mg/kg. Ocular toxicities accounted for the DLTs observed, as previously reported with monomethylauristatin-F payloads. Further studies are warranted to investigate clinical activity of this agent in patients with 5T4-expressing tumors.Trial registration ID: NCT01891669.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antibodies, Monoclonal, Humanized/adverse effects
- Antibodies, Monoclonal, Humanized/pharmacokinetics
- Antibodies, Monoclonal, Humanized/therapeutic use
- Antigens, Neoplasm/adverse effects
- Antigens, Neoplasm/therapeutic use
- Antineoplastic Agents, Immunological/adverse effects
- Antineoplastic Agents, Immunological/pharmacokinetics
- Antineoplastic Agents, Immunological/therapeutic use
- Female
- Humans
- Immunoconjugates/adverse effects
- Immunoconjugates/pharmacokinetics
- Immunoconjugates/therapeutic use
- Keratitis/chemically induced
- Male
- Maximum Tolerated Dose
- Membrane Glycoproteins/antagonists & inhibitors
- Middle Aged
- Neoplasms/drug therapy
- Neoplasms/metabolism
- Oligopeptides/adverse effects
- Oligopeptides/pharmacokinetics
- Oligopeptides/therapeutic use
- Photophobia/chemically induced
- Treatment Outcome
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Affiliation(s)
- Geoffrey I Shapiro
- Early Drug Development Center, Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Ave, Mayer 446, Boston, MA, 02215, USA.
| | | | | | | | | | | | | | - Carrie T Taylor
- Pfizer Oncology, La Jolla, CA, USA.
- Pfizer Early Oncology Development and Clinical Research, 10777 Science Center Drive, CB-1, San Diego, CA, 92121, USA.
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5
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Leal M, Wentland J, Han X, Zhang Y, Rago B, Duriga N, Spriggs F, Kadar E, Song W, McNally J, Shakey Q, Lorello L, Lucas J, Sapra P. Preclinical Development of an anti-5T4 Antibody-Drug Conjugate: Pharmacokinetics in Mice, Rats, and NHP and Tumor/Tissue Distribution in Mice. Bioconjug Chem 2015; 26:2223-32. [PMID: 26180901 DOI: 10.1021/acs.bioconjchem.5b00205] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pharmacokinetics of an antibody (huA1)-drug (auristatin microtubule disrupting MMAF) conjugate, targeting 5T4-expressing cells, were characterized during the discovery and development phases in female nu/nu mice and cynomolgus monkeys after a single dose and in S-D rats and cynomolgus monkeys from multidose toxicity studies. Plasma/serum samples were analyzed using an ELISA-based method for antibody and conjugate (ADC) as well as for the released payload using an LC-MS/MS method. In addition, the distribution of the Ab, ADC, and released payload (cys-mcMMAF) was determined in a number of tissues (tumor, lung, liver, kidney, and heart) in two tumor mouse models (H1975 and MDA-MB-361-DYT2 models) using similar LBA and LC-MS/MS methods. Tissue distribution studies revealed preferential tumor distribution of cys-mcMMAF and its relative specificity to the 5T4 target containing tissue (tumor). Single dose studies suggests lower CL values at the higher doses in mice, although a linear relationship was seen in cynomolgus monkeys at doses from 0.3 to 10 mg/kg with no evidence of TMDD. Evaluation of DAR (drug-antibody ratio) in cynomolgus monkeys (at 3 mg/kg) indicated that at least half of the payload was still on the ADC 1 to 2 weeks after IV dosing. After multiple doses, the huA1 and conjugate data in rats and monkeys indicate that exposure (AUC) increases with increasing dose in a linear fashion. Systemic exposure (as assessed by Cmax and AUC) of the released payload increased with increasing dose, although exposure was very low and its pharmacokinetics appeared to be formation rate limited. The incidence of ADA was generally low in rats and monkeys. We will discuss cross species comparison, relationships between the Ab, ADC, and released payload exposure after multiple dosing, and insights into the distribution of this ADC with a focus on experimental design as a way to address or bypass apparent obstacles and its integration into predictive models.
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Affiliation(s)
- Mauricio Leal
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Pearl River, New York 10965, United States
| | - JoAnn Wentland
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - Xiaogang Han
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - Yanhua Zhang
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - Brian Rago
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - Nicole Duriga
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Andover, Massachusetts 01810, United States
| | - Franklin Spriggs
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Andover, Massachusetts 01810, United States
| | - Eugene Kadar
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - Wei Song
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - James McNally
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Andover, Massachusetts 01810, United States
| | - Quazi Shakey
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Andover, Massachusetts 01810, United States
| | - Leslie Lorello
- Pharmacokinetics, Dynamics and Metabolism, Pfizer Inc. , Groton, Connecticut 06340, United States
| | - Judy Lucas
- Oncology Research Unit, Pfizer Inc. , Pearl River, New York 10965, United States
| | - Puja Sapra
- Oncology Research Unit, Pfizer Inc. , Pearl River, New York 10965, United States
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6
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Bornstein GG. Antibody Drug Conjugates: Preclinical Considerations. AAPS JOURNAL 2015; 17:525-34. [PMID: 25724883 DOI: 10.1208/s12248-015-9738-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 02/09/2015] [Indexed: 01/29/2023]
Abstract
The development path for antibody drug conjugates (ADCs) is more complex and challenging than for unmodified antibodies. While many of the preclinical considerations for both unmodified and antibody drug conjugates are shared, special considerations must be taken into account when developing an ADC. Unlike unmodified antibodies, an ADC must preferentially bind to tumor cells, internalize, and traffic to the appropriate intracellular compartment to release the payload. Parameters that can impact the pharmacological properties of this class of therapeutics include the selection of the payload, the type of linker, and the methodology for payload drug conjugation. Despite a plethora of in vitro assays and in vivo models to screen and evaluate ADCs, the challenge remains to develop improved preclinical tools that will be more predictive of clinical outcome. This review will focus on preclinical considerations for clinically validated small molecule ADCs. In addition, the lessons learned from Mylotarg®, the first in class FDA-approved ADC, are highlighted.
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Affiliation(s)
- Gadi G Bornstein
- Centers for Therapeutic Innovation (CTI), Pfizer Inc., 450 East 29th Street, New York, New York, 10016, USA,
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7
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Zhao Y, Malinauskas T, Harlos K, Jones EY. Structural insights into the inhibition of Wnt signaling by cancer antigen 5T4/Wnt-activated inhibitory factor 1. Structure 2014; 22:612-20. [PMID: 24582434 PMCID: PMC3988984 DOI: 10.1016/j.str.2014.01.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/30/2013] [Accepted: 01/13/2014] [Indexed: 01/10/2023]
Abstract
The tumor antigen 5T4/WAIF1 (Wnt-activated inhibitory factor 1; also known as Trophoblast glycoprotein TPBG) is a cell surface protein targeted in multiple cancer immunotherapy clinical trials. Recently, it has been shown that 5T4/WAIF1 inhibits Wnt/β-catenin signaling, a signaling system central to many developmental and pathological processes. Wnt/β-catenin signaling is controlled by multiple inhibitors and activators. Here, we report crystal structures for the extracellular domain of 5T4/WAIF1 at 1.8 Å resolution. They reveal a highly glycosylated, rigid core, comprising eight leucine-rich repeats (LRRs), which serves as a platform to present evolutionarily conserved surface residues in the N-terminal LRR1. Structural and cell-based analyses, coupled with previously reported in vivo data, suggest that Tyr325 plus the LRR1 surface centered on a second exposed aromatic residue, Phe97, are essential for inhibition of Wnt/β-catenin signaling. These results provide a structural basis for the development of 5T4/WAIF1-targeted therapies that preserve or block 5T4/WAIF1-mediated inhibition of Wnt/β-catenin signaling.
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Affiliation(s)
- Yuguang Zhao
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Karl Harlos
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK.
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8
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Shah DK, King LE, Han X, Wentland JA, Zhang Y, Lucas J, Haddish-Berhane N, Betts A, Leal M. A priori prediction of tumor payload concentrations: preclinical case study with an auristatin-based anti-5T4 antibody-drug conjugate. AAPS JOURNAL 2014; 16:452-63. [PMID: 24578215 DOI: 10.1208/s12248-014-9576-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 01/23/2014] [Indexed: 11/30/2022]
Abstract
The objectives of this investigation were as follows: (a) to validate a mechanism-based pharmacokinetic (PK) model of ADC for its ability to a priori predict tumor concentrations of ADC and released payload, using anti-5T4 ADC A1mcMMAF, and (b) to analyze the PK model to find out main pathways and parameters model outputs are most sensitive to. Experiential data containing biomeasures, and plasma and tumor concentrations of ADC and payload, following A1mcMMAF administration in two different xenografts, were used to build and validate the model. The model performed reasonably well in terms of a priori predicting tumor exposure of total antibody, ADC, and released payload, and the exposure of released payload in plasma. Model predictions were within two fold of the observed exposures. Pathway analysis and local sensitivity analysis were conducted to investigate main pathways and set of parameters the model outputs are most sensitive to. It was discovered that payload dissociation from ADC and tumor size were important determinants of plasma and tumor payload exposure. It was also found that the sensitivity of the model output to certain parameters is dose-dependent, suggesting caution before generalizing the results from the sensitivity analysis. Model analysis also revealed the importance of understanding and quantifying the processes responsible for ADC and payload disposition within tumor cell, as tumor concentrations were sensitive to these parameters. Proposed ADC PK model provides a useful tool for a priori predicting tumor payload concentrations of novel ADCs preclinically, and possibly translating them to the clinic.
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Affiliation(s)
- Dhaval K Shah
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, 455 Kapoor Hall, Buffalo, New York, 14214, USA,
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9
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Mahato R, Tai W, Cheng K. Prodrugs for improving tumor targetability and efficiency. Adv Drug Deliv Rev 2011; 63:659-70. [PMID: 21333700 PMCID: PMC3132824 DOI: 10.1016/j.addr.2011.02.002] [Citation(s) in RCA: 247] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/14/2011] [Accepted: 02/03/2011] [Indexed: 12/14/2022]
Abstract
As the mainstay in the treatment of various cancers for several decades, chemotherapy is successful but still faces challenges including non-selectivity and high toxicity. Improving the selectivity is therefore a critical step to improve the therapeutic efficacy of chemotherapy. Prodrug is one of the most promising approaches to increase the selectivity and efficacy of a chemotherapy drug. The classical prodrug approach is to improve the pharmaceutical properties (solubility, stability, permeability, irritation, distribution, etc.) via a simple chemical modification. This review will focus on various targeted prodrug designs that have been developed to increase the selectivity of chemotherapy drugs. Various tumor-targeting ligands, transporter-associated ligands, and polymers can be incorporated in a prodrug to enhance the tumor uptake. Prodrugs can also be activated by enzymes that are specifically expressed at a higher level in tumors, leading to a selective anti-tumor effect. This can be achieved by conjugating the enzyme to a tumor-specific antibody, or delivering a vector expressing the enzyme into tumor cells.
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Affiliation(s)
- Rubi Mahato
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO 64108
| | - Wanyi Tai
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO 64108
| | - Kun Cheng
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte Street, Kansas City, MO 64108
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Dressel R, Guan K, Nolte J, Elsner L, Monecke S, Nayernia K, Hasenfuss G, Engel W. Multipotent adult germ-line stem cells, like other pluripotent stem cells, can be killed by cytotoxic T lymphocytes despite low expression of major histocompatibility complex class I molecules. Biol Direct 2009; 4:31. [PMID: 19715575 PMCID: PMC2745366 DOI: 10.1186/1745-6150-4-31] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 08/28/2009] [Indexed: 01/09/2023] Open
Abstract
Background Multipotent adult germ-line stem cells (maGSCs) represent a new pluripotent cell type that can be derived without genetic manipulation from spermatogonial stem cells (SSCs) present in adult testis. Similarly to induced pluripotent stem cells (iPSCs), they could provide a source of cellular grafts for new transplantation therapies of a broad variety of diseases. To test whether these stem cells can be rejected by the recipients, we have analyzed whether maGSCs and iPSCs can become targets for cytotoxic T lymphocytes (CTL) or whether they are protected, as previously proposed for embryonic stem cells (ESCs). Results We have observed that maGSCs can be maintained in prolonged culture with or without leukemia inhibitory factor and/or feeder cells and still retain the capacity to form teratomas in immunodeficient recipients. They were, however, rejected in immunocompetent allogeneic recipients, and the immune response controlled teratoma growth. We analyzed the susceptibility of three maGSC lines to CTL in comparison to ESCs, iPSCs, and F9 teratocarcinoma cells. Major histocompatibility complex (MHC) class I molecules were not detectable by flow cytometry on these stem cell lines, apart from low levels on one maGSC line (maGSC Stra8 SSC5). However, using a quantitative real time PCR analysis H2K and B2m transcripts were detected in all pluripotent stem cell lines. All pluripotent stem cell lines were killed in a peptide-dependent manner by activated CTLs derived from T cell receptor transgenic OT-I mice after pulsing of the targets with the SIINFEKL peptide. Conclusion Pluripotent stem cells, including maGSCs, ESCs, and iPSCs can become targets for CTLs, even if the expression level of MHC class I molecules is below the detection limit of flow cytometry. Thus they are not protected against CTL-mediated cytotoxicity. Therefore, pluripotent cells might be rejected after transplantation by this mechanism if specific antigens are presented and if specific activated CTLs are present. Our results show that the adaptive immune system has in principle the capacity to kill pluripotent and teratoma forming stem cells. This finding might help to develop new strategies to increase the safety of future transplantations of in vitro differentiated cells by exploiting a selective immune response against contaminating undifferentiated cells. Reviewers This article was reviewed by Bhagirath Singh, Etienne Joly and Lutz Walter.
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Affiliation(s)
- Ralf Dressel
- Department of Cellular and Molecular Immunology, University of Göttingen, Heinrich-Düker-Weg 12, 37073 Göttingen, Germany.
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