The Experts below are selected from a list of 337629 Experts worldwide ranked by ideXlab platform
Kerry A Chester - One of the best experts on this subject based on the ideXlab platform.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion Protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Antibody-directed enzyme prodrug therapy (ADEPT) is an experimental cancer treatment in which an enzyme linked either chemically or genetically to tumour-targeting antibody is given intravenously. When the antibody–enzyme has cleared from the circulation, a prodrug is given and is converted to active drug in the tumour by the targeted enzyme (Bagshawe et al, 1988). An illustration of the ADEPT concept is shown in Figure 1. ADEPT aims to overcome the shortcomings of systemic cancer treatment such as lack of tumour selectivity and drug resistance. Clinical ADEPT studies (Bagshawe et al, 1995; Napier et al, 2000; Francis et al, 2002) have used the bacterial enzyme carboxypeptidase G2 (CP) conjugated to A5B7, a monoclonal anticarcinoembryonic antigen (CEA) F(ab)2. This antibody–enzyme conjugate, termed A5CP, has demonstrated feasibility of ADEPT and evidence of Therapeutic response in patients with advanced CEA-expressing adenocarcinomas. The use of CP has advantage over human enzymes in that there is no human enzyme with equivalent substrate specificity so that the danger of prodrug activation by host enzyme is avoided. However, the development of human anti-CP antibody (HACA) and human anti-mouse antibody (HAMA) was a serious limitation of ADEPT with A5CP. HACA were observed in 97% and HAMA in 100% after single administration of A5CP (Napier et al, 2000; Francis et al, 2002). Hence, methods of reducing immunogenicity of the antibody–enzyme molecule are required since neutralising antibodies can inactivate Therapeutics (Baert et al, 2003) and are potentially detrimental to the patient. Furthermore, Protein Therapeutics are of increasing importance in the treatment of cancer, so a means to reduce antibody response is likely to be applicable to other Therapeutic Proteins.
A Mayer - One of the best experts on this subject based on the ideXlab platform.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion Protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Antibody-directed enzyme prodrug therapy (ADEPT) is an experimental cancer treatment in which an enzyme linked either chemically or genetically to tumour-targeting antibody is given intravenously. When the antibody–enzyme has cleared from the circulation, a prodrug is given and is converted to active drug in the tumour by the targeted enzyme (Bagshawe et al, 1988). An illustration of the ADEPT concept is shown in Figure 1. ADEPT aims to overcome the shortcomings of systemic cancer treatment such as lack of tumour selectivity and drug resistance. Clinical ADEPT studies (Bagshawe et al, 1995; Napier et al, 2000; Francis et al, 2002) have used the bacterial enzyme carboxypeptidase G2 (CP) conjugated to A5B7, a monoclonal anticarcinoembryonic antigen (CEA) F(ab)2. This antibody–enzyme conjugate, termed A5CP, has demonstrated feasibility of ADEPT and evidence of Therapeutic response in patients with advanced CEA-expressing adenocarcinomas. The use of CP has advantage over human enzymes in that there is no human enzyme with equivalent substrate specificity so that the danger of prodrug activation by host enzyme is avoided. However, the development of human anti-CP antibody (HACA) and human anti-mouse antibody (HAMA) was a serious limitation of ADEPT with A5CP. HACA were observed in 97% and HAMA in 100% after single administration of A5CP (Napier et al, 2000; Francis et al, 2002). Hence, methods of reducing immunogenicity of the antibody–enzyme molecule are required since neutralising antibodies can inactivate Therapeutics (Baert et al, 2003) and are potentially detrimental to the patient. Furthermore, Protein Therapeutics are of increasing importance in the treatment of cancer, so a means to reduce antibody response is likely to be applicable to other Therapeutic Proteins.
Theodore W Randolph - One of the best experts on this subject based on the ideXlab platform.
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particle formation and aggregation of a Therapeutic Protein in nanobubble suspensions
Journal of Pharmaceutical Sciences, 2016Co-Authors: Jared R Snell, John F Carpenter, Chen Zhou, Theodore W RandolphAbstract:Abstract The generation of nanobubbles following reconstitution of lyophilized trehalose formulations has recently been reported. Here, we characterize particle formation and aggregation of recombinant human interleukin-1 receptor antagonist (rhIL-1ra) in reconstituted formulations of lyophilized trehalose. Particle characterization methods including resonant mass measurement and nanoparticle tracking analysis were used to count and size particles generated upon reconstitution of lyophilized trehalose formulations. In addition, accelerated degradation studies were conducted to monitor rhIL-1ra aggregation in solutions containing various concentrations of suspended nanobubbles. Reconstitution of lyophilized trehalose formulations with solutions containing rhIL-1ra reduced nanobubble concentrations and generated negatively buoyant particles attributed to aggregated rhIL-1ra. Furthermore, levels of rhIL-1ra aggregation following incubation in aqueous solution correlated with concentrations of suspended nanobubbles. The results of this study suggest that nanobubbles may be a contributor to Protein aggregation and particle formation in reconstituted, lyophilized Therapeutic Protein formulations.
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silicone oil microdroplets can induce antibody responses against recombinant murine growth hormone in mice
Journal of Pharmaceutical Sciences, 2016Co-Authors: Carly Fleagle Chisholm, John F Carpenter, Abby E Baker, Kaitlin R Soucie, Raul M Torres, Theodore W RandolphAbstract:Abstract Therapeutic Protein products can cause adverse immune responses in patients. The presence of subvisible particles is a potential contributing factor to the immunogenicity of parenterally administered Therapeutic Protein formulations. Silicone oil microdroplets, which derive from silicone oil used as a lubricating coating on barrels of prefilled glass syringes, are often found in formulations. In this study, we investigated the potential of silicone oil microdroplets to act as adjuvants to induce an immune response in mice against a recombinant murine Protein. Antibody responses in mice to subcutaneous injections of formulations of recombinant murine growth hormone (rmGH) that contained silicone oil microdroplets were measured and compared to responses to oil-free rmGH formulations. When rmGH formulations containing silicone oil microdroplets were administered once every other week, anti-rmGH antibodies were not detected. In contrast, mice exhibited a small IgG1 response against rmGH when silicone oil–containing rmGH formulations were administered daily, and an anti-rmGH IgM response was observed at later time points. Our findings showed that silicone oil microdroplets can act as an adjuvant to promote a break in immunological tolerance and induce antibody responses against a recombinant self-Protein.
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immunogenicity of aggregates of recombinant human growth hormone in mouse models
Journal of Pharmaceutical Sciences, 2009Co-Authors: Amber Haynes Fradkin, John F Carpenter, Theodore W RandolphAbstract:Aggregation of recombinant Therapeutic Protein products is a concern due to their potential to induce immune responses. We examined the immunogenicity of Protein aggregates in commercial formulations of recombinant human growth hormone produced by freeze-thawing or agitation, two stresses commonly encountered during manufacturing, shipping and handling of Therapeutic Protein products. In addition, we subjected each preparation to high-pressure treatment to reduce the size and concentration of aggregates present in the samples. Aggregates existing in a commercial formulation, as well as aggregates induced by freeze-thawing and agitation stresses enhanced immunogenicity in one or more mouse models. The use of high-pressure treatment to reduce size and concentrations of aggregates within recombinant human growth hormone formulations reduced their overall immunogenicity in agreement with the “immunon” hypothesis. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3247–3264, 2009
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silicone oil and agitation induced aggregation of a monoclonal antibody in aqueous solution
Journal of Pharmaceutical Sciences, 2009Co-Authors: Renuka Thirumangalathu, Sampathkumar Krishnan, Theodore W Randolph, Margaret Speed Ricci, David N Brems, John F CarpenterAbstract:Silicone oil, which is used as a lubricant or coating in devices such as syringes, needles and pharmaceutical containers, has been implicated in aggregation and particulation of Proteins and antibodies. Aggregation of Therapeutic Protein products induced by silicone oil can pose a challenge to their development and commercialization. To systematically characterize the role of silicone oil on Protein aggregation, the effects of agitation, temperature, pH and ionic strength on silicone oil-induced loss of monomeric anti-streptavidin IgG 1 antibody were examined. Additionally, the influences of excipients polysorbate20 and sucrose on Protein aggregation were investigated. In the absence of agitation, Protein absorbed to silicone oil with approximately monolayer coverage, however silicone oil did not stimulate aggregation during isothermal incubation unless samples were also agitated. A synergistic stimulation of aggregation by a combination of agitation and silicone oil was observed. Solution conditions which reduced colloidal stability of the antibody, as assessed by determination of osmotic second virial coefficients, accelerated aggregation during agitation with silicone oil. Polysorbate20 completely inhibited silicone oil-induced monomer loss during agitation. A formulation strategy optimizing colloidal stability of the antibody as well as incorporation of surfactants such as polysorbate20 is proposed to reduce silicone oil-induced aggregation of Therapeutic Protein products.
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overlooking subvisible particles in Therapeutic Protein products gaps that may compromise product quality
Journal of Pharmaceutical Sciences, 2009Co-Authors: John F Carpenter, Theodore W Randolph, Gerhard Winter, Wim Jiskoot, Daan J A Crommelin, Russell C Middaugh, Yingxin Fan, Susan Kirshner, Daniela Verthelyi, Steven KozlowskiAbstract:Therapeutic Protein products provide unique and effective treatments for numerous human diseases and medical conditions. In many cases, these treatments are used chronically to slow disease progression, reduce morbidity and/or to replace essential Proteins that are not produced endogenously in patients. Therefore, any factor that reduces or eliminates the effectiveness of the treatment can lead to patient suffering and even death. One means by which efficacy of Therapeutic Proteins can be compromised is by an immune response, resulting in antibody-mediated neutralization of the Protein’s activity or alterations in bioavailability.1,2 For example, in the case of treatment of hemophilia A, neutralizing antibodies to Factor VIII can cause life-threatening bleeding episodes, resulting in significant morbidity and necessitating treatment with a prolonged course of a tolerance-inducing therapy to reverse immunity.3,4 In other cases, drug-induced antibodies to a Therapeutic version of an endogenous Protein can cross-react with and neutralize the patient’s endogenous Protein. If the endogenous Protein serves a non-redundant biological function, such an immune response can have devastating results. For example, pure red cell aplasia can result from neutralizing antibodies to epoetin alpha. 1,2 It is well established that Protein aggregates in Therapeutic Protein products can enhance immunogenicity2, and such an effect is therefore an important risk factor to consider when assessing product quality. The purpose of this commentary is to accomplish the following: provide brief summaries on the factors affecting Protein aggregation and the key aspects of Protein aggregates that are associated with immunogenicity; emphasize the current scientific gaps in understanding and analytical limitations for quantitation of species of large Protein aggregates that are referred to as subvisible particles, with specific consideration of those particles 0.1–10 μm in size; offer a rationale for why these gaps may compromise the safety and/or efficacy of a product; provide scientifically sound, risked based recommendations/conclusions for assessment and control of such aggregate species. Causes of Protein Aggregation Proteins usually aggregate from partially unfolded molecules, which can be part of the native state ensemble of molecules.5 Even though product formulations are developed to maximize and maintain the fraction of the Protein molecules present in the native state, significant amounts of aggregates can form, especially over pharmaceutically-relevant time scales and under stress conditions. For example, exposure to interfaces (e.g., air-liquid and solid-liquid), light, temperature fluctuations or minor impurities can induce aggregation. Such exposure can occur during processing steps, as well as in the final product container during storage, shipment and handling. Furthermore, Protein particles (visible and subvisible) can be generated from Protein alone or from heterogeneous nucleation on foreign micro- and nanoparticles that are shed, for example, from filling pumps or product container/closures.6–8 The levels and sizes of Protein particles present in a given product can be changed by many factors relevant to commercial production of Therapeutic Proteins. Such factors include a change in the type of filling pump during scale-up to commercial manufacturing, changes in formulation or container/closure, and even unintentional changes in the manufacturing process such as alterations in filling pump mechanical parameters or other unforeseen factors.8,9 Thus, unless appropriate quality controls are in place for subvisible particles, a product that was safe and effective in clinical trials may unexpectedly cause adverse events in patients after commercialization. Effects of Aggregate Characteristics on Immunogenicity From work on fundamental aspects of immunology and vaccine development, it is known that large Protein assemblies with repetitive arrays of antigens, in which the Protein molecules have native conformation, are usually the most potent at inducing immune responses.2,10,11 Furthermore, efforts to develop more effective vaccines have shown that adsorbing antigenic Proteins to nano- or microparticles comprised of other materials (e.g., colloidal aluminum salts or polystyrene) can greatly increase immunogenicity.12,13 Applying these lessons to Therapeutic Protein products, it has been argued that large aggregates containing Protein molecules with native-like conformation pose the greatest risk of causing adverse immune responses in patients.2 Thus, for example, particles of Therapeutic Proteins formed by adsorption of Protein molecules onto foreign micro- and nanoparticles might be particularly prone to cause immunogenicity. These particles contain numerous Protein molecules, and in the two examples published to date, the adsorbed Protein molecules were shown to retain their native conformations.6,8 Unfortunately, lacking are published studies that comprehensively investigate the range of parameters that could influence immunogenicity of aggregates. Because each Protein may differ in aggregate formation and consequences, factors that need to be investigated include but are not limited to type, amount and size of aggregates, as well as Protein conformation in aggregates, on a case by case basis. Of course, other factors, particularly pertaining to patient status and treatment protocol, are also critical in determining the propensity to generate immune responses. These include immune competence of the patients, route of administration, and dosing frequency and duration. Given the consequences of aggregate-induced immunogenicity in patients, it is important to understand these issues and to reduce the risk to product quality for every Therapeutic Protein product. Because the exact characteristics and levels of Protein aggregates that lead to an enhanced immune response are unclear and may differ among Proteins, it is not possible to predict, a priori, the in vivo effects of different sizes, types or quantities of aggregates for Therapeutic Protein products. In such situations, careful analysis of the relationship between clinical performance and the presence of Protein aggregates in relevant clinical trial material may help in the design of suitable control strategies that ensure product quality. However, the validity and utility such correlations are only optimized when the full spectrum of Protein aggregate species are thoroughly characterized by multiple and orthogonal techniques.
B Tolner - One of the best experts on this subject based on the ideXlab platform.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion Protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Antibody-directed enzyme prodrug therapy (ADEPT) is an experimental cancer treatment in which an enzyme linked either chemically or genetically to tumour-targeting antibody is given intravenously. When the antibody–enzyme has cleared from the circulation, a prodrug is given and is converted to active drug in the tumour by the targeted enzyme (Bagshawe et al, 1988). An illustration of the ADEPT concept is shown in Figure 1. ADEPT aims to overcome the shortcomings of systemic cancer treatment such as lack of tumour selectivity and drug resistance. Clinical ADEPT studies (Bagshawe et al, 1995; Napier et al, 2000; Francis et al, 2002) have used the bacterial enzyme carboxypeptidase G2 (CP) conjugated to A5B7, a monoclonal anticarcinoembryonic antigen (CEA) F(ab)2. This antibody–enzyme conjugate, termed A5CP, has demonstrated feasibility of ADEPT and evidence of Therapeutic response in patients with advanced CEA-expressing adenocarcinomas. The use of CP has advantage over human enzymes in that there is no human enzyme with equivalent substrate specificity so that the danger of prodrug activation by host enzyme is avoided. However, the development of human anti-CP antibody (HACA) and human anti-mouse antibody (HAMA) was a serious limitation of ADEPT with A5CP. HACA were observed in 97% and HAMA in 100% after single administration of A5CP (Napier et al, 2000; Francis et al, 2002). Hence, methods of reducing immunogenicity of the antibody–enzyme molecule are required since neutralising antibodies can inactivate Therapeutics (Baert et al, 2003) and are potentially detrimental to the patient. Furthermore, Protein Therapeutics are of increasing importance in the treatment of cancer, so a means to reduce antibody response is likely to be applicable to other Therapeutic Proteins.
Peter Amlot - One of the best experts on this subject based on the ideXlab platform.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion Protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.
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modifying an immunogenic epitope on a Therapeutic Protein a step towards an improved system for antibody directed enzyme prodrug therapy adept
British Journal of Cancer, 2004Co-Authors: A Mayer, S K Sharma, B Tolner, Nigel P Minton, Des Purdy, Peter Amlot, G Tharakan, R H J Begent, Kerry A ChesterAbstract:Antibody-directed enzyme prodrug therapy (ADEPT) is an experimental cancer treatment in which an enzyme linked either chemically or genetically to tumour-targeting antibody is given intravenously. When the antibody–enzyme has cleared from the circulation, a prodrug is given and is converted to active drug in the tumour by the targeted enzyme (Bagshawe et al, 1988). An illustration of the ADEPT concept is shown in Figure 1. ADEPT aims to overcome the shortcomings of systemic cancer treatment such as lack of tumour selectivity and drug resistance. Clinical ADEPT studies (Bagshawe et al, 1995; Napier et al, 2000; Francis et al, 2002) have used the bacterial enzyme carboxypeptidase G2 (CP) conjugated to A5B7, a monoclonal anticarcinoembryonic antigen (CEA) F(ab)2. This antibody–enzyme conjugate, termed A5CP, has demonstrated feasibility of ADEPT and evidence of Therapeutic response in patients with advanced CEA-expressing adenocarcinomas. The use of CP has advantage over human enzymes in that there is no human enzyme with equivalent substrate specificity so that the danger of prodrug activation by host enzyme is avoided. However, the development of human anti-CP antibody (HACA) and human anti-mouse antibody (HAMA) was a serious limitation of ADEPT with A5CP. HACA were observed in 97% and HAMA in 100% after single administration of A5CP (Napier et al, 2000; Francis et al, 2002). Hence, methods of reducing immunogenicity of the antibody–enzyme molecule are required since neutralising antibodies can inactivate Therapeutics (Baert et al, 2003) and are potentially detrimental to the patient. Furthermore, Protein Therapeutics are of increasing importance in the treatment of cancer, so a means to reduce antibody response is likely to be applicable to other Therapeutic Proteins.
