UNLABELLED: Three thiol reactive reagents were developed for the chemoselective conjugation of desferrioxamine (Df) to a monoclonal antibody via engineered cysteine residues (thio-trastuzumab). The in vitro stability and in vivo imaging properties of site-specifically radiolabeled (89)Zr-Df-thio-trastuzumab conjugates were investigated. METHODS: The amino group of desferrioxamine B was acylated by bromoacetyl bromide, N-hydroxysuccinimidyl iodoacetate, or N-hydroxysuccinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate to obtain thiol reactive reagents bromoacetyl-desferrioxamine (Df-Bac), iodoacetyl-desferrioxamine (Df-Iac) and maleimidocyclohexyl-desferrioxamine (Df-Chx-Mal), respectively. Df-Bac and Df-Iac alkylated the free thiol groups of thio-trastuzumab by nucleophilic substitution forming Df-Ac-thio-trastuzumab, while the maleimide reagent Df-Chx-Mal reacted via Michael addition to provide Df-Chx-Mal-thio-trastuzumab. The conjugates were radiolabeled with (89)Zr and evaluated for serum stability, and their positron emission tomography (PET) imaging properties were investigated in a BT474M1 (HER2-positive) breast tumor mouse model. RESULTS: The chemoselective reagents were obtained in 14% (Df-Bac), 53% (Df-Iac) and 45% (Df-Chx-Mal) yields. Site-specific conjugation of Df-Chx-Mal to thio-trastuzumab was complete within 1 h at pH 7.5, while Df-Iac and Df-Bac respectively required 2 and 5 h at pH 9. Each Df modified thio-trastuzumab was chelated with (89)Zr in yields exceeding 75%. (89)Zr-Df-Ac-thio-trastuzumab and (89)Zr-Df-Chx-Mal-thio-trastuzumab were stable in mouse serum and exhibited comparable PET imaging capabilities in a BT474M1 (HER2-positive) breast cancer model reaching 20-25 %ID/g of tumor uptake and a tumor to blood ratio of 6.1-7.1. CONCLUSIONS: The new reagents demonstrated good reactivity with engineered thiol groups of trastuzumab and very good chelation properties with (89)Zr. The site-specifically (89)Zr-labeled thio-antibodies were stable in serum and showed PET imaging properties comparable to lysine conjugates. Copyright 2010 Elsevier Inc. All rights reserved.
UNLABELLED: Three thiol reactive reagents were developed for the chemoselective conjugation of desferrioxamine (Df) to a monoclonal antibody via engineered cysteine residues (thio-trastuzumab). The in vitro stability and in vivo imaging properties of site-specifically radiolabeled (89)Zr-Df-thio-trastuzumab conjugates were investigated. METHODS: The amino group of desferrioxamine B was acylated by bromoacetyl bromide, N-hydroxysuccinimidyl iodoacetate, or N-hydroxysuccinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate to obtain thiol reactive reagents bromoacetyl-desferrioxamine (Df-Bac), iodoacetyl-desferrioxamine (Df-Iac) and maleimidocyclohexyl-desferrioxamine (Df-Chx-Mal), respectively. Df-Bac and Df-Iac alkylated the free thiol groups of thio-trastuzumab by nucleophilic substitution forming Df-Ac-thio-trastuzumab, while the maleimide reagent Df-Chx-Mal reacted via Michael addition to provide Df-Chx-Mal-thio-trastuzumab. The conjugates were radiolabeled with (89)Zr and evaluated for serum stability, and their positron emission tomography (PET) imaging properties were investigated in a BT474M1 (HER2-positive) breast tumormouse model. RESULTS: The chemoselective reagents were obtained in 14% (Df-Bac), 53% (Df-Iac) and 45% (Df-Chx-Mal) yields. Site-specific conjugation of Df-Chx-Mal to thio-trastuzumab was complete within 1 h at pH 7.5, while Df-Iac and Df-Bac respectively required 2 and 5 h at pH 9. Each Df modified thio-trastuzumab was chelated with (89)Zr in yields exceeding 75%. (89)Zr-Df-Ac-thio-trastuzumab and (89)Zr-Df-Chx-Mal-thio-trastuzumab were stable in mouse serum and exhibited comparable PET imaging capabilities in a BT474M1 (HER2-positive) breast cancer model reaching 20-25 %ID/g of tumor uptake and a tumor to blood ratio of 6.1-7.1. CONCLUSIONS: The new reagents demonstrated good reactivity with engineered thiol groups of trastuzumab and very good chelation properties with (89)Zr. The site-specifically (89)Zr-labeled thio-antibodies were stable in serum and showed PET imaging properties comparable to lysine conjugates. Copyright 2010 Elsevier Inc. All rights reserved.
Authors: Yonghua Zhan; Emily B Ehlerding; Sixiang Shi; Stephen A Graves; Shreya Goel; Jonathan W Engle; Jimin Liang; Weibo Cai Journal: J Biomed Nanotechnol Date: 2018-05-01 Impact factor: 4.099
Authors: Jai Woong Seo; Lisa M Mahakian; Sarah Tam; Shengping Qin; Elizabeth S Ingham; Claude F Meares; Katherine W Ferrara Journal: Nucl Med Biol Date: 2014-09-28 Impact factor: 2.408
Authors: François Guérard; Yong-Sok Lee; Raphaël Tripier; Lawrence P Szajek; Jeffrey R Deschamps; Martin W Brechbiel Journal: Chem Commun (Camb) Date: 2012-12-19 Impact factor: 6.222