18F-labeled anti-human CD20 cys-diabody for same-day immunoPET in a model of aggressive B cell lymphoma in human CD20 transgenic mice.
Eur J Nucl Med Mol Imaging
; 46(2): 489-500, 2019 02.
Article
em En
| MEDLINE
| ID: mdl-30456475
ABSTRACT
PURPOSE:
Metabolic imaging using [18F]FDG is the current standard for clinical PET; however, some malignancies (e.g., indolent lymphomas) show low avidity for FDG. The majority of B cell lymphomas express CD20, making it a valuable target both for antibody-based therapy and imaging. We previously developed PET tracers based on the humanised anti-CD20 antibody obinutuzumab (GA101). Preclinical studies showed that the smallest bivalent fragment, the cys-diabody (GAcDb, 54.5 kDa) with a peak uptake at 1-2 h post-injection and a biological half-life of 2-5 h, is compatible with short-lived positron emitters such as fluorine-18 (18F, t1/2 110 min), enabling same-day imaging.METHODS:
GAcDb was radiolabeled using amine-reactive N-succinimidyl 4-[18F]-fluorobenzoate ([18F]SFB), or thiol-reactive N-[2-(4-[18F]-fluorobenzamido)ethyl]maleimide ([18F]FBEM) for site-specific conjugation to C-terminal cysteine residues. Both tracers were used for immunoPET imaging of the B cell compartment in human CD20 transgenic mice (hCD20TM). [18F]FB-GAcDb immunoPET was further evaluated in a disseminated lymphoma (A20-hCD20) syngeneic for hCD20TM and compared to [18F]FDG PET. Tracer uptake was confirmed by ex vivo biodistribution.RESULTS:
The GAcDb was successfully 18F-radiolabeled using two different conjugation methods resulting in similar specific activities and without impairing immunoreactivity. Both tracers ([18F]FB-GAcDb and [18F]FBEM-GAcDb) specifically target human CD20-expressing B cells in transgenic mice. Fast blood clearance results in high contrast PET images as early as 1 h post injection enabling same-day imaging. [18F]FB-GAcDb immunoPET detects disseminated lymphoma disease in the context of normal tissue expression of hCD20, with comparable sensitivity as [18F]FDG PET but with added specificity for the therapeutic target.CONCLUSIONS:
[18F]FB-GAcDb and [18F]FBEM-GAcDb could monitor normal B cells and B cell malignancies non-invasively and quantitatively in vivo. In contrast to [18F]FDG PET, immunoPET provides not only information about the extent of disease but also about presence and localisation of the therapeutic target.Palavras-chave
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Radioisótopos de Flúor
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Linfoma de Células B
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Antígenos CD20
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Tomografia por Emissão de Pósitrons
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Anticorpos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Eur J Nucl Med Mol Imaging
Assunto da revista:
MEDICINA NUCLEAR
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Estados Unidos