Site-Specifically Labeled Antibody–Drug Conjugate for Simultaneous Therapy and ImmunoPET

Adumeau, Pierre; Vivier, Delphine; Sharma, Sai Kiran; Wang, Jessica; Zhang, Terry; Chen, Aimei; Agnew, Brian; Zeglis, Brian M.

doi:10.1021/acs.molpharmaceut.7b00802

Cited by 40 publications

(35 citation statements)

References 30 publications

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“…Dual isotope imaging will therefore also be useful for the evaluation of experimental tumour therapies [35] to guide e.g. radiotherapy dose painting [36] in preclinical models, or to study in detail the delivery of antibody-drug conjugates [37]. Another advantage is the halving of the number of animals for therapy evaluation studies.…”

Section: Discussionmentioning

confidence: 99%

Dual-isotope imaging allows in vivo immunohistochemistry using radiolabelled antibodies in tumours

Knight

Mosley

Kersemans

et al. 2019

Nuclear Medicine and Biology

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While radiolabelled antibodies have found great utility as PET and SPECT imaging agents in oncological investigations, a notable shortcoming of these agents is their propensity to accumulate non-specifically within tumour tissue. The degree of this non-specific contribution to overall tumour uptake is highly variable and can ultimately lead to false conclusions. Therefore, in an effort to obtain a reliable measure of inter-individual differences in non-specific tumour uptake of radiolabelled antibodies, we demonstrate that the use of dual-isotope imaging overcomes this issue, enables true quantification of epitope expression levels, and allows non-invasive in vivo immunohistochemistry. The approach involves co-administration of (i) an antigen-targeting antibody labelled with zirconium-89 ( 89 Zr), and (ii) an isotype-matched non-specific control IgG antibody labelled with indium-111 ( 111 In). As an example, the anti-HER2 antibody trastuzumab was radiolabelled with 89 Zr, and co-administered intravenously together with its 111 In-labelled non-specific counterpart to mice bearing human breast cancer xenografts with differing HER2 expression levels (MDA-MB-468 [HER2-negative], MDA-MB-231 [low-HER2], MDA-MB-231/H2N [medium-HER2], and SKBR3 [high-HER2]). Simultaneous PET/SPECT imaging using a MILabs Vector4 small animal scanner revealed stark differences in the intratumoural distribution of [ 89 Zr]Zr-trastuzumab and [ 111 In]In-IgG, highlighting regions of HER2-mediated uptake and non-specific uptake, respectively. Normalisation of the tumour uptake values and tumour-to-blood ratios obtained with [ 89 Zr]Zr-trastuzumab against those obtained with [ 111 In]In-IgG yielded values which were most strongly correlated (R = 0.94; P = 0.02) with HER2 expression levels for each breast cancer type determined by Western blot and in vitro saturation binding assays, but not non-normalised uptake values. Normalised intratumoural distribution of [ 89 Zr]Zr-trastuzumab correlated well with intratumoural heterogeneity HER2 expression.

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Section: Discussionmentioning

confidence: 99%

Dual-isotope imaging allows in vivo immunohistochemistry using radiolabelled antibodies in tumours

Knight

Mosley

Kersemans

et al. 2019

Nuclear Medicine and Biology

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“…Beyond chemically mediated transformations, several groups have begun to adapt the exquisite specificity and selectivity of enzymes for antibody (protein) functionalization and radiotracer synthesis. A wide array of enzyme-mediated reactions are available (14), but three examples that have already been used in radiochemistry include applications of transglutaminase (4,38); glycan modification (8,(39)(40)(41)(42) with multi-step transformations using a-2,6-sialyltransferase, b-1,4-galactosidase, and mutated b-1,4galactosyltransferase; and sortase-A-mediated conjugation using proteins engineered to express the LPXTG tags (Fig. 4) (25,43,44).…”

Section: Enzyme-mediated Functionalization Methodsmentioning

confidence: 99%

The Impact of Emerging Bioconjugation Chemistries on Radiopharmaceuticals

Fay

Holland

2019

J Nucl Med

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The use of radiolabeled antibodies, immunoglobulin fragments, and other proteins are an increasingly important sector of research for diagnostic imaging and targeted radiotherapy in nuclear medicine. As with all radiopharmaceuticals, efficient radiochemistry is a prerequisite to clinical translation. For proteins, variations in the primary amino acid sequence, the secondary structures, and tertiary folds, as well as differences in the size, charge, polarity, lipophilicity, and the presence of posttranslational modifications, add complexity to the system. The choice of radionuclide or chelate, and its impact on the thermodynamic, kinetic, and metabolic stability of a radiotracer, has attracted much attention but the chemistry by which the radionuclide is conjugated to the protein scaffold is of equal importance. Recently, a wealth of creative advances in protein ligation methods based on chemical, photochemical, and enzyme-mediated processes has emerged. As radiochemists explore alternative bioconjugation strategies, this article considers their potential impact on radiotracer design.

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“…Likewise, the radiolabeling and stability analysis of the 89 Zr-labeled radioimmunoconjugates were performed according to established protocols (21). Cell culture and flow cytometry experiments with BT474, U937, and RAW264.7 cells were performed using a BD LSR-II instrument (BD Biosciences) using standard procedures (22). Finally, all in vivo experiments-including the establishment of BT474 xenografts as well as PET imaging and biodistribution studies-were performed according to published protocols approved by the Institutional Animal Care and Use Committees of MSKCC and Hunter College (22).…”

Section: Methodsmentioning

confidence: 99%

The Impact of FcγRI Binding on Immuno-PET

et al. 2019

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Antibodies are promising vectors for PET imaging. However, the high uptake of radioimmunoconjugates in nontarget tissues such as the liver and spleen hampers their performance as radiotracers. This off-target uptake can lead to suboptimal tumor-to-background activity concentration ratios, decreasing the contrast of images and reducing their diagnostic utility. A possible cause of this uptake is the sequestration of radioimmunoconjugates by immune cells bearing Fc-γ-receptors (FcγR) that bind to the Fc regions of antibodies. Methods: Since the heavy chain glycans influence the affinity of FcγR for the Fc domain, we set out to investigate whether radioimmunoconjugates with truncated glycans would exhibit altered binding to FcγRI and, in turn, improved in vivo performance. Using the HER2-targeting antibody trastuzumab, we synthesized a series of desferrioxamine-bearing immunoconjugates with differing glycosylation states and interrogated their FcγRI binding via surface plasmon resonance, enzyme-linked immunosorbent assay, and flow cytometry. Furthermore, we labeled these immunoconjugates with 89 Zr and explored their biodistribution in athymic nude, NSG, and humanized NSG mice bearing human epidermal growth factor receptor 2-expressing human breast cancer xenografts. Results: We observed a strong correlation between the impaired in vitro FcγRI binding of deglycosylated immunoconjugates and significant decreases in the in vivo off-target uptake of the corresponding 89 Zrlabeled radioimmunoconjugates (i.e., liver activity concentrations are reduced by ∼3.5-fold in humanized NSG mice). These reductions in off-target uptake were accompanied by concomitant increases in the tumoral activity concentrations of the glycoengineered radioimmunoconjugates, ultimately yielding improved tumor-to-healthy organ contrast and higher quality PET images. Conclusion: Our findings suggest that the deglycosylation of antibodies represents a facile strategy for improving the quality of immuno-PET in animal models as well as in certain patient populations.

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Site-Specifically Labeled Antibody–Drug Conjugate for Simultaneous Therapy and ImmunoPET

Cited by 40 publications

References 30 publications

Dual-isotope imaging allows in vivo immunohistochemistry using radiolabelled antibodies in tumours

Dual-isotope imaging allows in vivo immunohistochemistry using radiolabelled antibodies in tumours

The Impact of Emerging Bioconjugation Chemistries on Radiopharmaceuticals

The Impact of FcγRI Binding on Immuno-PET

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