Site-specific conjugation of recognition tags to trastuzumab for peptide nucleic acid-mediated radionuclide HER2 pretargeting
Year: 2019
Type: article
Abstract: Pretargeting is a promising strategy to reach high imaging contrast in a shorter time than by targeting with directly radiolabeled monoclonal antibodies (mAbs). One of problems in pretargeting is a site-specific, reproducible and uniform conjugation of recognition tags to mAbs. To solve this issue we propose a photoconjugation to covalently couple a recognition tag to a mAb via a photoactivatable Z domain. The Z-domain, a 58-amino acid protein derived from the IgG-binding B-domain of Staphylococcus aureus protein A, has a well-characterized binding site in the Fc portion of IgG. We tested the feasibility of this approach using pretargeting based on hybridization between peptide nucleic acids (PNAs). We have used photoconjugation to couple trastuzumab with the PNA-based hybridization probe, HP1. A complementary [57Co]Co-labeled PNA hybridization probe ([57Co]Co-HP2) was used as the secondary targeting probe. In vitro studies demonstrated that trastuzumab-ZHP1 bound specifically to human epidermal growth factor receptor 2 (HER2)-expressing cells with nanomolar affinity. The binding of the secondary [57Co]Co-HP2 probe to trastuzumab-PNA-pretreated cells was in the picomolar affinity range. A two-fold increase in SKOV-3 tumor targeting was achieved when [57Co]Co-HP2 (0.7 nmol) was injected 48 h after injection of trastuzumab-ZHP1 (0.5 nmol) compared with trastuzumab-ZHP1 alone (0.8 ± 0.2 vs. 0.33 ± 0.06 %ID/g). Tumor accumulation of [57Co]Co-HP2 was significantly reduced by pre-saturation with trastuzumab or when no trastuzumab-ZHP1 was preinjected. A tumor-to-blood uptake ratio of 1.5 ± 0.3 was achieved resulting in a clear visualization of HER2-expressing xenografts as confirmed by SPECT imaging. In conclusion, the feasibility of stable site-specific coupling of a PNA-based recognition tag to trastuzumab and successful pretargeting has been demonstrated. This approach can hopefully be used for a broad range of mAbs and recognition tags.
Source: Biomaterials
Institutions: KTH Royal Institute of Technology, Uppsala University
Language: English
Subfield: Radiology, Nuclear Medicine and Imaging
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,466
Awards: G1127578775, G1309440839, G1898511768, G1960764132, G2724597251, Radionuclide molecular imaging of prostate cancer: staging and in vivo phenotyping of tumours for personalised medicine, IT for better learning, G3059481870, G417012215, Compl. ProNova VINN Excellence Centre Etapp 4, G4688419475, G4759698377, G5112088614, ESCAPE Cancer - Engineered SCAffold Proteins Engaged for CANCER therapy, G562523829, Engineered scaffold proteins for radionuclide tumour targeting, G6630518017, G6869577927, Technologies for chemical engineering of therapeutic proteins, Innovative IoT toolkit for CAE simulations
OpenAlex ID: W2913299306