creators_name: Rathore , Yogesh 
creators_name: Shukla , Jaya 
creators_name: Laroiya, Ishita 
creators_name: Deep , Amar 
creators_name: Lakhanpal , Tamanna 
creators_name: Kumar , Rajender
creators_name: Singh , Harmandeep 
creators_name: Bal, Amanjit
creators_name: Singh , Gurpreet 
creators_name: Thakur , Krishan Gopal 
creators_name: Mittal , B R 
type: article
datestamp: 2022-07-25 06:03:17
lastmod: 2022-07-25 06:03:17
metadata_visibility: show
title: Development 68Ga trastuzumab Fab and bioevaluation by PET imaging in HER2/neu expressing breast cancer patients
ispublished: pub
subjects: QR
keywords: 68Ga trastuzumab Fab; breast cancer; HER2/neu; immunoPET; trastuzumab Fab
note: The copyright of this article belongs to Wolters Kluwer
abstract: Introduction: Receptors on breast cancer cells play a crucial role in the management of patients. Trastuzumab is a widely used drug for the treatment of HER2/neu expressing tumors. ImmunoPET with trastuzumab is not feasible due to slow pharmacokinetics. Fragment of antigen-binding (Fab) radiolabeled with positron emitters can be used for immunoPET.

Methods: Fab has been generated by papain digestion and conjugated with the bifunctional chelating agent NOTA. The SDS-PAGE and MALDI-TOF were used to see the integrity of Fab and conjugated Fab. In-vitro stability and target specificity for HER2/neu receptors were performed in plasma and receptor binding with bio-layer interferometry (BLI) techniques. Radiolabeling was standardized with 68GaCl3 and PET imaging was performed in seven patients showing 18F fluorodeoxyglucose (18F-FDG) uptake and correlated with HER2/neu expression by immunohistochemistry.

Results: Fab production was optimized at molar ratio 23:1 of trastuzumab and papain at 37 °C with a constant stirrer at 850 rpm for 22-24 h, at pH 8. Conjugation with NOTA was standardized at molar ratio 1:25 of trastuzumab Fab and NOTA. Molecular mass of trastuzumab Fab-NOTA was found approximately 46.3 kDa (~1/3 of intact antibody). Trastuzumab Fab-NOTA showed radiolabelling efficiency of 48-70% with incubation time 15 min at 37-40 °C and pH 4.5-5.0. BLI demonstrated the affinity of trastuzumab, trastuzumab Fab and trastuzumab Fab-NOTA towards HER2/neu receptor with KD of <1pM, ~0.5nM and ~20nM, respectively. All immunohistochemistry proven patients showed uptake in primary breast lesion and lymph nodes.

Conclusion: Trastuzumab Fab-NOTA is suitable for radiolabelling with 68Ga and ImmunoPET imaging of HER2/neu receptor.
date: 2022-04-01
date_type: published
publication: Nuclear Medicine Communications 
volume: 43
number: 4
publisher: Wolters Kluwer
pagerange: 458-467
refereed: TRUE
official_url: https://journals.lww.com/nuclearmedicinecomm/Abstract/2022/04000/Development_68Ga_trastuzumab_Fab_and_bioevaluation.11.aspx
citation:   Rathore , Yogesh  and Shukla , Jaya  and Laroiya, Ishita  and Deep , Amar  and Lakhanpal , Tamanna  and Kumar , Rajender and Singh , Harmandeep  and Bal, Amanjit and Singh , Gurpreet  and Thakur , Krishan Gopal  and Mittal , B R   (2022) Development 68Ga trastuzumab Fab and bioevaluation by PET imaging in HER2/neu expressing breast cancer patients.  Nuclear Medicine Communications , 43 (4).  pp. 458-467.