title: Development 68Ga trastuzumab Fab and bioevaluation by PET imaging in HER2/neu expressing breast cancer patients
creator: Rathore , Yogesh 
creator: Shukla , Jaya 
creator: Laroiya, Ishita 
creator: Deep , Amar 
creator: Lakhanpal , Tamanna 
creator: Kumar , Rajender
creator: Singh , Harmandeep 
creator: Bal, Amanjit
creator: Singh , Gurpreet 
creator: Thakur , Krishan Gopal 
creator: Mittal , B R 
subject: QR Microbiology
description: 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.
publisher: Wolters Kluwer
date: 2022-04-01
type: Article
type: PeerReviewed
relation: https://journals.lww.com/nuclearmedicinecomm/Abstract/2022/04000/Development_68Ga_trastuzumab_Fab_and_bioevaluation.11.aspx
identifier:   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.      
relation: http://crdd.osdd.net/open/2992/