Towards translational ImmunoPET/MR imaging of invasive Pulmonary Aspergillosis: The Humanized Monoclonal Antibody JF5 detects Aspergillus Lung Infections in Vivo
Invasive pulmonary aspergillosis (IPA)is a frequently fatal lung disease of neutropenic patients caused by the ubiquitous airborne fungus Aspergillus fumigatus. Diagnosis of IPA is a major challenge as clinical manifestations of the disease are nonspecific, and methods for the detection of circulating biomarkers such as β-D-glucan or galactomannan (GM) in the bloodstream lack specificity or sensitivity.
In a previous study, ISCA Diagnostics and co-workers developed a novel non-invasive procedure for IPA diagnosis based on antibody-guided positron emission tomography and magnetic resonance imaging (ImmunoPET/MRI) using a [64Cu]DOTA-labelled mouse monoclonal antibody (mAb), mJF5. The highly specific tracer allows repeated imaging of A. fumigatus lung infections and differentiation of IPA from pulmonary inflammation and from infections caused by bacteria.
To enable translation of the tracer to a clinical setting, ISCA Diagnostics’ aim was to develop a humanised version of the antibody JF5 (hJF5), and to evaluate its performance in pre-clinical imaging of lung infection using a [64Cu]NODAGA-hJF5 tracer.
Fusion Antibodies developed a humanized version of JF5 (hJF5), using CDR grafting and applied its proprietary CDRx™ platform. Fusion Antibodies delivered the following package of Antibody Humanization services:
- Antibody humanization design
- Plasmid synthesis and cloning
- Transient expression
- Stable cell line development
Results and conclusion
The results show both mJF5 and hJF5 bind to the antigenic determinant β1,5-galactofuranose (Galf) present in the target mannoprotein antigen. ELISA tests reveal unlabelled humanized hJF5 and hJF5-NODAGA antibodies exhibit increased binding with the purified mannoprotein antigen compared to murine mJF5 and mJF5-NODAGA. Furthermore, uptake of humanized hJF5-NODAGA in the lungs of infected mice was significantly higher compared to murine mJF5. This trend in uptake was further evidenced by ex vivo autoradiography of the lungs of infected mice.
Fusion Antibodies successfully developed a humanized version of the Aspergillus-specific mAb JF5. The improved imaging capabilities of hJF5 provides an excellent platform for clinical studies of IPA detection using antibody-guided molecular imaging (Thornton  Frontiers in Microbiology 9: 691).
The JF5 humanization project represents another successful project for Fusion Antibodies and is a case study example of the robust nature of Fusion Antibodies’ CDRxTM Humanization platform.