Sikozile Ncembu

Conference 2022 Pre-recorded Presentation

 

Video title

Therapeutically targeting CD64 in acute myeloid leukemia single-chain based antibody immunotoxin

 

Authors and Affiliations

Ncembu S.1, Tai S.1, Barth S.2 & Harrison S.T.L1

1. Centre for Bioprocess Engineering Research (CeBER), Department of Chemical Engineering, Faculty of Engineering and the Built Environment, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
2. Institute of Infectious Disease and Molecular Medicine (IDM), Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa

 

Abstract

Background

Cancer immunotherapy is a promising innovative and effective treatment for many forms of cancer. Among hematologic malignancies, acute myeloid leukemia (AML) remains an unmet medical need as it is primarily treated with chemotherapy, which is associated with severe side effects. H22(scFv)- ETA’ is an immunotherapeutic recombinant protein comprising of truncated Pseudomonas exotoxin A (PE) and a humanised scFv antibody against CD64. The overexpression of CD64 on monocytic blast cells in patients with AML combined with its rapid internalisation make it an attractive target antigen for antibody-based targeted therapies.

Methods

H22(scFv)- ETA’ is recombinantly expressed in E. coli Bl21 (DE3) and purified by metal ion affinity chromatography and size exclusion chromatography. The volumetric mass transfer coefficient (kLa) is used as a scale-up criterion to achieve effective batch and fed-batch fermentation processes. The therapeutic efficacy of H22(scFv)- ETA’ is evaluated by several biological assays, including binding assays using flow cytometry and cytotoxicity using Annexin-V bioassay.

Results

H22(scFv)- ETA’ was successfully produced in shake flasks. In the current phase of the study, various conditions are being investigated to optimise production and to conduct a scale-up production to achieve sufficient quantity to perform preclinical and eventually clinical studies. Binding studies demonstrated specificity against CD 64-positive AML derived tumour cells. H22(scFv)- ETA’ was shown to destroy CD64-positive AML-derived tumour cells on both HL -60 and monoblast U937 cell lines.

Conclusions

H22(scFv)- ETA’ is efficacious against eliminating CD64-positive AML tumour cells in vitro, with binding activity showing targeted tumour cell killing. CD64 is demonstrated as a target for future clinical applications, providing the basis for a novel therapeutic strategy to treat AML. The development of successful scale-up production of H22(scFv)- ETA’ is critical as it provides insight into a process that can be established in pilot-scale in the context of biopharmaceutical manufacturing.