Exploring the Biological Activity of a Humanized Anti-CD99 ScFv and Antibody for Targeting T Cell Malignancies

• Published in: Biomolecules (Basel, Switzerland) Switzerland), 2024-11, Vol.14 (11), p.1422
• Main Authors: Takheaw, Nuchjira, Pamonsupornwichit, Thanathat, Chaiwut, Ratthakorn, Kotemul, Kamonporn, Sornsuwan, Kanokporn, Juntit, On-Anong, Yasamut, Umpa, Cheyasawan, Passaworn, Laopajon, Witida, Kasinrerk, Watchara, Tayapiwatana, Chatchai
• Format: Article
• Language: English
• Subjects: 12E7 Antigen - immunology; 12E7 Antigen - metabolism; Acute lymphoblastic leukemia; Analysis; Animals; Antibodies; Antibodies, Monoclonal, Humanized - immunology; Antibodies, Monoclonal, Humanized - pharmacology; Antibodies, Monoclonal, Humanized - therapeutic use; antibody humanization; antibody therapy; Antigen presentation; Antigenic determinants; Apoptosis; Apoptosis - drug effects; Biological activity; Cancer; Cancer therapies; CD99; CD99 antigen; Cell Line, Tumor; Cells; E coli; Epitopes; Health aspects; Humans; Immunoreactivity; Leukemia; Lymphocytes; Lymphocytes T; Lymphoma; Malignancy; Mice; Minimal residual disease; Molecular weight; Monoclonal antibodies; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - drug therapy; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - immunology; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - metabolism; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - therapy; Proteins; Single-Chain Antibodies - immunology; Single-Chain Antibodies - pharmacology; T cell malignancies; T cells; T-Lymphocytes - immunology; T-Lymphocytes - metabolism; Therapeutic targets
• ISSN: 2218-273X; 2218-273X
• DOI: 10.3390/biom14111422

CD99, a type I transmembrane protein, emerges as a promising therapeutic target due to its heightened expression in T cell acute lymphoblastic leukemia (T-ALL). This characteristic renders it a potential marker for minimal residual disease detection and an appealing target for antibody-based treatments. Previous studies have revealed that a mouse monoclonal antibody, mAb MT99/3, selectively binds to CD99, triggering apoptosis in T-ALL/T-LBL cells while preserving the integrity of healthy cells. By targeting CD99, mAb MT99/3 suppresses antigen presentation and disrupts T cell functions, offering promise for addressing hyperresponsive T cell conditions. To facilitate clinical translation, we developed a humanized ScFv variant of mAb MT99/3, termed HuScFvMT99/3 in "ScFvkh" design. Structural analysis confirms its resemblance to the original antibody, and the immunoreactivity of HuScFvMT99/3 against CD99 is preserved. The fully humanized version of antibody HuMT99/3 was further engineered, exhibiting similar binding affinity at the 10 M level and specificity to the CD99 epitope without antigenic shift. HuMT99/3 demonstrates remarkable selectivity, recognizing both malignant and normal T cells but inducing apoptosis only in T-ALL/T-LBL cells, highlighting its potential for safe and targeted therapy.