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Published on: August 16, 2019
Preclinical evaluation of a novel CAR-T therapy utilizing a scFv antibody highly specific to
Linan Wang1, Masahiro Matsumoto2, Yasushi Akahori3
1Department of Personalized Cancer Immunotherapy, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan.
Abstract:
Despite the revolutionary success of chimeric antigen receptor (CAR)-T therapy for hematological malignancies, successful CAR-T therapies for solid tumors remain limited. One major obstacle is the scarcity of tumor-specific cell-surface molecules. One potential solution to overcome this barrier is to utilize antibodies that recognize peptide/major histocompatibility complex (MHCs) in a T cell receptor (TCR)-like fashion, allowing CAR-T cells to recognize intracellular tumor antigens. This study reports a highly specific single-chain variable fragment (scFv) antibody against the MAGE-A4p230-239/human leukocyte antigen (HLA)-A∗02:01 complex (MAGE-A4 pMHC), screened from a human scFv phage display library. Indeed, retroviral vectors encoding CAR, utilizing this scFv antibody as a recognition component, efficiently recognized and lysed MAGA-A4+ tumor cells in an HLA-A∗02:01-restricted manner. Additionally, the adoptive transfer of T cells modified by the CAR-containing glucocorticoid-induced tumor necrosis factor receptor (TNFR)-related receptor (GITR) intracellular domain (ICD), but not CD28 or 4-1BB ICD, significantly suppressed the growth of MAGE-A4+ HLA-A∗02:01+ tumors in an immunocompromised mouse model. Of note, a comprehensive analysis revealed that a broad range of amino acid sequences of the MAGE-A4p230-239 peptide were critical for the recognition of MAGE-A4 pMHC by these CAR-T cells, and no cross-reactivity to analogous peptides was observed. Thus, MAGE-A4-targeted CAR-T therapy using this scFv antibody may be a promising and safe treatment for solid tumors.
Insights
Chimeric antigen receptor (CAR)-T therapy shows promise for solid tumors by targeting intracellular antigens like MAGE-A4. A novel antibody enables CAR-T cells to recognize MAGE-A4+ tumors, significantly suppressing growth in preclinical models.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Chimeric antigen receptor (CAR)-T cell therapy has revolutionized hematological cancer treatment but faces challenges in solid tumors due to limited surface antigen targets.
- Recognizing intracellular tumor antigens via peptide-MHC complexes presents a strategy to broaden CAR-T therapy applicability.
- Major histocompatibility complex (MHC)-restricted recognition by T cell receptor (TCR)-like antibodies is key for targeting intracellular antigens.
Purpose of the Study:
- To develop and evaluate a novel CAR-T cell therapy targeting the intracellular tumor antigen MAGE-A4 presented by HLA-A*02:01.
- To assess the efficacy of CAR-T cells engineered with a specific single-chain variable fragment (scFv) antibody against the MAGE-A4 peptide/MHC complex.
- To investigate the role of different intracellular domains (GITR, CD28, 4-1BB) in CAR-T cell function against solid tumors.
Main Methods:
- Screening of a human scFv phage display library to identify antibodies targeting the MAGE-A4 peptide/MHC complex.
- Engineering retroviral vectors encoding CARs with the identified scFv for T cell modification.
- In vitro assessment of CAR-T cell recognition and lysis of MAGE-A4+ tumor cells.
- In vivo efficacy studies in immunocompromised mice using MAGE-A4+ HLA-A*02:01+ tumors and adoptive T cell transfer.
Main Results:
- A highly specific scFv antibody targeting the MAGE-A4 peptide/MHC complex (MAGE-A4 pMHC) was identified.
- CAR-T cells utilizing this scFv demonstrated efficient and HLA-A*02:01-restricted recognition and lysis of MAGE-A4+ tumor cells.
- Adoptive transfer of T cells modified with CARs containing the GITR intracellular domain significantly suppressed tumor growth, outperforming CD28 or 4-1BB domains.
- Analysis confirmed critical amino acid sequences in the MAGE-A4 peptide for recognition, with no observed cross-reactivity to analogous peptides.
Conclusions:
- A novel MAGE-A4-specific CAR-T cell therapy targeting peptide/MHC complexes is feasible for solid tumors.
- CAR-T cells engineered with a GITR intracellular domain show potent anti-tumor activity against MAGE-A4+ HLA-A*02:01+ tumors in vivo.
- The specificity of the identified antibody for the MAGE-A4 pMHC complex suggests a potentially safe therapeutic approach.
- This strategy offers a promising avenue for developing effective CAR-T therapies for solid tumors expressing intracellular antigens.
