Determination of human γδ T cell-mediated cytotoxicity using a non-radioactive assay system

Preclinical evaluation of a novel CAR-T therapy utilizing a scFv antibody highly specific to MAGE-A4p230-239/HLA-A∗02:01 complex

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.

Personal Neoantigens From Patients With NSCLC Induce Efficient Antitumor Responses

Objective

To develop a neoantigen-targeted personalized cancer treatment for non-small cell lung cancer (NSCLC), neoantigens were obtained from collected human lung cancer samples, and the utility of neoantigen and neoantigen-reactive T cells (NRTs) was assessed.

Methods

Tumor specimens from three patients with NSCLC were obtained and analyzed by whole-exome sequencing, and neoantigens were predicted accordingly. Dendritic cells and T lymphocytes were isolated, NRTs were elicited and IFN-γ ELISPOT tests were conducted. HLA-A2.1/K^b transgenic mice were immunized with peptides from HLA-A*02:01⁺patient with high immunogenicity, and NRTs were subjected to IFN-γ, IL-2 and TNF-α ELISPOT as well as time-resolved fluorescence assay for cytotoxicity assays to verify the immunogenicity in vitro. The HLA-A*02:01⁺lung cancer cell line was transfected with minigene and inoculated into the flanks of C57BL/6^nu/nu mice and the NRTs induced by the immunogenic polypeptides from autologous HLA-A2.1/K^b transgenic mice were adoptively transfused to verify their immunogenicity in vivo.

Results

Multiple putative mutation-associated neoantigens with strong affinity for HLA were selected from each patient. Immunogenic neoantigen were identified in all three NSCLC patients, the potency of ACAD8-T105I, BCAR1-G23V and PLCG1-M425L as effective neoantigen to active T cells in suppressing tumor growth was further proven both in vitro and in vivo using HLA-A2.1/Kb transgenic mice and tumor-bearing mouse models.

Conclusion

Neoantigens with strong immunogenicity can be screened from NSCLC patients through the whole-exome sequencing of patient specimens and machine-learning-based neoantigen predictions. NRTs shown efficient antitumor responses in transgenic mice and tumor-bearing mouse models. Our results indicate that the development of neoantigen-based personalized immunotherapies in NSCLC is possible.

Precis

Neoantigens with strong immunogenicity were screened from NSCLC patients. This research provides evidence suggesting that neoantigen-based therapy might serve as feasible treatment for NSCLC.

Fast-acting γδ T-cell subpopulation and protective immunity against infections

Unique Vγ2Vδ2 (Vγ9Vδ2) T cells existing only in human and non-human primates, account for the majority of circulating γδ T cells in human adults. Vγ2Vδ2 T cells are the sole γδ T-cell subpopulation capable of recognizing the microbial (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) produced by selected pathogens during infections. Recent seminal studies in non-human primate models have demonstrated that the unique HMBPP-specific Vγ2Vδ2 T cells are fast-acting, multi-functional, and protective during infections. This article reviews the recent seminal observations of Vγ2Vδ2 T cells in protective mechanisms against tuberculosis and other infections.

A luciferase lysis assay reveals in vivo malignant cell sensitization by phosphoantigen prodrugs

Human Vγ9Vδ2 T cells respond to small phosphorus-containing compounds, often called phosphoantigens, which are now known to be intracellular ligands of the immune receptor butyrophilin 3A1 (BTN3A1). In order to compare the efficiency of butyrophilin ligands, we developed a luciferase-based lysis assay that measures the direct cytolysis by Vγ9Vδ2 T cells of luciferase-expressing K562 leukemia cells sensitized by phosphoantigen prodrugs. Our results show that the luciferase-based lysis assay allows in vitro and in vivo assessment of phosphoantigen activity in a way that does not require the extensive processing of flow cytometry or ELISA based approaches. In cellular assays, the structure activity relationships of phosphoantigen prodrugs correlate with ELISA-based activation assays, though phosphoantigen induced target cell lysis occurs at lower concentrations relative to T cell interferon γ production measured by ELISA. In mice dosed with phosphoantigens, a racemic aryl phosphonamidate prodrug, methyl 2-[[[(E)-5-hydroxy-4-methyl-pent-3-enyl]-(1-naphthyloxy)phosphoryl]amino]acetate (1-Nap/GlyOMe C-HMBP, 5), sensitized subcutaneous K562 tumors within minutes, and this effect was maintained at least four hours after treatment. In vivo activity of compound 5 was stronger than that of an equivalent dose of zoledronate. This luciferase lysis assay can be used for evaluation of phosphoantigens due to its time efficiency, high sensitivity, and in vivo compatibility and demonstrates rapid in vitro and in vivo sensitization of tumor cells by phosphoantigen prodrugs.