First immunotherapeutic CAR-T cells against the immune checkpoint protein HLA-G.

Background: CAR-T cells immunotherapy is a breakthrough in the treatment of hematological malignancies such as acute lymphoblastic leukemia (ALL) and B-cell malignancies. However, CAR-T therapies face major hurdles such as the lack of tumor-specific antigen (TSA), and immunosuppressive tumor microenvironment sometimes caused by the tumorous expression of immune checkpoints (ICPs) such as HLA-G. Indeed, HLA-G is remarkable because it is both a potent ICP and a TSA.

Inhibition of iNKT Cells by the HLA-G-ILT2 Checkpoint and Poor Stimulation by HLA-G-Expressing Tolerogenic DC.

Invariant Natural Killer T (iNKT) cells are a small and distinct population of T cells crucial in immunomodulation. After activation by alpha-GalactosylCeramide (αGC), an exogenic glycolipid antigen, iNKT cells can rapidly release cytokines to enhance specific anti-tumor activity. Several human clinical trials on iNKT cell-based anti-cancer are ongoing, however results are not as striking as in murine models.

HLA-G Neo-Expression on Tumors.

HLA-G is known to modulate the immune system activity in tissues where physiological immune-tolerance is necessary (i.e., maternal-fetal interface, thymus, and cornea).

CD28/4-1BB CD123 CAR T cells in blastic plasmacytoid dendritic cell neoplasm.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is associated with a remarkably poor prognosis and with no treatment consensus. The identification of relevant therapeutic targets is challenging. Here, we investigated the immune functions, antileukemia efficacy and safety of CD28/4-1BB CAR T cells targeting CD123 the interleukin (IL)-3 receptor alpha chain which is overexpressed on BPDCN.

A First-in-Human Phase I Study of INVAC-1, an Optimized Human Telomerase DNA Vaccine in Patients with Advanced Solid Tumors.

Purpose: Human telomerase reverse transcriptase (hTERT) is highly expressed in >85% of human tumors and is thus considered as a good tumor-associated antigen candidate for vaccine development. We conducted a phase I study to investigate the safety, tolerability, clinical response, and immunogenicity of INVAC-1, a DNA plasmid encoding a modified hTERT protein in patients with relapsed or refractory solid tumors.

Patients And Methods: INVAC-1 was either administered by intradermal route followed by electroporation or by Tropis, a needle-free injection system.

A Modified mRNA Vaccine Targeting Immunodominant NS Epitopes Protects Against Dengue Virus Infection in HLA Class I Transgenic Mice.

Dengue virus (DENV) induces strong T and B cell responses upon infection. Hence, it is difficult to determine the contribution of cell-mediated immunity alone in the long lasting protection against DENV infection and disease. Numerous CD4+ and CD8+ T cell epitopes have been identified, mainly in the non-structural proteins of DENV.

A DNA telomerase vaccine for canine cancer immunotherapy.

Telomerase reverse transcriptase (TERT) is highly expressed in more than 90% of canine cancer cells and low to absent in normal cells. Given that immune tolerance to telomerase is easily broken both naturally and experimentally, telomerase is an attractive tumor associated antigen for cancer immunotherapy. Indeed, therapeutic trials using human telomerase peptides have been performed.

Strong antigen-specific T-cell immunity induced by a recombinant human TERT measles virus vaccine and amplified by a DNA/viral vector prime boost in IFNAR/CD46 mice.

Cancer immunotherapy is seeing an increasing focus on vaccination with tumor-associated antigens (TAAs). Human telomerase (hTERT) is a TAA expressed by most tumors to overcome telomere shortening. Tolerance to hTERT can be easily broken both naturally and experimentally and hTERT DNA vaccine candidates have been introduced in clinical trials.

APOBEC3A intratumoral DNA electroporation in mice.

Human APOBEC3A (A3A) cytidine deaminase shows pro-apoptotic properties resulting from hypermutation of genomic DNA, induction of double-stranded DNA breaks (DSBs) and G1 cell cycle arrest. Given this, we evaluated the antitumor efficacy of A3A by intratumoral electroporation of an A3A expression plasmid. DNA was repeatedly electroporated into B16OVA, B16Luc tumors of C57BL/6J mice as well as the aggressive fibrosarcoma Sarc2 tumor of HLA-A*0201/DRB1*0101 transgenic mice using noninvasive plate electrodes.

Anticancer DNA vaccine based on human telomerase reverse transcriptase generates a strong and specific T cell immune response.

Human telomerase reverse transcriptase (hTERT) is overexpressed in more than 85% of human cancers regardless of their cellular origin. As immunological tolerance to hTERT can be overcome not only spontaneously but also by vaccination, it represents a relevant universal tumor associated antigen (TAA). Indeed, hTERT specific cytotoxic T lymphocyte (CTL) precursors are present within the peripheral T-cell repertoire.

Optimization of a gene electrotransfer procedure for efficient intradermal immunization with an hTERT-based DNA vaccine in mice.

DNA vaccination consists in administering an antigen-encoding plasmid in order to trigger a specific immune response. This specific vaccine strategy is of particular interest to fight against various infectious diseases and cancer. Gene electrotransfer is the most efficient and safest non-viral gene transfer procedure and specific electrical parameters have been developed for several target tissues.

Universal cancer peptide-based therapeutic vaccine breaks tolerance against telomerase and eradicates established tumor.

Purpose: To evaluate CD4(+) helper functions and antitumor effect of promiscuous universal cancer peptides (UCP) derived from telomerase reverse transcriptase (TERT).

Experimental Design: To evaluate the widespread immunogenicity of UCPs in humans, spontaneous T-cell responses against UCPs were measured in various types of cancers using T-cell proliferation and ELISPOT assays. The humanized HLA-DRB1*0101/HLA-A*0201 transgenic mice were used to study the CD4(+) helper effects of UCPs on antitumor CTL responses.

Immunogenicity of a recombinant lentiviral vector carrying human telomerase tumor antigen in HLA-B*0702 transgenic mice.

Over expression of telomerase represents a hallmark of cancer cells and the induction of T cell immunity against this universal tumor antigen have gained promising interest for anticancer immunotherapy. In this study we evaluated a recombinant lentiviral vector expressing the human telomerase reverse transcriptase (lv-hTERT) vaccination in the humanized HLA-B*0702 transgenic (HLA-B7 Tg) mice. A single lv-hTERT vector immunization induces potent and broad HLA-B7-restricted CTL responses against hTERT.

Targeting human telomerase reverse transcriptase with recombinant lentivector is highly effective to stimulate antitumor CD8 T-cell immunity in vivo.

The success of active immunotherapy is based on the vaccine's ability to overcome immune tolerance through recalibrating the immune system so that it is able to recognize tumor antigens as foreign rather than self. In this study, we used a lentiviral vector system to target human telomerase reverse transcriptase (lv-hTERT), a widely expressed tumor antigen. Immunization of HLA-A*0201 transgenic HHD mice with recombinant lv-hTERT vector induces potent and diversified cytotoxic T lymphocyte responses that recognize in vitro murine tumor cells, which overexpress telomerase.

Design of a HIV-1-derived HLA-B07.02-restricted polyepitope construct.

Objective: To design a vaccine construct containing various but conserved HIV-1-derived epitopes and generating broad CD8 T cell responses.

Methods: HLA-B7 transgenic H-2KD KO transgenic mice were used to identify potential new HLA-B07.02-restricted HIV-1-derived epitopes.

Presentation of telomerase reverse transcriptase, a self-tumor antigen, is down-regulated by histone deacetylase inhibition.

Histone deacetylases (HDAC) modify the architecture of chromatin, leading to decreased gene expression, an effect that is reversed by HDAC inhibition. The balance between deacetylation and acetylation is central to many biological events including the regulation of cell proliferation and cancer but also the differentiation of immune T cells. The effects of HDAC inhibition on the interaction between antitumor effector T cells and tumor cells are not known.

Immunogenicity and tolerance following HIV-1/HBV plant-based oral vaccine administration.

Transgenic tobacco plants expressing a HIV-1 polyepitope associated with hepatitis B (HBV) virus-like particles (VLPs) were previously described. It is demonstrated here that oral administration of these transgenic plants to humanized HSB mice to boost DNA-priming can elicit anti-HIV-1 specific CD8+ T cell activation detectable in mesenteric lymph nodes. Nevertheless, a significant regulatory T cell activation was induced in vivo by the vaccination protocols.

B subunit of Shiga toxin-based vaccines synergize with alpha-galactosylceramide to break tolerance against self antigen and elicit antiviral immunity.

The nontoxic B subunit of Shiga toxin (STxB) targets in vivo Ag to dendritic cells that preferentially express the glycolipid Gb(3) receptor. After administration of STxB chemically coupled to OVA (STxB-OVA) or E7, a polypeptide derived from HPV, in mice, we showed that the addition of alpha-galactosylceramide (alpha-GalCer) resulted in a dramatic improvement of the STxB Ag delivery system, as reflected by the more powerful and longer lasting CD8(+) T cell response observed even at very low dose of immunogen (50 ng). This synergy was not found with other adjuvants (CpG, poly(I:C), IFN-alpha) also known to promote dendritic cell maturation.

Immunogenic HLA-B7-restricted peptides of hTRT.

Telomerase reverse transcriptase (TRT) is the first bona fide common tumor antigen. While several 9mer peptides of the human TRT have been identified for HLA-A2, little information exists on peptides for the remaining HLA types. Here, we used a multi-step approach to select and characterize a panel of HLA-B7 9mer peptides as candidate immunogens.

Immunogenic HLA-B*0702-restricted epitopes derived from human telomerase reverse transcriptase that elicit antitumor cytotoxic T-cell responses.

Purpose: The human telomerase reverse transcriptase (hTERT) is considered as a potential target for cancer immunotherapy because it is preferentially expressed in tumor cells. To increase the applicability of hTERT-based immunotherapy, we set out to identify CTL epitopes in hTERT restricted by HLA-B*0702 molecule, a common MHC class I allele.

Experimental Design: HLA-B*0702-restricted peptides from hTERT were selected by using a method of epitope prediction and tested for their immunogenicity in human (in vitro) and HLA-B*0702 transgenic mice (in vivo).

Telomerase reverse transcriptase as target for anti-tumor T cell responses in humans.

Human telomerase reverse transcriptase, a ribonucleoprotein intimately connected with the process of cell immortalization, is overexpressed in the vast majority of cancer cells, irrespective of their histological origin. Telomerase is currently viewed as the first antigen with the characteristics of common tumor antigen in humans, and it constitutes a potentially valuable target for attempts to control tumors through CD8 T cell immunity. Telomerase is a self antigen, making it possible that self tolerance imposes severe restrictions on our ability to generate effective anti-tumor immune responses in humans.

Antigenicity and immunogenicity of peptide analogues of a low affinity peptide of the human telomerase reverse transcriptase tumor antigen.

Human telomerase reverse transcriptase (hTRT) is a potential target for therapeutic vaccination against cancer. Therefore, it is critically important to identify T cell epitopes useful to induce cytotoxic T cell responses. Here we used a positional scanning combinatorial peptide library to identify peptide analogues for a previously characterized low affinity hTRT peptide (p572).

Identification of cryptic MHC I-restricted epitopes encoded by HIV-1 alternative reading frames.

Human immunodeficiency virus (HIV) 1 major histocompatibility complex (MHC) I-restricted epitopes are widely believed to be derived from viral proteins encoded by primary open reading frames. However, the HIV-1 genome contains alternative reading frames (ARFs) potentially encoding small polypeptides. We have identified a panel of epitopes encoded by ARFs within the gag, pol, and env genes.