Alpha-fetoprotein Peptide Research Articles

Heat shock protein 70/alpha-fetoprotein epitope peptide induced specific immunity against hepatocarcinoma

To study anti-tumor immunity mechanism induced by a reconstructed peptide complex-heat shock protein 70 (HSP70) and alphafetop-rotein (AFP), Mic e were immunized with AFP peptide, HSP70 and HSP70-AFP peptide complex es respectively. The killing effects of IFN-γ, TNF-α, perforin, granzyme B and CD8+ T cells on H22 cells were detected in each group of CD8+ T cell culture supernatants and investigate theimmune effect of heat shock protein 70 (HSP70)-alpha-fetoprotein (AFP)epitope peptide complex on mouse H22 hepatoma cells.

Abstract 2299: ET1402L1-CART, a T cell therapy targeting the intracellular tumor antigen AFP, demonstrates potent antitumor activity in hepatocellular carcinoma models

Abstract Hepatocellular carcinoma (HCC) is the 5th most prevalent and 3rd most lethal cancer worldwide, due to limited treatment options. The lack of tumor-specific membrane targets is one of the key challenges currently facing immunotherapy for solid tumors, where on-target/off-tumor activity can lead to severe adverse responses. Most HCCs overexpress Alpha-Fetoprotein (AFP), a secreted fetal glycoprotein rarely expressed in adult tissues, making AFP an ideal target for immunotherapy. However, since AFP is only expressed intracellularly and secreted, it cannot be targeted with traditional antibodies against cell-surface antigens. To overcome this limitation, we exploited the fact that intracellular antigens, including AFP, are processed into peptides and presented by class I major histocompatibility complexes (MHCs) on the surface of tumor cells. Using an antibody discovery platform optimized for identifying candidates that bind peptide/MHC complexes, we developed ET1402L1, a fully-human scFv specifically targeting an immunogenic AFP peptide complexed with human leukocyte antigen (HLA)-A*02:01. ET1402L1 binds HLA-A*02:01/AFP with exquisite specificity and does not cross-react with naked HLA-A*02:01 molecules or with HLA-A*02:01 complexed with a panel of control peptides from endogenous human proteins. T cells engineered to express a second generation chimeric antigen receptor (CAR) constructed with ET1402L1 responded to HLA-A*02:01/AFP-expressing cells by degranulating and releasing IFN-γ, IL-2, IL-6, IL-8, IL-10, GM-CSF, and TNFα in an antigen-selective manner. In a cell killing assay, ET1402L1-CART selectively lysed HCC cells that expressed both HLA-A*02:01 and AFP, while sparing cells from multiple tissue types that were negative for either. In vivo, ET1402L1-CART demonstrated potent anti-tumor activity in multiple HCC xenograft models. While intravenous administration of ET1402L1-CART significantly inhibited the growth of established subcutaneous (s.c.) Hep G2 tumors (an HCC cell line positive for HLA-A*02:01 and AFP), intratumoral delivery resulted in rapid and prolonged tumor regression with complete regression observed in 75% of animals. These effects were recapitulated in a s.c. tumor model using another liver-derived HLA-A*02:01-positive cell line (SK-HEP-1) engineered to express the AFP peptide. Lastly, intraperitoneal injection of ET1402L1-CART led to regression of tumors in a disseminated abdominal HCC xenograft model. Our data demonstrates that CAR-T cell therapy targeting intracellular antigens via peptide/MHC complexes can effectively eradicate solid tumors in vivo. This approach expands the spectrum of antigens available for redirected T cell therapy against solid malignancies and provides a promising future therapy for HCC. A phase I clinical trial testing ET1402L1-CART in HCC patients is expected to begin in 2016. Citation Format: Hong Liu, Yiyang Xu, Jingyi Xiang, Li Long, Shon Green, Zhiyuan Yang, Jingwei Lu, Neal Cheng, Lucas H. Horan, Bin Liu, Su Yan, Pei Wang, Juan Diaz, Lian-xing Liu, Vivien Chan, Cheng Liu. ET1402L1-CART, a T cell therapy targeting the intracellular tumor antigen AFP, demonstrates potent antitumor activity in hepatocellular carcinoma models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2299.

Different alpha fetoprotein epitope-specific CD8 T cells possess distinct antitumor function (VAC13P.1130)

Abstract Using lentivector (lv) immunization and epitope-optimization, we have recently identified three CD8 epitopes in the hepatocellular carcinoma (HCC) associated antigen of murine alpha fetoprotein (AFP) that could effectively activate CD8 T cells in mice, resulting in potent antitumor effect that can completely prevent mice from tumor challenge and prevent carcinogen-induce autochthonous HCC. In this report, we studied whether the epitope-specific CD8 responses can be further enhanced by peptide boost and investigate if the newly identified epitope specific T cells can kill AFP+ tumor cells and have equal antitumor activity. We found that the lv-primed AFP-specific CD8 responses can be boosted by AFP peptides even at the peak of primary responses. As much as 20 folds increase of AFP-specific CD8 responses can be achieved by peptide boost. However, the kinetics and the antitumor effect of different epitope-specific CD8 responses are drastically different. While the epitope AFP499-specific CD8 T cells possess potent CTL activity against AFP+ tumor cells and generate strong antitumor effect in vivo, the AFP212-specific CD8 T cells have a very limited CTL activity and antitumor effect though they can produce high level of IFNg. The mechanisms underpinning the functional differences will be reported. This finding demonstrates that cancer vaccines must be able to elicit tumor-killing immune effector cells in order to generate antitumor effect.

Engineering AFP and GPC3 to create highly immunogenic gene vaccines to prevent carcinogen-induced murine autochthonous hepatocellular carcinoma (VAC12P.1015)

Abstract In this study, we investigated whether alpha-fetoprotein (AFP) and glypican 3 (GPC3) could be engineered to create effective vaccines to potently activate CD8 T cells to prevent clinically relevant carcinogen-induced autochthonous hepatocellular carcinoma (HCC) in mice. We found that the approach of epitope-optimization created a highly immunogenic AFP and GPC3 and that immunization with lentivector expressing the epitope-optimized AFP and GPC3, but not wild-type AFP and GPC3, potently activated CD8 T cells. Critically, the activated CD8 T cells not only cross-recognized native AFP peptides, but also recognized and killed tumor cells expressing native AFP and GPC3 protein. Immunization with lentivector expressing optimized AFP, but not native AFP, completely protected mice from tumor challenge and reduced the incidence of carcinogen-induced autochthonous HCC. In addition, prime-boost immunization with the optimized AFP significantly increased the frequency of AFP-specific memory CD8 T cells in the liver that were highly effective against emerging HCC tumor cells, further enhancing the tumor prevention of carcinogen-induced autochthonous HCC. Our data demonstrate that epitope-optimization is required to potently activate AFP- and GPC3- specific CD8 T cells, generating effective antitumor effect to prevent carcinogen-induced HCC in mice. Our study provides a roadmap to develop effective human HCC vaccines that may result in an improved antitumor effect.

Epitope-optimized alpha-fetoprotein genetic vaccines prevent carcinogen-induced murine autochthonous hepatocellular carcinoma

Immunization with effective cancer vaccines can offer a much needed adjuvant therapy to fill the treatment gap after liver resection to prevent relapse of hepatocellular carcinoma (HCC). However, current HCC cancer vaccines are mostly based on native shared-self/tumor antigens that are only able to induce weak immune responses. In this study we investigated whether the HCC-associated self/tumor antigen of alpha-fetoprotein (AFP) could be engineered to create an effective vaccine to break immune tolerance and potently activate CD8 T cells to prevent clinically relevant carcinogen-induced autochthonous HCC in mice. We found that the approach of computer-guided methodical epitope-optimization created a highly immunogenic AFP and that immunization with lentivector expressing the epitope-optimized AFP, but not wild-type AFP, potently activated CD8 T cells. Critically, the activated CD8 T cells not only cross-recognized short synthetic wild-type AFP peptides, but also recognized and killed tumor cells expressing wild-type AFP protein. Immunization with lentivector expressing optimized AFP, but not native AFP, completely protected mice from tumor challenge and reduced the incidence of carcinogen-induced autochthonous HCC. In addition, prime-boost immunization with the optimized AFP significantly increased the frequency of AFP-specific memory CD8 T cells in the liver that were highly effective against emerging HCC tumor cells, further enhancing the tumor prevention of carcinogen-induced autochthonous HCC. Epitope-optimization is required to break immune tolerance and potently activate AFP-specific CD8 T cells, generating effective antitumor effect to prevent clinically relevant carcinogen-induced autochthonous HCC in mice. Our study provides a practical roadmap to develop effective human HCC vaccines that may result in an improved outcome compared to the current HCC vaccines based on wild-type AFP.

Mapping of Structure-Function Peptide Sites on the Human Alpha-fetoprotein Amino Acid Sequence

The structure of alpha-fetoprotein (AFP) is presented in light of AFP membership and position in the albuminoid gene family in comparison to other gene family members. Ontogenetic AFP gene expression is reviewed considering AFP mRNA presence in various tissues at different times during development. The multiple molecular variant forms of AFP are discussed in relation to published reports of AFP binding proteins and cell surface receptors. The atlas further shows AFP as a protein consisting of multiple peptide-cassettes consisting of amino acid (AA) sequence stretches matched to peptide segments on prohormones and biological response modifier proteins. Such AFP peptide segments could potentially serve as delivery agents which could target vascular, neuroendocrine, or gastrointestinal cells. A discussion follows in which peptide epitopes, extracellular matrix proteins, serine proteases, extracellular matrix, and cellular adhesion AA identity sites on AFP are considered. The AFP molecule is also viewed as a carrier/transport protein based on AA sequence comparison of various proteins that bind hydrophobic ligands and heavy metals similar to AFP binding of such components. An analysis of transcription factors, tumor suppressors, and AA-rich motifs follows, interfaced with dimerization and nuclear localization sequence matches identified on the AFP molecule. Emphasis is further placed upon homeodomain and apoptosis AA sequence identities given that AFP serves as a fetal, phase-specific protein throughout embryogenesis, histogenesis, and organogenesis. AFP AA sequences are further presented as peptide identification sites for growth

Comprehensive analysis of the α-fetoprotein-specific CD8+ T cell responses in patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide, with a poor prognosis and limited therapeutic options. Therefore, the development of novel therapeutic strategies is of high priority. alpha-Fetoprotein (AFP) is overexpressed in the majority of HCCs. Priming of immune responses against AFP results in significant protective antitumoral T cell responses in the mouse model. Little information is available about the hierarchy, breadth, frequency, and peripheral versus intrahepatic distribution of AFP-specific CD8(+) T cell responses in patients with HCC. To address these important issues we comprehensively analyzed CD8(+) T cell responses against full-length AFP in peripheral blood, tumor liver tissue, and nontumor liver tissue from patients with HCC using overlapping AFP peptides. The AFP-specific CD8(+) T cell response was also tested in peripheral blood and liver from patients chronically infected with hepatitis C virus (HCV) and compared to the HCV-specific CD8(+) T cell response. The majority of patients with HCC showed AFP-specific responses, with many responses directed against previously unreported epitopes. These responses were primarily detectable in the HCC tissue and mainly targeted the C-terminus of AFP. Interestingly, AFP-specific T cells were not only found in patients with HCC but also in patients with chronic HCV infection, other liver diseases, and less frequently in healthy subjects. In patients with HCC, a high frequency of AFP-specific CD8(+) T cells directed against different epitopes suggest that AFP has a strong and broad immunogenicity. Further, CD8(+) T cells specific for the self-antigen AFP are present in the normal T cell repertoire and are not centrally or peripherally deleted. Our results provide support for strategies to boost AFP-specific CD8(+) T cell responses in patients with HCC but also demonstrate a diversity of immune responses that may be needed for protection.

Alpha-fetoprotein (AFP)-derived peptides as epitopes for hepatoma immunotherapy: a commentary.

The various immunological roles of human alpha-fetoprotein (HAFP), and its correlation with hepatomas, that is, hepatocellular carcinomas (HCCs), are not often addressed together in biomedical reports considering that HAFP is an established biomarker for hepatomas. Studies reporting measurement of HAFP serum levels in hepatoma patients in basic/clinical research settings has greatly increased over the years. Recent reports have now expanded our base knowledge in the mounting of an immune response against AFP, a self antigen, during hepatoma tumorigenesis. Advances in the detection and identification of AFP-derived peptide epitopes are opening new vistas of knowledge regarding the immunological role of AFP-peptides as T cell stimulating antigens in the course of hepatoma growth and progression. The present commentary addresses HAFP-derived peptides as immunologic responders in HCC and their use in the study and generation of AFP-peptide sensitized T cells directed against hepatoma cells. Attempts were further made to relate the AFP-derived peptide epitopes to T cell activities during the course of hepatoma immunotherapies and to profile the traits and properties of the peptides themselves. Hence, the present commentary was divided into two sections; (1) the characterization, properties, and traits of AFP peptide epitopes, and (2) the use of AFP-derived peptides in the therapeutic induction of T cells primed against hepatoma cells using both in vivo and in vitro models.