个体化肿瘤特异TCR的筛选策略

基因修饰T细胞疗法在肿瘤治疗领域取得突破性进展，主要包括嵌合抗原受体基因修饰T（chimeric antigen receptor engineered T，CAR-T）细胞和T细胞受体基因修饰T（T-cell receptor modified T，TCR-T）细胞。虽然CAR-T细胞疗法在血液系统 肿瘤治疗领域呈现良好的临床治疗效果，但CAR-T细胞仅能识别肿瘤细胞膜抗原（占细胞全部抗原的比例约10%），而TCR-T细 胞可以识别人白细胞抗原（human leukocyte antigen，HLA）提呈的细胞内抗原，因此TCR-T细胞可以识别更多种类的肿瘤抗原，进 而实现对CAR-T细胞的合理补充。由于TCR-T细胞需要同时识别细胞内抗原和对应的HLA，而不同患者的HLA分型和表达的 肿瘤抗原都可能存在巨大差异，因此有必要为每个/每类肿瘤患者定制个体化的TCR-T细胞，其中的关键为筛选特异识别肿瘤抗 原的TCR。当前主要有筛选靶向“已知”肿瘤抗原TCR和筛选靶向“未知”肿瘤抗原TCR的两种策略，但其各有适用性，应针对每 个患者制定适合的筛选方法，以制备多种肿瘤特异性TCR-T细胞，从而实现个体化TCR-T细胞的肿瘤治疗。     

MAGE家族蛋白质生理功能的研究进展

MAGE家族基因编码的肿瘤排斥抗原已经被人们应用于肿瘤免疫治疗，最近的研究发现MAGE家族还包含一类特殊的基因在正常组织也有表达，且在细胞信号转导，细胞凋亡调控以及哺乳动物胚胎发育过程中起明显的传递和协同作用。但是人们对MAGE家族基因及其蛋白质的功能仍然知之甚少。本文对近年来MAGE家族蛋白质生理功能的研究进展作一综述。     

Peptide Vaccines for Treatment of Colon Cancer: Have We Made Progress?

Colorectal cancer (CRC) is the third most common cancer diagnosis and cause of cancer-related death in the USA. It accounts for more than one million cases diagnosed each year worldwide. In the past 10 years, new drugs have been approved, but the survival times are still modest. Alternative therapeutic strategies are clearly needed. A large number of tumor antigens and epitopes recognized by cytotoxic T lymphocytes (CTLs) have been identified in CRC. Cancer vaccines, designed to activate immune effectors (T cells and antibodies), to prevent recurrence, or to treat advanced cancers, have demonstrated clinical benefit in melanoma, prostate cancer, and lymphoma. Immunotherapy that targets tumor-associated antigens (TAAs) on cancer cells or tumor stroma is under investigation. This review discusses CRC immune responsiveness, current status of CRC vaccines, challenges, and future directions. New therapeutic modalities hold a promise to improve the patient’s clinical outcome.     

The tumor antigen repertoire identified in tumor-bearing neu transgenic mice predicts human tumor antigens

FVB/N mice transgenic for nontransforming rat neu develop spontaneous breast cancers that are neu positive and estrogen receptor negative, mimicking premenopausal human breast cancer. These animals have been widely used as a model for immunobased therapies targeting HER-2/neu. In this study, we used serological analysis of recombinant cDNA expression libraries to characterize the antigenic repertoire of neu transgenic (neu-tg) mice and questioned the ability of this murine model to predict potential human tumor antigens. After screening 3 x 10(6) clones from 3 different cDNA libraries, 15 tumor antigens were identified, including cytokeratin 2-8, glutamyl-prolyl-tRNA synthetase, complement C3, galectin 8, and serine/threonine-rich protein kinase 1. Multiple proteins involved in the Rho/Rho-associated, coiled coil-containing protein kinase (Rock) signal transduction pathway were found to be immunogenic, including Rock1, Rho/Rac guanine nucleotide exchange factor 2, and schistosoma mansoni adult worm antigen preparation 70. All of the identified antigens are self-proteins that are expressed in normal tissues in addition to breast tumors and the majority of the antigens are intracellular proteins. More than half of the mouse tumor antigens have human homologues that have been reported previously as tumor antigens. Finally, the tumor-specific antibody immunity and marked immune cell infiltration that was observed in mice with spontaneous tumors were not observed in mice with transplanted tumors. Our results indicate that neu-tg mice bearing spontaneous tumors develop humoral immunity to their tumors similar to cancer patients and that tumor antigens identified in transgenic mouse may predict immunogenic human homologues.     

In situ vaccination: Cancer immunotherapy both personalized and off‐the‐shelf

As cancer immunotherapy continues to benefit from novel approaches which cut immune ‘brake pedals’ (e.g. anti‐PD1 and anti‐CTLA4 antibodies) and push immune cell gas pedals (e.g. IL2, and IFNα) there will be increasing need to develop immune ‘steering wheels’ such as vaccines to guide the immune system specifically toward tumor associated antigens. Two primary hurdles in cancer vaccines have been: identification of universal antigens to be used in ‘off‐the‐shelf’ vaccines for common cancers, and 2) logistical hurdles of ex vivo production of individualized whole tumor cell vaccines. Here we summarize approaches using ‘in situ vaccination’ in which intratumoral administration of off‐the‐shelf immunomodulators have been developed to specifically induce (or amplify) T cell responses to each patient''s individual tumor. Clinical studies have confirmed the induction of systemic immune and clinical responses to such approaches and preclinical models have suggested ways to further potentiate the translation of in situ vaccine trials for our patients.     

Ductular carcinoma of the breast: serum antibodies to tumor-associated antigens.

Serum antibodies to tumor-associated antigens of breast carcinoma have been studied by indirect immunofluorescence in 109 patients with breast carcinoma and 125 controls, including age/sex matched normal individuals, patients with nonmalignant disease, and patients with malignant disease other than breast cancer. We report here that sera of a large proportion of patients with ductular carcinoma of the breast have antibodies to cell surface and/or intracellular antigens of autologous tumor cells and include evidence that the antigens are absent from a considerable range of normal and other types of malignant tissues. In addition to testing of control sera, specificity of the reacting antibodies was investigated further by testing of sera with normal breast tissue and the absorption of sera from breast cancer patients with various normal tissues and cancer cells. The significance of the findings in breast cancer is discussed.     

Vaccination for malignant melanoma: recent developments

The identification of tumor-associated antigens recognized by cellular or humoral effectors of the immune system has opened new perspectives for cancer immunotherapy. Different categories of cancer-associated antigens have been described as targets for CD8+ T cells in vitro and in vivo: (1) 'cancer-testis' (CT) antigens expressed in different tumors and normal testis; (2) melanocyte differentiation antigens; (3) point mutations of normal genes; (4) antigens that are overexpressed in malignant tissues, and (5) viral antigens. Clinical trials with antigenic peptides have been initiated to induce specific immunological responses in vivo. Immunological and clinical parameters for the assessment of peptide-specific reactions have been defined: DTH, CD8+ T cell, autoimmune and tumor regression responses. Preliminary results show that tumor-associated peptides alone elicit specific DTH and CD8+ T cell responses associated with tumor regression after intradermal vaccination. Granulocyte macrophage colony-stimulating factor has been shown to enhance peptide-specific immune reactions by amplification of dermal antigen-presenting dendritic cells. Complete tumor regressions have been observed after the induction of CD8+ T cell responses by peptide immunization. Based on these results, active immunotherapy with tumor-associated antigens may be a promising approach for patients in adjuvant treatment situations, who are at high risk for tumor recurrence. Recently, a strategy utilizing spontaneous antibody responses to tumor-associated antigens (SEREX) has led to the identification of a new CT antigen, NY-ESO-1. NY-ESO-1-specific spontaneous humoral and cellular immune responses were found in approximately 50% of patients with NY-ESO-1-positive tumors. Clinical studies have been initiated to evaluate the immunological effects of immunization with NY-ESO-1 peptides in cancer patients with detectable or absent immunity against NY-ESO-1.     

Cancer immunotherapy in clinical oncology

The identification of tumor-associated antigens recognized by cellular or humoral effectors of the immune system has opened new perspectives for cancer therapy. Different groups of cancer-associated antigens have been described as targets for cytotoxic T lymphocytes (CTLs) in vitro and in vivo: 1) cancer-testis (CT) antigens, which are expressed in different tumors and normal testis; 2) melanocyte differentiation antigens; 3) point mutations of normal genes; 4) antigens that are overexpressed in malignant tissues; and 5) viral antigens. Clinical studies with peptides derived from these antigens have been initiated to induce specific CTL responses in vivo. Immunological and clinical parameters for the assessment of peptide-specific reactions have been defined, i.e., delayed-type hypersensitivity (DTH), CTL, autoimmmune, and tumor regression responses. Preliminary results demonstrate that tumor-associated peptides alone elicit specific DTH and CTL responses leading to tumor regression after intradermal injection. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was proven effective in enhancing peptide-specific immune reactions by amplification of dermal peptide-presenting dendritic cells. Long-lasting complete tumor regressions have been observed after induction of peptide-specific CTLs. However, in single cases with disease progression after an initial tumor response, either a loss of the respective tumor antigen targeted by CTLs or of the presenting major histocompatibility complex (MHC) class I allele was detected as a mechanism of immune escape under immunization. Based on these observations, cytokines to enhance antigen and MHC class I expression in vivo are being evaluated to prevent immunoselection. Recently, a strategy utilizing spontaneous antibody responses to tumor-associated antigens (SEREX) has led to the identification of a new CT antigen, NY-ESO-1, which is regarded as one of the most immunogenic antigens known today inducing spontaneous immune responses in 50% of patients with NY-ESO-1-expressing cancers. Clinical studies involving antigenic constructs that induce both antibody and CTL responses will show whether these are more effective for immunotherapy of cancer.     

CAR-NK cell in cancer immunotherapy; A promising frontier

Chimeric antigen receptors (CARs) have a unique facet of synthetic biology and offer a paradigm shift in personalized medicine as they can use and redirect the patient's immune cells to attack cancer cells. CAR-natural killer (NK) cells combine the targeted specificity of antigens with the subsequent intracellular signaling ability of the receptors to increase their anti-cancer functions. Importantly, CAR-NK cells can be utilized as universal cell-based therapy without requiring human leukocyte antigen (HLA) matching or earlier contact with tumor-associated antigens (TAAs). Indeed, CAR-NK cells can be adapted to recognize various antigens, hold higher proliferation capacity, and in vivo persistence, show improved infiltration into the tumors, and the ability to overcome the resistant tumor microenvironment leading to sustained cytotoxicity against tumors. Accumulating evidence from recent in vivo studies rendering CAR-NK cell anti-cancer competencies renewed the attention in the context of cancer immunotherapy, as these redirected effector cells can be used in the development of the “off-the-shelf” anti-cancer immunotherapeutic products. In the current review, we focus on the therapeutic efficacy of CAR-NK cell therapies for treating various human malignancies, including hematological malignancies and solid tumors, and will discuss the recent findings in this regard, with a special focus on animal studies.     

Intracellular tumor-associated antigens represent effective targets for passive immunotherapy

Monoclonal antibody (mAb) therapy against tumor antigens expressed on the tumor surface is associated with clinical benefit. However, many tumor antigens are intracellular molecules that generally would not be considered suitable targets for mAb therapy. In this study, we provide evidence challenging this view through an investigation of the efficacy of mAb directed against NY-ESO-1, a widely expressed immunogen in human tumors that is expressed intracellularly rather than on the surface of cells. On their own, NY-ESO-1 mAb could neither augment antigen-specific CD8(+) T-cell induction nor cause tumor eradication. To facilitate mAb access to intracellular target molecules, we combined anti-NY-ESO-1 mAb with anticancer drugs to accentuate the release of intracellular NY-ESO-1 from dying tumor cells. Strikingly, combination therapy induced a strong antitumor effect that was accompanied by the development of NY-ESO-1-specific effector/memory CD8(+) T cells that were not elicited by single treatments alone. The combinatorial effect was also associated with upregulation of maturation markers on dendritic cells, consistent with the organization of an effective antitumor T-cell response. Administration of Fc-depleted F(ab) mAb or combination treatment in Fcγ receptor-deficient host mice abolished the therapeutic effect. Together, our findings show that intracellular tumor antigens can be captured by mAbs and engaged in an efficient induction of CD8(+) T-cell responses, greatly expanding the possible use of mAb for passive cancer immunotherapy.     

CTL-defined Cancer Vaccines: Perspectives for Active Immunotherapeutic Interventions in Minimal Residual Disease

The characterization of tumor-associated antigens recognized by cellular or humoral effectors of the immune system has opened new perspectives for cancer therapy. Several categories of cancer-associated antigens have been described as targets for cytotoxic T lymphocytes (CTL) in vitro and in vivo: (1) Cancer-Testis (CT) antigens expressed in different tumors and normal testis, (2) melanocyte differentiation antigens, (3) point mutations of normal genes, (4) antigens that are overexpressed in malignant tissues, and (5) viral antigens. Clinical studies with peptides derived from these antigens have been initiated to induce specific CTL responses in vivo. Immunological and clinical parameters for the assessment of peptide-specific reactions have been defined, i.e. induction of DTH-, CTL-, autoimmune-, and tumor-regression responses. Preliminary results demonstrate that tumor-associated peptides alone elicit specific DTH- and CTL-responses leading to tumor regression after intradermal injection. GM-CSF was proven effective to enhance peptide-specific immune reactions by amplification of dermal peptide-presenting dendritic cells. Long lasting complete tumor regressions have been observed after induction of CTL by peptide immunization. Based on these results, active immunotherapy with tumor-associated antigens may be a promising approach for patients with minimal residual disease, who are at high risk for tumor recurrence. However, in single cases with disease progression after an initial tumor response either a loss of the respective tumor antigen targeted by CTL or of the presenting MHC class I molecule was detected as mechanisms of immune escape under immunization in vivo. Based on these observations, cytokines to enhance antigen- and MHC-class I expression in vivo are being evaluated to prevent immunoselection. Recently, a strategy utilizing spontaneous antibody responses to tumor-associated antigens (SEREX) has led to the identification of a new CT antigen, NY-ESO-1. In a melanoma patient with high titer antibody against NY-ESO-1 also a strong HLA-A2 restricted CTL reactivity against the same antigen was found. Clinical studies involving tumor antigens that induce both antibody- and CTL-responses will show whether these are better candidates for immunotherapy of cancer.     

Mapping tumor epitope space by direct selection of single-chain Fv antibody libraries on prostate cancer cells

The identification of tumor-specific cell surface antigens is a critical step toward the development of targeted therapeutics for cancer. The epitope space at the tumor cell surface is highly complex, composed of proteins, carbohydrates, and other membrane-associated determinants including post-translational modification products, which are difficult to probe by approaches based on gene expression. This epitope space can be efficiently mapped by complementary monoclonal antibodies. By selecting human antibody gene diversity libraries directly on the surface of prostate cancer cells, we have taken a functional approach to identifying fully human, tumor-specific monoclonal antibodies without prior knowledge of their target antigens. Selection conditions have been optimized to favor tumor-specific antibody binding and internalization. To date, we have discovered >90 monoclonal antibodies that specifically bind and enter prostate cancer cells, with little or no binding to control cells. These antibodies are able to efficiently deliver intracellular payloads when attached to nanoparticles such as liposomes. In addition, a subset of the antibodies displayed intrinsic antiproliferative activity. These tumor-specific internalizing antibodies are likely to be useful for targeted therapeutics either alone or in combination with effector molecules. The antigens they bind constitute a tumor-specific internalizing epitope space that is likely to play a significant role in cancer cell homeostasis. Targeting components of this epitope space may facilitate development of immunotherapeutic and small molecule-based strategies as well as the use of other therapeutic agents that rely upon delivery to the interior of the tumor cell.     

Determination of 35 cell surface antigen levels in malignant pleural effusions identifies CD24 as a marker of disseminated tumor cells

Many targets have been identified in solid tumors for antibody therapy but it is less clear what surface antigens may be most commonly expressed on disseminated tumor cells. Using malignant pleural effusions as a source of disseminated tumor cells, we compared a panel of 35 antigens for their cancer specificity, antigen abundance and functional significance. These antigens have been previously implicated in cancer metastasis and fall into four categories: (i) cancer stem cell, (ii) epithelial‐mesenchymal transition, (iii) metastatic signature of in vivo selection and (iv) tyrosine kinase receptors. We determined the antigen density of all 35 antigens on the cell surface by flow cytometry, which ranges from 3 × 10³–7 × 10⁶ copies per cell. Comparison between the malignant and benign pleural effusions enabled us to determine the antigens specific for cancer. We further chose six antigens and examined the correlation between their expression levels and tumor formation in immunocompromised mice. We concluded that CD24 is one of the few antigens that could simultaneously meet all three criteria of an ideal target. It was specifically and abundantly expressed in malignant pleural effusions; CD24^high tumor cells formed tumors in mice at a faster rate than CD24^low tumor cells, and shRNA‐mediated knockdown of CD24 in HT29 cells confirmed a functional requirement for CD24 in the colonization of the lung. Concomitant consideration of antigen abundance, specificity and functional importance can help identify potentially useful markers for disseminated tumor cells.     

Expression of fetal antigens and tumor-specific antigens in SV40-transformed cells. II. Tumor transplantation studies

The effect of immunization with fetal antigens and tumor-specific antigens on the transplantation of SVT2, a BALB/c mouse tumor induced by Simian virus 40 (SV40), has been studied. Hyperimmunization with 5,000 R X-irradiated, syngeneic fetuses of 1–2 weeks' gestation or syngeneic spleen cells gave no protection to SVT2 cell challenge. In contrast, immunization with SV40 or SV40-transformed cells gave a 100- to 1,000-fold protection. These results gave additional evidence that fetal antigens are different from tumor-specific transplantation antigen (TSTA).     

A high throughput method for identifying personalized tumor-associated antigens

Circulating autoantibodies against tumor-associated antigens (TAAs) and their pattern of glycosylation can be used as diagnostic indicators of cancer. Using random peptide library screening, we identified patient-specific sets of peptides recognized by colon cancer patients'' serum IgG and IgM antibodies. We demonstrate a strategy for analyzing BLAST search results for identifying tumor-associated antigens represented by peptides that mimic sequential epitopes. Statistical analysis of the frequency with which the proteins are retrieved by BLAST homology searching and an estimation of the probability of a match by chance can identify the proteins that are the real targets of the immune response against tumors. In addition, we observed an over-expression of the mRNA for the match-producing protein only in the corresponding tumor sample, out of fourteen tumor and normal samples analyzed. This observation confirms that personalized tumor-associated antigens can be identified by BLAST homology search following random peptide library screening on cancer patient''s serum antibodies.     

Tumor-infiltrating B lymphocytes as a potential source of identifying tumor antigen in human lung cancer

Functional studies using freshly isolated tumor-infiltrating B lymphocytes(TIB) are difficult to perform and interpret. Here we document a novel function of TIB using fresh human lung cancer tissues engrafted in SCID mice; they are at activated state and produce tumor-specific antibodies in tumor microenvironment: (a) TIB engrafted in SCID mice produced human IgG; (b) IgG derived from TIB highly bound intracellular and membrane-bound antigens of autologous cancer cells; and (c) less recognition of autoantigens expressed on normal lymphocytes by IgG derived from TIB compared with IgG from the serum of the patient. On the basis of the novel findings presented in this study, we modified the original serological analysis of antigens by recombinant cDNA expression cloning design in a patient with lung cancer who expressed unusually favorable clinical evolution and analyzed humoral immunity against identified mutated p53 antigen. This study provides the first demonstration that antibodies derived from TIB recognize tumor antigens by serological analysis of antigens by recombinant cDNA expression cloning methodology and circulating anti-p53 antibodies in sera derived from TIB in tumor microenvironment. Our approach using TIB may allow the identification of key antigens in the humoral cancer-related immune system.     

Effect of local radiotherapy on the antibody levels against EBV-induced early and capsid antigens (EA and VCA) in patients with certain malignant tumours

Antibodies to tumour-related and EBV-associated intracellular antigens were studied in 14 cases of Burkitt's lymphoma, 50 of nasopharyngeal carcinoma, 10 of maxillary carcinoma and 95 cases of other tumours, all of whom received radiotherapy in Nairobi. For up to 1 month after radiotherapy the cases of Burkitt's lymphoma recorded an increase in antibodies to early antigens (EA) amounting to, on average, about one titre step (p<0.001). During the same interval there was a small but significant increase in antibodies to viral capsid antigen (VCA) (mean 0.6 titre step; p<0.001). The patients with nasopharyngeal and maxillary carcinoma, too, showed a small but statistically significant increase in antibodies to VCA 2-6 months after radiotherapy (p<0.01 and 0.001, respectively), but no increase in antibodies to EA. On the contrary, in nasopharyngeal carcinoma patients there was a significant decrease in antibodies to EA 2-3 months after radiotherapy. In the group of other tumours there was no evidence of a change in antibodies to the intracellular antigens studied during any of the relevant intervals.     

Immunity to tumor antigens: potential implications in human neuroblastoma.

Immune reactions to tumor-specific and tumor-associated antigens have been demonstrated in animals with neoplasms with in vitro and in vovo techniques. Some of the antigens detected in vitro induce transplantation resistance in vivo, while others do not. Human neuroblastoma cells cultivated in vitro have been shown to possess common antigens to which lymphocytes from neuroblastoma patients react. Whether it is possible to augment the immune reactivity of patients with neuroblastoma to these common antigens and, if so, whether this heightened immune reactivity would have clinically beneficial effects are as yet unknown. These reactions are complex, involving both cellular and humoral mechanisms. The fact that one type of immune response can be detected to one type of antigen present in a tumor in vitro does not necessarily mean that the immune response is effective in vivo. Responses to other tumor antigens may be deficient, or the immune response may be depressed. This may be due to active suppression of and/or selective deficiencies in critical cell populations required for an augmented immune response; this possibility may be evaluated with techniques allowing for in vitro sensitization to tumor antigens.     

Targeted therapy of solid malignancies via HLA class II antigens: a new biotherapeutic approach?

Intracellular signals, delivered in professional antigen-presenting cells following the engagement of major histocompatibility complex (MHC) class II molecules, activate a variety of cellular functions that also contribute to efficient antigen presentation. As far as human malignancies, the signaling ability of human leukocyte antigens (HLA) class II molecules is a rather well-characterized event in hematologic tumors; in contrast, very limited evidences are available in solid neoplasias of different histotypes that may constitutively express HLA class II antigens. Among solid malignancies, a significant proportion of human cutaneous melanomas have been shown to express HLA class II molecules, and cutaneous melanoma undoubtedly represents a 'model disease' to investigate tumor immunobiology, to unveil the molecular basis underlying the interactions between neoplastic cells and host's immune system, and ultimately to set up new bio-immunotherapeutic approaches. Upcoming preclinical evidences unveil a signaling potential of HLA-DR antigens expressed on melanoma cells, and suggest for the clinical implication of HLA class II molecules as novel therapeutic targets. Therefore, in this review, we will focus on the emerging role of HLA class II antigens as intracellular signal transducing elements in neoplastic cells of the melanocytic lineage, emphasizing their foreseeable role in targeted therapy of human melanoma and potentially of HLA class II antigens-positive tumors of different histology.     

Radiobiological basis of SBRT and SRS

Stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) have been demonstrated to be highly effective for a variety of tumors. However, the radiobiological principles of SBRT and SRS have not yet been clearly defined. It is well known that newly formed tumor blood vessels are fragile and extremely sensitive to ionizing radiation. Various lines of evidence indicate that irradiation of tumors with high dose per fraction, i.e. >10 Gy per fraction, not only kills tumor cells but also causes significant damage in tumor vasculatures. Such vascular damage and ensuing deterioration of the intratumor environment then cause ischemic or indirect/secondary tumor cell death within a few days after radiation exposure, indicating that vascular damage plays an important role in the response of tumors to SBRT and SRS. Indications are that the extensive tumor cell death due to the direct effect of radiation on tumor cells and the secondary effect through vascular damage may lead to massive release of tumor-associated antigens and various pro-inflammatory cytokines, thereby triggering an anti-tumor immune response. However, the precise role of immune assault on tumor cells in SBRT and SRS has not yet been clearly defined. The “4 Rs” for conventional fractionated radiotherapy do not include indirect cell death and thus 4 Rs cannot account for the effective tumor control by SBRT and SRS. The linear-quadratic model is for cell death caused by DNA breaks and thus the usefulness of this model for ablative high-dose SBRT and SRS is limited.