Colorectal cancer vaccines: Tumor-associated antigens vs neoantigens

Therapeutic options for the treatment of colorectal cancer(CRC) are diverse but still not always satisfying. Recent success of immune checkpoint inhibition treatment for the subgroup of CRC patients suffering from hypermutated tumors suggests a permanent role of immune therapy in the clinical management of CRC. Substantial improvement in treatment outcome could be achieved by development of efficient patient-individual CRC vaccination strategies. This mini-review summarizes the current knowledge on the two general classes of targets: tumor-associated antigens(TAAs) and tumorspecific antigens. TAAs like carcinoembryonic antigen and melanoma associated antigen are present in and shared by a subgroup of patients and a variety of clinical studies examined the efficacy of different TAA-derived peptide vaccines. Combinations of several TAAs as the next step and the development of personalized TAA-based peptide vaccines are discussed. Improvements of peptidebased vaccines achievable by adjuvants and immunestimulatory chemotherapeutics are highlighted. Finally, we sum up clinical studies using tumor-specific antigens-in CRC almost exclusively neoantigens-which revealed promising results; particularly no severe adverse events were reported so far. Critical progress for clinical outcomes can be expected by individualizing neoantigen-based peptide vaccines and combining them with immunestimulatory chemotherapeutics and immune checkpoint inhibitors. In light of these data and latest developments, truly personalized neoantigen-based peptide vaccines can be expected to fulfill modern precision medicine's requirements and will manifest as treatment pillar for routine clinical management of CRC.

Synthesis of S-linked tumor-associated carbohydrate antigen STn

Modified tumor-associated carbohydrate antigens could be used to develop anti-cancer vaccines.Carbohydrate antigens in which thioglycosidic linkages are used instead of O-glycosidic linkages may be more immunogenic and may stimulate the production of antibodies capable of recognizing naturally occurring carbohydrates due to their enhanced resistance to endogenous glycosidases and their inherent non-self antigen character.For this purpose,a new S-linked tumor-associated carbohydrate antigen STn has been successfully synthesized for the first time.

Identification of novel HLA-A 0201-restricted epitopes from anterior gradient-2 as a tumor-associated antigen against colorectal cancer

Anterior gradient-2 （AGR2） promotes tumor growth, cell migration and cellular transformation and its enhanced expression is almost completely restricted to malignant tissues, thus making AGR2 an interesting target for the development of immunotherapeutic strategies. We investigated whether the AGR2 molecule comprises human leukocyte antigen （HLA）-A 0201-binding epitopes recognized by human cytotoxic T lymphocytes （CTLs）, which could be targeted in dendritic cell （DC）-based cancer immunotherapy against colorectal cancer （CRC）. We reviewed the sequence of AGR2 for peptides that could potentially bind to HLA-A 0201 with the aid of a computer-based program. Five candidate peptides with different binding scores were synthesized and tested. These peptides were then assessed for their immunogenicity to elicit specific immune responses mediated by CTLs in vitro by means of enzyme-linked immunospot assays and CTL assays. AGR2 was highly expressed in several CRC cell lines, including DK01, DLD1, KM 12C, HCT-8 and HT-29. DCs pulsed with AGR2-P2 （aa 11-19; LLVALSYTL） or AGR2-P4 （aa 127-135; RIMFVDPSL） generated potent CTLs that could lyse T2 cells pulsed with AGR2-P2 or AGR2-P4 and HLA-A0201＋ AGR2-positive CRC cell lines in a strong dose-dependent and HLA-A 0201-restricted manner. In conclusion, these novel epitopes derived from AGR2 protein may be attractive candidates for DC-based immunotherapy for CRC.

CAR T cells redirected against tumor-specific antigen glycoforms: can low-sugar antigens guarantee a sweet success?

Immune-based therapies have experienced a pronounced breakthrough in the past decades as they acquired multiple US Food and Drug Administration(FDA)approvals for various indications.To date,six chimeric antigen receptor T cell(CAR-T)therapies have been permitted for the treatment of certain patients with relapsed/refractory hematologic malignancies.However,several clinical trials of solid tumor CAR-T therapies were prematurely terminated,or they reported life-threatening treatment-related damages to healthy tissues.The simultaneous expression of target antigens by healthy organs and tumor cells is partly responsible for such toxicities.Alongside targeting tumor-specific antigens,targeting the aberrantly glycosylated glycoforms of tumor-associated antigens can also minimize the off-tumor effects of CAR-T therapies.Tn,T,and sialyl-Tn antigens have been reported to be involved in tumor progression and metastasis,and their expression results from the dysregulation of a series of glycosyltransferases and the endoplasmic reticulum protein chaperone,Cosmc.Moreover,these glycoforms have been associated with various types of cancers,including prostate,breast,colon,gastric,and lung cancers.Here,we discuss how underglycosylated antigens emerge and then detail the latest advances in the development of CAR-T-based immunotherapies that target some of such antigens.

Chimeric antigen receptor-engineered T-cell therapy for liver cancer

Background: Chimeric antigen receptor-engineered T-cell(CAR-T) therapy is a newly developed immunotherapy used in the treatment of cancers. Because CAR-T therapy has shown great success in treating CD19-positive hematological malignancies, its application has been explored in the treatment of solid tumors, such as liver cancer. In this review, we discuss the immune characteristics of liver cancer, the obstacles encountered during the application of CAR-T therapy, and preclinical and clinical progress in the use of CAR-T therapy in patients with liver cancer.Data sources: The data on CAR-T therapy related to liver cancers were collected by searching Pub Med and the Web of Science databases prior to December 2017 with the keywords "chimeric antigen receptor","CAR-T", "liver cancer", "hepatocellular carcinoma", and "solid tumor". Additional articles were identified by manual search of references found in the primary articles. The data for clinical trials were collected by searching Clinical Trials.gov.Results: The liver has a tolerogenic nature in the intrahepatic milieu and its tumor microenvironment significantly affects tumor progression. The obstacles that reduce the efficacy of CAR-T therapy in solid tumors include a lack of specific tumor antigens, limited trafficking and penetration of CAR-T cells to tumor sites, and an immunosuppressive tumor microenvironment. To overcome these obstacles, several strategies have emerged. In addition, several strategies have been developed to manage the side effects of CAR-T, including enhancing the selectivity of CARs and controlling CAR-T activity. To date, no clinical trials of CAR-T therapy against HCC have been completed. However, preclinical studies in vitro and in vivo have shown potent antitumor efficacy. Glypican-3, mucin-1, epithelial cell adhesion molecule, carcinoembryonic antigen, and other targets are currently being studied.Conclusions: The application of CAR-T therapy for liver cancer is just beginning to be explored and more research is needed. However, we are optimistic that CAR-T therapy will offer a new approach for the treatment of liver cancers in the future.

Combination immunotherapy of glioblastoma with dendritic cell cancer vaccines,anti-PD-1 and poly I:C

Glioblastoma(GBM)is a lethal cancer with limited therapeutic options.Dendritic cell(DC)-based cancer vaccines provide a promising approach for GBM treatment.Clinical studies suggest that other immunotherapeutic agents may be combined with DC vaccines to further enhance antitumor activity.Here,we report a GBM case with combination immunotherapy consisting of DC vaccines,anti-programmed death-1(anti-PD-1)and poly I:C as well as the chemotherapeutic agent cyclophosphamide that was integrated with standard chemoradiation therapy,and the patient remained disease-free for 69 months.The patient received DC vaccines loaded with multiple forms of tumor antigens,including mRNA-tumor associated antigens(TAA),mRNA-neoantigens,and hypochlorous acid(HOCl)-oxidized tumor lysates.Furthermore,mRNA-TAAs were modified with a novel TriVac technology that fuses TAAs with a destabilization domain and inserts TAAs into full-length lysosomal associated membrane protein-1 to enhance major histocompatibility complex(MHC)class I and II antigen presentation.The treatment consisted of 42 DC cancer vaccine infusions,26 anti-PD-1 antibody nivolumab administrations and 126 poly I:C injections for DC infusions.The patient also received 28 doses of cyclophosphamide for depletion of regulatory T cells.No immunotherapy-related adverse events were observed during the treatment.Robust antitumor CD4t and CD8t T-cell responses were detected.The patient remains free of disease progression.This is the first case report on the combination of the above three agents to treat glioblastoma patients.Our results suggest that integrated combination immunotherapy is safe and feasible for long-term treatment in this patient.A large-scale trial to validate these findings is warranted.

Preliminary study of the diagnosis of pancreatic cancer with a serum pancreatic cancer－associated antigen

The serum of 40 normal subjects, 61 cases of various malignant diseases except pancreatic cancer,53 cases of various benign diseases and 33 cases of pancreatic cancer was examined with ELISA to determine the serum level of pancreatic cancer-associated ant

The prognostic value of preoperative serum levels of CEA,CA19-9 and CA72-4 in patients with colorectal cancer

INTRODUCTIONCarcinoembryonic antigen ( CEA) , originally described by Gold and Freedman [1] in 1965, is now an acknowledged member of immunoglobulin superfamily[2],with a role as an intracellular adhesion molecule[3].Carbohydrate antigen 19-9(CA19-9), obtained with a monoclonal antibody produced by immunizing a monoclonal antibody produced by immunizing a mouse with a colonic cancer cell line in 1979[4],is a ligand for E-selectin that plays an important role in the addhesion of cancer cells to endothelial cells [5,6].

联合应用多项肿瘤标志诊断卵巢恶性肿瘤的价值

目的探讨CA125等7种肿瘤标志联合应用对卵巢恶性肿瘤的诊断价值。方法对430例卵巢包块手术前患者(卵巢恶性肿瘤110例,卵巢良性肿瘤320例)及50例正常妇女血清应用ELISA法进行检测。检测项目包括糖类抗原CA125(CA125)、肿瘤相关物质(TSGF)、唾液酸(SA)、癌胚抗原(CEA)、甲胎蛋白(AFP)、促性腺激素(hCG)和铁蛋白(Fer)。结果卵巢恶性肿瘤患者血清中CA125、TSGF、SA、CEA、AFP及Fer水平明显高于卵巢良性肿瘤或对照组,F=177.24,P<0.0001;F=52.49,P<0.0001;F=3.38,P=0.0347;F=6.88,P=0.0011;F=34.94,P<0.0001;F=8.23,P=0.0003;F=124.37,P<0.0001。在7项肿瘤标志中,CA125单独诊断价值最大。单独应用CA125诊断卵巢恶性肿瘤的敏感性、特异性及准确性分别为86.4%、82.8%及83.7%。联合应用7项肿瘤标志时,以任意一项及一项以上异常指标为诊断标准时,诊断卵巢恶性肿瘤的敏感性、特异性及准确性分别为95.5%、45.6%和58.4%;以任意两项及两项以上异常指标为诊断标准时,分别为93.6%、80.6%和84.0%;以任意3项及3项以上异常指标为诊断标准时,分别为87.3%、90.3%和89.5%。结论7项肿瘤标志联合检测对提高卵巢恶性肿瘤诊断的敏感性、特异性及准确性有一定意义,其中CA125、TSGF及SA3项肿瘤标志阳性诊断价值最大。

Significance of serum tumor markers CA50 and CEA in gastric cancer

AIMS The CAS0 and CEA are well-described human tumor-as- sociated antigens most useful clinically in gastrointestinal cancer. In this study we compared these markers in sera from patients with malignant and benign digestive tract diseases. METHODS Using a side-phase radioimmunoassay,CA50 and CEA serum levels were measured in 33 control subjects and 86 patients with gastric cancer(n=34),gastric ulcer(n=27)and chronic atrophic gastritis(n=25).Carcinoma of the stomach was found in the antrum(n=22),in the body(n=3),and the fundus(n=9),and histopathologically,was divided into adeno- carcinoma(n=21),squamous cancer(n=4)and not divided (n=9).Gastric ulcer,when present,appeared in the antrun(18 patients),the body(3)and the fundus(9)and chronic atrophic gastritis was all associated with intestinal metaplasia(IM). RESULTS The normal ranges established for CA50 and CEA in the control group were 16.26+6.14 kU/L and 3.12±1.03/μg/L respectively.In the patients with gastric cancer,serum levels of CA50(112.67±38.36 kU/L)and CEA(10.28±3.76μg/L) were elevated significantly(P<0.01,respectively),the former being>22 kU/L in 18 of 34 patients(53%;range,5-1 550 kU/ L),and the latter>5 μg/L in 19 of 34 patients(55.8%,range, 0.5-17.4 μg/L).A statistically significant correlation was found between the levels of CA50 and GEA(r=0.648,P<0.01). The serum levels of CA50(46.4±25.9 kU/L,P<0.01 )and CEA(6.85±2.43 μg/L,P<0.01)were much lower in patients with gastric ulcer or chronic atrophic gastritis(P>0.05). CONCLUSIONS Based on these results,it is concluded that CA50 and CEA are indicators for advanced gastric cancer,and af- ter surgery,their serum levels may decrease considerably. Overall,there is such a close correlation between them that in clinical practice they might be of great value to the diagnosis of gastric cancer.

Hepatocellular carcinoma-specific immunotherapy with synthesized α1,3-galactosyl epitope-ulsed dendritic cells and cytokine-induced killer cells

AIM： To evaluate the safety and clinical efficacy of a new immunotherapy using both α-Gal epitope-pulsed dendritic cells （DCs） and cytokine-induced killer cells. METHODS： Freshly collected hepatocellular carcinoma （HCC） tumor tissues were incubated with a mixture of neuraminidase and recombinant αl,3-galactosyltrans- ferase （αI,3GT） to synthesize α-Gal epitopes on car- bohydrate chains of the glycoproteins of tumor mem- branes. The subsequent incubation of the processed membranes in the presence of human natural anti-Gal IgG resulted in the effective phagocytosis to the tumor membrane by DCs. Eighteen patients aged 38-78 years with stage 111 primary HCC were randomly chosen for the study; 9 patients served as controls, and 9 patients were enrolled in the study group.RESULTS： The evaluation demonstrated that the pro- cedure was safe; no serious side effects or autoimmune diseases were observed. The therapy significantly pro- longed the survival of treated patients as compared with the controls （17.1 ± 2.01 mo vs 10.1 ±4.5 mo, P = 0.00121）. After treatment, all patients in the study group had positive delayed hypersensitivity and robust systemic cytotoxicity in response to tumor lysate as measured by interferon-y-expression in peripheral blood mononuclear cells using enzyme-linked immunosorbent spot assay. They also displayed increased numbers of CD8-, CD45RO- and CD56-positive cells in the peripheral blood and decreased α-fetoprotein level in the se- rum. CONCLUSION： This new tumor-specific immunotherapy is safe, effective and has a great potential for the treat- ment of tumors.

Emergence of immunotherapy as a novel way to treat hepatocellular carcinoma

Tumor immunity proceeds through multiple processes, which consist of antigen presentation by antigen presenting cells(APCs) to educate effector cells and destruction by the effector cytotoxic cells. However, tumor immunity is frequently repressed at tumor sites. Malignantly transformed cells rarely survive the attack by the immune system, but cells that do survive change their phenotypes to reduce their immunogenicity. The resultant cells evade the attack by the immune system and form clinically discernible tumors. Tumor microenvironments simultaneously contain a wide variety of immune suppressive molecules and cells to dampen tumor immunity. Moreover, the liver microenvironment exhibits immune tolerance to reduce aberrant immune responses to massively-exposed antigens via the portal vein, and immune dysfunction is frequently associated with liver cirrhosis, which is widespread in hepatocellular carcinoma(HCC) patients. Immune therapy aims to reduce tumor burden, but it is also expected to prevent non-cancerous liver lesions from progressing to HCC, because HCC develops or recurs from noncancerous liver lesions with chronic inflammatory states and/or cirrhosis and these lesions cannot be cured and/or eradicated by local and/or systemic therapies. Nevertheless, cancer immune therapy should augment specific tumor immunity by using two distinct measures: enhancing the effector cell functions such as antigen presentation capacity of APCs and tumor cell killing capacity of cytotoxic cells, and reactivating the immune system in immune-suppressive tumor microenvironments. Here, we will summarize the current status and discuss the future perspective on immune therapy for HCC.

SIGNIFICANCE OF CEA AND CA242 IN THE DIAGNOSIS OF COLORECTAL CARCINOMA

Carcinoembryonic antigen (CEA) is frequently used in the diagnosis of the colorectal carcinoma. CA242 is a novel unique tumor-associated antigen characterized by higher tumor specificity and sensitivity for colorectal cancer, as compared with other mucin antigens. In this study, preoperative levels of serum CEA and CA242 were measured in 63 cases of colorectal carcinoma. It was disclosed that the positive rate of CA242 was higher than that of CEA, particularly in patients with colon cancer.The combined determination of CEA and CA242 significantly increased the sensitivity and accuracy in the detection of colorectal cancer as compared with the use of CEA alone (P<0.o1). In patients with advanced disease the positive rate was markedly elevated, especially in patients with liver metastasis. The results indicate that the combined use of CEA and CA242 assays is an useful adjunct diagnostic measure for colorectal carcinoma, and is helpful in the assessment of the stage of the disease as well as in making treatment Plan.

Immunosuppressive tumor microenvironment contributes to tumor progression in diffuse large B-cell lymphoma upon anti-CD19 chimeric antigen receptor T therapy

Anti-CD19 chimeric antigen receptor(CAR)-T cell therapy has achieved 40%–50%long-term complete response in relapsed or refractory diffuse large B-cell lymphoma(DLBCL)patients.However,the underlying mechanism of alterations in the tumor microenvironments resulting in CAR-T cell therapy failure needs further investigation.A multi-center phase I/II trial of anti-CD19 CD28z CAR-T(FKC876,ChiCTR1800019661)was conducted.Among 22 evaluable DLBCL patients,seven achieved complete remission,10 experienced partial remissions,while four had stable disease by day 29.Single-cell RNA sequencing results were obtained from core needle biopsy tumor samples collected from long-term complete remission and early-progressed patients,and compared at different stages of treatment.M2-subtype macrophages were significantly involved in both in vivo and in vitro anti-tumor functions of CAR-T cells,leading to CAR-T cell therapy failure and disease progression in DLBCL.Immunosuppressive tumor microenvironments persisted before CAR-T cell therapy,during both cell expansion and disease progression,which could not be altered by infiltrating CAR-T cells.Aberrant metabolism profile of M2-subtype macrophages and those of dysfunctional T cells also contributed to the immunosuppressive tumor microenvironments.Thus,our findings provided a clinical rationale for targeting tumor microenvironments and reprogramming immune cell metabolism as effective therapeutic strategies to prevent lymphoma relapse in future designs of CAR-T cell therapy.

Chemical Synthesis of Globo H and Mannobiose Glycopolymers and their Immunological Stimulation

Tumor-associated carbohydrate antigens(TACAs)provide a special class of tumor-specific antigens that show promising applications in cancer immunotherapy.However,the weak immunogenicity and structural complexity of TACAs are obstacles to their clinical application.Here,based on a fast and low-cost purification strategy for oligosaccharide synthesis,the synthesis of tumour-associated carbohydrate antigens Globo H and mannobiose which resembles repeat unit of mannan was achieved.To enhance the immunogenicity and multivalent effect,Globo H and mannobiose were covalently attached to degradable polymer backbones.2D spindle-like lamellar micelle and globular micelle were obtained from glycopolymer through a solvent-exchange method of self-assembly.The glyconanoparticle showed good biocompatibility and degradability.Immunological functions of these glyconanoparticles such as stimulation of BMDC to cause upregulation of inflammatory factors were preliminarily explored.

Stepping forward:T-cell redirecting bispecific antibodies in cancer therapy

T cell-redirecting bispecific antibodies are specifically designed to bind to tumor-associated antigens,thereby engaging with CD3 on the T cell receptor.This linkage between tumor cells and T cells actively triggers T cell activation and initiates targeted killing of the identified tumor cells.These antibodies have emerged as one of the most promising avenues within tumor immunotherapy.However,despite success in treating hematological malignancies,significant advancements in solid tumors have yet to be explored.In this review,we aim to address the critical challenges associated with T cellredirecting bispecific antibodies and explore novel strategies to overcome these obstacles,with the ultimate goal of expanding the application of this therapy to include solid tumors.

Overcoming tumor antigen heterogeneity in CAR-T cell therapy for malignant mesothelioma(MM)

Malignant mesothelioma(MM)is a rare,aggressive solid tumor with limited therapeutic options and poor therapeutic response.The role of immunotherapy in MM is now well established and therapeutic options,such as checkpoint inhibitors,are increasingly being approved.Chimeric antigen receptor(CAR)-T cell therapy is successfully implemented in several hematologic cancers,but currently has inadequate effect in solid tumors,owing to several limitations,such as trafficking and infiltration,limited T cell persistence and exhaustion,the immunosuppressive TME and tumor antigen heterogeneity.The lack of uniform and universal expression of tumor-associated antigens(TAAs)on tumor cells,as well as TAA heterogeneity following tumor editing post-therapy,are issues of significant importance to CAR-T cell and associated antigen-targeting therapies.Our review discusses the concept of tumor antigen heterogeneity in MM,the consequences for CAR-T cell therapies and the strategies to overcome it.

Synthesis of N(OMe)-linked TF antigen analogue

Tumor-associated carbohydrate antigens （TACAs）, important molecular markers on tumor cells, are major targets for the development of anti-cancer vaccines. However, due to the immunotolerance and weak immunogenicity, native TACAs cannot induce powerful immune response. The use of modified TACAs such as N-glycosides could be an alternative strategy to overcome this problem. Herein, the synthesis of N（OMe）-linked analogue of tumor-associated disaccharide antigen Thomsen-Friedenreich （TF） by the glycosylation reaction is described.

Persistence of tumor-infiltrating CD8 T cells is tumor-dependent but antigen-independent

How tumor-infiltrating lymphocytes(TILs)that are tumor-specific but functionally tolerant persist in the antigen-expressing tumor tissue is largely unknown.We have previously developed a modified TRansgenic Adenocarcinoma of the Mouse Prostate(TRAMP)model where prostate cancer cells express the T-cell epitope SIYRYYGL(SIY)recognized by CD8 T cells expressing the 2C T-cell receptor(TCR)(referred to as TRP-SIY mice).In TRP-SIY mice,activated 2C T cells rapidly become tolerant following infiltration into the prostate tumor.In this study,we show that tolerant 2C T cells persist in the prostate tumor of TRP-SIY mice by proliferating slowly in a tumor-dependent,but antigen-,interleukin(IL)-7-and IL-15-independent manner.We also show that disappearance of 2C T cells from the lymphoid organs of TRP-SIY mice are due to antigen-induced T-cell contraction rather than altered trafficking or generalized T-cell depletion in the mice.Finally,we show that clonal T cells unreactive to SIY are equally capable of persisting in the prostate tumor.These findings suggest that while functional tolerance of TILs is induced by antigen,persistence of tolerant TILs in the tumor tissue is mediated by a novel mechanism:slow proliferation independent of antigen and homeostatic cytokines.These results also allow CD8 T-cell survival in the tumor environment to be compared with T-cell survival in chronic infection.

mRNA cancer vaccines:Advances,trends and challenges

Patients exhibit good tolerance to messenger ribonucleic acid(m RNA)vaccines,and the choice of encoded molecules is flexible and diverse.These vaccines can be engineered to express full-length antigens containing multiple epitopes without major histocompatibility complex(MHC)restriction,are relatively easy to control and can be rapidly mass produced.In 2021,the U.S.Food and Drug Administration(FDA)approved the first m RNA-based coronavirus disease 2019(COVID-19)vaccine produced by Pfizer and Bio NTech,which has generated enthusiasm for m RNA vaccine research and development.Based on the above characteristics and the development of m RNA vaccines,m RNA cancer vaccines have become a research hotspot and have undergone rapid development,especially in the last five years.This review analyzes the advances in m RNA cancer vaccines from various perspectives,including the selection and expression of antigens/targets,the application of vectors and adjuvants,different administration routes,and preclinical evaluation,to reflect the trends and challenges associated with these vaccines.