以T细胞受体为基础的免疫疗法研究进展

T细胞是机体抗肿瘤免疫的核心,以T细胞功能调控为基础的免疫检查点疗法已经在多种肿瘤的临床治疗中取得了重大突破,以基因工程化T细胞为基础的过继性免疫细胞疗法在血液瘤治疗中取得了重要进展,免疫治疗已经对肿瘤的临床治疗产生了深刻变革,成为肿瘤临床治疗策略的重要组成部分。T细胞受体（T cell receptor,TCR）赋予了T细胞识别肿瘤抗原的特异性,能够识别由主要组织相容性复合体（major histocompatibility complex,MHC）呈递的包括胞内抗原在内的广泛肿瘤抗原,具有高度的抗原敏感性,因而具有广泛的抗肿瘤应用前景。2022年第一款TCR药物的上市开启了TCR药物开发的新纪元,多项TCR药物临床研究表现出潜在的肿瘤治疗价值。本文综述了以TCR为基础的免疫治疗策略研究进展,包括T细胞受体工程化T细胞（T cell receptor-engineered T cell,TCR-T）和TCR蛋白药物,以及基于TCR信号的其他免疫细胞疗法,以期为以TCR为基础的免疫治疗策略开发提供参考。     

个性化肿瘤新抗原疫苗中抗原肽预测研究进展

失控的突变导致肿瘤的发生,其中某些非同义突变(错义、移码、融合)多肽,被蛋白酶体降解成短肽后被抗原提呈细胞(antigen-presenting cells,APCs)识别,呈递至引流淋巴结,符合主要组织相容性复合物(major histocompatibility complex,MHC)结合基序的短肽,继而被T细胞表面因子捕获而产生免疫反应,引发肿瘤的消退,我们称之为"新抗原"(neoantigens).这类抗原由于未受胸腺的阴性筛选,被T细胞识别为"异类",不易受免疫耐受机制的影响,从而可作为免疫介导肿瘤治疗的有效靶点.新一代测序技术极大推动了新抗原疫苗的可行性,但从测序识别肿瘤的体细胞突变到TCR (Tcell receptor)识别新抗原产生免疫反应,中间存在着大量的候选假阳性新抗原多肽,这对于针对新抗原而设计疫苗无疑是难以跨越的障碍.一套有效合理的筛选方法,是新抗原疫苗制备过程中不可或缺的一环.然而国内未见相关综述报道,本文调研了目前新抗原免疫治疗过程中的新抗原肽预测及筛选研究进展.     

CD4+T细胞在肿瘤免疫治疗中的作用

近年来,人们对CD4 T细胞在肿瘤免疫治疗中的作用给予了极大的关注,CD4 T细胞不仅可通过IFN-γ依赖性等机制直接杀伤肿瘤细胞,而且在CD8 T细胞的激活、记忆性的细胞毒性T细胞(CTL)应答的产生、维持以及促进其存活等过程中发挥着重要作用,同时激活CD4 T细胞和CD8 T细胞是免疫治疗的理想策略;另外,CD4 CD25 调节性T细胞(Treg细胞)可能被肿瘤表达的自身抗原所诱导,与肿瘤免疫耐受的维持和抗肿瘤应答的下调有关,被认为是免疫治疗失败的主要原因,抑制该细胞亚群可增强治疗性肿瘤疫苗的临床效果.现就CD4 T细胞在肿瘤免疫治疗中的作用的研究进展作一综述.     

Nature:肿瘤特异性抗原表位检测,推动个体化肿瘤免疫治疗

<正>近日,来自德国的科学家在国际学术期刊nature发表文章,提出了一种靶向癌症病人全谱肿瘤特异性突变的个体化肿瘤免疫治疗方案。肿瘤特异性突变是癌症免疫治疗的理想靶向目标,因为它们在健康组织中不表达,因此能够作为新抗原被成熟T细胞所识别。但根据肿瘤特异性突变开发疫苗进行系统性癌症免疫治疗仍存在很大障碍,每个癌症病人都有其独特的肿瘤特异性突变存在,因此要先对其肿瘤特异性突变     

MHC分子与肿瘤免疫及治疗的研究进展

恶性肿瘤是危害人类生命健康的重大疾病,主要组织相容性复合体(major histocompatibility complex, MHC) I类分子和II类分子与肿瘤的发生、发展关系密切,近年来越来越受到人们的关注。MHC I类分子和II类分子的表达和调控影响着肿瘤细胞的增殖,并能够诱导肿瘤免疫,从而在一定程度上可抑制肿瘤细胞的增殖。根据肿瘤免疫中涉及的MHC分子参与的抗原递呈及T细胞受体识别等机理,在临床上可以为肿瘤治疗提供新的手段。因此,了解MHC分子与肿瘤免疫及治疗的最新研究进展非常必要。现从MHC分子的结构和功能、在肿瘤细胞中的表达及调控、与肿瘤免疫的关系及其在肿瘤免疫及治疗领域的应用等4个方面进行介绍,以期为肿瘤的免疫治疗等相关研究提供有意义的参考。     

乳腺癌免疫治疗：生物标志物、药物及疫苗

虽然近年来肿瘤的治疗取得较大进展,乳腺癌依旧是威胁女性健康的主要杀手。近年来,乳腺癌相关的免疫治疗取得较大进展,肿瘤浸润淋巴细胞(TILs)、程序性死亡受体 1(PD 1)及其配体PD L1、肿瘤突变负荷等肿瘤标志物对乳腺癌免疫治疗具有预测作用,并与乳腺癌的预后相关。免疫检查点抑制剂,例如PD-1/PD-L1及细胞毒性T淋巴细胞抗原4(CTLA 4)抑制剂在乳腺癌中取得极大进展,各期临床试验结果显示不同的效用。肿瘤疫苗的使用为乳腺癌免疫治疗的另一途径,虽然部分疫苗在临床试验中取得较好成效,但绝大多数仍需深入研究,乳腺癌免疫治疗之途仅为开端,依旧需要大量研究。本文简要介绍了乳腺癌免疫治疗相关的生物标志物、免疫检查点抑制剂以及肿瘤疫苗的研究进展。     

树突状细胞在肿瘤免疫治疗中的应用研究进展

树突状细胞（DC）是人体内最强的抗原提呈细胞。未成熟的DC可摄取抗原并迁移至淋巴器官,将抗原信息传递给免疫系统,引发免疫应答。研究表明,DC在启动抗肿瘤免疫中发挥着强大的功能。近年来,以DC为基础的肿瘤疫苗已成为肿瘤免疫治疗的热点。简要综述了各种DC疫苗的制备和临床应用。     

CAR-NK细胞在肿瘤免疫治疗中的研究进展

自然杀伤细胞(NK细胞)具有细胞毒性效应,无需抗原预先致敏,就能自发杀伤靶细胞,抵挡恶性肿瘤和病原的入侵,参与免疫监视和抗肿瘤应答免疫。嵌合抗原受体(chimeric antigen receptor,CAR)主要由来源于抗体的单链抗体(single-chain variable fragment,sc Fv)的胞外识别区和来自于T细胞抗原受体(TCR)的CD3ζ组成,能特异性地识别肿瘤细胞表面的抗原和通过胞内的信号传导区域激活淋巴细胞,增强淋巴细胞的靶向性和活性,从而杀伤多种肿瘤。目前大多数的CAR研究都集中在T细胞,但巨额的花费、额外的毒性等都极大地限制了CAR-T细胞的广泛应用。CAR-NK细胞因能提供一种安全、有效的抗肿瘤免疫治疗,受到越来越多的重视。主要阐述CAR-NK细胞在肿瘤免疫治疗中的最新研究进展,以期为后续免疫治疗研究和NK细胞研究提供参考。     

IL-15扩增的OT-Ⅰ细胞持续抑制小鼠黑色素瘤生长

过继免疫治疗(adoptive cell transfer,ACT)是肿瘤治疗中一种有效的免疫治疗手段,但是在没有化疗或者放疗等辅助治疗手段时,过继免疫治疗缓解肿瘤生长的效果非常短暂.为了探索一种更为有效的过继免疫治疗手段,我们使用白介素15(IL-15)体外扩增OT-ⅠCD8 T细胞,使其分化成为中央记忆性T细胞(central memory T cells,TCM),并将其过继转移至携带B16-OVA肿瘤的小鼠中.我们发现,与IL-2体外扩增的CD8 T细胞(effector T cells,TEFF)相比,TCM对肿瘤的生长具有长时间的缓解作用,而IL-2分化的TEFFs治疗肿瘤在短暂的缓解后反弹性生长.进一步的研究发现,TCM治疗的小鼠脾脏内肿瘤抗原特异性的T细胞数量和比例明显高于TEFF组,并且RT-PCR分析表明TCM治疗的小鼠肿瘤内细胞高表达MHCⅠ类分子.这些现象提示了抗原提呈对过继细胞转移治疗的效果具有重要作用.我们的研究对于发展更为有效的肿瘤免疫治疗具有提示意义.     

肿瘤疫苗的研究进展

作为一种前景光明的肿瘤治疗方式,肿瘤疫苗能帮助机体产生针对肿瘤抗原的特异性免疫应答和长期的免疫记忆来治疗肿瘤,是癌症免疫治疗领域重要的研究方向。目前,肿瘤疫苗按制剂方式主要可以分为四类,即细胞疫苗、病毒疫苗、多肽类疫苗和核酸类疫苗。这些疫苗能通过增强机体内抗肿瘤免疫反应而发挥清除肿瘤细胞、抑制肿瘤生长的功能。该综述将对肿瘤疫苗的作用机制、基础研究与临床试验的最新进展进行讨论,以期为深入理解肿瘤疫苗、开发新型肿瘤疫苗提供有益的参考。     

Melanoma cancer vaccines and anti-tumor T cell responses

Melanoma is a disease which has been shown to be responsive to immune intervention. This has been suggested by reports of spontaneous responses of metastatic disease with strong immune infiltrates, and supported by recent data correlating clinical response after IFNalpha treatment with development of generalized autoimmunity. Since the identification of melanoma-associated tumor antigens, many groups have performed clinical trials to take advantage of this discovery with melanoma-specific cancer vaccines. These trials, in which multiple antigen delivery strategies have been tested in hundreds of patients, have demonstrated that these vaccines are safe, immunogenic, and yield a low frequency of objective clinical responses. The ability to perform careful immunological monitoring has allowed important insights into the nature of the anti-tumor immunity generated by these vaccinations. While many trials have found that the absolute frequency of T cells specific for a vaccine-encoded antigen are a marker of immunization, it does not correlate with objective clinical response. Induction of broad immunity to multiple tumor antigens, taking advantage of cross-reactive T cells and activation of persistent T cells may be more important. Harnessing additional modes of amplifying immune responses (lymphodepletion, cytokine support, inhibition of negative immune self-regulation) are now being tested and should improve clinical responses from 5% to 10% complete response seen currently.     

DNA fusion vaccines enter the clinic

Induction of effective immune attack on cancer cells in patients requires conversion of weak tumor antigens into strong immunogens. Our strategy employs genetic technology to create DNA vaccines containing tumor antigen sequences fused to microbial genes. The fused microbial protein engages local CD4+ T cells to provide help for anti-tumor immunity, and to reverse potential regulation. In this review, we focus on induction of CD8+ T cells able to kill target tumor cells. The DNA vaccines incorporate tumor-derived peptide sequences fused to an engineered domain of tetanus toxin. In multiple models, this design induces strong CD8+ T-cell responses, able to suppress tumor growth. For clinical relevance, we have used “humanized” mice expressing HLA-A2, successfully inducing cytolytic T-cell responses against a range of candidate human peptides. To overcome physical restriction in translating to patients, we have used electroporation. Clinical trials of patients with cancer are showing induction of responses, with preliminary indications of suppression of tumor growth and evidence for clinically manageable concomitant autoimmunity.     

Lessons to be learned from primary renal cell carcinomas: novel tumor antigens and HLA ligands for immunotherapy

The lack of sufficient well-defined tumor-associated antigens is still a drawback on the way to a cytotoxic T-lymphocyte-based immunotherapy of renal cell carcinoma (RCC). We are trying to define a larger number of such targets by a combined approach involving HLA ligand characterization by mass spectrometry and gene expression profiling by oligonucleotide microarrays. Here, we present the results of a large-scale analysis of 13 RCC specimens. We were able to identify more than 700 peptides, mostly from self-proteins without any evident tumor association. However, some HLA ligands derived from previously known tumor antigens in RCC. In addition, gene expression profiling of tumors and a set of healthy tissues revealed novel candidate RCC-associated antigens. For several of them, we were able to characterize HLA ligands after extraction from the tumor tissue. Apart from universal RCC antigens, some proteins seem to be appropriate candidates in individual patients only. This underlines the advantage of a personalized therapeutic approach. Further analyses will contribute additional HLA ligands to this repertoire of universal as well as patient-individual tumor antigens.Tobias Krüger and Oliver Schoor contributed equally to this work.     

Heat shock protein–peptide complexes as immunotherapy for human cancer

Heat shock proteins (Hsps), ubiquitous in nature, act as chaperones for peptides and other proteins. They have been implicated in loading immunogenic peptides onto major histocompatibility complex molecules for presentation to T cells. When isolated from tumor cells, Hsps are complexed with a wide array of peptides, some of which serve as tumor-specific antigens. Animal studies have demonstrated that heat shock protein–peptide complexes (HSPPCs) from tumor cells can act as vaccines to prevent or treat tumors. Potent and specific tumor antigens have long been the holy grail in cancer immunotherapy; HSPPCs from tumor cells could become a safe and reliable source of tumor-specific antigens for clinical application.     

The reverse proteomics for identification of tumor antigens

The identification of tumor antigens is essential for the development of anticancer therapeutic vaccines and clinical diagnosis of cancer. SEREX (serological analysis of recombinant cDNA expression libraries) has been used to identify such tumor antigens by screening sera of patients with cDNA expression libraries. SEREX-defined antigens provide markers for the diagnosis of cancers. Potential diagnostic values of these SEREX-defined antigens have been evaluated. SEREX is also a powerful method for the development of anticancer therapeutics. The development of anticancer vaccines requires that tumor antigens can elicit antigen-specific antibodies or T lymphocytes. More than 2000 antigens have been discovered by SEREX. Peptides derived from some of these antigens have been evaluated in clinical trials. This review provides information on the application of SEREX for identification of tumor-associated antigens (TAA) for the development of cancer diagnostics and anticancer therapeutics.     

Immune responses against allogeneic and syngeneic tumors in aged C57BL/6 mice

Aged C57BL/6 (B6) mice could reject allogeneic BALB/c RL male 1 tumor as efficiently as young B6 mice. However, in vitro analysis showed impaired generation of cytotoxic T cell response in aged B6 mice against allogeneic tumor. The reaction could be augmented by the addition of recombinant interleukin-2 (rIL-2). Enzyme-linked immunospots (ELISPOT) produced by CD8+ T cells purified from spleen cells showed no reduction in aged mice. The findings suggested that the number of CD8+ T cells capable of reacting against allogeneic H-2 antigens was similar in young and aged B6 mice. Low cytotoxic T lymphocyte (CTL) responsiveness in aged B6 mice appeared to have resulted from low responsiveness of CD4+ T cells producing IL-2. Although CTL generation was apparently impaired, strong multiple antigenicity of allogeneic tumor evoked a rejection response in aged B6 mice. On the other hand, no rejection response was observed against syngeneic EL4 tumor in aged B6 mice even after depletion of CD4+ CD25+ immunoregulatory cells. Depletion of CD4+ CD25+ cells caused rejection of EL4 tumor in young B6 mice. The findings suggested that aged B6 mice were incapable of inducing effector cells against weak tumor antigens. Only marginal CTL response and small number of ELISPOTs were generated in young but not aged B6 mice against EL4. Addition of rIL-2 to the culture augmented EL4 killing and ELISPOTs in spleen cells from young and aged B6 mice.     

A listing of human tumor antigens recognized by T cells: March 2004 update

The technological advances occurred in the last few years have led to a great increase in the number of tumor associated antigens (TAA) that are currently available for clinical applications. In this review we provide a comprehensive list of human tumor antigens as reported in the literature updated at Feburary 2004. The list includes all T cell-defined epitopes, while excluding analogs or artificially modified epitopes, as well as virus-encoded and antibodies-recognized antigens. TAAs are listed in alphabetical order along with the epitope sequence and the HLA allele which restricts recognition by T cells. Data on the tissue distribution of each antigen are also provided together with an extensive bibliography that allows a rapid search for any additional information may be needed on each single antigen or epitope. Overall, the updated list is a database tool for clinicians, scientists and students who have an interest in the field of tumor immunology and immunotherapy.     

Minor structural changes in a mutated human melanoma antigen correspond to dramatically enhanced stimulation of a CD4+ tumor-infiltrating lymphocyte line

While most immunotherapies for cancer have focused on eliciting specific CD8+ cytotoxic T lymphocyte killing of tumor cells, a mounting body of evidence suggests that stimulation of anti-tumor CD4+ T cell help may be required for highly effective therapy. Several MHC class II-restricted tumor antigens that specifically activate such CD4+ helper T lymphocytes have now been identified, including one from a melanoma tumor that is caused by a single base-pair mutation in the glycolytic enzyme triosephosphate isomerase. This mutation results in the conversion of a threonine residue to isoleucine within the antigenic epitope, concomitant with a greater than five log-fold increase in stimulation of a CD4+ tumor-infiltrating lymphocyte line. Here, we present the crystal structures of HLA-DR1 in complex with both wild-type and mutant TPI peptide antigens, the first structures of tumor peptide antigen/MHC class II complexes recognized by CD4+ T cells to be reported. These structures show that very minor changes in the binding surface for T cell receptor correspond to the dramatic differences in T cell stimulation. Defining the structural basis by which CD4+ T cell help is invoked in an anti-tumor immune response will likely aid the design of more effective cancer immunotherapies.     

Augmentation by serum-induced helper cells of T cell-mediated cytotoxic response against tumor associated antigens and alloantigens

Summary In vitro T cell-mediated cytotoxic responses to tumor associated antigens or alloantigens can be augmented by the addition of small amounts (0.1 to 1%) of syngeneic (mouse) or xenogeneic (rabbit) serum in the standard lymphocyte culture medium. Further studies showed that the augmentation is mediated by helper cells, which are induced by culturing the spleen cells or lymph node cells in the presence of these sera. In the syngeneic system performed with mixed lymphocyte tumor cell cultures (MLTC), the serum-induced helper cells are found to be resistant to the lysis of anti-Thy 1.2 antibody and are radioresistant; thus they have the characteristics of macrophages. In the allogeneic system performed with mixed lymphocyte culture (MLC), the serum-induced helper cells are also found to be resistant to the lysis of anti-Thy 1.2 antibody but are radiosensitive. In the latter case, however, removal of T cells abolishes the helper cell generation and only the T cell-enriched fraction provides for the generation of helper cells, indicating that the helper cells for MLC are probably derived from T cells but lose their susceptibility to anti-Thy 1.2 antibody lysis upon culturing in vitro. A study of the mode of action of the helper cells for MLC showed that they are probably needed at a later stage of cytotoxic response for the amplification of the killing efficiency of the T effector cells whereas the helper cells for MLTC are needed in the early induction phase of the immune response. These results indicate that although serum can augment the cytotoxic responses both in the syngeneic and in the allogeneic systems, the mechanism for the augmentation differs: macrophagelike helper cells are responsible for the augmentation of cytotoxic response to tumor associated antigens, whereas augmentation of cytotoxic response to alloantigens appears to be mediated by a subpopulation of T helper cells. Supported by a grant from the Japan Society for the Promotion of Science (T. I.).