Targeting cytotoxic T lymphocytes for cancer immunotherapy

In light of their preeminent role in cellular immunity, there is considerable interest in targeting of cytotoxic T-lymphocytes to cancer. This review summarises the active and passive immunotherapeutic approaches under development to achieve this goal, emphasising how recent advances in tumour immunology and gene transfer have impacted upon this field.     

Adoptive immunotherapy by avidin-driven cytotoxic T lymphocyte-tumor bridging

We have shown previously that T cells, tagged with biotinylated anti-CD3 antibody fragments, can exert avidin-dependent cytolytic activity on suitably biotinylated tumor cells in vitro. In this study, we demonstrate that avidin-driven CTL-tumor bridging in vivo leads to growth inhibition of murine tumors WEHI-164 fibrosarcoma and RMA lymphoma. The biodistribution of biotin-tagged 111In-labeled T cells demonstrated a selective avidin-dependent and time-dependent accumulation of radioactivity at tumor sites. The specificity of lymphocyte tumor localization was demonstrated by the concurrent time-dependent decrease of radioactivity in the blood and in all other organs. Furthermore, we documented a therapeutic effect of the adoptively transferred T cells, i.e., a significant delay of tumor growth at early stages. All of the experiments included a control group of mice, which received all of the reagents, except avidin. These avidin-minus mice showed no specific localization and no delay in tumor growth, indicating that avidin bridging was essential for T-cell activity at tumor sites.     

Adoptive immunotherapy for pancreatic cancer: cytotoxic T lymphocytes stimulated by the MUC1-expressing human pancreatic cancer cell line YPK-1

MUC1 is a tumor-associated antigen that is overexpressed in invasive ductal carcinomas of the pancreas (PC). MUC1-specific cytotoxic T lymphocytes (CTLs) recognize MUC1 molecules in a HLA-unrestricted manner. In this study, we performed adoptive immunotherapy (AIT) in patients with PC with CTLs stimulated by the MUC1-expressing human PC cell line YPK-1. To induce CTLs, peripheral blood mononuclear cells (PBMCs) were cultured for 3 days with inactivated YPK-1 cells and then stimulated with interleukin (IL)-2 for 7 days. The cytotoxicity of these cells against human cancer cell lines was analyzed, and a variety of antibodies were evaluated for their ability to inhibit cytotoxicity. We treated 8 patients with unresectable PC and 20 patients with resectable PC postsurgically. CTLs were induced as described above, suspended in 100 ml saline and injected intravenously. Induced CTLs were cytotoxic against 5 MUC1-expressing PC cell lines and a breast cancer cell line, regardless of the HLA phenotype. Low cytotoxicity was observed in 7 MUC1-negative cancer cell lines. Anti-CD3 monoclonal antibody (mAb) or anti-CD8 mAb strongly inhibited cytotoxicity against YPK-1, whereas anti-class I mAb showed no inhibition. YPK-1 cells incubated with anti-MUC1 mAb also showed low cytotoxicity. Clinically, the median survival time was 5.0 months for patients with unresectable PC treated with AIT. None of the 5 patients without liver metastasis showed hepatic recurrence. The median survival time was 17.8 months for 18 out of 20 patients with resectable PC who underwent curative surgery, and the 1-, 2- and 3-year survival rates after surgery were 83.3, 32.4, and 19.4%, respectively. Liver metastasis was found in only one patient and no side effects of AIT were observed. CTLs stimulated by a MUC1-expressing human pancreatic cancer cell line showed a strong tumor cytotoxic activity in a MUC1-specific and MHC-unrestricted manner. AIT with stimulated CTLs significantly suppressed the postsurgical hepatic recurrence of PC. Adjuvant immunotherapy with CTLs may be useful in the postsurgical treatment of PC.     

T lymphocytes isolated from patients with advanced colorectal cancer are suitable for gene immunotherapy approaches

Despite improvements in treatment, the 5-year survival for metastatic colorectal cancer remains poor. Novel approaches such as gene immunotherapy are being investigated to improve treatment. Retroviral gene transfer methods have been shown to transduce primary human T lymphocytes effectively resulting in the expression of therapeutic genes. However, a number of defects have been identified in T lymphocytes isolated from patients bearing tumour, which may have critical implications for the development of gene-targeted T cells as an anticancer therapy. To address this issue, primary T lymphocytes were isolated from patients with advanced colorectal cancer and tested for their ability to be transduced and to express subsequently a chimeric immune receptor consisting of a single-chain antibody fragment antigen-binding moiety specific for carcinoembryonic antigen (CEA) fused to the T cell receptor (TCR) CD3zeta chain. In 10 out of 10 patients, T lymphocytes were transduced, expanded in the absence of selection and tested for functional activity against CEA-expressing tumour cells. In each case, functional-specific cytotoxic activity was observed. Negligible activity was found in control cultures. This study highlights the feasibility of patient-derived T lymphocytes as a source of immune cells for autologous gene immunotherapy approaches.     

Clinical efficacy of adoptive immunotherapy by IL-4 activated tumor-infiltrating lymphocytes in patients with advanced cancer

Background Adoptive immunotherapy using tumor-infiltrating lymphocytes (TILs) has been used to treat malignant melanoma and renal cell carcinoma, although the clinical efficacy of this method has not yet been proved. To improve clinical efficacy, it is important to induce sufficient amounts of tumor-infiltrating lymphocytes to fight the tumor. In this study, we investigated the clinical efficacy of adoptive immunotherapy using interleukin (IL)-2 activated tumor-infiltrating lymphocytes combined with IL-4. Methods Tumor-infiltrating lymphocytes from patients with non-malignant melanoma and non-renal cell carcinoma were cultured with IL-2 monotherapy (n=10) and combination therapy with IL-4+IL-2 (n=20). Comparing the 2 groups, we investigated the clinical benefits of adoptive immunotherapy, considering safety, clinical efficacy, survival periods, and quality of life. Results By using the IL-4+IL-2 combination, we successfully transferred 6.5 times more activated tumor-infiltrating lymphocytes, as compared to cell counts using IL-2 monotherapy. The response rate achieved was 58.8% (2 complete and 8 partial responses) without any side effects in the IL-4+IL-2 group. Furthermore, the IL-4+IL-2 group had longer survival periods and improved quality of life, compared to the IL-2 monotherapy group. Conclusion The IL-4+IL-2 combination improved the clinical efficacy of adoptive immunotherapy, and improved quality of life in patients with non-malignant melanoma and non-renal cell carcinoma.     

表达嵌合T细胞受体的T淋巴细胞介导的肿瘤过继性免疫治疗作用研究

目的:构建嵌合T细胞受体(chimeric T cell receptor,chTCR),它包括识别肿瘤相关抗原erbB2的单链抗体、共刺激分子CD28和CD3的信号转导链ζ,将其依次克隆入载体pcDNA3中,电转染入人外周血T淋巴细胞,使嵌合T细胞受体在T细胞表面表达,并验证其在体外和体内的抗肿瘤作用,为肿瘤的过继性免疫治疗提供新思路。方法:抗erbB2的单链抗体(由本所保存),人CD28分子的部分胞外段、跨膜区和胞内段,CD3ζ链的胞内段(分别由RT-PCR的方法获得)依次克隆入载体pcDNA3中,经酶切鉴定正确后,电转染进入人外周血T淋巴细胞,利用流式细胞仪检测T细胞结合Her2蛋白的功能;细胞杀伤试剂金检测T细胞的抗原特异性杀伤功能;并在裸鼠体内验证其对人的乳腺癌细胞株BT-474移植瘤的杀伤效应。结果:成功构建了抗erbB2嵌合T细胞受体并表达在人的T淋巴细胞表面,体外证明能结合Her2肿瘤抗原,并有抗原特异性的杀伤功能,在BALB／c裸鼠体内对表达erbB2的肿瘤细胞BT～474有显著的抑制肿瘤生长的作用。结论:表达嵌合T细胞受体的T淋巴细胞在体外和体内有抗原特异性的杀伤肿瘤的作用,是一种新的肿瘤过继性的免疫治疗策略。     

Cyclin D1-specific cytotoxic T lymphocytes are present in the repertoire of cancer patients: implications for cancer immunotherapy

PURPOSE: Cyclin D1, a key cell cycle regulator, is overexpressed in multiple types of cancer. Such tumor-associated genes may be useful targets for cancer immunotherapy. Nevertheless, it had previously been suggested that efficient T cells recognizing cyclin D1-derived epitopes are absent from the repertoire because of thymic deletion. We attempted to induce autologous CTL from healthy donors and patients with cyclin D1-overexpressing tumors using a highly efficient T-cell expansion system based on CD40-activated B cells as antigen-presenting cells. EXPERIMENTAL DESIGN: Cyclin D1-derived, HLA-A*0201-restricted epitopes were predicted by multiple computer algorithms, screened in HLA-A2-binding assays, and used for T-cell stimulation. The generated CTL lines and clones were analyzed by IFN-gamma enzyme-linked immunosorbent spot assay or cytolysis assay. RESULTS: After screening, at least two naturally processed and presented HLA-A*0201-binding cyclin D1 epitopes were identified. CTL specific for these epitopes could be successfully generated from HLA-A2(+) donors. T cells efficiently recognized target cells pulsed with the cognate peptide and cyclin D1-expressing tumor cell lines in an HLA-A*0201-restricted manner. More importantly, HLA-A*0201-matched, primary cyclin D1(+) tumor cells were efficiently recognized by cyclin D1-specific CTL. These CTL could be generated from patients with mantle cell lymphoma and cyclin D1(+) colon cancer. CONCLUSIONS: These results underscore that cyclin D1 needs to be considered as a target for broad-based antitumor immunotherapy.     

肿瘤的过继性细胞免疫疗法

Adoptive cellular immunotherapy (ACI) achieves the elimination and control of tumor by mobilizing the body's immune function. It also has targeted efficacy and mild untoward effects. Cytokine-induced killer cells and tumor-infiltrating lymphocytes have been widely used in clinic and have obtained preliminary efficacy. With the development and clinical application of the specific gene transfer of T cell, it will further increase the efficacy of immunotherapy. At present, improving cell culture technology and cell function and using with other treatment are the key links to improve the efficacy of ACI.     

Clinical application of adoptive immunotherapy by cytotoxic T lymphocytes induced from tumor-infiltrating lymphocytes

The tumor-infiltrating lymphocytes (TIL) were cultured with interleukin 2 (IL-2) to induce the cytotoxic T lymphocytes possessing autologous tumor-killing activity from 21 cancer patients (11 with solid tumor and 10 with malignant peritoneal or pleural effusions), and transferred into 7 patients as IL-2-activated TIL adoptively. The clinical application of activated TIL by adoptive transfer could result the complete regression of malignant pleural effusions in a patient with pancreatic cancer, and the nearly complete regression of malignant ascites in a patient with gastric cancer. The autologous tumor cells were isolated at the purity of more than 90% by Ficoll-Hypaque and Percoll discontinuous gradients, and then the TIL were cultured with IL-2 until 4 weeks. The optimal concentration of IL-2 was 1,500 IU/ml to obtain maximum proliferation and autologous tumor killing activity. The cytotoxic activities of activated TIL at 3 weeks-incubation was 72 +/- 15, 42 +/- 26, 27 +/- 21 and 22 +/- 15% against K562, Daudi, KATO-III and autologous tumor, respectively. By negative selection method, it was clarified that the killer cells recognizing autologous tumor consisted of CD4 or CD8 positive T lymphocyte in 43% of patients. The CD8 positive cells and CD56 positive cells increased, the CD4 positive cells and CD16 positive cells decreased by flow cytometry. The activated TIL could lyse not only cultured tumor cell lines, also other autologous tumor cells. The CD56+ cells were isolated by the Panning method, these cells could not lyse autologous tumor cells. Thus, it was indicated that the cytotoxic T lymphocytes recognizing autologous tumor could be generated from TIL and the adoptive immunotherapy of activated TIL was effective in cancer therapy.     

Adoptive immunotherapy for recurrent glioblastoma multiforme using lymphokine activated killer cells and recombinant interleukin-2

Thirteen patients with recurrent glioblastoma were treated with adoptively transferred autologous lymphokine activated killer (LAK) cells and recombinant interleukin-2 (rIL-2). Patients' blood mononuclear cells (MNC) obtained by leukapheresis were cultured at 2.5 million MNC per ml for 3 to 5 days in media containing 1000 U rIL-2/ml. After incubation, the nonadherent MNC from all cultures (0.5-5 X 10(9] were combined and concentrated for infusion in 5 to 10 ml saline containing 10(6) U rIL-2. Nine patients received one injection of LAK cells and rIL-2 into the brain tissue immediately surrounding the tumor cavity during craniotomy for subtotal tumor removal (Group 1). On each of the 3 days after surgery, patients received boosters of 10(6) U rIL-2 delivered into the tumor cavity through a skin flap or via an Ommaya reservoir. Approximately 1 to 2 weeks after this series of injections, these patients were treated with a second cycle of LAK cells and rIL-2 injected into the tumor cavity using the reservoir. Four patients received both adoptive immunotherapy cycles by intracavitary injection (Group 2). In this relatively small patient pool, neither age, sex, Karnofsky score, treatment history, nor anticonvulsant and steroid dosage appeared to influence a patient's ability to make LAK cells. The therapy, itself, was well-tolerated by all patients although they all displayed symptoms of aseptic meningitis and increased intracranial pressure, i.e., headache, fever, malaise on the days of LAK cell and/or rIL-2 infusion. The therapy did not appear to have a significant impact on patient survival (mean, 30 weeks) especially for those patients with a high postsurgical tumor burden. As the therapy is safe, the authors believe its efficacy can best be tested in patients with a newly diagnosed or recurrent glioblastoma which lies in an area where a near-total resection is possible.     

Adoptive immunotherapy using autologous lymphocytes sensitized with HLA class I-matched allogeneic tumor cells

A 29-year-old female breast cancer patient with multiple bone metastases (HLA-A2) was treated with adoptive transfer using autologous peripheral blood mononuclear cells (PBMCs) activated with the HLA-A2-matched allogeneic GC022588 gastric cancer cell line and interleukin-2 plus an immobilized anti-CD3 antibody culture system. The relief of bone pain in parallel with a decrease of serum carcinoembryonic antigen levels was obtained just after the administration of GC022588-activated effector lymphocytes, and a good quality of life was accomplished for 4 months. The GC022588-activated effector lymphocytes included 44% CD4+, 77% CD8+, and 26% CD4+CD8+ phenotypes, and expressed 25% killing activity against GC022588 stimulator cells at an E/T ratio of 50:1. T cell receptor (TCR) usage analysis for the effector cells showed oligoclonal expression of TCRVbeta1, 3, 9, and 11, especially TCRVbeta5.2, 12, 13.1 and 17, and their killing activity was significantly inhibited in the presence of anti-TCRalphabeta antibody and anti-TCRVbeta12 antibody. SSCP analysis revealed clonotypic bands of TCRVbeta12. These results suggest that shared antigens exist between breast and gastric adenocarcinomas. Allogeneic tumor cells can stimulate PBMCs to generate effector cells with selected TCRCDR3 usages that recognize tumor antigens. These effector lymphocytes may be good candidates for the adoptive immunotherapy of cancer.     

In vitro induction of potent tumor-specific cytotoxic T lymphocytes using TLR agonist-activated AML-DC

Dendritic cells (DCs) are recognized as key regulators of the immune system. Active DC immunization protocols are quickly obtaining interest as an alternative therapeutic approach in acute myeloid leukemia patients. Despite apparent progress in DC-based immunotherapy, some discrepancies were reported in generating potent DCs and their source. In addition to monocytes, DCs can be differentiated from leukemic blasts of acute myeloid leukemia (AML) patients (AML-DC) possessing the ability of stimulating anti-leukemic immune response. In this study, we differentiated peripheral blood blasts of 16 out of 20 AML patients in vitro in the presence of GM-CSF and IL-4 into immature AML-DC. Then, DCs matured using different combinations of Toll-like receptor (TLR) ligands to obtain functional DCs as demonstrated by cell morphology, immunophenotype, and functional activity. Autologous cytotoxic T cell induction of matured DCs was evaluated in four patients and compared with immature counterparts. Our results showed that although the TLR3 agonist (Poly I:C) has a synergistic effect on the TLR4 agonist (lipopolysaccharide, LPS), the addition of the TLR7/8 agonist (R848) is necessary to reinforce the effect of LPS or LPS?+?POLY(I:C) to produce efficient DCs with the higher level of IL-12 (30 to 90 times). Such DCs activate allogeneic T cells and effectively prime autologous cytotoxic T cells in vitro. In contrast, FSL-1 as a TLR2/6 agonist has a negative effect on LPS?+?Poly(I:C) and LPS?+?R848 to produce IL-12. Thus, DCs prepared using a maturation mixture including a TLR7/8 agonist may be used as a potential tool for DC-based immunotherapy purposes in leukemic patients.     

Adoptive transfer of tumor cytotoxic macrophages generated in vitro from circulating blood monocytes: a new approach to cancer immunotherapy.

Cells of the macrophage lineage are considered to be of special importance in the defense of the host against tumor development and spread. Immunotherapeutic strategies to stimulate macrophage (MAC) tumor cytotoxicity make use of activating compounds such as gamma-interferon which are given systemically. However, there are several lines of evidence that in malignant disease the generation of cytotoxic effector MACs is impaired. Both defective cell maturation and loss of responsiveness to activation are described. Here, a first clinical phase I trial of adoptive immunotherapy in cancer patients using autologous MACs generated in vitro from blood monocytes (MOs) is reported. Mononuclear cells were isolated by cytapheresis and density centrifugation and cultured in hydrophobic Teflon bags for 7 days with 2% autologous serum and recombinant human gamma-interferon being present for the last 18 h. Cytotoxic MO-derived MACs were then purified by countercurrent elutriation and reinfused into the patient. A total of 72 therapies have been performed with patients being treated i.v. (n = 8) and i.p. (n = 7). In vitro generated MACs proved to be mature as judged by the expression of maturation-associated surface molecules (MAX antigens, CD16, CD51, CD71), were cytotoxic to U937 tumor cells, and were efficient secretory cells. Cell dose escalation was performed in the first patients beginning with 10(8) MACs to finally infuse the total number of cells recovered from one single cycle of isolation and culture. MAC yield varied from 1 to 17 x 10(8) representing 13-79% of MOs initially seeded. Adoptive MAc transfer was well tolerated. Side effects observed were low-grade fever (less than 38.5 degrees C), induction of the coagulation cascade, and abdominal discomfort after i.p. application. The procoagulant activity of MAC autografts was cell dose dependent and demonstrated by detection of circulating fibrin monomers and thrombin-antithrombin complexes. Biological responses observed included elevated serum neopterin levels and the appearance of interleukin-6 in sera and ascitic fluids. Indication of a possible therapeutic effect was only observed in i.p.-treated patients and consisted of disappearance of malignant ascites in 2 of 7 patients.     

Alpha-interferon activated cytotoxic lymphocytes in hairy cell leukemia patients: evaluation of cytotoxic events

To further define the mechanisms responsible for the alpha-interferon (alpha-IFN) efficacy in the treatment of hairy cell leukemia (HCL), experiments were carried out to specify the cytotoxic events taking place following this type of therapy. Although an increased natural killer (NK) activity was demonstrable after alpha-IFN treatment, evidence has been provided that hairy cells were not specifically lysed either by fresh autologous/allogenic NK lymphocytes or by lymphokine activated killer (LAK) cells. This property could not be induced in vitro by alpha-IFN or by interleukin-2 (IL-2). Our data favour the hypothesis that the increase of NK cell activity observed following alpha-IFN therapy has not a direct antineoplastic effect but is likely to be of relevance for a non-specific enhancement of the host immune system. In alpha-IFN treated HCL this latter property may account for the better resistance to infections which usually represents the major cause of mortality in these patients.     

Tetramer-blocking assay for defining antigen-specific cytotoxic T lymphocytes using peptide-MHC tetramer

Peptide-MHC tetramers have been engineered to allow accurate detection of antigen-specific cytotoxic C lymphocytes (CTL) by flow cytometry. Here, we propose a novel use for peptide-MHC tetramers in the specific and sensitive analysis of the cytotoxic function of antigen-specific CTL by blocking MHC-restricted antigen-specific cytotoxicity. We found that pretreatment of ovalbumin (OVA)-specific CD8(+) CTL (OT-1 CTL), derived from OT-1 T-cell receptor (TCR)-transgenic mice, with OVA(257-264) peptide-H-2K(b) tetramer caused a marked inhibition of the cytotoxicity against OVA-expressing EG-7 tumor cells. OVA(257-264) peptide-H-2K(b) tetramer did not block the cytotoxicity mediated by 2C mouse (H-2(b))-derived CD8(+) CTL, which recognize allo (H-2L(d)) antigens. Moreover, OT-I CTL activity was not inhibited by an irrelevant HBV(208-216) peptide-H-2K(b) tetramer. These results indicate that the blocking of CTL activity with peptide-MHC tetramer was caused by interference with the interaction between the TCR and H-2K(b)-OVA(257-264) peptide complex, but not with the CD8-MHC class I interaction. The blocking activity of OVA(257-264) peptide-H-2K(b) tetramer was reversible because OT-I CTL pretreated with the tetramer recovered their cytotoxicity after culturing with interleukin-2 for 24 h. The same results were also demonstrated in freshly isolated, in vivo-primed OT-1 CTL sorted by the tetramer. These results demonstrate that peptide-MHC tetramer is a useful tool for defining MHC-restricted antigen-specific CTL function. Moreover, our finding implies that the measurement of CTL activity immediately after tetramer-guided sorting is not a suitable method for evaluating the function of in vivo-induced tetramer-positive CTL. We believe that the tetramer-blocking assay presented here will be useful for functionally monitor the induction of MHC-restricted antigen-specific CTL during vaccination therapy against tumor and infectious diseases.     

Fibronectin promotes the proliferation of cytotoxic T lymphocytes generated from cancer patients.

We studied whether fibronectin (FN) enhances the activity of autologous tumour-reactive cytotoxic T lymphocytes (CTLs) generated from cancer patients. The proliferation of CTLs stimulated by immobilised anti-CD3 monoclonal antibody and interleukin 2 (IL-2) was enhanced three or four times by immobilised FN. whereas soluble FN did not alter the DNA synthesis of CTLs. Moreover, the cytotoxic activity of CTLs was augmented by FN stimulation against autologous tumour cells [4 h 51Cr release assay: FN(+) 16.7 +/- 4.7% vs FN (-) 11.8 +/- 3.1%; 16 h 51Cr release assay: FN(+) 24.8 +/- 4.7% vs FN (-) 16.5 +/- 5.7%, P<0.05]. The major cell surface phenotype of CTLs with FN was CD3+, CD4+ and CD25+ in 6 weeks'' culture. Cytotoxicity against autologous tumour cells was inhibited by anti-HLA class I monoclonal antibody (MAb). The autologous tumour-killing activity of CTLs was suppressed by the elimination of CD4+ cells. Moreover, the cytokine production of CTLs was augmented by FN stimulation. Especially, the production of IL-2, interferon gamma (IFN-gamma), and granulocyte macrophage colony-stimulating factor (GM-CSF) was significantly augmented by FN stimulation (P<0.05). Thus, CTLs generated by FN might have both killer and helper functions, since they could lyse autologous tumour cells and secrete various cytokines, including IL-2.     

T lymphocytes related biomarkers for predicting immunotherapy efficacy in non-small cell lung cancer

The immune environment is a determinant of whether patients with cancer can benefit from immunotherapy. Immune checkpoint inhibitors (ICIs) have improved the prognosis of patients with different types of malignancies and have initiated a transformation in tumor therapy. However, some patients cannot achieve a long-term response and several patients even have no response to ICIs therapy. Thus, potential biomarkers that can effectively predict the efficacy of ICIs are essential for their clinical application and for the selection of patients. The accuracy of well-known biomarkers, such as expression of programmed cell death ligand 1 and tumor mutational burden, remains controversial. One of the critical factors for immune responses in the tumor microenvironment is tumor antigen-specific T cell. The density and distribution of tumor-infiltrating lymphocytes, T cells activation and T lymphocytes phenotypes in peripheral blood and serum cytokines have been observed in different types of solid cancer. Although the association with immunotherapy prognosis is in dispute, the prospect of T cell-related biomarkers is encouraged. The present review discusses whether these factors are associated with clinical outcomes of patients with non-small cell lung cancer. The association between several serum cytokines and ICIs therapy efficacy is also discussed.