T-cell clones that react against autologous human tumors

Artificial intelligence for quantifying immune infiltrates interacting with stroma in colorectal cancer

Background

We proposed an artificial intelligence-based immune index, Deep-immune score, quantifying the infiltration of immune cells interacting with the tumor stroma in hematoxylin and eosin-stained whole-slide images of colorectal cancer.

Methods

A total of 1010 colorectal cancer patients from three centers were enrolled in this retrospective study, divided into a primary (N = 544) and a validation cohort (N = 466). We proposed the Deep-immune score, which reflected both tumor stroma proportion and the infiltration of immune cells in the stroma region. We further analyzed the correlation between the score and CD3⁺ T cells density in the stroma region using immunohistochemistry-stained whole-slide images. Survival analysis was performed using the Cox proportional hazard model, and the endpoint of the event was the overall survival.

Result

Patients were classified into 4-level score groups (score 1–4). A high Deep-immune score was associated with a high level of CD3⁺ T cells infiltration in the stroma region. In the primary cohort, survival analysis showed a significant difference in 5-year survival rates between score 4 and score 1 groups: 87.4% vs. 58.2% (Hazard ratio for score 4 vs. score 1 0.27, 95% confidence interval 0.15–0.48, P < 0.001). Similar trends were observed in the validation cohort (89.8% vs. 67.0%; 0.31, 0.15–0.62, < 0.001). Stratified analysis showed that the Deep-immune score could distinguish high-risk and low-risk patients in stage II colorectal cancer (P = 0.018).

Conclusion

The proposed Deep-immune score quantified by artificial intelligence can reflect the immune status of patients with colorectal cancer and is associate with favorable survival. This digital pathology-based finding might advocate change in risk stratification and consequent precision medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03666-3.

Cancer Immunoprevention: Current Status and Future Directions

Cancer is one of the most serious diseases affecting health and the second leading cause of death worldwide. Despite the development of various therapeutic modalities to deal with cancer, limited improvement in overall survival of patients has been yielded. Since there is no certain cure for cancer, detection of premalignant lesions, and prevention of their progression are vital to the decline of high morbidity and mortality of cancer. Among approaches to cancer prevention, immunoprevention has gained further attention in recent years. Deep understanding of the tumor/immune system interplay and successful prevention of virally-induced malignancies by vaccines have paved the way toward broadening cancer immunoprevention application. The identification of tumor antigens in premalignant lesions was the turning point in cancer immunoprevention that led to designing preventive vaccines for various malignancies including multiple myeloma, colorectal, and breast cancer. In addition to vaccines, immune checkpoint inhibitors are also being tested for the prevention of oral squamous cell carcinoma (SCC), and imiquimod which is an established drug for the prevention of skin SCC, is a non-specific immunomodulator. Herein, to provide a bench-to-bedside understanding of cancer immunoprevention, we will review the role of the immune system in suppression and promotion of tumors, immunoprevention of virally-induced cancers, identification of tumor antigens in premalignant lesions, and clinical advances of cancer immunoprevention.

Tumor Microenvironment: What have we Learned Studying the Immune Response in this Puzzling Battlefield?

Recent developments hallmark the progress in the understanding of tumor immunology and related therapeutic strategies. The administration of interleukin-2 (IL-2) to patients with cancer has shown that immune manipulation can mediate the regression of established cancers. The identification of the genes encoding cancer antigens and the development of means for effectively immunizing against these antigens has opened new avenues for the development of active immunization of patients with cancer. However, an efficient immune response against tumor comprises an intricate molecular network still poorly understood. Only when the code governing immune responsiveness of cancer will be deciphered, new therapeutic strategies could be designed to fit biologically defined mechanisms of immune rejection of cancer.

In this review, we propose that the mechanisms regulating tumor rejection in response to vaccination will be more efficiently identified by following the evolution of treatment induced events within the tumor microenvironment taking advantage of recently developed technological tools. As a model, we will discuss the observed immune response to tumor antigen -specific immunization and its relationship with the systemic administration of IL-2.

Manipulation of regulatory T cells and antigen-specific cytotoxic T lymphocyte-based tumour immunotherapy

The most potent killing machinery in our immune system is the cytotoxic T lymphocyte (CTL). Since the possibility for self-destruction by these cells is high, many regulatory activities exist to prevent autoimmune destruction by these cells. A tumour (cancer) grows from the cells of the body and is tolerated by the body's immune system. Yet, it has been possible to generate tumour-associated antigen (TAA) -specific CTL that are also self-antigen specific in vivo, to achieve a degree of therapeutic efficacy. Tumour-associated antigen-specific T-cell tolerance through pathways of self-tolerance generation represents a significant challenge to successful immunotherapy. CD4(+)  CD25(+)  FoxP3(+) T cells, referred to as T regulatory (Treg) cells, are selected in the thymus as controllers of the anti-self repertoire. These cells are referred to as natural T regulatory (nTreg) cells. According to the new consensus (Nature Immunology 2013; 14:307-308) these cells are to be termed as (tTreg). There is another class of CD4(+) Treg cells also involved in regulatory function in the periphery, also phenotypically CD4(+)  CD25(±) , classified as induced Treg (iTreg) cells. These cells are to be termed as peripherally induced Treg (pTreg) cells. In vitro-induced Treg cells with suppressor function should be termed as iTreg. These different Treg cells differ in their requirements for activation and in their mode of action. The current challenges are to determine the degree of specificity of these Treg cells in recognizing the same TAA as the CTL population and to circumvent their regulatory constraints so as to achieve robust CTL responses against cancer.

Immunotherapy for malignant gliomas

Cancer immunotherapy aims to harness the innate ability of the immune system to recognize and destroy malignant cells. Immunotherapy for malignant gliomas is an emerging field that promises the possibility of highly specific and less toxic treatment compared to conventional chemotherapy. In addition, immunotherapy has the added benefit of sustained efficacy once immunologic memory is induced. Although there are numerous therapeutic agents that boost general immune function and facilitate improved antitumor immunity, to date, immunotherapy for gliomas has focused primarily on active vaccination against tumor-specific antigens. The results of numerous early phase clinical trials demonstrate promising results for vaccine therapy, but no therapy has yet proven to improve survival in a randomized, controlled trial. The major barrier to immunotherapy in malignant gliomas is tumor-induced immunosuppression. The mechanisms of immunosuppression are only now being elucidated, but clearly involve a combination of factors including regulatory T cells, tumor-associated PD-L1 expression, and CTLA-4 signaling. Immunomodulatory agents have been developed to combat these immunosuppressive factors and have demonstrated efficacy in other cancers. The future of glioma immunotherapy likely lies in a combination of active vaccination and immune checkpoint inhibition.

Anti-tumor immunity and mechanism of immunosuppression mediated by tumor cells: role of tumor-derived soluble factors and cytokines

The immune system plays a crucial role in the protection against tumor growth and progression. However, the activation of the immune system against the neoplastic cells does not always occur and, therefore, tumor cells are able to grow and progress continually in the host. It has now been realized that tumor cells themselves produce many of the important factors that are responsible for dismounting of effective immune response. These tumor-derived soluble factors invariably subdue the functions of almost every immune cell population. Therefore, we attempted to underline the mechanism of anti-tumor immune response and immunosuppression induced by tumor cells.

Immunodeficiency reduces neural stem/progenitor cell apoptosis and enhances neurogenesis in the cerebral cortex after stroke

Acute inflammation in the poststroke period exacerbates neuronal damage and stimulates reparative mechanisms, including neurogenesis. However, only a small fraction of neural stem/progenitor cells survives. In this report, by using a highly reproducible model of cortical infarction in SCID mice, we examined the effects of immunodeficiency on reduction of brain injury, survival of neural stem/progenitor cells, and functional recovery. Subsequently, the contribution of T lymphocytes to neurogenesis was evaluated in mice depleted for each subset of T lymphocyte. SCID mice revealed the reduced apoptosis and enhanced proliferation of neural stem/progenitor cells induced by cerebral cortex after stroke compared with the immunocompetent wild-type mice. Removal of T lymphocytes, especially the CD4(+) T-cell population, enhanced generation of neural stem/progenitor cells, followed by accelerated functional recovery. In contrast, removal of CD25(+) T cells, a cell population including regulatory T lymphocytes, impaired functional recovery through, at least in part, suppression of neurogenesis. Our findings demonstrate a key role of T lymphocytes in regulation of poststroke neurogenesis and indicate a potential novel strategy for cell therapy in repair of the central nervous system.

The effect of high gravidity on the carcinogenesis of mammary gland in TA2 mice

PROBLEM

Spontaneous breast cancer in Tientsin Albinao 2 (TA2) mice, like human pregnancy-associated breast cancer (PABC), often occurs in pregnancy and puerperium, especially in mice with high gravidity. We hypothesized that the dysfunction of cellular immunity caused by the increase of 17beta-estradiol (E2) and progesterone (P) might be one of the reasons for carcinogenesis of mammary gland.

METHOD OF STUDY

We investigated the T lymphocyte subsets and the concentration of serum hormone and cytokines in cancer-bearing, pregnant or postpartum TA2 mice using flow cytometry, chemiluminescent immunoassay, and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

The number of T lymphocytes and the concentration of E2, P, interleukin-2 (IL-2), IL-4, and interferon-gamma (IFN-gamma) changed with the increase of pregnancy and puerperium. During four pregnancies, elevated E2 and P resulted in a decrease in the number of CD3(+), CD4(+) T lymphocytes, CD4(+)/CD8(+) ratio, and the concentration of IL-2, IL-4, and IFN-gamma. Data in the fourth pregnancy were the closest to those of cancer-bearing mice.

CONCLUSION

T lymphocyte subsets and concentration of IL-2, IL-4, and IFN-gamma are affected by E2 and P during multiple pregnancy and delivery to some degree, which may contribute to the genesis of spontaneous breast cancer in TA2 mice.

Therapeutic potential of immunostimulatory monoclonal antibodies

The aim of cancer immunotherapy is to employ the specificity of the immune system to provide a more effective, less toxic, treatment compared with conventional therapies. Although many strategies have been used to try to generate effective anticancer immune responses, very few have reached mainstream clinical use. A new approach introduced over the last few years is to use immunostimulatory mAbs (monoclonal antibodies) to boost weak endogenous antitumour immune responses to levels which are therapeutic. Such agonistic or antagonistic mAbs bind to key receptors in the immune system acting to enhance antigen presentation, provide co-stimulation or to counteract immunoregulation. In animal models, this approach has been shown to promote powerful tumour-specific T-cell responses capable of clearing established tumour and leaving the animal with long-term immunity. In addition to this impressive therapy seen in tumour models, these same mAbs also have the potential to be therapeutically useful in autoimmune and infectious diseases. This review discusses the use of these mAbs as therapeutic agents, their advantages and disadvantages and the challenges that need to be overcome to use them clinically.

Regulatory T cells and tumor immunity

Central deletion of "self-reactive" T cells has been the textbook paradigm for inducing "self-tolerance" in the periphery and the concept of a role of T cell-mediated suppression in this process has long been controversial. A decisive shift in the opinion on suppressor T cells has lately occurred with the observations of Sakaguchi's group that linked a class of CD4+CD25+ T cells to the prevention of autoimmunity from neonatal thymectomy in mice. These CD4+CD25+ T cells have been named T regulatory (Treg) cells. They are believed to be selected in the thymus as an anti-self repertoire. Hence they were referred to as natural T regulatory (nTreg) cells. Presently, in addition to their role in autoimmunity, they are believed to exert regulatory function in infection, in transplantation immunity as well as in tumor immunity. In contrast to these nTreg cells, another class of CD4+ Treg cells also exercises regulatory function in the periphery. These Treg cells are also CD4+ T cells and after activation they also become phenotypically CD4+CD25+. They are, however induced in the periphery as Treg cells. Hence, they are termed as induced Treg (iTreg) cells. There are major differences in the biology of these two types of Treg cells. They differ in their requirements for activation and in their mode of action. Nonetheless, evidence indicates that both nTreg cells and iTreg cells are involved in the control of tumor immunity. The question of how to circumvent their regulatory constraints, therefore, has become a major challenge for tumor immunologists.

Part I: Vaccines for solid tumours

Active specific immunotherapy holds great potential in the search for new therapeutic approaches for patients with cancer. Much preclinical and clinical evidence has shown that the immune system can be polarised against malignant cells by several vaccination strategies. Although no anticancer vaccine can be recommended outside clinical trials at present, tumour response and immunological findings in animals and humans should prompt researchers to investigate further the potential of this biotherapy. We summarise strategies for cancer vaccines so far implemented in the clinical setting, report the results of more than 200 clinical trials published over the past two decades, and discuss insights into preclinical tumour immunology that might aid the design of the next generation of cancer vaccines.

Colorectal cancer vaccines: principles, results, and perspectives

In the search for novel therapeutic approaches to treat patients with colorectal carcinoma, anticancer vaccination holds promise. A large body of preclinical and clinical evidence has demonstrated that the immune system can be polarized against malignant cells by means of several active specific immunotherapy strategies. Although no vaccination regimen can be currently recommended outside clinical trials, tumor response and immunologic findings observed in animal models and humans prompt researchers to explore further the antitumor potential of such biotherapy in an effort to reproduce in a larger set of patients the cascade of molecular events that characterizes the successful tumor immune rejection currently observed in a minority of vaccinated subjects. In this work, we summarize the principles and the main results of cancer vaccine strategies so far implemented for the treatment of patients with colorectal carcinoma. We also discuss the most recent preclinical tumor immunology insights that might change the way to design the next generation of cancer vaccines, hopefully improving the effectiveness of such a biotherapeutic approach.

Cancer vaccine development: on the way to break immune tolerance to malignant cells

Exploiting a naturally occurring defense system, the immunotherapeutic approach embodies an ideal nontoxic treatment for cancer. Despite the evidence that immune effectors can play a significant role in controlling tumor growth either in natural conditions or in response to therapeutic manipulation, the cascade of molecular events leading to tumor rejection by the immune system remains to be fully elucidated. Nevertheless, some recent tumor immunology advancements might drastically change the way to design the next generation of cancer vaccines, hopefully improving the effectiveness of this therapeutic approach. In the present work, we will focus on three main areas of particular interest for the development of novel vaccination strategies: (a) cellular or molecular mechanisms of immune tolerance to malignant cells; (b) synergism between innate and adaptive immune response; (c) tumor-immune system interactions within the tumor microenvironment.

IL-4 protects tumor cells from anti-CD95 and chemotherapeutic agents via up-regulation of antiapoptotic proteins

We recently proposed that Th1 and Th2 cytokines exert opposite effects on the pathogenesis and clinical outcome of organ-specific autoimmunity by altering the expression of genes involved in target cell survival. Because a Th2 response against tumors is associated with poor prognosis, we investigated the ability of IL-4 to protect tumor cells from death receptor- and chemotherapy-induced apoptosis. We found that IL-4 treatment significantly reduced CD95 (Fas/APO-1)- and chemotherapeutic drug-induced apoptosis in prostate, breast, and bladder tumor cell lines. Analysis of antiapoptotic protein expression revealed that IL-4 stimulation resulted in up-regulation of cellular (c) FLIP/FLAME-1 and Bcl-x(L). Exogenous expression of cFLIP/FLAME-1 inhibited apoptosis induced by CD95 and to a lesser extent by chemotherapy, while tumor cells transduced with Bcl-x(L) were substantially protected both from CD95 and chemotherapeutic drug stimulation. Moreover, consistent IL-4 production and high expression of both cFLIP/FLAME-1 and Bcl-x(L) were observed in primary prostate, breast, and bladder cancer in vivo. Finally, primary breast cancer cells acquired sensitivity to apoptosis in vitro only in the absence of IL-4. Thus, IL-4 protects tumor cells from CD95- and chemotherapy-induced apoptosis through the up-regulation of antiapoptotic proteins such as cFLIP/FLAME-1 and Bcl-x(L). These findings may provide useful information for the development of therapeutic strategies aimed at restoring the functionality of apoptotic pathways in tumor cells.

Dissecting tumor responsiveness to immunotherapy: the experience of peptide-based melanoma vaccines

Recent years have witnessed important breakthroughs in our understanding of tumor immunology. A variety of immunotherapeutic strategies has shown that immune manipulation can induce the regression of established cancer in humans. The identification of the genes encoding tumor-associated antigens (TAA) and the development of means for immunizing against these antigens have opened new avenues for the development of an effective anticancer immunotherapy. However, an efficient immune response against tumor requires an intricate cross-talk between cancer and immune system cells, which is still poorly understood. Only when the molecular basis underlying tumor susceptibility to an immune response is deciphered could new therapeutic strategies be designed to fit biologically defined mechanisms of cancer immune rejection. In this article, we address some of the critical issues that have been identified in cancer immunotherapy, in part from our own studies on immune therapies in melanoma patients treated with peptide-based vaccination regimens. This is not meant to be a comprehensive overview of the immunological phenomena accompanying cancer patient vaccination but rather emphasizes some emergent findings, puzzling controversies and unanswered questions that characterize this complex field of oncology. In addition to reviewing the main immunological concepts underlying peptide-based vaccination, we also review the available data regarding naturally occurring and therapeutically induced anticancer immune response, both at the peripheral and intratumoral level. The hypothesized role of innate immunity in predetermining tumor responsiveness to immunotherapeutic manipulation is also discussed.

Advances in gene therapy for malignant melanoma

BACKGROUND

The recent developments in the field of gene transfer have advanced the use of gene therapy as a novel strategy against a variety of human malignancies. Due to its unique set of characteristics, melanoma represents a suitable target for the clinical translation of the different gene transfer approaches recently developed. The goal of gene therapy targeted to melanoma cells is to introduce "suicide" genes, to transfer tumor suppressor genes, to inactivate aberrant oncogene expression, or to introduce genes encoding immunologically relevant molecules. Gene therapy targeted to the host's immune cells has been developed as an additional strategy to redirect immune responses against melanoma.

METHODS

The authors reviewed the published gene transfer studies in experimental models, as well as the results of gene therapy clinical trials for patients with melanoma.

RESULTS

Clinical trials have shown the feasibility and safety of gene therapy against malignant melanoma. Although no major successes have been reported, the positive results observed in some patients support the potential for gene therapy in the management of this disease.

CONCLUSIONS

Gene therapy of melanoma using current gene transfer approaches is feasible and safe. Better vector technology as well as increased understanding of the "bystander effect" triggered by gene transfer approaches would provide the tools to validate gene therapy as an effective modality of treatment for malignant melanoma.

Overview analysis of adjuvant therapies for melanoma--a special reference to results from vaccinia melanoma oncolysate adjuvant therapy trials

A phase III, randomized, double-blind, multi-institutional vaccinia melanoma oncolysate (VMO) trial was performed for patients with stage III (AJCC) melanoma. When compared with the control vaccinia virus (V) therapy, VMO therapy did not show clinical efficacy in the final analysis of data from this trial. However, the data did allude to significant therapeutic efficacy with VMO therapy if it had been compared with an observation arm. Therefore, a comparative overview statistical analysis was performed to identify the therapeutic efficacy of VMO. This review compares VMO results with data from the treatment and observation arms of other prominent randomized anti-melanoma biologic trials (i.e., ECOG EST 1684; SWOG, IFN-gamma (J. Natl. Cancer Inst. 87 (1995) 1710); WHO IFN-alfa-2a (ASCO 14 (1995) 410); Mayo IFN-alfa-2a (J. Clin. Oncol. 13 (1995) 2776); French IFN-alfa-2a (ASCO 15 (1996) 437). The analysis was carried out comparing the disease-free interval (DFI) and overall survival (OS). The analysis shows that the VMO results are fairly comparable to the results of the treatment arms from the ECOG and Mayo trials at the 5-year mark; percent DFI 0.37, 0.37, and 0.4, percent OS 0.48, 0.46, 0.47, respectively. In some cases, VMO DFI is superior to the observation arms from other studies; ECOG, Mayo, and WHO; 0.37 versus 0.26, 0.3, 0.27 (4 years), respectively. These comparative results suggest that the vaccinia arm is not a true observation arm in the VMO trial, and the VMO could have shown an enhanced efficacy had the trial included a no-treatment observation control arm.

Clinical implications of the new biology in the development of melanoma vaccines

There has been a resurgence in clinical research of vaccine therapies, particularly for the treatment of melanoma. The renewed interest in this field is attributable to an increased understanding regarding the immune response to tumors and the immunobiology of melanoma. Molecular biology techniques have enabled investigators to develop genetically engineered tumor vaccines that are intended to favor the type 1 immune response over the type 2 response. Melanoma-associated antigens have been characterized at the molecular level and are currently being investigated in clinical trials. Dendritic cell biology has also provided a potent method to present antigens to the host for immunization. Lastly, vaccines are being explored as a method to generate immune T-cells for adoptive immunotherapy. These new areas of clinical investigation will be reviewed in the context of the historical developments that have laid the foundations of this field.

Overview of melanoma vaccines: active specific immunotherapy for melanoma patients

Although a phase III trial has yet to show a statistically significant improvement in the disease-free or overall survival of melanoma patients receiving vaccine therapy, several phase II trials have shown enhanced disease-free and overall survival of patients who develop a humoral and/or cellular response to a melanoma vaccine. The challenge of active specific immunotherapy research is to determine which combination of humoral and cellular immune responses optimizes clinical outcome and how to monitor the immune response effectively. This review identifies key components of a successful melanoma vaccine, discusses new ways to modulate and stimulate the immune system, and summarizes some of the important clinical trials of active specific immunotherapy for patients with melanoma.

Update on active specific immunotherapy with melanoma vaccines

Although a randomized clinical trial has yet to show a statistically significant improvement in the survival of patients receiving vaccine therapy for malignant melanoma, several studies have shown enhanced survival of patients developing an immune response to a melanoma vaccine. The knowledge and techniques of modern molecular biology and immunology suggest multiple strategies to augment this response. The challenge of immunotherapy research is to determine which combination of approaches leads to a favorable clinical response and how to monitor that response effectively. This review identifies components of a successful vaccine, discusses new ways to modulate and stimulate the immune system, and summarizes some of the more interesting clinical trials of melanoma vaccine immunotherapy.

CD4+ Th0 cell clones, isolated from a metastatic lymph node of a melanoma patient, possess cytolytic function

In the present study T lymphocytes isolated from a metastatic lymph node (T-LNL) of a melanoma patient have been cloned. In the attempt to verify whether T-LNL may acquire in vitro functional activities in the absence of tumour-associated antigens, they were cloned utilizing allogenic lymphocytes as feeder cells. Nineteen clones generated from T-LNL proved to be CD4+ and, among these, five were able to kill autologous and allogeneic human melanoma cells in HLA-class-II-restricted way. On the basis of their cytokine production, these CD4+ cytolytic T-LNL clones were shown to belong to the Th0 subset and three of them expressed the V beta 17 chain of the T cell receptor. These results suggest the presence of melanoma-specific but functionally inactive lymphocytes with T cell receptor oligoclonality in the lymph node environment. These specific T cells may acquire in vitro the capacity to kill autologous and allogeneic tumours without any induction by autologous melanoma cells.

Induction of tumor-specific T lymphocyte responses in vivo by prothymosin alpha

We have recently reported that administration of ProT alpha to DBA/2 mice before the inoculation of syngeneic L1210 leukemic cells prolonged the survival of these animals by (a) inducing tumoricidal peritoneal macrophages, (b) enhancing natural killer (NK) and inducing lymphokine-activated killer (LAK) activities in splenocytes and (c) inducing the production of interleukin-2 and tumor necrosis factor alpha [Papanastasiou et al. (1992) Cancer Immunol Immunother 35:145; Baxevanis et al. (1994) Cancer Immunol Immunothera 38:281]. In this report we demonstrated that ProT alpha, when administered simultaneously with L1210 tumor cells, is capable of generating in DBA/2 animals tumor-specific CD8+ cytotoxic T lymphocytes (CTL). The ProT alpha-induced CD8+ CTL lysed their syngeneic L1210 targets in a major histocompatibility complex (MHC)-restricted fashion since monoclonal antibodies (mAb) against the H-2Kd allelic product could inhibit the cytotoxic response. Mice receiving only ProT alpha developed non-MHC-restricted cytotoxic activity (NK, and LAK activities) whereas those receiving ProT alpha and L1210 tumor cells developed both MHC-restricted (CTL) and non-MHC-restricted cytotoxic activities and survived longer. The ProT alpha-induced CD8+ CTL activity was regulated by ProT alpha-induced L1210-specific syngeneic CD4+ cells. This was shown in two different ways: first, CD8(+)-cell-mediated cytotoxic responses against L1210 targets were associated with L1210-specific and MHC-restricted proliferative responses of syngeneic CD4+ cells and, second, CD4+ cells from mice that had received both ProT alpha and L1210 tumor cells could enhance in vitro the otherwise weak, MHC-restricted and L1210-specific cytotoxicity of syngeneic CD8+ cells from mice that had received only L1210 cells. Our data suggest that ProT alpha is capable of inducing nonspecific, as well as tumor-specific CTL responses in vivo. This is of importance since ProT alpha may prove to be useful in clinical protocols aimed at cancer immunotherapy.

[Immunotherapy of malignant melanoma. New prospects]

Malignant melanoma is an immunogenic tumor which can induce host humoral and cellular responses, and is a good model for development of anti-cancer immunotherapy. During the last decade systemically-administrated interferon and interleukin-2 have been used. Advances in immunology and molecular biology could allow a more specific and active immunotherapy. Perspectives include chemo-immunotherapy, monoclonal antibodies alone or in combination with cytotoxic agents, adoptive immunotherapy with tumor-infiltrating lymphocytes (TIL), gene therapy designed to increase tumor immunogenicity, and active immunotherapy with vaccines.

Non-fastidious, melanoma-specific CD8+ cytotoxic T lymphocytes from choroidal melanoma patients

To characterize the anti-melanoma reactivity of CD8+ cytotoxic T lymphocytes (CTL) from choroidal melanoma patients, CTL clones were isolated from the peripheral blood of three patients after mixed lymphocyte/tumor cell culture (MLTC). Clones were derived from lymphocytes stimulated by allogeneic (OCM-1, A24, A28) or autologous (OCM-3, A1, A30) melanoma cells. Their reactivity against a panel of HLA-typed melanoma and nonmelanoma cells was assessed, to determine whether a single CTL clone could recognize and lyse a variety of allogeneic melanoma cell lines. While proportionately more clones derived from autologous MLTC were melanoma-specific than allogeneic MLTC (42% versus 14%), melanoma-specific CTL were recovered from both. Notably, a novel melanoma specificity was identified. These CTL clones were termed non-fastidious because they were capable of lysing melanoma cells with which they had no HLA class I alleles in common. Nonetheless, lysis was mediated by the HLA class I molecule. Since lysis was specific for melanoma cells, these CTL appeared to recognize a shared melanoma peptide(s). Because of their prevalence, we propose that non-fastidious CTL are integral to human anti-melanoma T cell immunity. This reinforces clinical findings that allogeneic melanomas can substitute for autologous tumors in active specific immunotherapy. By circumventing the need for autologous melanoma, it is possible to treat patients after removal of the primary choroidal melanoma in an attempt to prevent metastasis.

Interferon beta enhances the natural killer activity of patients with bladder carcinoma

We have investigated the effect of interferon beta (INF beta) on the natural killer (NK) cytotoxic activity of peripheral blood mononuclear cells (PBMC) from patients with superficial and infiltrative transitional-cell carcinoma of the bladder (TCC) against both NK-sensitive and NK-resistant target cells. The normal NK activity found in PBMC from these patients can be significantly enhanced by short-term incubation (18 h) with INF beta (P < 0.05). The depressed NK cytotoxic activity found in PBMC from patients with infiltrative TCC can also be significantly enhanced, but not normalized, by short-term incubation with INF beta (P < 0.05). In kinetic studies we found that the maximal levels of the INF beta-promoted cytotoxic activity against NK-sensitive and against NK-resistant target cells in PBMC from TCC patients were reached after 18 h of culture. Short-term-INF beta-incubated PBMC from patients with TCC of the bladder also showed marked cytotoxic activity against NK-resistant target cells. The effector cells of the INF beta-induced cytotoxic activity in PBMC from patients with TCC were CD16+ CD3- NK cells. This cytotoxic inducer effect of INF beta synergized with that of interleukin-2. In conclusion, INF beta can enhance the NK activity of PMBC from patients with TCC of the bladder.

Therapeutic effect of a vaccinia colon oncolysate prepared with interleukin-2-gene encoded vaccinia virus studied in a syngeneic CC-36 murine colon hepatic metastasis model

Vaccinia CC-36 murine colon oncolysate (VCO) prepared with interleukin-2-gene encoded recombinant vaccinia virus (IL-2VCO) was used in the treatment of a syngeneic murine colon adenocarcinoma (CC-36) hepatic metastasis to test the beneficial effect of the interleukin-2-gene encoded vaccinia virus over a control recombinant vaccinia virus in producing a vaccinia oncolysate tumor cell vaccine. Results suggest that the IL-2VCO treatment significantly reduced the hepatic tumor burden in comparison with the controls that received either IL-2-gene-encoded recombinant vaccinia virus or a plain recombinant vaccinia virus or vaccinia oncolysate prepared with the plain recombinant virus. The survival of mice treated with IL-2VCO was also improved in comparison with mice treated with other preparations. The induction of a cytolytic T lymphocyte response was examined to elucidate the mechanism of the induction of antitumor responses in IL-2VCO-treated mice. Fresh peripheral blood lymphocytes (PBL) isolated from IL-2VCO-treated mice showed a higher cytolytic activity against CC-36 tumor cell target when compared to PBL from the mice of other treatment groups, suggesting that the IL-2VCO induced an antitumor cytolytic T lymphocyte response. These results suggest that a vaccinia oncolysate, prepared with recombinant vaccinia virus encoding an immunomodulating cytokine gene will enhance antitumor responses in the host.

Isolation and in vitro expansion of lymphocytes infiltrating non-small cell lung carcinoma: functional and molecular characterisation for their use in adoptive immunotherapy

Tumour infiltrating lymphocytes (TIL) have the capability of recognising and lysing autologous cancer cells, both in vitro and in vivo. Advanced non-small cell lung carcinoma (NSCLC) is partially insensitive to chemo radiotherapy and has a poor prognosis: thus, for this, an immunotherapeutic approach could be attempted. We expanded in vitro 46 out of 70 samples of TIL derived from NSCLC. From proliferating TILS, a number varying from 10 to 50 x 10(9) cells was obtained. These lymphocytes belonged to the T cell lineage, had the capability of growing for 45-60 days and lysed autologous better than allogeneic cancer cells. In addition, analysis of the restriction maps of T cell receptor (TRC)-beta, demonstrated that an oligoclonal population of T cells was preselected in vivo, near the tumour site, and might be expanded in vivo, using phytohaemagglutin and interleukin 2 while maintaining the same characteristics of the original population. These results give a clear rationale for the use of in vitro expanded TIL from NSCLC in protocols of adoptive immunotherapy in patients with residual disease following surgery.

Recombinant interleukin-2 corrects in vitro the immunological defect of endometriosis

PROBLEM

It has been shown recently that women with endometriosis have several immunological defects. In particular, these patients have a defect in peripheral blood natural killer cell activity and have lost their capacity of recognizing and lysing autologous endometrial cells.

METHOD

We evaluated the effect of recombinant interleukin-2 (rIL-2) on peripheral blood lymphocytes obtained from both healthy donors and endometriosis patients. The generation of a strong cytolytic activity against autologous endometrial cells was obtained from both normal donors and endometriosis patients.

RESULTS

Interestingly, these cytolytic cells belong to the T-cell lineage and do not recognize both autologous keratinocytes and allogeneic endometrial cells, thus suggesting a mechanism of specific recognition of autologous cells.

CONCLUSION

The capability of restoring cytolytic activity using rIL-2 suggests a new immunotherapeutic approach for the treatment of severe endometriosis.

Cytokines as adjuvants: effect on the immunogenicity of NeuAc alpha 2-6GalNAc alpha-O-Ser/Thr (sialyl-Tn)

Sialyl-Tn, defined by monoclonal antibody (MAb) B72.3, shows restricted normal-tissue distribution but is expressed in a wide variety of carcinomas. To analyze the immunogenicity of sialyl-Tn, mice were immunized with ovine submaxillary mucin (OSM) in combination with monophosphoryl lipid A (MPLA), liposomes, or adjuvants that activate macrophages (rIL-1, rIFN-gamma, rM-CSF, IL-1-derived peptides) or T cells (rIL-2). The level and specificity of the immune response were analyzed by ELISA. rIL-1 and rIFN-gamma induced a very high and specific antibody response, whereas the effect of rM-CSF was dose-dependent: at a low dose it induced a high-level specific antibody response and at the high dose level it induced a polyclonal non-specific response. These results indicate that cytokines are powerful adjuvants which modulate both the magnitude and specificity of the immune response. More studies are necessary to determine the optimal doses in animal models and in active specific immunotherapy of patients with cancer.

Clonal analysis of in vivo activated CD8+ cytotoxic T lymphocytes from a melanoma patient responsive to active specific immunotherapy

To study in vivo activated cytolytic T cells, CD8+ T cells clones were isolated from a melanoma patient (HLA A2, A11) treated with active specific immunotherapy for 5 years. CD8+ T lymphocytes, purified by fluorescence-activated cell sorting, were cloned directly from the peripheral blood without antigen-presenting cells in the presence of irradiated autologous melanoma cells and recombinant interleukin-2 (IL-2) and IL-4. These conditions were inhibitory to de novo in vitro immunization. Of the 28 cytolytic CD8+ T cell clones, 21 lysed the autologous melanoma cell line (M7) but not the autologous lymphoblastoid cell line (LCL-7) nor the two melanoma cell line, M1 (HLA A28) and M2 (HLA A28, A31), used to immunize the patient. The remaining 7 clones were also melanoma-specific, although their reactivities were broader, lysing several melanoma cell lines but not HLA-matched lymphoblastoid cells. Eight clones from the first group, ostensibly self-MHC-restricted, were expanded for further analysis. All expressed cluster determinants characteristic of mature, activated T cells, but not those of thymocytes, naive T cells, B cells or natural killer (NK) cells. They also expressed CD13, a myeloid marker. Of the 8 clones, 3 expressed both CD4 and CD8, but dual expression was not correlated with specificity of lysis. Two CD8+ and 2 CD4+ CD8+ clones were specific for the autologous melanoma cells, the other 4 were also reactive against other HLA-A2-positive melanomas. Cytotoxicity for both singly and doubly positive clones was restricted by HLA class I but not class II antigens. Analysis of the RNA expression of the T cell receptor (TCR) V alpha and V beta gene segments revealed heterogeneous usage by the A2-restricted clones and, perhaps, also by the broadly melanoma-specific clones. Apparent TCR-restricted usage was noted for the self-MHC-restricted clones; 2 of the 4 expressed the V alpha 17/V beta 7 dimer. Since the T cell clones were derived from separate precursors of circulating cytotoxic T lymphocytes (CTL), the V alpha 17/V beta 7 TCR was well represented in the peripheral blood lymphocytes of this patient. In summary, we show that melanoma cells presented their own antigens to stimulate the proliferation of melanoma-reactive CD8+ CTL. CTL with a range of melanoma specificities and different TCR alpha beta dimers were encountered in this patient, perhaps as a result of hyperimmunization.(ABSTRACT TRUNCATED AT 400 WORDS)

Lesion-specific activation of cloned human tumor-infiltrating lymphocytes by autologous tumor cells: induction of proliferation and cytokine production

To investigate the mechanisms by which tumor-infiltrating lymphocytes exert their antitumor effects, tumor-specific tumor-infiltrating lymphocyte clones, as well as autologous tumor cell lines from primary and secondary tumors of two patients during the course of melanoma progression were established. Enrichment for tumor-infiltrating lymphocytes expressing CD25, as well as low concentrations of interleukin-2 (30 IU/ml) in the culture medium, led to a preferential outgrowth of cells that express the high-affinity interleukin-2 receptor. All of these expressed CD2, CD3, CD11, and CD25. Coculture of tumor-infiltrating lymphocyte clones with irradiated, autologous tumor cells induced an up to 480% greater proliferative responses than recombinant interleukin-2 alone. Approximately 60% of the tumor-infiltrating lymphocyte clones showed cytotoxicity against the relevant tumor in a 4-h 51Cr-release assay. When tested in an 18-h 51Cr-release assay, the number of tumor-infiltrating lymphocyte clones exhibiting cytotoxicity against the relevant tumor increased to over 85%. In response to autologous tumor cells, nine of 15 clones secreted interferon-gamma, tumor necrosis factor-alpha, or both. Cytokine production was not restricted to either CD4+ or CD8+ T cells because both CD4+ and CD8+ tumor-infiltrating lymphocyte clones secreted cytokines. Tumor-infiltrating lymphocyte tumor interaction appears to be lesion specific because induction of proliferation and cytokine production, as well as susceptibility to cytolysis, was found not only restricted to the autologous system, but also to the specific lesion. The pattern of tumor-infiltrating lymphocyte tumor interaction specificity indicates a possible loss of antigens expressed on the tumor during disease progression.

Lack of HLA class I antigen expression by melanoma cells SK-MEL-33 caused by a reading frameshift in beta 2-microglobulin messenger RNA

The lack of HLA class I antigen expression by the melanoma cell line SK-MEL-33 is caused by a unique lesion in beta 2-microglobulin (beta 2-mu). Sequencing of beta 2-mu mRNA detected a guanosine deletion at position 323 in codon 76 that causes a frameshift with a subsequent introduction of a stop codon at a position 54 base upstream of the normal position of the stop codon in the message. The loss of 18 amino acids and the change of 6 amino acids, including a cysteine at position 80 in the carboxy terminus of beta 2-mu, are likely to cause marked changes in the structure of the polypeptide. The latter may account for the inability of beta 2-mu to associate with HLA class I heavy chains and for its lack of reactivity with the anti-beta 2-mu mAb tested. HLA class I antigen expression on SK-MEL-33 cells was reconstituted after transfection with a wild-type B2m gene, therefore indicating that the abnormality of endogenous B2m gene is the only mechanism underlying lack of HLA class I antigen expression by SK-MEL-33 cells. The guanosine deletion in B2m gene was detected also in the melanoma tissue from which SK-MEL-33 cells had originated. Therefore, the molecular lesion identified in the SK-MEL-33 melanoma cell line is not caused by a mutation acquired during growth in vitro but is likely to reflect a somatic mutation during tumor progression.

Analysis of cytolytic effector cell response in vitro against autologous human tumor cells genetically altered to synthesize interleukin-2

Recently, there has been a surge of interest in gene therapy in cancer particularly with cytokine transduced tumor cells as a novel form of tumor vaccine. In two autologous human tumor systems, using the tumor cells engineered to produce interleukin-2 by gene transduction techniques, we have examined whether or not such genetically altered cells are capable of inducing a tumor specific cytolytic T cell (CTL) response, in vitro, in co-culture with the respective autologous peripheral blood lymphocytes (PBL). We found that in neither system did co-cultures of the IL-2 producing tumor cells and the autologous PBL generate much cytolytic effector cell activity directed against the respective tumor cells, although these co-cultures did lead to the generation of substantial levels of natural killer (NK) cell activity when measured against the prototype NK sensitive target K562 line. More surprisingly, the levels of lymphokine activated killer cell responses against the respective autologous targets that could be generated in the PBL with exogenous IL-2 alone were compromised by the presence of the autologous tumor cells in the co-culture.

T-cell responses against products of oncogenes: generation and characterization of human T-cell clones specific for p21 ras-derived synthetic peptides

Peptides derived from mutated human proto-oncogenes bound to HLA may represent a novel type of tumor-specific antigen. Mutated ras genes are the oncogenes most frequently identified in human cancer. The transforming genes carry a mutation in codons 12, 13, or 61. We have investigated whether the T-cell repertoire of healthy individuals contains T cells capable of recognizing and responding to oncogene-derived peptides. Synthetic peptides derived from mutated p21 ras proto-oncogenes, covering mutations at codons 12 or 13 were selected. It was feasible to elicit T-cell responses and isolate several new T-cell clones (TCC) with specificity for a number of different mutated ras peptides after repeated in vitro immunization. Four TCC were characterized with respect to fine specificity and HLA restriction. TCC B and I were restricted by HLA-DR molecules, and recognized the mutated p21 ras-derived peptide carrying Arg and Lys at residue 12, respectively. TCC E and F were restricted by HLA-DQ molecules, the former being specific for a mutated p21 ras-derived peptide with Val in position 13 and the latter more broadly reactive. Peptide competition experiments with a panel of ten peptides derived from p21 ras indicated that all could bind to HLA-DQ molecules of the T-cell donor, while several were also able to bind his HLA-DR molecules. These results show that several p21 ras mutations resulting in aa substitutions at residues 12 or 13 could be recognized by T cells derived from precursor T cells of relatively low frequency present in the normal repertoire of a single donor.

Presence of activated lymphocytes in the urine of patients with superficial bladder cancer after intravesical immunotherapy with bacillus Calmette-Guérin

To study the mode of action of intravesical bacillus Calmette-Guérin (BCG) immunotherapy in the prevention and cure of superficial bladder cancer, flow-cytofluorometric analysis of the cellular immunological reaction in the urine of patients was performed. Fresh urine-derived leucocytes were obtained from eight patients before (t0) and 24 h (t24) and 48 h (t48) after repeated intravesical BCG instillations (at least 5 instillations). For two patients urine-derived leucocytes were investigated at the first BCG instillation. The number of leucocytes in the urine was markedly increased 24 h after repeated BCG instillations, indicating a local cellular immunological reaction induced by BCG. The mean number of cells per milliliter of urine at that time was 2.9 x 10(6) +/- 3.6 x 10(6) (n = 8). These leucocytes consisted mainly of granulocytes (75 +/- 11%, n = 8). In addition monocytes/macrophages (4 +/- 2%, n = 8) and T lymphocytes were present (1 +/- 1%, n = 5). The relative increase of monocytes/macrophages in the urine after BCG application tended to be higher compared to the other leucocyte subtypes. As T lymphocytes may play an important role in the BCG-mediated anti-tumour activity, subsets of lymphocytes were further characterized at t0, t24, and t48 after repeated BCG instillations. The lymphocyte population consisted mainly of T cells (86% CD3+, t0). Most of the T cells were CD4+ (helper/inducer) and were significantly decreased at 48 h (62 +/- 9% at t0 vs 49 +/- 6% at t48). Lymphocytes partly expressed HLA-DR antigens (44%, t0). The percentage of lymphocytes with interleukin-2 (IL-2) receptors (CD25+) was significantly increased at 24 h and 48 h, compared to pre-instillation values (19 +/- 11% and 10 +/- 4% vs 3 +/- 3% respectively). Natural killer cells (CD16+ and/or CD56+) and B cells (CD19+) were less numerous (10% and 19% at t0 respectively). After the first BCG instillation the increase in the number of leucocytes in urine seemed to be less compared to the numbers after repeated BCG instillations. Lymphocytes could not be detected in the urine collected before or after the first BCG instillation. In conclusion, we demonstrated the presence of considerable numbers of leucocytes in the urine 24 h after repeated BCG instillations, i.e. shortly after immunological activation. The antigen expression of the lymphocytes suggested that they may represent the lymphocytes in the bladder wall. Expression of HLA-DR and IL-2 receptors on lymphocytes indicated activation of T cells by the intravesical BCG treatment.(ABSTRACT TRUNCATED AT 400 WORDS)