Pancreatic carcinoma-specific immunotherapy using synthesised alpha-galactosyl epitope-activated immune responders: findings from a pilot study

Self-Tumor Antigens in Solid Tumors Turned into Vaccines by α-gal Micelle Immunotherapy

A major reason for the failure of the immune system to detect tumor antigens (TAs) is the insufficient uptake, processing, and presentation of TAs by antigen-presenting cells (APCs). The immunogenicity of TAs in the individual patient can be markedly increased by the in situ targeting of tumor cells for robust uptake by APCs, without the need to identify and characterize the TAs. This is feasible by the intra-tumoral injection of α-gal micelles comprised of glycolipids presenting the carbohydrate-antigen "α-gal epitope" (Galα1-3Galβ1-4GlcNAc-R). Humans produce a natural antibody called "anti-Gal" (constituting ~1% of immunoglobulins), which binds to α-gal epitopes. Tumor-injected α-gal micelles spontaneously insert into tumor cell membranes, so that multiple α-gal epitopes are presented on tumor cells. Anti-Gal binding to these epitopes activates the complement system, resulting in the killing of tumor cells, and the recruitment of multiple APCs (dendritic cells and macrophages) into treated tumors by the chemotactic complement cleavage peptides C5a and C3a. In this process of converting the treated tumor into a personalized TA vaccine, the recruited APC phagocytose anti-Gal opsonized tumor cells and cell membranes, process the internalized TAs and transport them to regional lymph-nodes. TA peptides presented on APCs activate TA-specific T cells to proliferate and destroy the metastatic tumor cells presenting the TAs. Studies in anti-Gal-producing mice demonstrated the induction of effective protection against distant metastases of the highly tumorigenic B16 melanoma following injection of natural and synthetic α-gal micelles into primary tumors. This treatment was further found to synergize with checkpoint inhibitor therapy by the anti-PD1 antibody. Phase-1 clinical trials indicated that α-gal micelle immunotherapy is safe and can induce the infiltration of CD4+ and CD8+ T cells into untreated distant metastases. It is suggested that, in addition to converting treated metastases into an autologous TA vaccine, this treatment should be considered as a neoadjuvant therapy, administering α-gal micelles into primary tumors immediately following their detection. Such an immunotherapy will convert tumors into a personalized anti-TA vaccine for the period prior to their resection.

The clinical terrain of immunotherapies in heterogeneous pancreatic cancer: unravelling challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is the most common and aggressive type of pancreatic cancer and has abysmal survival rates. In the past two decades, immunotherapeutic agents with success in other cancer types have gradually been trialled against PDACs at different stages of cancer progression, either as a monotherapy or in combination with chemotherapy. Unfortunately, to this day, chemotherapy still prolongs the survival rates the most and is prescribed in clinics despite the severe side effects in other cancer types. The low success rates of immunotherapy against PDAC have been attributed most frequently to its complex and multi-faceted tumour microenvironment (TME) and low mutational burden. In this review, we give a comprehensive overview of the immunotherapies tested in PDAC clinical trials thus far, their limitations, and potential explanations for their failure. We also discuss the existing classification of heterogenous PDACs into cancer, cancer-associated fibroblast, and immune subtypes and their potential opportunity in patient selection as a form of personalisation of PDAC immunotherapy. © 2023 The Pathological Society of Great Britain and Ireland.

The Role of Immunotherapy in Pancreatic Cancer

Pancreatic adenocarcinoma remains one of the most lethal cancers globally, with a significant need for improved therapeutic options. While the recent breakthroughs of immunotherapy through checkpoint inhibitors have dramatically changed treatment paradigms in other malignancies based on considerable survival benefits, this is not so for pancreatic cancer. Chemotherapies with modest benefits are still the cornerstone of advanced pancreatic cancer treatment. Pancreatic cancers are inherently immune-cold tumors and have been largely refractory to immunotherapies in clinical trials. Understanding and overcoming the current failures of immunotherapy through elucidating resistance mechanisms and developing novel therapeutic approaches are essential to harnessing the potential durable benefits of immune-modulating therapy in pancreatic cancer patients.

The Next Frontier in Pancreatic Cancer: Targeting the Tumor Immune Milieu and Molecular Pathways

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with abysmal prognosis. It is currently the third most common cause of cancer-related mortality, despite being the 11th most common cancer. Chemotherapy is standard of care in all stages of pancreatic cancer, yet survival, particularly in the advanced stages, often remains under one year. We are turning to immunotherapies and targeted therapies in PDAC in order to directly attack the core features that make PDAC notoriously resistant to chemotherapy. While the initial studies of these agents in PDAC have generally been disappointing, we find optimism in recent preclinical and early clinical research. We find that despite the immunosuppressive effects of the PDAC tumor microenvironment, new strategies, such as combining immune checkpoint inhibitors with vaccine therapy or chemokine receptor antagonists, help elicit strong immune responses. We also expand on principles of DNA homologous recombination repair and highlight opportunities to use agents, such as PARP inhibitors, that exploit deficiencies in DNA repair pathways. Lastly, we describe advances in direct targeting of driver mutations and metabolic pathways and highlight some technological achievements such as novel KRAS inhibitors.

Biosynthesis of α-Gal Epitopes (Galα1-3Galβ1-4GlcNAc-R) and Their Unique Potential in Future α-Gal Therapies

The α-gal epitope is a carbohydrate antigen which appeared early in mammalian evolution and is synthesized in large amounts by the glycosylation enzyme α1,3galactosyltransferase (α1,3GT) in non-primate mammals, lemurs, and New-World monkeys. Ancestral Old-World monkeys and apes synthesizing α-gal epitopes underwent complete extinction 20–30 million years ago, and their mutated progeny lacking α-gal epitopes survived. Humans, apes, and Old-World monkeys which evolved from the surviving progeny lack α-gal epitopes and produce the natural anti-Gal antibody which binds specifically to α-gal epitopes. Because of this reciprocal distribution of the α-gal epitope and anti-Gal in mammals, transplantation of organs from non-primate mammals (e.g., pig xenografts) into Old-World monkeys or humans results in hyperacute rejection following anti-Gal binding to α-gal epitopes on xenograft cells. The in vivo immunocomplexing between anti-Gal and α-gal epitopes on molecules, pathogens, cells, or nanoparticles may be harnessed for development of novel immunotherapies (referred to as “α-gal therapies”) in various clinical settings because such immune complexes induce several beneficial immune processes. These immune processes include localized activation of the complement system which can destroy pathogens and generate chemotactic peptides that recruit antigen-presenting cells (APCs) such as macrophages and dendritic cells, targeting of antigens presenting α-gal epitopes for extensive uptake by APCs, and activation of recruited macrophages into pro-reparative macrophages. Some of the suggested α-gal therapies associated with these immune processes are as follows: 1. Increasing efficacy of enveloped-virus vaccines by synthesizing α-gal epitopes on vaccinating inactivated viruses, thereby targeting them for extensive uptake by APCs. 2. Conversion of autologous tumors into antitumor vaccines by expression of α-gal epitopes on tumor cell membranes. 3. Accelerating healing of external and internal injuries by α-gal nanoparticles which decrease the healing time and diminish scar formation. 4. Increasing anti-Gal–mediated protection against zoonotic viruses presenting α-gal epitopes and against protozoa, such as Trypanosoma, Leishmania, and Plasmodium, by vaccination for elevating production of the anti-Gal antibody. The efficacy and safety of these therapies were demonstrated in transgenic mice and pigs lacking α-gal epitopes and producing anti-Gal, raising the possibility that these α-gal therapies may be considered for further evaluation in clinical trials.

Pancreatic Cancer and Immunotherapy: A Clinical Overview

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with high mortality. The vast majority of patients present with unresectable, advanced stage disease, for whom standard of care chemo(radio)therapy may improve survival by several months. Immunotherapy has led to a fundamental shift in the treatment of several advanced cancers. However, its efficacy in PDAC in terms of clinical benefit is limited, possibly owing to the immunosuppressive, inaccessible tumor microenvironment. Still, various immunotherapies have demonstrated the capacity to initiate local and systemic immune responses, suggesting an immune potentiating effect. In this review, we address PDAC's immunosuppressive tumor microenvironment and immune evasion methods and discuss a wide range of immunotherapies, including immunomodulators (i.e., immune checkpoint inhibitors, immune stimulatory agonists, cytokines and adjuvants), oncolytic viruses, adoptive cell therapies (i.e., T cells and natural killer cells) and cancer vaccines. We provide a general introduction to their working mechanism as well as evidence of their clinical efficacy and immune potentiating abilities in PDAC. The key to successful implementation of immunotherapy in this disease may rely on exploitation of synergistic effects between treatment combinations. Accordingly, future treatment approaches should aim to incorporate diverse and novel immunotherapeutic strategies coupled with cytotoxic drugs and/or local ablative treatment, targeting a wide array of tumor-induced immune escape mechanisms.

Do novel treatment strategies enhance T cell-mediated Immunity: Opportunities and challenges in pancreatic cancer immunotherapy

Although immunotherapy is successful when included as component of treatment strategies for advanced cancers, data are insufficient for evaluating its efficacy for treating patients with pancreatic cancer (PC). PC is remarkably resistant to current immunotherapies because of its strongly immunosuppressive tumor microenvironment comprising immunosuppressive cells such as myeloid-derived suppressor cells and regulatory T cells, which limit the efficacy of T cell infiltration. Thus, the ability to achieve robust and durable intrinsic T cell efficacy may represent the key for improving patients' outcomes. Recent studies show that the efficacy of immunotherapy for treating PC will be significantly improved when combined with novel treatment strategies. This review summarizes the latest research in this rapidly progressing area and provides an overview of how current therapies enhance T cell-mediated immunotherapies that employ immune checkpoint inhibitors, cytokines, cell receptor modulators, tumor microenvironment regulators, vaccines, and gene-targeted immunotherapies. We highlight novel discoveries, which promise to guide future management of PC, and clinical trials aimed to increase the overall survival rate of patients with PC.

Amplifying immunogenicity of prospective Covid-19 vaccines by glycoengineering the coronavirus glycan-shield to present α-gal epitopes

The many carbohydrate chains on Covid-19 coronavirus SARS-CoV-2 and its S-protein form a glycan-shield that masks antigenic peptides and decreases uptake of inactivated virus or S-protein vaccines by APC. Studies on inactivated influenza virus and recombinant gp120 of HIV vaccines indicate that glycoengineering of glycan-shields to present α-gal epitopes (Galα1-3Galβ1-4GlcNAc-R) enables harnessing of the natural anti-Gal antibody for amplifying vaccine efficacy, as evaluated in mice producing anti-Gal. The α-gal epitope is the ligand for the natural anti-Gal antibody which constitutes ~1% of immunoglobulins in humans. Upon administration of vaccines presenting α-gal epitopes, anti-Gal binds to these epitopes at the vaccination site and forms immune complexes with the vaccines. These immune complexes are targeted for extensive uptake by APC as a result of binding of the Fc portion of immunocomplexed anti-Gal to Fc receptors on APC. This anti-Gal mediated effective uptake of vaccines by APC results in 10-200-fold higher anti-viral immune response and in 8-fold higher survival rate following challenge with a lethal dose of live influenza virus, than same vaccines lacking α-gal epitopes. It is suggested that glycoengineering of carbohydrate chains on the glycan-shield of inactivated SARS-CoV-2 or on S-protein vaccines, for presenting α-gal epitopes, will have similar amplifying effects on vaccine efficacy. α-Gal epitope synthesis on coronavirus vaccines can be achieved with recombinant α1,3galactosyltransferase, replication of the virus in cells with high α1,3galactosyltransferase activity as a result of stable transfection of cells with several copies of the α1,3galactosyltransferase gene (GGTA1), or by transduction of host cells with replication defective adenovirus containing this gene. In addition, recombinant S-protein presenting multiple α-gal epitopes on the glycan-shield may be produced in glycoengineered yeast or bacteria expression systems containing the corresponding glycosyltransferases. Prospective Covid-19 vaccines presenting α-gal epitopes may provide better protection than vaccines lacking this epitope because of increased uptake by APC.

Novel fusion cells derived from tumor cells expressing the heterologous α-galactose epitope and dendritic cells effectively target cancer

Tumor cells/dendritic cells (DCs) fusion cells (tumor/DC) represent a promising immunotherapeutic strategy but are still under performed in clinical trials for cancer treatment. To further boost their anticancer efficacy, here we developed a novel design for fusing dendritic cells with MDA-MB-231 cells expressing the heterologous α-galactose (α-gal) epitope and assessed its anticancer activities both in vitro and in vivo. The high expression of α-gal in MDA-MB-231 (Gal⁺)/DC correlated with enhanced DC activation. When applied to T cells, MDA-MB-231 (Gal⁺)/DC significantly stimulated T-cell proliferation and activation, promoted productions of cytokines IL-2 and IFN-γ, and enhanced T-cell-mediated cytotoxicity against MDA-MB-231 cells. MDA-MB-231 (Gal⁺)/DC inhibited proliferation and promoted apoptosis of tumor cells in vivo, prolonged mouse survival, and significantly boosted anticancer immunity by increasing CD4⁺ and CD8⁺ T cells systemically and elevating serum levels of cytokines and IgG. These results suggested that fusing dendritic cells with tumor cells expressing the heterologous α-gal epitope provides a novel therapeutic strategy for cancer treatment.

Pancreatic carcinoma-specific immunotherapy using novel tumor specific cytotoxic T cells

Pancreatic cancer represents one of the most lethal human cancers. Investigation of the effective targeting to the tumor cells is essential for both primary tumors and metastases. Tumor specific cytotoxic T lymphocytes (CTLs) have recently been considered to be the attractive vehicles for delivering therapeutic agents toward various tumor diseases. This study was to explore the distribution pattern of CTL carrying the lentiviral vectors with the characteristic of adenoviral E1 gene under the control of the cell activation-dependent CD40 ligand promoter (Lenti/hCD40L/E1AB). Following transduction with adenoviral particles containing chimeric type 5 and type 35 fiber proteins (Ad5/35-TRAIL), these CTLs produced infectious virus when exposed to SW1990 cells. We found that the novel CTL harboring Lenti/hCD40L/E1AB and Ad5/35-TRAIL inhibited pancreatic cancer cell growth and angiogenesis in vitro and in vivo. Furthermore, Ad5/35-TRAIL transduced CTL induced significant apoptosis in pancreatic carcinoma cell lines and upregulated IFN-gamma (IFN-γ) secretion of CTLs. Importantly, Ad5/35-TRAIL transduced CTLs had no inhibitory effect on normal cells. Thus, the novel CTLs may be safe and feasible for the development of gene therapy approaches to pancreatic carcinoma.

Clinical Outcomes of Specific Immunotherapy in Advanced Pancreatic Cancer: A Systematic Review and Meta-Analysis

Specific immunotherapies, including vaccines with autologous tumor cells and tumor antigen-specific monoclonal antibodies, are important treatments for PC patients. To evaluate the clinical outcomes of PC-specific immunotherapy, we performed a systematic review and meta-analysis of the relevant published clinical trials. The effects of specific immunotherapy were compared with those of nonspecific immunotherapy and the meta-analysis was executed with results regarding the overall survival (OS), immune responses data, and serum cancer markers data. The pooled analysis was performed by using the random-effects model. We found that significantly improved OS was noted for PC patients utilizing specific immunotherapy and an improved immune response was also observed. In conclusion, specific immunotherapy was superior in prolonging the survival time and enhancing immunological responses in PC patients.

Combination of cytokine-induced killer and dendritic cells pulsed with antigenic α-1,3-galactosyl epitope-enhanced lymphoma cell membrane for effective B-cell lymphoma immunotherapy

BACKGROUND AIMS

Refractory B-cell lymphomas are difficult to successfully treat with current chemotherapeutic regimens; however, immunotherapy may be an effective form of treatment for these patients.

METHODS

Fourteen refractory lymphoma patients (age, 29-74 y) were enrolled in the trial. α-1,3-galactosyl (α-Gal) epitopes were synthesized on lymphoma cell membranes with the use of bovine recombinant α-1,3-galactosyltransferase (α-GT) and neuraminidase to enhance tumor immunogenicity. Subsequent incubation of processed cell membranes with autologous dendritic cells (DCs) in the presence of human serum containing abundant natural anti-α-Gal immunoglobulin G led to the effective phagocytosis of tumor membranes by DCs. The pulsed DCs and autologous cytokine-induced killer cells were then co-cultured to promote maximum cytotoxicity to lymphoma cells and were infused back into the donor lymphoma patients. Therapeutic responses were assessed by clinical observation, laboratory tests and a computed tomography scan at 6 months after treatment.

RESULTS

Complete and partial remission occurred in four and three patients, respectively. The disease status remained unchanged in five patients, and disease progression was observed in two patients. No serious side effects or autoimmune diseases were observed in any participants. Serum lactate dehydrogenase and β2-macroglobulin decreased in 11 and 14 patients, respectively. All patients showed robust systemic cytotoxicity in response to tumor lysate as measured by interferon-γ expression in peripheral blood mononuclear cells after treatment (P < 0.001). The number of peripheral immune effector cells (CD3(+)/CD4(+), CD8(+)/CD28(+) and CD16(+)/CD56(+) cells) increased significantly (P < 0.05) 3 months after treatment.

CONCLUSIONS

Lymphoma cell-specific α-Gal immunotherapy is safe, effective and has great potential for the treatment of refractory B-cell lymphoma.

Natural anti-carbohydrate antibodies contributing to evolutionary survival of primates in viral epidemics?

Humans produce multiple natural antibodies against carbohydrate antigens on gastrointestinal bacteria. Two such antibodies appeared in primates in recent geological times. Anti-Gal, abundant in humans, apes and Old-World monkeys, appeared 20-30 million years ago (mya) following inactivation of the α1,3GT gene (GGTA1). This gene encodes in other mammals the enzyme α1,3galactosyltransferase (α1,3GT) that synthesizes α-gal epitopes (Galα1-3Galβ1-4GlcNAc-R) which bind anti-Gal. Anti-Neu5Gc, found only in humans, appeared in hominins <6 mya, following elimination of N-glycolylneuraminic-acid (Neu5Gc) because of inactivation of CMAH, the gene encoding hydroxylase that converts N-acetylneuraminic-acid (Neu5Ac) into Neu5Gc. These antibodies, were initially produced in few individuals that acquired random mutations inactivating the corresponding genes and eliminating α-gal epitopes or Neu5Gc, which became nonself antigens. It is suggested that these evolutionary selection events were induced by epidemics of enveloped viruses, lethal to ancestral Old World primates or hominins. Such viruses presented α-gal epitopes or Neu5Gc, synthesized in primates that conserved active GGTA1 or CMAH, respectively, and were lethal to their hosts. The natural anti-Gal or anti-Neu5Gc antibodies, produced in offspring lacking the corresponding carbohydrate antigens, neutralized and destroyed viruses presenting α-gal epitopes or Neu5Gc. These antibodies further induced rapid, effective immune responses against virus antigens, thus preventing infections from reaching lethal stages. These epidemics ultimately resulted in extinction of primate populations synthesizing these carbohydrate antigens and their replacement with offspring populations lacking the antigens and producing protective antibodies against them. Similar events could mediate the elimination of various carbohydrate antigens, thus preventing the complete extinction of other vertebrate species.

Phase I study to evaluate toxicity and feasibility of intratumoral injection of α-gal glycolipids in patients with advanced melanoma

Effective uptake of tumor cell-derived antigens by antigen-presenting cells is achieved pre-clinically by in situ labeling of tumor with α-gal glycolipids that bind the naturally occurring anti-Gal antibody. We evaluated toxicity and feasibility of intratumoral injections of α-gal glycolipids as an autologous tumor antigen-targeted immunotherapy in melanoma patients (pts). Pts with unresectable metastatic melanoma, at least one cutaneous, subcutaneous, or palpable lymph node metastasis, and serum anti-Gal titer ≥1:50 were eligible for two intratumoral α-gal glycolipid injections given 4 weeks apart (cohort I: 0.1 mg/injection; cohort II: 1.0 mg/injection; cohort III: 10 mg/injection). Monitoring included blood for clinical, autoimmune, and immunological analyses and core tumor biopsies. Treatment outcome was determined 8 weeks after the first α-gal glycolipid injection. Nine pts received two intratumoral injections of α-gal glycolipids (3 pts/cohort). Injection-site toxicity was mild, and no systemic toxicity or autoimmunity could be attributed to the therapy. Two pts had stable disease by RECIST lasting 8 and 7 months. Tumor nodule biopsies revealed minimal to no change in inflammatory infiltrate between pre- and post-treatment biopsies except for 1 pt (cohort III) with a post-treatment inflammatory infiltrate. Two and four weeks post-injection, treated nodules in 5 of 9 pts exhibited tumor cell necrosis without neutrophilic or lymphocytic inflammatory response. Non-treated tumor nodules in 2 of 4 evaluable pts also showed necrosis. Repeated intratumoral injections of α-gal glycolipids are well tolerated, and tumor necrosis was seen in some tumor nodule biopsies after tumor injection with α-gal glycolipids.

Primary analysis for clinical efficacy of immunotherapy in patients with pancreatic cancer

Aims: Immunotherapy is an important treatment for pancreatic cancer (PC) patients. To evaluate the therapeutic efficacy of immunotherapy in the treatment of PC, we performed a systemic review and meta-analysis of the relevant published clinical trials, collectively referred to as DC, DC-CIK, LAK, NK and GM-CSF secreting PC cell lines. Materials & methods: A total of 413 patients in 11 eligible trials with PC were selected for the present meta-analysis. Results: The estimated pooled overall survival showed a significant improvement for PC patients who received immunotherapy compared with nonimmunotherapy. The lymphocyte subsets, immune cytokine levels and serum cancer markers in the peripheral blood of PC patients were significantly improved after immunotherapy. Conclusion: The results showed that immunotherapy can improve the efficacy of the treatment of PC patients.

Immunotherapy for pancreatic ductal adenocarcinoma: an overview of clinical trials

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death and current therapeutic strategies are often unsatisfactory. Identification and development of more efficacious therapies is urgently needed. Immunotherapy offered encouraging results in preclinical models during the last decades, and several clinical trials have explored its therapeutic application in PDAC. The aim of this review is to summarize the results of clinical trials conducted to evaluate the future perspective of immunotherapy in the treatment of PDAC.

Current adjuvant therapeutic approaches for pancreatic cancer

Pancreatic cancer continues to be the fourth leading cause of death despite advancements in surgical and adjuvant therapeutic approaches. In the present review, the current cytotoxic therapeutic approaches and advanced targeted therapies are objectively discussed with consideration to the current literature.

Trial watch: Dendritic cell-based anticancer therapy

The use of patient-derived dendritic cells (DCs) as a means to elicit therapeutically relevant immune responses in cancer patients has been extensively investigated throughout the past decade. In this context, DCs are generally expanded, exposed to autologous tumor cell lysates or loaded with specific tumor-associated antigens (TAAs), and then reintroduced into patients, often in combination with one or more immunostimulatory agents. As an alternative, TAAs are targeted to DCs in vivo by means of monoclonal antibodies, carbohydrate moieties or viral vectors specific for DC receptors. All these approaches have been shown to (re)activate tumor-specific immune responses in mice, often mediating robust therapeutic effects. In 2010, the first DC-based preparation (sipuleucel-T, also known as Provenge®) has been approved by the US Food and Drug Administration (FDA) for use in humans. Reflecting the central position occupied by DCs in the regulation of immunological tolerance and adaptive immunity, the interest in harnessing them for the development of novel immunotherapeutic anticancer regimens remains high. Here, we summarize recent advances in the preclinical and clinical development of DC-based anticancer therapeutics.

An update on new adoptive immunotherapy strategies for solid tumors with cytokine-induced killer cells

INTRODUCTION

Cytokine-induced killer (CIK) cells are mainly CD3(+)CD56(+) NKT cells exhibiting non-MHC-restricted cytotoxicity against a broad range of tumors. Much research is going on to improve CIK cell effectivity and to evaluate the clinical benefit of different combinations with conventional therapies.

AREAS COVERED

This review provides an update on in vitro/in vivo studies and clinical trials applying CIK cells for the treatment of solid tumors. This comprises attempts using additional cytokines, genetic engineering and combinations with different conventional and modern therapies.

EXPERT OPINION

Since our last review, much effort has been made to improve CIK cell cytotoxicity and clinical effectivity. Targeted CIK cell therapy and combinations of CIK cells with antiangiogenic drugs or oncolytic viruses are examples of recent outstanding achievements in the field of adoptive CIK cell therapy. The clinical application of CIK cells in combination with conventional therapies, especially, obtained promising results. However, the best combination and the optimal therapy schedule have yet to be defined.

Clinical studies applying cytokine-induced killer cells for the treatment of gastrointestinal tumors

Tumors of the gastrointestinal system represent a significant share of solid tumors worldwide. Despite the advances in diagnosis and treatment, the prognosis of gastrointestinal tumors is still very poor and improved therapies are indispensable. Cytokine-induced killer (CIK) cells are feasible for an immunotherapeutic approach as they are easily available and have an advantageous biologic profile; they are rapidly proliferating and their high cytotoxicity is non-MHC-restricted. We summarize and discuss twenty recent clinical studies applying CIK cells for the treatment of gastric, pancreatic, hepatocellular, and colorectal cancer. Autologous CIK cells were transfused intravenously, intraperitoneally, or via the common hepatic artery. In all studies side effects and toxicity of CIK cell therapy were mild and easily controllable. The combination of CIK cell therapy with conventional adjuvant or palliative therapies was superior to the standard therapy alone, indicating the benefit of CIK cell therapy for cancer patients. Thus, CIK cells represent a promising immunotherapy for the treatment of gastrointestinal tumors. The optimal treatment schedule and ideal combination with conventional therapies should be evaluated in further clinical studies.

S-1 plus CIK as second-line treatment for advanced pancreatic cancer

This study aimed to evaluate the efficacy and tolerability of S-1 (Tegafur, Gimeracil, and Oteracil Potassium Capsules) plus CIK (Cytokine-induced killer cells) in patients with advanced pancreatic cancer who had previously received gemcitabine-based therapy. In this prospective study, fifty-eight patients were randomly divided into two groups. One group (CT group) was given S-1 alone, and the other group (immuno-CT group) was given S-1 plus CIK. S-1 was administered orally twice a day at 80 mg/m(2)/day on days 1-21 of a 28-day cycle till disease progression or unacceptable toxicity occurred. CIK was given for one cycle of 28 days. The disease control rate for S-1 and CIK was 40.0 and 53.6%, respectively (p = 0.621). The serum CA19-9 level decreased for more than 25% was significantly different (33.3 and 60.7 % in CT group and immuno-CT group, respectively, p = 0.037). The median time to progression was 2.5 (95% CI 2.3-2.8) and 2.9 (95% CI 2.6-3.2) months (p = 0.037) for CT group and immuno-CT group, respectively. The median overall survival was 6.1 (95% CI 5.7-6.5) and 6.6 (95% CI 6.1-7.1) months (p = 0.09) for CT group and immuno-CT group, respectively. The difference in hematological toxicity, including leukocytopenia, anemia, and neutropenia, was insignificant between the two groups. In contrast, the differences in non-hematological toxicity, fatigue, and non-infective fever were significantly different between the two groups (p < 0.05). The S-1 plus CIK regimen was well tolerated in a second-line setting in patients with gemcitabine-refractory and advanced pancreatic cancer.