Tremelimumab (CP-675,206), a cytotoxic T lymphocyte associated antigen 4 blocking monoclonal antibody in clinical development for patients with cancer

Nivolumab in combination with ipilimumab for the treatment of melanoma

Melanoma patients develop resistance to most therapies, including chemo- and targeted-therapy drugs. Single-agent therapies are ineffective due to the heterogeneous nature of tumors comprising several subpopulations. Treatment of melanoma with immune-based therapies such as anti-cytotoxic T-lymphocyte activation-4 and anti-programmed death-1 antibodies has shown modest but long-lasting responses. Unfortunately, only subsets of melanoma patients respond to antibody-based therapies. Heterogeneity in lymphocyte infiltration and low frequency of anti-melanoma-reactive T-cells in tumor lesions are partly responsible for a lack of response to antibody-based therapies. Both antibodies have same biological function but they bind to different ligands at various phases of T-cell activity. Thus, combination therapy of antibodies has shown superior response rates than single-agent therapy. However, toxicity is a cause of concern in these therapies. Future identification of therapy-response biomarkers, mobilization of tumor-reactive T-cell infiltration using cancer vaccines, or non-specific targeted-therapy drugs will minimize toxicity levels and provide long-term remissions in melanoma patients.

Immune checkpoint therapy for non-small-cell lung cancer: an update

The role of immunotherapy in treatment of non-small-cell lung cancer (NSCLC) has been gaining interest over the past few years. This has been driven primarily by promising results from trials evaluating antagonist antibodies that target co-inhibitory immune checkpoints expressed on tumor cells and immune cells within the tumor microenvironment. Immune checkpoints exist to dampen or terminate immune activity to guard against autoimmunity and allow for self-tolerance. However, tumors can take advantage of these immune checkpoint pathways to evade destruction. Antibodies that block inhibitory checkpoints, such as anti-CTLA-4, anti-PD1 and anti-PD-L1 antibodies have demonstrated delayed tumor growth and increased survival. Novel therapies are now investigating combining checkpoint inhibitors with chemotherapy, targeted therapy, radiation and vaccines to produce synergistic antitumor activity.

Immune related adverse events associated with anti-CTLA-4 antibodies: systematic review and meta-analysis

BACKGROUND

Targeting CTLA-4 is a recent strategic approach in cancer control: blocking CTLA-4 enhances an antitumor immunity by promoting T-cell activation and cytotoxic T-lymphocyte proliferation. This induction of a tolerance break against the tumor may be responsible for immune-related adverse events (irAEs). Our objective was to assess the incidence and nature of irAEs in oncologic patients receiving anti-CTLA-4 antibodies (ipilimumab and tremelimumab).

METHODS

A systematic search of literature up to February 2014 was performed in MEDLINE, EMBASE, and Cochrane databases to identify relevant articles. Paired reviewers independently selected articles for inclusion and extracted data. Pooled incidence was calculated using R(©), package meta.

RESULTS

Overall, 81 articles were included in the study, with a total of 1265 patients from 22 clinical trials included in the meta-analysis. Described irAEs consisted of skin lesions (rash, pruritus, and vitiligo), colitis, and less frequently hepatitis, hypophysitis, thyroiditis, and some rare events such as sarcoidosis, uveitis, Guillain-Barré syndrome, immune-mediated cytopenia and polymyalgia rheumatic/Horton. The overall incidence of all-grade irAEs was 72 % (95 % CI, 65-79 %). The overall incidence of high-grade irAEs was 24 % (95 % CI, 18-30 %). The risk of developing irAEs was dependent of dosage, with incidence of all-grade irAEs being evaluated to 61 % (95 % CI, 56-66 %) for ipilimumab 3 mg/kg and 79 % (95 % CI, 69-89 %) for ipilimumab 10 mg/kg. Death due to irAEs occurred in 0.86 % of patients. The median time of onset of irAEs was about 10 weeks (IQR, 6-12) after the onset of treatment, corresponding with the first three cycles but varied according to the organ system involved. Such immune activation could also be indicative for tumor-specific T-cell activation and irAE occurrence was associated with clinical response to CTLA-4 blocking in 60 % of patients.

CONCLUSION

The price of potential long-term survival to metastatic tumors is an atypical immune toxicity, reflecting the mechanism of action of anti-CTLA-4 antibodies. A better knowledge of these irAEs and its management in a multidisciplinary approach will help to reduce morbidity and therapy interruptions.

Clinical Development of Immune Checkpoint Inhibitors

Recent progress in cancer immunotherapy has been remarkable. Most striking are the clinical development and approval of immunomodulators, also known as immune checkpoint inhibitors. These monoclonal antibodies (mAb) are directed to immune checkpoint molecules, which are expressed on immune cells and mediate signals to attenuate excessive immune reactions. Although mAbs targeting tumor associated antigens, such as anti-CD20 mAb and anti-Her2 mAb, directly recognize tumor cells and induce cell death, immune checkpoint inhibitors restore and augment the antitumor immune activities of cytotoxic T cells by blocking immune checkpoint molecules on T cells or their ligands on antigen presenting and tumor cells. Based on preclinical data, many clinical trials have demonstrated the acceptable safety profiles and efficacies of immune checkpoint inhibitors in a variety of cancers. The first in class approved immune checkpoint inhibitor is ipilimumab, an anti-CTLA-4 (cytotoxic T lymphocyte antigen-4) mAb. Two pivotal phase III randomized controlled trials demonstrated a survival benefit in patients with metastatic melanoma. In 2011, the US Food and Drug Administration (FDA) approved ipilimumab for metastatic melanoma. Several clinical trials have since investigated new agents, alone and in combination, for various cancers. In this review, we discuss the current development status of and future challenges in utilizing immune checkpoint inhibitors.

Immune checkpoint blockade

Since the development and approval of Ipilimumab, the first immune checkpoint inhibitor licensed for the treatment of metastatic melanoma, clinicians have gained a better understanding of the mode of action, management of toxicities, and assessment of response to this class of drugs. Several antibodies are now in development, aimed at blocking novel immune checkpoint molecules, such as PD-1 and it's corresponding ligand PD-L1. This article summarizes the mechanism of action, preclinical development, and subsequent clinical studies of immune checkpoint antibodies in melanoma.

Improved survival with T cell clonotype stability after anti-CTLA-4 treatment in cancer patients

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) blockade can promote antitumor T cell immunity and clinical responses. The mechanism by which anti-CTLA-4 antibodies induces antitumor responses is controversial. To determine the effects of CTLA-4 blockade on the T cell repertoire, we used next-generation deep sequencing to measure the frequency of individual rearranged T cell receptor β (TCRβ) genes, thereby characterizing the diversity of rearrangements, known as T cell clonotypes. CTLA-4 blockade in patients with metastatic castration-resistant prostate cancer and metastatic melanoma resulted in both expansion and loss of T cell clonotypes, consistent with a global turnover of the T cell repertoire. Overall, this treatment increased TCR diversity as reflected in the number of unique TCR clonotypes. The repertoire of clonotypes continued to evolve over subsequent months of treatment. Whereas the number of clonotypes that increased with treatment was not associated with clinical outcome, improved overall survival was associated with maintenance of high-frequency clones at baseline. In contrast, the highest-frequency clonotypes fell with treatment in patients with short overall survival. Stably maintained clonotypes included T cells having high-avidity TCR such as virus-reactive T cells. Together, these results suggest that CTLA-4 blockade induces T cell repertoire evolution and diversification. Moreover, improved clinical outcomes are associated with less clonotype loss, consistent with the maintenance of high-frequency TCR clonotypes during treatment. These clones may represent the presence of preexisting high-avidity T cells that may be relevant in the antitumor response.

64Cu-DOTA-anti-CTLA-4 mAb enabled PET visualization of CTLA-4 on the T-cell infiltrating tumor tissues

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) targeted therapy by anti-CTLA-4 monoclonal antibody (mAb) is highly effective in cancer patients. However, it is extremely expensive and potentially produces autoimmune-related adverse effects. Therefore, the development of a method to evaluate CTLA-4 expression prior to CTLA-4-targeted therapy is expected to open doors to evidence-based and cost-efficient medical care and to avoid adverse effects brought about by ineffective therapy. In this study, we aimed to develop a molecular imaging probe for CTLA-4 visualization in tumor. First, we examined CTLA-4 expression in normal colon tissues, cultured CT26 cells, and CT26 tumor tissues from tumor-bearing BALB/c mice and BALB/c nude mice by reverse transcription polymerase chain reaction (RT-PCR) analysis and confirmed whether CTLA-4 is strongly expressed in CT26 tumor tissues. Second, we newly synthesized ⁶⁴Cu-1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid-anti-mouse CTLA-4 mAb (⁶⁴Cu-DOTA-anti-CTLA-4 mAb) and evaluated its usefulness in positron emission tomography (PET) and ex-vivo biodistribution analysis in CT26-bearing BALB/c mice. High CTLA-4 expression was confirmed in the CT26 tumor tissues of tumor-bearing BALB/c mice. However, CTLA-4 expression was extremely low in the cultured CT26 cells and the CT26 tumor tissues of tumor-bearing BALB/c nude mice. The results suggested that T cells were responsible for the high CTLA-4 expression. Furthermore, ⁶⁴Cu-DOTA-anti-CTLA-4 mAb displayed significantly high accumulation in the CT26 tumor, thereby realizing non-invasive CTLA-4 visualization in the tumor. Together, the results indicate that ⁶⁴Cu-DOTA-anti-CTLA-4 mAb would be useful for the evaluation of CTLA-4 expression in tumor.

Immune modulation for cancer therapy

BACKGROUND

Immune modulation in cancer refers to a range of treatments aimed at harnessing a patient's immune system to achieve tumour control, stabilisation, and potential eradication of disease. A novel therapeutic drug class called immune checkpoint-blocking antibodies modulate T-cell pathways that regulate T cells and have the potential to reinvigorate an antitumour immune response. Ipilimumab was the first FDA-approved immune checkpoint antibody licensed for the treatment of metastatic melanoma (MM) and blocks a checkpoint molecule called cytotoxic T-lymphocyte antigen 4 (CTLA-4).

METHODS

Herein we review the preclinical and clinical development of ipilimumab. We outline the mode of action of these agents and other immune checkpoint inhibitors, the management of their toxicities, and how to adequately assess response to treatment.

RESULTS

As a result of these data, a number of other antibodies that block novel checkpoint molecules including programmed death-1 (PD-1), and corresponding ligands such as programmed death ligand-1 (PD-L1) are under preclinical and clinical development, and have demonstrated activity in multiple tumour types.

CONCLUSIONS

This review will summarise the mechanism of action and clinical development of immune checkpoint antibodies, as well as lessons learned in the management and assessment of patients receiving these agents.

Immune therapies for malignant mesothelioma

Malignant mesothelioma (MM) is a rare disease which can develop in pleura, pericardium or peritoneum and in which the therapies available have limited efficacy and are associated with various side effects. Therefore, there is a need for more targeted and more effective therapies which are able to halt the disease progression. Among them immune therapies actively or passively directed against various structures of the MM cells seem to be particularly promising given their inhibitory potential demonstrated in both experimental and early clinical studies. Mesothelin in particular seem to be not only a biomarker of disease activity but also a therapeutic target. This review discusses the immune therapies currently investigated for MM.

CTLA4 blockade broadens the peripheral T-cell receptor repertoire

PURPOSE

To evaluate the immunomodulatory effects of cytotoxic T-lymphocyte-associated protein 4 (CTLA4) blockade with tremelimumab in peripheral blood mononuclear cells (PBMC).

EXPERIMENTAL DESIGN

We used next-generation sequencing to study the complementarity-determining region 3 (CDR3) from the rearranged T-cell receptor (TCR) variable beta (V-beta) in PBMCs of 21 patients, at baseline and 30 to 60 days after receiving tremelimumab.

RESULTS

After receiving tremelimumab, there was a median of 30% increase in unique productive sequences of TCR V-beta CDR3 in 19 out of 21 patients, and a median decrease of 30% in only 2 out of 21 patients. These changes were significant for richness (P = 0.01) and for Shannon index diversity (P = 0.04). In comparison, serially collected PBMCs from four healthy donors did not show a significant change in TCR V-beta CDR3 diversity over 1 year. There was a significant difference in the total unique productive TCR V-beta CDR3 sequences between patients experiencing toxicity with tremelimumab compared with patients without toxicity (P = 0.05). No relevant differences were noted between clinical responders and nonresponders.

CONCLUSIONS

CTLA4 blockade with tremelimumab diversifies the peripheral T-cell pool, representing a pharmacodynamic effect of how this class of antibodies modulates the human immune system.

Blood mRNA expression profiling predicts survival in patients treated with tremelimumab

PURPOSE

Tremelimumab (ticilimumab, Pfizer), is a monoclonal antibody (mAb) targeting cytotoxic T lymphocyte-associated antigen-4 (CTLA-4). Ipilimumab (Yervoy, BMS), another anti-CTLA-4 antibody, is approved by the U.S. Federal Drug Administration (FDA). Biomarkers are needed to identify the subset of patients who will achieve tumor control with CTLA-4 blockade.

EXPERIMENTAL DESIGN

Pretreatment peripheral blood samples from 218 patients with melanoma who were refractory to prior therapy and receiving tremelimumab in a multicenter phase II study were measured for 169 mRNA transcripts using reverse transcription polymerase chain reaction (RT-PCR). A two-class latent model yielded a risk score based on four genes that were highly predictive of survival (P < 0.001). This signature was validated in an independent population of 260 treatment-naïve patients with melanoma enrolled in a multicenter phase III study of tremelimumab.

RESULTS

Median follow-up was 297 days for the training population and 386 days for the test population. Expression levels of the 169 genes were closely correlated across the two populations (r = 0.9939). A four-gene model, including cathepsin D (CTSD), phopholipase A2 group VII (PLA2G7), thioredoxin reductase 1 (TXNRD1), and interleukin 1 receptor-associated kinase 3 (IRAK3), predicted survival in the test population (P = 0.001 by log-rank test). This four-gene model added to the predictive value of clinical predictors (P < 0.0001).

CONCLUSIONS

Expression levels of CTSD, PLA2G7, TXNRD1, and IRAK3 in peripheral blood are predictive of survival in patients with melanoma treated with tremelimumab. Blood mRNA signatures should be further explored to define patient subsets likely to benefit from immunotherapy.

Enhanced autoimmunity associated with induction of tumor immunity in thyroiditis-susceptible mice

BACKGROUND

Immunotherapeutic modalities to bolster tumor immunity by targeting specific sites of the immune network often result in immune dysregulation with adverse autoimmune sequelae. To understand the relative risk for opportunistic autoimmune disorders, we studied established breast cancer models in mice resistant to experimental autoimmune thyroiditis (EAT). EAT is a murine model of Hashimoto's thyroiditis, an autoimmune syndrome with established MHC class II control of susceptibility. The highly prevalent Hashimoto's thyroiditis is a prominent autoimmune sequela in immunotherapy, and its relative ease of diagnosis and treatment could serve as an early indicator of immune dysfunction. Here, we examined EAT-susceptible mice as a combined model for induction of tumor immunity and EAT under the umbrella of disrupted regulatory T cell (Treg) function.

METHODS

Tumor immunity was evaluated in female CBA/J mice after depleting Tregs by intravenous administration of CD25 monoclonal antibody and/or immunizing with irradiated mammary adenocarcinoma cell line A22E-j before challenge; the role of T cell subsets was determined by injecting CD4 and/or CD8 antibodies after tumor immunity induction. Tumor growth was monitored 3×/week by palpation. Subsequent EAT was induced by mouse thyroglobulin (mTg) injections (4 daily doses/week over 4 weeks). For some experiments, EAT was induced before establishing tumor immunity by injecting mTg+interleukin-1, 7 days apart. EAT was evaluated by mTg antibodies and thyroid infiltration.

RESULTS

Strong resistance to tumor challenge after Treg depletion and immunization with irradiated tumor cells required participation of both CD4(+) and CD8(+) T cells. This immunity was not altered by induction of mild thyroiditis with our protocol of Treg depletion and adjuvant-free, soluble mTg injections. However, the increased incidence of mild thyroiditis can be directly related to Treg depletion needed to achieve strong tumor immunity. Moreover, when a subclinical, mild thyroiditis was induced with soluble mTg and low doses of interleukin-1, to simulate pre-existing autoimmunity in patients subjected to cancer immunotherapy, mononuclear infiltration into the thyroid was enhanced.

CONCLUSIONS

Our current findings indicate that genetic predisposition to autoimmune disease could enhance autoimmunity during induction of tumor immunity in thyroiditis-susceptible mice. Thus, HLA genotyping of cancer patients should be part of any risk assessment.

Immunity, inflammation and cancer: a leading role for adenosine

Cancer is a complex disease that is dictated by both cancer cell-intrinsic and cell-extrinsic processes. Adenosine is an ancient extracellular signalling molecule that can regulate almost all aspects of tissue function. As such, several studies have recently highlighted a crucial role for adenosine signalling in regulating the various aspects of cell-intrinsic and cell-extrinsic processes of cancer development. This Review critically discusses the role of adenosine and its receptors in regulating the complex interplay among immune, inflammatory, endothelial and cancer cells during the course of neoplastic disease.

Abstract B80: A Phase II randomized, double-blind, placebo-controlled study of tremelimumab for second- and third-line treatment in patients with unresectable pleural or peritoneal mesothelioma

Malignant mesothelioma (MM) is an uncommon cancer, caused principally by asbestos exposure. No treatments after first-line platinum-pemetrexed (1) have shown survival benefit (2), thus novel approaches are needed. Asbestos exposure induces immunosuppression and immune dysfunction in the mesothelium environment mainly by hyperactivation of regulatory T lymphocytes and over-production of cytokines that inhibit cytotoxic T lymphocytes and natural killer cells (3). Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4, CD152) modulates and eventually switches off T cell activation. Tremelimumab binds to the CTLA-4 antigen, preventing its negative regulatory signaling to cytotoxic T cells (4). Results from a single arm phase 2 study of tremelimumab in 29 patients with MM who progressed on a platinum-based regimen showed promising 1- and 2- year survival rates (48.3% and 36.7%) and a safety profile consistent with previous tremelimumab studies. Two patients had durable partial response (6 and 15+ mo.): 1 after initial progressive disease. The disease control rate (DCR) was 31.0%: 5 patients had prolonged stable disease (9 to 27+ mo.). In addition, absolute levels of CD4+ICOS+ T cells significantly correlated (P = .007) with favorable overall survival (ClinicalTrials.gov # NCT01649024)(5). This study has been expanded to include an additional 29 patients who receive tremelimumab every 4 weeks for 6 doses, then every 12 weeks until confirmed disease progression. The expansion study completed enrollment in July 2013 (ClinicalTrials.gov # NCT01655888). Here we describe the design of a phase 2, randomized, double-blind, placebo-controlled study that is enrolling patients with unresectable pleural or peritoneal MM who progressed following 1 or 2 prior treatments, including a first-line platinum-pemetrexed regimen. Patients are randomized in a 2:1 ratio to receive either tremelimumab or placebo with stratification by EORTC status (low- vs high-risk), line of therapy (second vs third), and anatomical site (pleural vs peritoneal). Enrollment will include 180 patients at approximately 150 centers in multiple countries. The primary endpoint is overall survival. Secondary endpoints are durable DCR; progression-free survival (PFS); patient-reported outcomes (pain, disease-related symptoms, and time to deterioration of disease-related symptoms); duration of response and overall response rate (ORR); tremelimumab safety profile, immunogenicity, and pharmacokinetics. Exploratory endpoints are DCR, PFS, duration of response and ORR based on immune-related response criteria. Health-related quality of life, disease-related symptoms, pain, and health status in patients with durable clinical activity, as well as the association of biomarkers with tremelimumab and clinical outcomes will also be explored (ClinicalTrials.gov #NCT01843374).

This study is sponsored by MedImmune.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B80.

Citation Format: Luana Calabro, Lee M. Krug, Alessandra DiPietro, Scott Antonia, Raffit Hassan, Rajesh Narwal, Paul Robbins, Dongyue Fu, Aiman Shalabi, Hesham Abdullah, Ramy Ibrahim, Hedy Kindler, Michele Maio. A Phase II randomized, double-blind, placebo-controlled study of tremelimumab for second- and third-line treatment in patients with unresectable pleural or peritoneal mesothelioma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B80.

Natural killer T cells in advanced melanoma patients treated with tremelimumab

A significant barrier to effective immune clearance of cancer is loss of antitumor cytotoxic T cell activity. Antibodies to block pro-apoptotic/downmodulatory signals to T cells are currently being tested. Because invariant natural killer T cells (iNKT) can regulate the balance of Th1/Th2 cellular immune responses, we characterized the frequencies of circulating iNKT cell subsets in 21 patients with melanoma who received the anti-CTLA4 monoclonal antibody tremelimumab alone and 8 patients who received the antibody in combination with MART-1_26–35 peptide-pulsed dendritic cells (MART-1/DC). Blood T cell phenotypes and functionality were characterized by flow cytometry before and after treatment. iNKT cells exhibited the central memory phenotype and showed polyfunctional cytokine production. In the combination treatment group, high frequencies of pro-inflammatory Th1 iNKT CD8⁺ cells correlated with positive clinical responses. These results indicate that iNKT cells play a critical role in regulating effective antitumor T cell activity.

Influence of the oncolytic parvovirus H-1, CTLA-4 antibody tremelimumab and cytostatic drugs on the human immune system in a human in vitro model of colorectal cancer cells

Introduction

Tumor-directed and immune-system-stimulating therapies are of special interest in cancer treatment. Here, we demonstrate the potential of parvovirus H-1 (H-1PV) to efficiently kill colorectal cancer cells and induce immunogenicity of colorectal tumors by inducing maturation of dendritic cells (DCs) alone and also in combination with cytostatic drugs in vitro. Using our cell culture model, we have additionally investigated the effects of anti-CTLA-4 (cytotoxic T-lymphocyte-associated antigen 4) receptor antibody tremelimumab on this process.

Materials and methods

Colon carcinoma cell lines were treated with different concentrations of cytostatic drugs or tremelimumab or were infected with H-1PV in different multiplicities of infection (MOIs), and viability was determined using MTT assays. Expression of CTLA-4 in colon carcinoma cell lines was measured by FACScan™. For the coculture model, we isolated monocytes using adherence, and differentiation into immature DCs (iDCs) was stimulated using interleukin-4 and granulocyte-macrophage colony-stimulating factor. Maturation of iDCs into mature DCs (mDCs) was induced by a cytokine cocktail. SW480 colon carcinoma cells were infected with H-1PV or treated with cytostatic drugs. Drug treated and H-1PV-infected SW480 colon carcinoma cells were cocultured with iDCs and expression of maturation markers was measured using FACScan™. Cytokine measurements were performed using enzyme-linked immunosorbent assay.

Results

Colon carcinoma cells SW480 were potently infected and killed by H-1PV. CTLA-4 expression in SW480 cells increased after infection with H-1PV and also after treatment with cytostatic drugs. Tremelimumab had no influence on viability of the colon carcinoma cell line. There was no maturation of iDCs after coculture with SW480; instead, H-1PV-infected or drug pretreated SW480 induced maturation. Cytokine production was higher for H-1PV-infected cells but was not significantly enhanced by tremelimumab treatment alone or in combination. Addition of tremelimumab did not interfere with the maturation process as measured by markers of maturation as well as by determination of cytokine levels.

Conclusion

By enhancing both cell death and immunogenicity of tumors, H-1PV is of special interest for tumor-directed therapy. These features make it a promising candidate for clinical application in human colorectal cancer. As tremelimumab does not significantly interfere with this process, an interesting therapeutic combination of active enhancement of tumor immunogenicity and independent masking of the CTLA-4 silencing process on tumor cells is highlighted.

Vaccines for pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) remains a highly lethal disease; new therapeutic modalities are urgently needed. A number of immunotherapies tested in preclinical models have shown promise. Early-phase clinical trials have demonstrated evidence of immune activation that in some cases correlates with clinical response. Moreover, recent evidence delineates the intricate role of inflammation in PDA, even at its earliest stages. Pancreatic ductal adenocarcinoma is thus ripe for immunotherapy; however, significant challenges remain before success can be realized. Future studies will need to focus on the discovery of novel PDA antigens and the identification of the multiple immune suppressive pathways within the PDA tumor microenvironment that inhibit an effective PDA-targeted immune response. Technologies are now available to rapidly advance discovery. Rapid translation of new discoveries into scientifically driven clinical trials testing combinations of immune agents will likely continue to shift the procarcinogenic tumor environment toward the most potent anticancer response.

Tremelimumab: a review of development to date in solid tumors

Tremelimumab is an investigational, fully human IgG monoclonal antibody directed against CTLA-4, a coinhibitory receptor that represses effector T-cell activity in cancer. Tremelimumab has produced promising anticancer responses in early clinical trials. However, a phase III trial of tremelimumab monotherapy versus chemotherapy in advanced melanoma was stopped early when no statistically significant difference in overall survival was observed between the two interventions. This article describes tremelimumab's putative mechanism of action, its preclinical pharmacology and clinical results to date across a range of cancer settings as monotherapy, as well as in combination with other therapies. The failure of the Phase III trial in melanoma is examined and factors affecting the possible future clinical development of tremelimumab are also explored.

Synthetic immunostimulatory oligonucleotides in experimental and clinical practice

BACKGROUND

Oligonucleotides belong to a class of macromolecules with great potential for research and various therapeutic applications. Their mechanisms of action are extremely diverse, although they are rather homogeneous in composition. Single-stranded oligodeoxynucleotides are not only inhibitors of gene expression, but their CpG sequence motifs may activate the innate immune response. Recent progress made in preclinical and clinical testing, as well as the case of the most recently discovered RNA interference technology, will help to overcome efficacy problems of the previous approaches of the 'standard therapy' of such diseases as tumors and various infections.

METHODS

The aim of this article is to present various therapeutic aspects of oligonucleotides, and to review the most significant therapeutic applications of synthetic oligonucleotides. This paper presents a comprehensive review of current literature on various therapeutic properties of synthetic oligonucleotides.

CONCLUSIONS

The available results gathered from preclinical and clinical studies suggest that TLR9-targeted therapy of oligonucleotides can stimulate both innate and adaptive immunity. It also appears that CpG ODNs are generally safe, although moderate adverse effects, based on a backbone-related mechanism have been reported. The presented studies demonstrate that adjuvant CpG ODN can unify an immune response that leads to enhanced antigen-specific Ab formation. CpG ODN may therefore provide a unique approach to enhancing the efficacy of immunization, including the strengthening of antitumor immunity.

Synergy between chemotherapeutic agents and CTLA-4 blockade in preclinical tumor models

Ipilimumab, a cytotoxic T-lymphocyte antigen-4 (CTLA-4) binding agent, has proven to be an effective monotherapy for metastatic melanoma and has shown antitumor activity in trials when administered with other therapeutic agents. We hypothesized that the combination of ipilimumab with chemotherapeutic agents, such as ixabepilone, paclitaxel, etoposide, and gemcitabine, may produce therapeutic synergy based on distinct but complementary mechanisms of action for each drug and unique cellular targets. This concept was investigated using a mouse homolog of ipilimumab in preclinical murine tumor models, including SA1N fibrosarcoma, EMT-6 mammary carcinoma, M109 lung carcinoma, and CT-26 colon carcinoma. Results of CTLA-4 blockade in combination with one of various chemotherapeutic agents demonstrate that synergy occurs in settings where either agent alone was not effective in inducing tumor regression. Furthermore, when combined with CTLA-4 blockade, ixabepilone, etoposide, and gemcitabine elicited prolonged antitumor effects in some murine models with induction of a memory immune response. Future investigations are warranted to determine which specific chemo-immunotherapy combinations, if any, will produce synergistic antitumor effects in the clinical setting.

Phase I study of tremelimumab (CP-675 206) plus PF-3512676 (CPG 7909) in patients with melanoma or advanced solid tumours

Background:

Tremelimumab, a fully human cytotoxic T-lymphocyte antigen 4 monoclonal antibody, and PF-3512676, a Toll-like receptor-9 agonist, are targeted immune modulators that elicit durable single-agent antitumour activity in advanced cancer.

Methods:

To determine the maximum tolerated dose (MTD) of these agents combined during this phase I study, patients received intravenous tremelimumab (6.0, 10.0, or 15.0 mg kg⁻¹) every 12 weeks plus subcutaneous PF-3512676 (0.05, 0.10, or 0.15 mg kg⁻¹) weekly. Primary end points were safety and tolerability; secondary end points included pharmacokinetics and antitumour activity.

Results:

Twenty-one patients with stage IV melanoma (n=17) or advanced solid tumours (n=4) were enrolled. Injection-site reactions (n=21; 100%), influenza-like illness (n=18; 86%), and diarrhoea (n=13; 62%) were the most common treatment-related adverse events (TAEs). Grade ⩾3 TAEs were reported (n=7; 33%). Dose-limiting toxicities (prespecified 6-week observation) occurred in one of the six patients in the 10 mg kg⁻¹ tremelimumab plus 0.05 mg kg⁻¹ PF-3512676 cohort (grade 3 hypothalamopituitary disorder) and two of the six patients in the 15 mg kg⁻¹ tremelimumab plus 0.05 mg kg⁻¹ PF-3512676 cohort (grade 3 diarrhoea). Consequently, 15 mg kg⁻¹ tremelimumab plus 0.05 mg kg⁻¹ PF-3512676 exceeded the MTD. Two melanoma patients achieved durable (⩾170 days) partial response. No human antihuman antibody responses to tremelimumab were observed.

Conclusion:

Weekly PF-3512676 (⩽0.15 mg kg⁻¹) plus tremelimumab (⩽10 mg kg⁻¹ every 12 weeks) was tolerable.

The engagement of CTLA-4 on primary melanoma cell lines induces antibody-dependent cellular cytotoxicity and TNF-α production

Background

CTLA-4 (Cytotoxic T lymphocyte antigen-4) is traditionally known as a negative regulator of T cell activation. The blocking of CTLA-4 using human monoclonal antibodies, such as Ipilimumab, is currently used to relieve CTLA-4-mediated inhibition of anti-tumor immune response in metastatic melanoma. Herein, we have analyzed CTLA-4 expression and Ipilimumab reactivity on melanoma cell lines and tumor tissues from cutaneous melanoma patients. Then, we investigated whether Ipilimumab can trigger innate immunity in terms of antibody dependent cellular cytotoxicity (ADCC) or Tumor Necrosis Factor (TNF)-α release. Finally, a xenograft murine model was set up to determine in vivo the effects of Ipilimumab and NK cells on melanoma.

Methods

CTLA-4 expression and Ipilimumab reactivity were analyzed on 17 melanoma cell lines (14 primary and 3 long-term cell lines) by cytofluorimetry and on 33 melanoma tissues by immunohistochemistry. CTLA-4 transcripts were analyzed by quantitative RT-PCR. Soluble CTLA-4 and TNF-α were tested by ELISA. Peripheral blood mononuclear cells (PBMC), NK and γδT cells were tested in ADCC assay with Ipilimumab and melanoma cell lines. TNF-α release was analyzed in NK-melanoma cell co-cultures in the presence of ipilimumab. In vivo experiments of xenotransplantation were carried out in NOD/SCID mice. Results were analyzed using unpaired Student’s t-test.

Results

All melanoma cell lines expressed mRNA and cytoplasmic CTLA-4 but surface reactivity with Ipilimumab was quite heterogeneous. Accordingly, about 2/3 of melanoma specimens expressed CTLA-4 at different level of intensity.

Ipilimumab triggered, via FcγReceptorIIIA (CD16), ex vivo NK cells as well as PBMC, IL-2 activated NK and γδT cells to ADCC of CTLA-4⁺ melanoma cells. No ADCC was detected upon interaction with CTLA-4^- FO-1 melanoma cell line. TNF-α was released upon interaction of NK cells with CTLA-4⁺ melanoma cell lines. Remarkably, Ipilimumab neither affected proliferation and viability nor triggered ADCC of CTLA-4⁺ T lymphocytes. In a chimeric murine xenograft model, the co-engraftment of Ipilimumab-treated melanoma cells with human allogeneic NK cells delayed and significantly reduced tumor growth, as compared to mice receiving control xenografts.

Conclusions

Our studies demonstrate that Ipilimumab triggers effector lymphocytes to cytotoxicity and TNF-α release. These findings suggest that Ipilimumab, besides blocking CTLA-4, can directly activate the elimination of CTLA-4⁺ melanomas.

Anti-CTLA-4 antibodies of IgG2a isotype enhance antitumor activity through reduction of intratumoral regulatory T cells

Antitumor activity of CTLA-4 antibody blockade is thought to be mediated by interfering with the negative regulation of T-effector cell (Teff) function resulting from CTLA-4 engagement by B7-ligands. In addition, a role for CTLA-4 on regulatory T cells (Treg), wherein CTLA-4 loss or inhibition results in reduced Treg function, may also contribute to antitumor responses by anti-CTLA-4 treatment. We have examined the role of the immunoglobulin constant region on the antitumor activity of anti-CTLA-4 to analyze in greater detail the mechanism of action of anti-CTLA-4 antibodies. Anti-CTLA-4 antibody containing the murine immunoglobulin G (IgG)2a constant region exhibits enhanced antitumor activity in subcutaneous established MC38 and CT26 colon adenocarcinoma tumor models compared with anti-CTLA-4 containing the IgG2b constant region. Interestingly, anti-CTLA-4 antibodies containing mouse IgG1 or a mutated mouse IgG1-D265A, which eliminates binding to all Fcγ receptors (FcγR), do not show antitumor activity in these models. Assessment of Teff and Treg populations at the tumor and in the periphery showed that anti-CTLA-4-IgG2a mediated a rapid and dramatic reduction of Tregs at the tumor site, whereas treatment with each of the isotypes expanded Tregs in the periphery. Expansion of CD8(+) Teffs is observed with both the IgG2a and IgG2b anti-CTLA-4 isotypes, resulting in a superior Teff to Treg ratio for the IgG2a isotype. These data suggest that anti-CTLA-4 promotes antitumor activity by a selective reduction of intratumoral Tregs along with concomitant activation of Teffs.

New therapeutical strategies in the treatment of metastatic disease

Metastatic melanoma is a very aggressive cancer. For decades, although dacarbazine has been the standard of care as first-line therapy, new therapies have now been shown their superiority either alone or in association with dacarbazine. Ipilimumab (anti-CTLA4 monoclonal antibody) and vemurafenib (BRAF V600E inhibitor) have been recently approved by the Food and Drugs Association and European Medicine Agency for their use in metastatic melanoma patients. Other compounds targeting the MAP kinase pathway (anti-MEK, anti-ERK, other anti-BRAF) are under clinical evaluation as well as molecules targeting alternate pathways. Along with the development of these targeted agents, an initial molecular characterization of each patient melanoma has become the first step to define the best therapeutic options. The recent published data shed the light on advanced melanoma management. Herein we review the latest development of these molecules and their impact on the treatment strategy.

Phase III randomized clinical trial comparing tremelimumab with standard-of-care chemotherapy in patients with advanced melanoma

PURPOSE

In phase I/II trials, the cytotoxic T lymphocyte-associated antigen-4-blocking monoclonal antibody tremelimumab induced durable responses in a subset of patients with advanced melanoma. This phase III study evaluated overall survival (OS) and other safety and efficacy end points in patients with advanced melanoma treated with tremelimumab or standard-of-care chemotherapy.

PATIENTS AND METHODS

Patients with treatment-naive, unresectable stage IIIc or IV melanoma were randomly assigned at a ratio of one to one to tremelimumab (15 mg/kg once every 90 days) or physician's choice of standard-of-care chemotherapy (temozolomide or dacarbazine).

RESULTS

In all, 655 patients were enrolled and randomly assigned. The test statistic crossed the prespecified futility boundary at second interim analysis after 340 deaths, but survival follow-up continued. At final analysis with 534 events, median OS by intent to treat was 12.6 months (95% CI, 10.8 to 14.3) for tremelimumab and 10.7 months (95% CI, 9.36 to 11.96) for chemotherapy (hazard ratio, 0.88; P = .127). Objective response rates were similar in the two arms: 10.7% in the tremelimumab arm and 9.8% in the chemotherapy arm. However, response duration (measured from date of random assignment) was significantly longer after tremelimumab (35.8 v 13.7 months; P = .0011). Diarrhea, pruritus, and rash were the most common treatment-related adverse events in the tremelimumab arm; 7.4% had endocrine toxicities. Seven deaths in the tremelimumab arm and one in the chemotherapy arm were considered treatment related by either investigators or sponsor.

CONCLUSION

This study failed to demonstrate a statistically significant survival advantage of treatment with tremelimumab over standard-of-care chemotherapy in first-line treatment of patients with metastatic melanoma.

Safety profile and pharmacokinetic analyses of the anti-CTLA4 antibody tremelimumab administered as a one hour infusion

Background

CTLA4 blocking monoclonal antibodies provide a low frequency but durable tumor responses in patients with metastatic melanoma, which led to the regulatory approval of ipilimumab based on two randomized clinical trials with overall survival advantage. The similarly fully human anti-CTLA4 antibody tremelimumab had been developed in the clinic at a fixed rate infusion, resulting in very prolonged infusion times. A new formulation of tremelimumab allowed testing a shorter infusion time.

Methods

A phase 1 multi-center study to establish the safety and tolerability of administering tremelimumab as a 1-hour infusion to patients with metastatic melanoma. Secondary endpoints included pharmacokinetic and clinical effects of tremelimumab.

Results

No grade 3 or greater infusion-related adverse events or other adverse events preventing the administration of the full tremelimumab dose were noted in 44 treated patients. The overall side effect profile was consistent with prior experiences with anti-CTLA4 antibodies. Objective tumor responses were noted in 11% of evaluable patients with metastatic melanoma, which is also consistent with the prior experience with CTLA4 antagonistic antibodies.

Conclusions

This study did not identify any safety concerns when tremelimumab was administered as a 1-hour infusion. These data support further clinical testing of the 1-hour infusion of tremelimumab. (Clinical trial registration number NCT00585000).

Immunosuppressive effect of regulatory T lymphocytes in lung cancer, with special reference to their effects on the induction of autologous tumor-specific cytotoxic T lymphocytes

It is not easy to induce cytotoxic T lymphocytes (CTLs) against cancer in in vitro culture. Regulatory T cells (Tregs) are considered to play a pivotal role in tumor immune escape. In this study, we analyzed the distribution of Tregs among tumor-infiltrating lymphocytes (TILs), regional lymph node lymphocytes (RLNLs) and peripheral blood lymphocytes (PBLs) in patients with lung cancer, and analyzed the effect of Tregs on the induction of CTLs in vitro. A total of 84 patients with non-small cell lung cancer underwent surgery between January 2003 and December 2004. The TILs, RLNLs and PBLs from these patients were subjected to a comparison analysis. The proportion of CD4(+)CD25(+)Foxp3(+) cells in these lymphocytes was determined by flow cytometry. The effects of Tregs on the induction of CTLs was analyzed by the depletion of Tregs in mixed lymphocyte-tumor cell culture (MLTC). The average proportions of Tregs in the TILs, RLNLs and PBLs were 10.4±9.5, 4.4±2.4 and 2.8±2.1%, respectively. The proportion of Tregs in the RLNLs was significantly higher than that in the PBLs (P<0.001); furthermore, TILs contained a larger number of Tregs than RLNLs (P=0.034). These Tregs substantially suppressed the induction of CTLs against autologous tumor cells. The depletion of Tregs in the MLTC resulted in the successful induction of CTLs. Tregs were found at a higher frequency in the TILs and RLNLs than in the PBLs in lung cancer patients. Since Tregs inhibited the induction of CTLs, the depletion of Tregs may represent a new therapeutic strategy for lung cancer patients.

Targeted cancer immunotherapy with oncolytic adenovirus coding for a fully human monoclonal antibody specific for CTLA-4

Promising clinical results have been achieved with monoclonal antibodies (mAbs) such as ipilimumab and tremelimumab that block cytotoxic T lymphocyte-associated antigen-4 (CTLA-4, CD152). However, systemic administration of these agents also has the potential for severe immune-related adverse events. Thus, local production might allow higher concentrations at the target while reducing systemic side effects. We generated a transductionally and transcriptionally targeted oncolytic adenovirus Ad5/3-Δ24aCTLA4 expressing complete human mAb specific for CTLA-4 and tested it in vitro, in vivo and in peripheral blood mononuclear cells (PBMCs) of normal donors and patients with advanced solid tumors. mAb expression was confirmed by western blotting and immunohistochemistry. Biological functionality was determined in a T-cell line and in PBMCs from cancer patients. T cells of patients, but not those of healthy donors, were activated by an anti-CTLA4mAb produced by Ad5/3-Δ24aCTLA4. In addition to immunological effects, a direct anti-CTLA-4-mediated pro-apoptotic effect was observed in vitro and in vivo. Local production resulted in 43-fold higher (P<0.05) tumor versus plasma anti-CTLA4mAb concentration. Plasma levels in mice remained below what has been reported safe in humans. Replication-competent Ad5/3-Δ24aCTLA4 resulted in 81-fold higher (P<0.05) tumor mAb levels as compared with a replication-deficient control. This is the first report of an oncolytic adenovirus producing a full-length human mAb. High mAb concentrations were seen at tumors with lower systemic levels. Stimulation of T cells of cancer patients by Ad5/3-Δ24aCTLA4 suggests feasibility of testing the approach in clinical trials.

Clinical trials of vaccines for immunotherapy in pancreatic cancer

A greater understanding of the molecular events that trigger oncogenesis and events that negatively regulate immune responses has allowed for the development of targeted therapies with specific vaccines to match tumor antigens coupled with immunotherapy specifically directed against that tumor's immunosuppressive microenvironment. In order to be effective, vaccine therapies need to both expand the immune response to tumors and overcome immunosuppressive microenvironments therein. Specifically, targeted therapy must be personalized for each cancer patient. While the idea of personalized targeted therapy may seem like a daunting task, it may not be that difficult as it could involve a relatively simple genetic test to identify gene mutations and additional immunohistochemical staining of tumors with antibodies directed against markers of negative immune regulation. The additional cost to personalize cancer therapy with these diagnostic tests is relatively small in comparison to the cost afforded to our healthcare system when inappropriate targeting therapies are administered to patients whose tumors do not express the targets of either the vaccine or the immune modulator. Despite the large cost, cancer patients whose tumors lack the targets of these therapies often receive no benefit from the therapy. The most illogical approach is to develop a study design and perform clinical trials of potential novel targeting drugs without knowledge or confirmation that the patients' tumors express the targets. Current cancer trials for pancreatic cancer patients are discussed in this article.

Neem leaf glycoprotein inhibits CD4+CD25+Foxp3+ Tregs to restrict murine tumor growth

Background: The presence of Tregs in tumors is associated with compromised tumor-specific immune responses and has a clear negative impact on survival of cancer patients. Thus, downregulation of Tregs is considered as a promising cancer immunotherapeutic approach. We have reported previously that neem leaf glycoprotein (NLGP) prophylaxis restricts tumor growth in mice by immune activation. In continuation, here, involvement of NLGP in the modulation of Tregs in association with tumor growth restriction is investigated. Results: NLGP downregulates CD4+CD25+Foxp3+ Tregs within tumors. NLGP-mediated downregulation of CCR4 along with its ligand CCL22 restricts Treg migration at the tumor site. NLGP is not apoptotic to Tregs but significantly downregulates the expression of Foxp3, CTLA4 and GITR. It also reverses the functional impairment of T-effector cells by Tregs, in terms of IFN-γ secretion, cellular proliferation and tumor cell cytotoxicity. NLGP also facilitates reconditioning of tumor microenvironment (hostile) by increasing IFN-γ and IL-12 but decreasing IL-10, TGF-β, VEGF and IDO, creating an antitumor niche. Interaction between Foxp3, p-NFATc3 and p-Smad2/3, needed for successful Treg function, is also inhibited by NLGP. Conclusion: All of these coordinated events might result in inhibition of Treg associated-tumor growth and therefore increased survivability of mice having NLGP treatment before or/and after tumor inoculation. Thus, the possibility of NLGP being an excellent tool as a T-cell anergy breaker by abrogating the suppressor functions of Tregs in cancer needs to be explored further in the clinic.

CD40 expression by human melanocytic lesions and melanoma cell lines and direct CD40 targeting with the therapeutic anti-CD40 antibody CP-870,893

Anti-CD40 antibodies are in clinical development in patients with metastatic melanoma, a cancer that has been reported earlier to express CD40. The antitumor activity of anti-CD40 antibodies may be mediated by direct cytotoxic effects on CD40-positive melanoma cells or indirectly through modulation of host cells. In these studies, biopsies of patients with primary and metastatic melanoma, short-term cultures, and established melanoma cell lines were analyzed for CD40 expression using a combination of methods including immunohistochemistry, flow cytometry, and gene expression profiling, and the cytotoxic effects of the anti-CD40 antibody CP-870,893 on melanoma cell lines were tested using cell viability assays. CD40 was expressed at a higher frequency in metastatic melanoma lesions compared with primary melanomas. There was a variable expression of CD40 in synchronous and metachronous melanoma metastases. Expression of CD40 was present in slightly over half of a large panel of short-term primary melanoma cultures, with a wide range of expression levels by flow cytometry. Similar results were obtained in established melanoma cell lines when analyzed at the mRNA level or by surface protein staining. In approximately one-third of cell lines, the expression of CD40 could be up-regulated with a histone deacetylase inhibitor. Treatment with increasing concentrations of CP-870,893 had no antitumor activity against either CD40-positive or negative melanoma cell lines. In conclusion, approximately one-third to one-half of melanomas expresses CD40 at variable levels. Direct exposure to a CD40-activating antibody does not lead to antitumor activity in melanoma cell lines, suggesting that the antitumor effects of these antibodies in the clinic may be indirectly mediated.

Systematic review of medical treatment in melanoma: current status and future prospects

The incidence of melanoma is increasing worldwide, and the prognosis for patients with high-risk or advanced metastatic melanoma remains poor despite advances in the field. Standard treatment for patients with thick (≥2.0 mm) primary melanoma with or without regional metastases to lymph nodes is surgery followed by adjuvant therapy or clinical trial enrollment. Adjuvant therapy with interferon-α and cancer vaccines is discussed in detail. Patients who progress to stage IV metastatic melanoma have a median survival of ≤1 year. Standard treatment with chemotherapy yields low response rates, of which few are durable. Cytokine therapy with IL-2 achieves durable benefits in a greater fraction, but it is accompanied by severe toxicities that require the patient to be hospitalized for support during treatment. A systematic literature review of treatments for advanced, metastatic disease was conducted to present the success of current treatments and the promise of those still in clinical development that may yield incremental improvements in the treatment of advanced, metastatic melanoma.

Current experience with CTLA4-blocking monoclonal antibodies for the treatment of solid tumors

Monoclonal antibodies (mAbs) specific for cytotoxic T lymphocyte-associated antigen 4 (CTLA4) are a novel form of immunotherapy for treatment of patients with advanced cancers. These anti-CTLA4 mAbs prevent normal downregulation of the immune system, thus prolonging and enhancing T-cell activation and potentially promoting an antitumor immune response. Clinical studies in patients with advanced cancers have indicated that CTLA4 blockade with mAbs is associated with antitumor activity in a small percentage of patients and has a manageable toxicity profile. The key limitations for broader applicability of this mode of therapy are better definition of the mechanism that leads to tumor rejection and the validation of favorable observations in single-arm studies into prospectively randomized clinical trials.

Clinical development of the anti-CTLA-4 antibody tremelimumab

Tremelimumab (formerly CP-675,206) is a fully human IgG2 monoclonal antibody tested in patients with cancer, of whom the majority have had metastatic melanoma. Clinical trials using tremelimumab demonstrate that this antibody can induce durable tumor regressions (up to 8 years at this time) in 7% to 10% of patients with metastatic melanoma. These tumor responses are mediated by the intratumoral infiltration of cytotoxic T lymphocytes (CTLs) as demonstrated in patient-derived tumor biopsies. Grade 3 or 4 toxicities in the range of 20% to 25% are mainly inflammatory or autoimmune in nature, which are on-target effects after inhibiting CTLA-4-mediated self-tolerance. The lack of survival advantage in the early analysis of a phase III clinical trial comparing tremelimumab with standard chemotherapy for metastatic melanoma highlights the importance of gaining a better understanding of how this antibody modulates the human immune system and how to better select patients for this mode of therapy.

[Expression and significance of gp96 and immune-related gene CTLA-4, CD8 in lung cancer tissues]

BACKGROUND AND OBJECTIVE

It has been proven that gp96 plays an important role in specific cytotoxic immune response which is involved in anti-tumor effect in the body. The aim of this study is to investigate the biological significance of heat shock protein gp96 and immune-related gene CTLA-4, CD8 expressions in lung cancer tissues of different progressive stages.

METHODS

We used Envision immunohistochemistry method to detect the levels of expression of gp96, CTLA-4, CD8 in tissue microarray, which contained 89 primary lung cancer tissues, 12 lymph node metastasis lung cancer tissues, 12 precancerous lesions and 10 normal lung tissues, and analyzed the relationship between their expressions and clinicopathological parameters.

RESULTS

(1) The positive rate of gp96 in primary lung cancer was remarkably higher than that in precancerous lesion and normal lung tissue (P<0.05). The positive rate of CTLA-4 in primary lung cancer tissue and precancerous lesion was significantly higher than that in normal lung tissue (P<0.05). The positive rate of CD8 in primary lung cancer tissue was significantly higher than that in normal lung tissue (P<0.05). The positive rate of gp96 in CD8-positive lymphocytes in the high expression group was less than that in the low group (P<0.05). (2) The positive rate of gp96 was closely related to sex, differentiation and clinical stage (P<0.05), but not to age, gross type, histological type and lymph node metastasis (P>0.05). The positive rate of CTLA-4 was closely related to age and differentiation (P<0.05), but not to sex, gross type, histological type, clinical stage and lymph node metastasis (P>0.05). CD8 expression was related to clinical stage (P<0.05), but not to sex, age, gross type, histological type, differentiation and lymph node metastasis (P>0.05). The positive rates of gp96, CTLA-4 were higher than that of CD8 in squamous cell carcinoma and SCLC, respectively. (3) There was positive correlation between gp96 and CTLA-4; there was negative correlation between gp96 and CD8, and there was negative correlation between CD8 and CTLA-4 (P<0.05).

CONCLUSION

Gene expression of PD-L1 on lung cancer cell line can decrease the cytolytic effect of CTL on target cells.

The treatment and prevention of mouse melanoma with an oral DNA vaccine carried by attenuated Salmonella typhimurium

Therapeutic vaccines of cancer are attractive for their capacity of breaking the immune tolerance and invoking long-term immune response targeting cancer cells without autoimmunity. An efficient antigen delivery system is the key issue of developing an effective cancer vaccine. Attenuated Salmonella typhimurium as the carrier of cancer vaccine are able to transfer DNA from the prokaryote to the eukaryote and preferentially replicate within the tumor tissue. Heat shock protein 70 delivers the tumor-associated antigens to antigen presenting cells through its polypeptide-binding domain and breaks immune tolerance of the cancer cells. Here we described a novel low-copy-number DNA vaccine based on the Hsp70-TAA complex and carried by the attenuated S. typhimurium strain SL3261. Oral administration of this vaccine elicited specific CTL-mediated lysis of the melanoma tumor cells and marked activation of the T-cells. The therapeutic vaccine effectively protected 57.1% C57BL/6J mice from lethal challenge with B16F10 melanoma tumor cells in prophylactic settings and eraicated 62.5% tumor growth in therapeutic settings. This approach may provide a new strategy for the prevention and treatment of cancer.

Modulation of cell signaling networks after CTLA4 blockade in patients with metastatic melanoma

Background

The effects on cell signalling networks upon blockade of cytotoxic T lymphocyte-associated antigen-4 (CTLA4) using the monoclonal antibody tremelimumab were studied in peripheral blood mononuclear cell (PBMC) samples from patients with metastatic melanoma.

Methodology/Principal

Findings Intracellular flow cytometry was used to detect phosphorylated (p) signaling molecules downstream of the T cell receptor (TCR) and cytokine receptors. PBMC from tremelimumab-treated patients were characterized by increase in pp38, pSTAT1 and pSTAT3, and decrease in pLck, pERK1/2 and pSTAT5 levels. These changes were noted in CD4 and CD8 T lymphocytes but also in CD14 monocytes. A divergent pattern of phosphorylation of Zap70, LAT, Akt and STAT6 was noted in patients with or without an objective tumor response.

Conclusions/Significance

The administration of the CTLA4-blocking antibody tremelimumab to patients with metastatic melanoma influences signaling networks downstream of the TCR and cytokine receptors both in T cells and monocytes. The strong modulation of signaling networks in monocytes suggests that this cell subset may be involved in clinical responses to CTLA4 blockade.

Clinical Trial Registration

clinicaltrials.gov; Registration numbers NCT00090896 and NCT00471887

INGN-225: a dendritic cell-based p53 vaccine (Ad.p53-DC) in small cell lung cancer: observed association between immune response and enhanced chemotherapy effect

IMPORTANCE OF THE FIELD

Novel approaches are needed for patients with small cell lung cancer (SCLC), as response after relapse is poor with standard therapies. p53 gene mutations often occur, resulting in tumoral protein overexpression and allowing for their recognition by p53-specific cytotoxic T cells.

AREAS COVERED IN THIS REVIEW

We describe the characteristics and manufacturing of INGN-225, a p53-modified adenovirus-tranduced dendritic cell vaccine, and review available data, to understand INGN-225's role in SCLC treatment. We discuss our pre-clinical, early Phase I/II, and ongoing randomized Phase II studies.

WHAT THE READER WILL GAIN

INGN-225 was well tolerated (all toxicities <or=grade 2) in the Phase I/II trial (54 patients receiving at least 1 dose). Specific anti-p53 immune response was positive in 18/43 (41.8%) patients, with overall post-INGN-225 response observed in 17/33 (51.5%) and immune response data available in 29 (14 positive, 15 negative). Post-INGN-225 response was observed in 11/14 (78.6%) and 5/15 (33%) patients with positive and negative immune responses, respectively.

TAKE HOME MESSAGE

INGN-225 is safe, induces a significant immune response, and appears to sensitize SCLC to subsequent chemotherapy. Improvements in immune response induction and understanding the chemotherapy-immunotherapy synergism will determine INGN-225's future role as an anticancer therapy.

Novel immunotherapies as potential therapeutic partners for traditional or targeted agents: cytotoxic T-lymphocyte antigen-4 blockade in advanced melanoma

The successful management of advanced melanoma remains an unmet need because of a resolutely poor prognosis and therapeutic options with limited effectiveness. Dacarbazine and fotemustine are the only approved chemotherapeutic agents for advanced melanoma, yet neither alone or in combination regimens has been shown to extend survival in randomized clinical trials. The only agent to be approved for advanced melanoma in the US in more than 30 years is high-dose bolus interleukin-2, but its use is associated with high toxicity and cost, and it has also failed to show a survival benefit. Our expanding knowledge of the complex factors and pathways regulating immune function has led to the advent of novel immunotherapeutic agents. Among these are ipilimumab and tremelimumab - fully human, monoclonal antibodies directed against cytotoxic T-lymphocyte antigen-4 (CTLA-4). The pivotal role of CTLA-4 in regulating T-cell function is established, and a series of preclinical studies provided proof-of-concept evidence of the antitumor activity of anti-CLTA-4 antibodies in combination with vaccines or chemotherapy. Subsequently, anti-CTLA-4 antibodies have shown encouraging results in clinical trials in advanced melanoma. Recent progress in the understanding of melanoma genetics and tumorigenesis has led to potential new therapeutic targets. Molecular targeted agents that inhibit the proliferation and survival of metastatic melanoma cells offer potential partners for anti-CTLA-4 antibodies in combined modality regimens. Novel combinations are reviewed in the context of creating an immunosupportive environment in the host.

Systemic therapy of non-resectable metastatic melanoma

In advanced metastatic melanoma (non-resectable stage III/IV), the prognosis still remains poor, with median survival times between six and twelve months. Systemic therapeutic approaches for metastatic melanoma include chemotherapy, immunotherapy, immunochemotherapy, small molecules and targeted therapy. In this review, we will focus on the various treatment modalities as well as new agents used for targeted therapy.

Dendritic cell vaccination as a treatment modality for melanoma

As melanoma is an immunogenic tumor, immunotherapy has been investigated as a possible treatment modality for melanoma patients at high risk of relapse and those with metastatic disease. In the past decade progress has been made, ranging from rather nonspecific stimulations of the immune system with IL-2 and IFN-alpha to more specific approaches based on vaccination with tumor antigens. Owing to their unique features, dendritic cells (DCs) represent an important tool for tumor antigen-specific immunotherapy. However, clinical vaccination trials with DCs showed sobering results with respect to objective responses and improvement of overall survival. In this review, principles and methods of DC-based vaccination are presented. Mechanisms impairing clinically successful vaccination strategies are described. Finally, we will discuss perspectives for future developments of DC-based vaccines that might lead melanoma treatment to a new era.

Assessing oncologic benefit in clinical trials of immunotherapy agents

BACKGROUND

USA Food and Drug Administration approval for cancer therapy requires demonstration of patient benefit as a marker of clinical efficacy. Prolonged survival is the gold standard for demonstration of efficacy, but other end points such as antitumor response, progression-free survival, quality of life, or surrogate end points may be used.

DESIGN

This study was developed based on discussion during a roundtable meeting of experts in the field of immunotherapy.

RESULTS

In most clinical trials involving cytotoxic agents, response end points use RECIST based on the premise that 'effective' therapy causes tumor destruction, target lesion shrinkage, and prevention of new lesions. However, RECIST may not be appropriate in trials of immunotherapy. Like other targeted agents, immunotherapies may mediate cytostatic rather than direct cytotoxic effects, and these may be difficult to quantify with RECIST. Furthermore, significant time may elapse before clinical effects are quantifiable because of complex response pathways. Effective immunotherapy may even mediate transient lesion growth secondary to immune cell infiltration.

CONCLUSIONS

RECIST may not be an optimal indicator of clinical benefit in immunotherapy trials. This article discusses alternative clinical trial designs and end points that may be more relevant for immunotherapy trials and may offer more effective prediction of survival in pivotal phase III studies.

Advanced malignant melanoma: immunologic and multimodal therapeutic strategies

Immunologic treatment strategies are established in malignant melanoma treatment, mainly focusing on Interleukin-2 in advanced disease and interferon alpha in the adjuvant situation. In advanced disease, therapies with IL-2, interferon and different chemotherapeutic agents were not associated with better patient survival in the vast majority of patients. Therefore, an overview of novel immunological agents and combined therapeutic approaches is presented in this review, covering allogenic and autologous vaccine strategies, dendritic cell vaccination, strategies for adoptive immunotherapy and T cell receptor gene transfer, treatment with cytokines and monoclonal antibodies against the CTLA-4 antigen. As emerging treatment strategies are based on individual molecular and immunological characterization of individual tumors/patients, tailored targeted drug therapies move into the focus of treatment strategies. Multimodal combination therapies with considerable potential in altering the immune response in malignant melanoma patients are currently emerging. As oncology moves forward into the field of personalized therapies, a careful molecular and immunological characterization of patients is crucial to select patients for individual targeted treatment.