Use of tumour-responsive T cells as cancer treatment

The stimulation of a tumour-specific T-cell response has several theoretical advantages over other forms of cancer treatment. First, T cells can home in to antigen-expressing tumour deposits no matter where they are located in the body-even in deep tissue beds. Additionally, T cells can continue to proliferate in response to immunogenic proteins expressed in cancer until all the tumour cells are eradicated. Finally, immunological memory can be generated, allowing for eradication of antigen-bearing tumours if they reoccur. We will highlight two direct methods of stimulating tumour-specific T-cell immunity: active immunisation with cancer vaccines and infusion of competent T cells via adoptive T-cell treatment. Preclinical and clinical studies have shown that modulation of the tumour microenvironment to support the immune response is as important as stimulation of the most appropriate effector T cells. The future of T-cell immunity stimulation to treat cancer will need combination approaches focused on both the tumour and the T cell.

Malignant stroke in an adolescent with a homozygous MTHFR 677CT mutation and intake of hormonal contraceptives

Severe stroke in children and adolescents with its devastating long term consequences remains a rare disorder with many open questions. Beside the well known risk factors such as infection or congenital and acquired heart disease, coagulation disorders have to be considered in the differential work up of the underlying aetiology. Here we report the case of an adolescent with a homozygote MTHFR 677CT mutation suffering a malignant stroke shortly after the start of oral contraceptives. Conclusion: Since prevention seems easily feasible, general screening for MTHFR mutations might be worthwhile in women before starting oral contraceptives.

Paclitaxel and carboplatin vs gemcitabine and vinorelbine in patients with adeno- or undifferentiated carcinoma of unknown primary: a randomised prospective phase II trial

Platinum/taxane combinations are widely used in patients with carcinoma of unknown primary (CUP), yielding response rates of 30% and median overall survival of 9-11 months in selected patients. Yet these combinations have not been subject to a randomised trial to overcome selection bias, a major problem in CUP. We randomised 92 patients to either paclitaxel/carboplatin (arm A) or the non-platinum non-taxane regimen gemcitabine/vinorelbine (arm B). The primary endpoint was rate of practicability as defined: application of >or=2 cycles of therapy (1) with a maximal delay of 1 week (2) and survival of >or=8 months (3). Practicability was shown in 52.4% (95% CI 36-68%) in arm A and in 42.2% (95% CI 28-58%) in arm B, respectively. The median overall survival, 1-year survival -rate and response rate of patients treated in arm A was 11.0 months, 38, and 23.8%, arm B 7.0 months, 29, and 20%. In conclusion, the paclitaxel/carboplatin regimen showed clinically meaningful activity in this randomised trial (Clinical trial registration number 219, 'Deutsches KrebsStudienRegister', German Cancer Society.)

Adoptive transfer of autologous, HER2-specific, cytotoxic T lymphocytes for the treatment of HER2-overexpressing breast cancer

The human epidermal growth factor receptor 2 (HER2) has been targeted as a breast cancer-associated antigen by immunotherapeutical approaches based on HER2-directed monoclonal antibodies and cancer vaccines. We describe the adoptive transfer of autologous HER2-specific T-lymphocyte clones to a patient with metastatic HER2-overexpressing breast cancer. The HLA/multimer-based monitoring of the transferred T lymphocytes revealed that the T cells rapidly disappeared from the peripheral blood. The imaging studies indicated that the T cells accumulated in the bone marrow (BM) and migrated to the liver, but were unable to penetrate into the solid metastases. The disseminated tumor cells in the BM disappeared after the completion of adoptive T-cell therapy. This study suggests the therapeutic potential for HER2-specific T cells for eliminating disseminated HER2-positive tumor cells and proposes the combination of T cell-based therapies with strategies targeting the tumor stroma to improve T-cell infiltration into solid tumors.

The immunogenicity of Bcr-Abl–expressing dendritic cells is dependent on the Bcr-Abl kinase activity and dominated by Bcr-Abl–regulated antigens

In Ph+ chronic myeloid leukemia (CML), the constitutively active Bcr-Abl kinase leads to the up-regulation and activation of multiple genes, which may subsequently result in the expression of leukemia-associated antigens. In this study, we investigated the immunogenicity of Bcr-Abl–regulated antigens by stimulating CD8+ T lymphocytes with autologous dendritic cells transfected with RNA coding for Bcr-Abl wild-type or a kinase-deficient mutant. Significant HLA class I–restricted T-cell responses were detected against antigens regulated by the Bcr-Abl kinase, but not toward the Bcr-Abl protein itself. The T-cell repertoire of a patient with CML in major molecular remission due to imatinib mesylate was also dominated by T cells directed against Bcr-Abl–regulated antigens. These results encourage the development of immunotherapeutic approaches against Bcr-Abl–regulated antigens for the treatment of CML patients with residual disease following therapy with Bcr-Abl kinase inhibitors.

Immunity to the HER-2/neu oncogenic protein

The study of oncogenic viruses led to the discovery that transforming retroviruses contain oncogenes homologous with and/or derived from cellular proto-oncogenes. In humans malignant transformation is often the result of the activation of proto-oncogenes. Normal proto-oncogenes can be activated to transforming proto-oncogenes by a variety of mechanisms including point mutation, translocation and amplification. Development of successful strategies for the immunotherapy of human cancers is an area of intense investigation. Part of the problem in developing cancer-specific immunotherapy has been the lack of well-defined tumour antigens. Our laboratory has focused on the question of whether oncogenic proteins expressed by transforming proto-oncogenes can serve as targets for immune attack. Some patients with HER-2/Neu-positive breast cancer have an existent immune response to the HER-2/neu protein with no clinical signs of autoimmunity, supporting the idea that overexpressed oncogenic proteins can be targeted in therapy without fear of destructive autoimmunity. The identification of candidate cytotoxic T lymphocyte epitopes might allow the generation of tumour-specific cytotoxic T lymphocytes for use in therapy and identify potential epitopes for peptide vaccines.

Reversible HLA multimers (Streptamers) for the isolation of human cytotoxic T lymphocytes functionally active against tumor- and virus-derived antigens

The development of MHC/peptide multimers has facilitated the visualization and purification of antigen-specific T cells. However, the persistence of multimers leads to prolonged T cell receptor signaling and subsequently to altered T-cell function. We have recently developed a new type of MHC/peptide multimers, which can be dissociated from the T cell. Herein, we have generated and tested for the first time reversible HLA/peptide multimers, termed Streptamers, for the isolation of human T cells. The Streptamer technique demonstrates the specificity and sensitivity of conventional HLA/peptide tetramers with regards to the sorting of human T lymphocytes. This is shown for T cells directed against immunogenic peptides derived from viral and tumor-associated antigens. We show that antigen-specific cytotoxic T cells remain functionally active following Streptamer dissociation, whereas lytic function and proliferation of the T cells is impaired in the presence of conventional tetramers. These novel HLA/peptide Streptamer reagents allow the isolation of antigen-specific T cells with preserved function and, therefore, facilitate the development of adoptive T cell transfer regimens for the treatment of patients with cancer or infectious diseases.

Ratio of trastuzumab levels in serum and cerebrospinal fluid is altered in HER2-positive breast cancer patients with brain metastases and impairment of blood-brain barrier

Patients receiving trastuzumab for HER2-overexpressing metastatic breast cancer seem to suffer from an increased risk of brain metastases, even in cases with responsive disease. To evaluate whether trastuzumab is able to penetrate the blood-brain barrier, we measured trastuzumab levels in the serum and in cerebrospinal fluid of metastatic breast cancer patients with brain metastases receiving trastuzumab for HER2-overexpressing metastatic breast cancer. In a pilot study, metastatic breast cancer patients with brain metastases and HER2-overexpressing tumors (HercepTest; Dako, Copenhagen, Denmark) were included. At different time points, trastuzumab levels in the serum and cerebrospinal fluid were measured using a newly developed immunoenzymatic test for trastuzumab. Six out of eight patients were evaluable for determination of trastuzumab level in the serum and cerebrospinal fluid. Before radiotherapy, median trastuzumab level in the serum was 52 054 ng/ml compared with 124 ng/ml in cerebrospinal fluid (ratio 420 : 1). After completion of radiotherapy, median trastuzumab level was 20 185 ng/ml in the serum and 226 ng/ml in cerebrospinal fluid, respectively (ratio 76 : 1). With concomitant meningeal carcinomatosis, trastuzumab level in the serum after radiotherapy was 17 431 and 356 ng/ml in cerebrospinal fluid (ratio 49 : 1). For the first time, we present clinical evidence that trastuzumab levels in cerebrospinal fluid are increased under conditions of an impaired blood-brain barrier such as meningeal carcinomatosis or radiotherapy. This evidence supports the concept of continuing trastuzumab therapy in patients with brain metastases treated by radiotherapy. Monitoring of trastuzumab levels in the serum and cerebrospinal fluid may enable individualized therapy strategies in metastatic breast cancer patients with brain metastases, and lead to a better understanding of trastuzumab pharmacokinetics in the cerebrospinal fluid and serum.

Designer T cells by T cell receptor replacement

T cell receptor (TCR) gene transfer is a convenient method to produce antigen-specific T cells for adoptive therapy. However, the expression of two TCR in T cells could impair their function or cause unwanted effects by mixed TCR heterodimers. With five different TCR and four different T cells, either mouse or human, we show that some TCR are strong--in terms of cell surface expression--and replace weak TCR on the cell surface, resulting in exchange of antigen specificity. Two strong TCR are co-expressed. A mouse TCR replaces human TCR on human T cells. Even though it is still poorly understood why some TCRalpha/beta combinations are preferentially expressed on T cells, our data suggest that, in the future, designer T cells with exclusive tumor reactivity can be generated by T cell engineering.

Brain metastases in HER2-overexpressing metastatic breast cancer: Comparative analysis of trastuzumab levels in serum and cerebrospinal fluid

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Purpose: Patients receiving trastuzumab for HER2-overexpressing MBC suffer from an increased risk to develop BM despite responsive visceral disease. The present pilot study was conducted to explore trastuzumab levels in S and CSF of MBC patients afflicted with BM, and to evaluate whether radiotherapy will lead to impairment the blood-brain barrier (BBB) to allow penetration of trastuzumab into CSF. Methods: Patients with BM from HER2-overexpressing MBC (IHC; DAKO Hercep Test) were included. Trastuzumab levels in S and CSF were determined at different time points by a newly developed immunoenzymatic test for functional, reactive trastuzumab. Results: Six out of 8 eligible patients were evaluable. Prior to whole-brain radiotherapy (WBRT), the median trastuzumab serum level was 52,054 ng/ml compared to a median CSF level of 124 ng/ml (ratio 420:1). After completion of WBRT, the median level of trastuzumab was 20,185 ng/ml in serum and 226 ng/ml in CSF (ratio 76:1). In two cases of concomitant meningeal carcinomatosis, the median serum level of trastuzumab after WBRT was 17,431 ng/ml and 356 ng/ml in CSF (ratio 49:1). Conclusion: These data indicate that the BBB prevent trastuzumab to reach adequate concentrations in CSF. These levels are increased under conditions of an impaired BBB, as is known for meningeal carcinomatosis and for patients receiving WBRT. The new test system in this pilot study provides the basis for the evaluation of radiotherapeutic strategies which allow most favorable penetration of trastuzumab into the CNS in patients receiving concomitant trastuzumab for HER2-overexpressing metastatic breast cancer.

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Application of intrathecal trastuzumab (Herceptintrade mark) for treatment of meningeal carcinomatosis in HER2-overexpressing metastatic breast cancer

Leptomeningeal carcinomatosis represents a rare manifestation of metastatic breast cancer (MBC). A 39-year-old female presenting with HER2-overexpressing MBC and suffering from meningeal carcinomatosis was treated with the humanized antibody trastuzumab directed to HER2 by intrathecal administration. The patient was diagnosed with HER2-overexpressing stage III breast cancer in December 2003. In August 2004, the patient developed a singular intracerebral metastasis which was resected by neurosurgery followed by whole-brain radiotherapy. Since MRI and cerebrospinal fluid (CSF) analyses indicated meningeal carcinomatosis, the patient was commenced on trastuzumab (6 mg/kg q3w) and capecitabine (2.500 mg/m2 d1-14, q3w). Prompted by clinical deterioration, 5 repeated doses of intrathecal methotrexate (15 mg/dose) were administered, yet without clinical improvement. There is initial evidence that trastuzumab does not reach an adequate concentration in CSF after intravenous application. Nevertheless, infiltration of trastuzumab into CSF is facilitated under conditions of an impaired blood-brain barrier, as it is known for meningeal carcinomatosis. For patients with leptomeningeal disease, intrathecal application of trastuzumab may provide an interesting therapeutical approach for patients with HER2 overexpressing metastatic breast cancer. Therefore, an Ommaya reservoir for intrathecal treatment with trastuzumab was placed surgically and intrathecal therapy was begun with escalating doses of trastuzumab (5-20 mg), which proved to be effective and well tolerated by the patient. Within 2 weeks after treatment, the patients' condition improved significantly and cell counts in CSF obtained from the Ommaya reservoir remained low for 11 months after first diagnosis of meningeal carcinomatosis when clinical symptoms and MRI indicated progression of meningeal and cerebral disease.

Infection of human dendritic cells with recombinant vaccinia virus MVA reveals general persistence of viral early transcription but distinct maturation-dependent cytopathogenicity

Vector-infected dendritic cells (DC) are evaluated for antigen delivery in experimental therapy of cancer and infectious diseases. Here, we investigated infections of immature or mature, monocyte-derived human DC with recombinant vaccinia virus MVA producing human Her-2/neu, a candidate tumor-associated antigen. Assessment of the molecular virus life cycle in infected DC revealed a general arrest at the level of viral early gene expression. When monitoring the phenotype of MVA-infected DC, including expression of cell surface markers, we found immature cells readily undergoing apoptosis. Nevertheless, we detected significant populations of viable DC being characterized by high level Her-2/neu expression and unimpaired display of costimulatory molecules. While infected viable immature DC failed to undergo maturation despite cytokine treatment, both DC populations efficiently presented MVA-produced target antigen. These findings allow to better define the requirements for MVA-mediated antigen delivery to DC and help to derive optimized vectors for this advanced therapy option.

A phase I vaccination study with tyrosinase in patients with stage II melanoma using recombinant modified vaccinia virus Ankara (MVA-hTyr)

A significant percentage of patients with stage II melanomas suffer a relapse after surgery and therefore need the development of adjuvant therapies. In the study reported here, safety and immunological response were analyzed after vaccination in an adjuvant setting with recombinant modified vaccinia virus Ankara carrying the cDNA for human tyrosinase (MVA-hTyr). A total of 20 patients were included and vaccinated three times at 4-week intervals with 5x10(8) IU of MVA-hTyr each time. The responses to the viral vector, to known HLA class I-restricted tyrosinase peptides, and to dendritic cells transfected with tyrosinase mRNA, were investigated by ELISpot assay on both ex vivo T cells and on T cells stimulated in vitro prior to testing. The delivery of MVA-hTyr was safe and did not cause any side effects above grade 2. A strong response to the viral vector was achieved, indicated by an increase in the frequency of MVA-specific CD4+ and CD8+ T cells and an increase in virus-specific antibody titers. However, no tyrosinase-specific T-cell or antibody response was observed with MVA-hTyr in any of the vaccinated patients. Although MVA-hTyr provides a safe and effective antigen-delivery system, it does not elicit a measurable immune response to its transgene product in patients with stage II melanoma after repeated combined intradermal and subcutaneous vaccination. We presume that modification of the antigen and/or prime-boost vaccination applying different approaches to antigen delivery may be required to induce an effective tyrosinase-specific immune response.

Isolation and expansion of tumor-reactive cytotoxic T-cell clones for adoptive immunotherapy

Attempts to treat patients with tumor-reactive cytotoxic T-lymphocytes (CTL) have been limited. This is due to the difficulty of isolating and expanding functionally active T-cells, which are present at extremely low frequencies in the peripheral blood. Recently developed multimers of the HLA-peptide complex mimic the natural ligand of the T-cell receptor and, therefore, fluorochrome-labeled multimers allow visualization and isolation of rare T-cells with defined specificity. Multimer-guided T-cell sorting permits the in vitro culture of antigen-specific T-cells as lines or clones. Cytolytic T-cells capable of recognizing HLA-peptide complexes endogenously processed by tumor cells are selected for further expansion, since lysis of tumor cells in vitro is a prerequisite for effective tumor elimination in vivo. The expansion of tumor-reactive CD8+ T-cells yields cell numbers sufficient for adoptive transfer. Tumor-reactive T-cells retain the functional activity in terms of cytolysis after expansion, encouraging their use in the immunotherapy of cancer patients.

Melanoma-reactive class I-restricted cytotoxic T cell clones are stimulated by dendritic cells loaded with synthetic peptides, but fail to respond to dendritic cells pulsed with melanoma-derived heat shock proteins in vitro

Immunization with heat shock proteins (hsp) isolated from cancer cells has been shown to induce a protective antitumor response. The mechanism of hsp-dependent cellular immunity has been attributed to a variety of immunological activities mediated by hsp. Hsp have been shown to bind antigenic peptides, trim the bound peptides by intrinsic enzymatic activity, improve endocytosis of the chaperoned peptides by APCs, and enhance the ability of APCs to stimulate peptide-specific T cells. We have investigated the potential capacity of hsp70 and gp96 to function as a mediator for Ag-specific CTL stimulation in an in vitro model for human melanoma. Repetitive stimulation of PBLs by autologous DCs loaded with melanoma-derived hsp did not increase the frequency of T cells directed against immunodominant peptides of melanoma-associated Ags Melan-A and tyrosinase. In contrast, repeated T cell stimulation with peptide-pulsed DCs enhanced the number of peptide-specific T cells, allowing HLA/peptide multimer-guided T cell cloning. We succeeded in demonstrating that the established HLA-A2-restricted CTL clones recognized HLA-A2(+) APCs exogenously loaded with the respective melanoma peptide as well as melanoma cells processing and presenting these peptides in the context of HLA-A2. We were not able to show that these melanoma-reactive CTL clones were stimulated by autologous dendritic cells pulsed with melanoma-derived hsp. These results are discussed with respect to various models for proving the role of hsp in T cell stimulation and to recent findings that part of the immunological antitumor activities reported for hsp are independent of the chaperoned peptides.

Phase II trial of irinotecan plus docetaxel in cisplatin-pretreated relapsed or refractory oesophageal cancer

This phase II trial assessed the toxicity and efficacy of irinotecan plus docetaxel in cisplatin-pretreated oesophageal cancer. Irinotecan 160 mg m(-2) plus docetaxel 65 mg m(-2) once every 3 weeks led to severe myelosuppression in four patients, all of whom experienced neutropenic fever. After amendment of this regimen, 24 patients (male/female=18/6; median age=58.5 years; ECOG performance status 0/1/2=9/11/4) with advanced oesophageal cancer (adenocarcinoma/epidermoid carcinoma=13/11) received irinotecan 55 mg m(-2) plus docetaxel 25 mg m(-2) on days 1, 8 and 15 of a 28-day cycle. Serious adverse events occurred in five patients, one with lethal outcome (pneumonia). Haematological toxicity >or=3 degrees was rare, whereas nonhaematological toxicity >or=3 degrees was noted in nine out of 24 patients (asthenia in five patients, diarrhoea in three patients, nausea/emesis in two patients, constipation in one patient). Median survival time was 26 (range 2-70) weeks. Response rate, assessed according to the WHO criteria, was 12.5% (95% CI 2.7-32.4%); rate of disease stabilisation (partial remission and stable disease) was 33.3% (95% CI 15.6-55.3%) with a median duration of 18.5 (range 16-51) weeks. Although the nonhaematological toxicity proved to be considerable, weekly irinotecan plus docetaxel is feasible and shows some activity in extensively pretreated patients with oesophageal cancer.

Identification of vaccinia virus epitope-specific HLA-A*0201-restricted T cells and comparative analysis of smallpox vaccines

Despite worldwide eradication of naturally occurring variola virus, smallpox remains a potential threat to both civilian and military populations. New, safe smallpox vaccines are being developed, and there is an urgent need for methods to evaluate vaccine efficacy after immunization. Here we report the identification of an immunodominant HLA-A*0201-restricted epitope that is recognized by cytotoxic CD8(+) T cells and conserved among Orthopoxvirus species including variola virus. This finding has permitted analysis and monitoring of epitope-specific T cell responses after immunization and demonstration of the identified T cell specificity in an A*0201-positive human donor. Vaccination of transgenic mice allowed us to compare the immunogenicity of several vaccinia viruses including highly attenuated, replication-deficient modified vaccinia virus Ankara (MVA). MVA vaccines elicited levels of CD8(+) T cell responses that were comparable to those induced by the replication-competent vaccinia virus strains. Finally, we demonstrate that MVA vaccination is fully protective against a lethal respiratory challenge with virulent vaccinia virus strain Western Reserve. Our data provide a basis to rationally estimate immunogenicity of safe, second-generation poxvirus vaccines and suggest that MVA may be a suitable candidate.

Gangliosides inhibit the development from monocytes to dendritic cells

Dendritic cell (DC) development and function is critical in the initiation phase of any antigen-specific immune response against tumours. Impaired function of DC is one explanation as to how tumours escape immunosurveillance. In the presence of various soluble tumour-related factors DC precursors lose their ability to differentiate into mature DC and to activate T cells. Gangliosides are glycosphingolipids shed by tumours of neuroectodermal origin such as melanoma and neuroblastoma. In this investigation we address the question of whether gangliosides suppress the development and function of monocyte-derived DC in vitro. In the presence of gangliosides, the monocytic DC precursors showed increased adherence, cell spreading and a reduced number of dendrites. The expression of MHC class II molecules, co-stimulatory molecules and the GM-CSF receptor (CD116) on the ganglioside-treated DC was significantly reduced. Furthermore, the function of ganglioside-treated DC was impaired as observed in endocytosis, chemotactic and T cell proliferation assays. In contrast to monocytic DC precursors, mature DC were unaffected even when higher doses of gangliosides were added to the culture. With regard to their carbohydrate structure, five different gangliosides (GM2, GM3, GD2, GD3, GT1b), which are typically shed by melanoma and neuroblastoma, were tested for their ability to suppress DC development and function. Suppression was induced by GM2, but not by the other gangliosides. These data suggest that certain gangliosides impair DC precursors, implying a possible mechanism for tumour escape.

Reduced virus specific T helper cell induction by autologous dendritic cells in patients with chronic hepatitis B - restoration by exogenous interleukin-12

Insufficient stimulatory capacities of autologous dendritic cells (DC) may contribute in part to impaired T cell stimulation and therefore viral persistence in patients with chronic hepatitis B virus (HBV) infection. In order to characterize the antigen presenting functions of DC from chronic HBV carriers and controls antigen specific T cell responses were analysed. CD34+ peripheral blood progenitor cells were differentiated to immature DC in the presence of GM-CSF, IL-6/IL-6R fusion protein and stem cell factor. Proliferative CD4+ T cell responses and specific cytokine release were analysed in co-cultures of DC pulsed with HBV surface and core antigens or tetanus toxoid and autologous CD4+ T cells. Cultured under identical conditions DC from chronic HBV carriers, individuals with acute resolved hepatitis B and healthy controls expressed similar phenotypical markers but chronic HBV carriers showed less frequent and weaker HBV antigen specific proliferative T helper cell responses and secreted less interferon-gamma while responses to the tetanus toxoid control antigen was not affected. Preincubation with recombinant IL-12 enhanced the HBV specific immune reactivities in chronic HBV patients and controls. In conclusion, the weak antiviral immune responses observed in chronic hepatitis B may result in part from insufficient T cell stimulating capacities of DC. Immunostimulation by IL-12 restored the HBV antigen specific T cell responses and could have some therapeutical benefit to overcome viral persistence.