Showing papers by "Anton Hagenbeek published in 2006"

Complement-Induced Cell Death by Rituximab Depends on CD20 Expression Level and Acts Complementary to Antibody-Dependent Cellular Cytotoxicity

Abstract: Purpose: The use of the CD20-specific antibody rituximab has greatly improved the response to treatment of CD20 + follicular lymphoma. Despite the success of rituximab, resistance has been reported and prognostic markers to predict individual response are lacking. The level of CD20 expression on tumors has been related to response, but results of several studies are contradictory and no clear relationship could be established. Complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) are thought to be important effector mechanisms, but the exact mechanism of rituximab-mediated cell kill is still unknown. Importantly, no data have been reported on the combined contribution of CDC and ADCC. Experimental Design: We have developed a system of clonally related CEM-CD20 cells by retroviral transfer of the human CD20 cDNA ( n = 90). This set of cells, with the CD20 molecule as the only variable, was used to study the importance of CD20 expression level on rituximab-mediated CDC, ADCC, and the combination. Results: We show a sigmoidal correlation of CD20 expression level and rituximab-mediated killing via CDC but not ADCC. On both high and low CD20-expressing cells, all CD20 molecules were translocated into lipid rafts after rituximab binding. Furthermore, CDC and ADCC act simultaneously and CDC-resistant cells are sensitive to ADCC and vice versa. Conclusions: These findings suggest that CDC depends on CD20 expression level and that both CDC and ADCC act complementary. These data give new insights into novel strategies to improve the efficacy of CD20-specific antibodies for the treatment of CD20 + tumors.

Combined-Modality Therapy for Clinical Stage I or II Hodgkin's Lymphoma: Long-Term Results of the European Organisation for Research and Treatment of Cancer H7 Randomized Controlled Trials

Abstract: Purpose In early-stage Hodgkin’s lymphoma (HL), subtotal nodal irradiation (STNI) and combined chemotherapy/radiotherapy produce high disease control rates but also considerable late toxicity. The aim of this study was to reduce this toxicity using a combination of low-intensity chemotherapy and involved-field radiotherapy (IF-RT) without jeopardizing disease control. Patients and Methods Patients with stage I or II HL were stratified into two groups, favorable and unfavorable, based on the following four prognostic factors: age, symptoms, number of involved areas, and mediastinalthoracic ratio. The experimental therapy consisted of six cycles of epirubicin, bleomycin, vinblastine, and prednisone (EBVP) followed by IF-RT. It was randomly compared, in favorable patients, to STNI and, in unfavorable patients, to six cycles of mechlorethamine, vincristine, procarbazine, prednisone, doxorubicin, bleomycin, and vinblastine (MOPP/ABV hybrid) and IF-RT. Results Median follow-up time of the 722 patients included was 9 years. In 333 favorable patients, the 10-year event-free survival rates (EFS) were 88% in the EBVP arm and 78% in the STNI arm (P .0113), with similar 10-year overall survival (OS) rates (92% v 92%, respectively; P .79). In 389 unfavorable patients, the 10-year EFS rate was 88% in the MOPP/ABV arm compared with 68% in the EBVP arm (P .001), leading to 10-year OS rates of 87% and 79%, respectively (P .0175). Conclusion A treatment strategy for early-stage HL based on prognostic factors leads to high OS rates in both favorable and unfavorable patients. In favorable patients, the combination of EBVP and IF-RT can replace STNI as standard treatment. In unfavorable patients, EBVP is significantly less efficient than MOPP/ABV.

Phase III Intergroup Study of Fludarabine Phosphate Compared With Cyclophosphamide, Vincristine, and Prednisone Chemotherapy in Newly Diagnosed Patients With Stage III and IV Low-Grade Malignant Non-Hodgkin's Lymphoma

Abstract: Purpose To compare the efficacy and safety of fludarabine phosphate with cyclophosphamide, vincristine, and prednisone (CVP) in 381 previously untreated, advanced-stage, low-grade (lg) non-Hodgkin's lymphoma (NHL) patients in a phase III, multicenter study. Patients and Methods Between 1993 and 1997, patients were randomly assigned to treatment with either fludarabine (25 mg/m2 intravenously [IV] daily for 5 days every 4 weeks) or CVP (cyclophosphamide 750 mg/m2 IV on day 1; vincristine, 1.4 mg/m2 IV on day 1; and prednisone, 40 mg/m2 orally on days 1 through 5 every 4 weeks). Results Overall response (OR) rates were significantly improved in the fludarabine arm versus the CVP arm, both for the intent-to-treat (ITT) population and assessable patients (P < .001). Complete response (CR) rates in the ITT population were also higher after fludarabine treatment. The CR rate was 38.6% for fludarabine compared with 15.0% for CVP. There were no statistically significant differences in time to progression (TTP), t...

The CD20/alphaCD20 'suicide' system: novel vectors with improved safety and expression profiles and efficient elimination of CD20-transgenic T cells

Abstract: Adoptive transfer of T lymphocytes is an attractive strategy for many experimental treatment strategies for cancer. Unfortunately, manipulated T cells could be responsible for serious adverse events. Retroviral CD20-transduced T cells may be able to control these unwanted effects. CD20-positive cells are sensitive to rituximab (RTX), a monoclonal antibody specific for CD20. This permits their selective elimination in vivo in case of adverse events. To this end, a system is required that permits efficient and safe transduction of donor T cells and effective elimination of CD20-positive T cells. We constructed different CD20-encoding retroviral vectors and investigated the impact of inclusion of the woodchuck post-transcriptional regulatory element (WPRE) and the chicken hypersensitivity site 4 insulator elements on the levels, homogeneity and stability of CD20 expression. Importantly, inclusion of either WPRE or insulator elements in the retroviral vector resulted in a dramatic improvement in the stability of CD20 expression. The insulator element also led to a much more homogeneous level of CD20 expression. We also show the efficient elimination of the CD20-transgenic T cells via RTX by different effector mechanisms. In conclusion, we have constructed CD20-encoding retroviral vectors with improved efficiency and safety profiles, which can be used as a suicide strategy.

mice: the impact of ex vivo manipulation on in vivo functionality

Abstract: OBJECTIVE Recent clinical trials of adoptive immunotherapy showed diminished reactivity of human T cells upon ex vivo manipulation. For a safe and effective clinical application of human T cells, it is necessary to improve ex vivo manipulation procedures and evaluate their impact on in vivo functionality. However, there is no preclinical model for quantitative assessment of in vivo functionality of human T cells. In this study, we investigated the feasibility of using the huPBMC- RAG2(-/-)gammac(-/-) xenogeneic mouse model. As a first example, we compared 3 different ex vivo culture conditions for human T cells. METHODS RAG2(-/-)gammac(-/-) mice received cultured human T cells that were stimulated via CD3 alone or costimulated via CD28 (CD3/28) and/or human 4-1BB (CD3/28/4-1BB). Engraftment levels and survival of the cells were measured. The dynamics of the human T cell phenotypes were analyzed during culture and in vivo, as well as the mechanism of the xenoresponse. RESULTS Engraftment potential was improved twofold for costimulation compared to CD3 alone (p < 0.001). Phenotypic analysis showed a strikingly similar pattern of development towards CD4(+) and CD8(+) effector and effector-memory cells, suggesting antigen-driven survival and expansion. All parameters used to analyze different effects on in vivo T-cell functionality, like culture condition, engraftment levels, survival of the cells over time, or xenogeneic graft-vs-host disease were absolutely independent of the distribution of the T cell population in vivo following contact with xeno-antigen. CONCLUSION The huPBMC-RAG2(-/-)gammac(-/-) xenogeneic transplant model is the most sensitive to date for in vivo functional evaluation of human T cells.

T cell receptor-transgenic primary T cells as a tool for discovery of leukaemia-associated antigens.

Abstract: Identification of a broad array of leukaemia-associated antigens is a crucial step towards immunotherapy of haematological malignancies. However, it is frequently hampered by the decrease of proliferative potential and functional activity of T cell clones used for screening procedures. Transfer of the genes encoding the T cell receptor (TCR) alpha and beta chains of leukaemia-specific clones into primary T cells may help to circumvent this obstacle. In this study, transfer of two minor histocompatibility antigen (minor H antigen)-specific TCRs was performed and the feasibility of the use of TCR-transgenic T cells for identification of minor H antigens through cDNA library screening was investigated. We found that TCR-transgenic cells acquired the specificity of the original clones and matched their sensitivity. Moreover, the higher scale of cytokine-production by TCR-transgenic T cells permits the detection of either small amounts of antigen-positive cells or cells expressing low amounts of an antigen. When applied in equal numbers, TCR-transgenic T cells and the original T cell clones produced similar results in the screening of a cDNA library. However, the use of increased numbers of TCR-transgenic T cells allowed detection of minute amounts of antigen, barely discernible by the T cell clone. In conclusion, TCR-transfer generates a large amount of functional antigen-specific cells suitable for screening of cDNA expression libraries for identification of cognate antigens.

Recommendations for revised response criteria for malignant lymphoma

Abstract: 7507 Background: Standardized response criteria are needed to interpret and compare clinical trials, and for approval of new therapeutic agents by regulatory agencies. Methods: The International Wo...

The therapeutic use of rituximab in non-Hodgkin's lymphoma: Therapeutic use of rituximab

Abstract: Abstract: The non‐Hodgkin's lymphomas (NHLs) comprise a heterogeneous collection of lymphoproliferative malignancies, which are most common in people aged over 55 years. Diffuse large B‐cell lymphoma (DLBCL) is the most common type of NHL, accounting for approximately 30% of all new patients. Follicular lymphoma (FL) is the second most common NHL sub‐type, and accounts for a further 22% of cases. While the incidence of most other cancers is decreasing, that of NHL is increasing steadily. During the 1970’s and 1980’s, worldwide NHL incidence rose by 3–4% per year. This rise has slowed in the 1990’s, but an annual increase of 1–2% is still being recorded. Over the last five years, the introduction of monoclonal antibodies, and specifically the anti‐CD20 monoclonal antibody, rituximab, has radically changed treatment of B‐cell NHL. Rituximab is a genetically engineered chimeric mouse/human monoclonal antibody which binds to the transmembrane antigen, CD20, a non‐glycosylated phosphoprotein, located on pre‐B and mature B lymphocytes. This antigen is expressed on over 95% of all B cell NHLs, and on normal B cells, but not on haematopoietic stem cells, normal or malignant plasma cells. The Fc domain of rituximab recruits immune effector functions to mediate B cell lysis. Possible mechanisms of cytotoxicity include complement‐dependent cytotoxicity (CDC) resulting from C1q binding, and antibody‐dependent cellular cytotoxicity (ADCC) mediated by one or more of the Fcγ receptors on the surface of granulocytes, macrophages and NK cells. It is also possible that the binding of rituximab to the CD20 antigen on the cell surface may directly induce apoptosis. For patients with both follicular and diffuse large B‐cell NHL, several large scale prospective randomised trials have demonstrated prolongation of remission when rituximab is incorporated into first line treatment, and, in follicular lymphoma, as a component of salvage therapy. As a result of these studies, current European indications for rituximab include: