131I-tositumomab therapy as initial treatment for follicular lymphoma

BACKGROUND

Advanced-stage follicular B-cell lymphoma is considered incurable. Anti-CD20 radioimmunotherapy is effective in patients who have had a relapse after chemotherapy or who have refractory follicular lymphoma, but it has not been tested in previously untreated patients.

METHODS

Seventy-six patients with stage III or IV follicular lymphoma received as initial therapy a single course of treatment with 131I-tositumomab therapy (registered as Tositumomab and Iodine I 131 Tositumomab [the Bexxar therapeutic regimen]). This consisted of a dosimetric dose of tositumomab and 131I-labeled tositumomab followed one week later by a therapeutic dose, delivering 75 cGy of radiation to the total body.

RESULTS

Ninety-five percent of the patients had any response, and 75 percent had a complete response. The use of polymerase chain reaction (PCR) to detect rearrangement of the BCL2 gene showed molecular responses in 80 percent of assessable patients who had a clinical complete response. After a median follow-up of 5.1 years, the actuarial 5-year progression-free survival for all patients was 59 percent, with a median progression-free survival of 6.1 years. The annualized rate of relapse progressively decreased over time: 25 percent, 13 percent, and 12 percent during the first, second, and third years, respectively, and 4.4 percent per year after three years. Of 57 patients who had a complete response, 40 remained in remission for 4.3 to 7.7 years. Hematologic toxicity was moderate, with no patient requiring transfusions or hematopoietic growth factors. No cases of myelodysplastic syndrome have been observed.

CONCLUSIONS

A single one-week course of 131I-tositumomab therapy as initial treatment can induce prolonged clinical and molecular remissions in patients with advanced follicular lymphoma.

Rituximab in Combination With Fludarabine Chemotherapy in Low-Grade or Follicular Lymphoma

Purpose

To evaluate the safety and efficacy of fludarabine plus rituximab in treatment-naïve or relapsed patients with low-grade and/or follicular non-Hodgkin's lymphoma.

Patients and Methods

This was an open-label, single-arm, single-center phase II study enrolling 40 patients. During the first week of the study, patients received two infusions of rituximab 375 mg/m2 administered 4 days apart. Seventy-two hours after the second infusion of rituximab, patients received the first of six cycles of fludarabine chemotherapy (25 mg/m2/d for 5 days on a 28-day cycle). Single infusions of rituximab were administered 72 hours before the second, fourth, and sixth cycles of fludarabine, and two infusions of rituximab were given 4 weeks after the last cycle of fludarabine. Treatment duration was 26 weeks.

Results

An overall response rate of 90% (80% complete response rate) was achieved in the intent-to-treat population. Similar response rates were seen in treatment-naïve and previously treated patients. The median duration of response has not been reached at 40+ months. The median follow-up time in this study is 44 months (range, 15 to 66 months). In patients positive for the 14;18 translocation in blood and/or marrow at enrollment, molecular remission was achieved in 88% of cases, with patients remaining negative for up to 4 years to date. Hematologic toxicity was manageable, and except for a 15% incidence of herpes simplex/zoster infections, infectious complications were rare. Nonhematologic toxicities were minimal.

Conclusion

Rituximab plus fludarabine was well tolerated and associated with an excellent complete response rate, including molecular remissions, in patients with low-grade or follicular lymphoma.

Successful high-titer immunoglobulin therapy for persistent parvovirus B19 infection in a lymphoma patient treated with rituximab-combined chemotherapy

A 40-year-old female diagnosed with follicular lymphoma was treated with rituximab-combined chemotherapy. Although she achieved complete remission, she developed progressive anemia and reticulocytopenia. Bone marrow examination revealed features of pure red cell aplasia and hemophagocytosis. In addition, the appearance of large pronormoblasts suggested that she was infected with parvovirus B19. Excess viral DNA in her bone marrow confirmed that her illness was caused by persistent parvovirus B19 infection. Serum immunoglobulin levels decreased beyond the lower normal limit, which indicated that her humoral immunity was impaired after rituximab-combined chemotherapy. Although she had been infected with parvovirus B19, she was re-infected and failed to control the viral expansion. High-titer immunoglobulin against parvovirus B19 was intravenously administrated and resulted in remarkable reticulocytosis and improvement of anemia. High-titer immunoglobulin, which contained a sufficient amount of neutralizing antibodies against parvovirus B19, likely inactivated most viruses in vivo. We successfully eradicated the virus after 2 courses of high-dose therapy at 0.5 g/kg/day every week followed by 8 courses of maintenance therapy at 0.1 g/kg/day every other week. It is important to consider that parvovirus B19 infection is a possible cause of progressive anemia in B-cell lymphoma patients treated with rituximab-combined chemotherapy. We propose that the use of high-titer immunoglobulin against parvovirus B19 may enable such immunocompromised patients to eradicate the virus before sufficient immune system reconstruction.

Enhanced efficacy of therapy with antisense BCL-2 oligonucleotides plus anti-CD20 monoclonal antibody in scid mouse/human lymphoma xenografts

Monoclonal anti-CD20 antibody (rituximab) is active, but not curative, therapy for B-cell non-Hodgkin's lymphoma. BCL-2 is an antiapoptotic protein whose expression is dysregulated in most indolent B-cell malignancies. Antisense oligonucleotides (AS-ODNs) that down-regulate BCL-2 expression induce apoptosis and chemosensitize B-cell lymphoma cells. We hypothesized that BCL-2 down-regulation by AS-ODNs would sensitize cells to rituximab and improve therapeutic results. There is enhanced apoptosis and reduction in cell numbers when DoHH2 cells are treated in vitro with rituximab plus BCL-2 AS-ODNs, compared with either agent alone. There is little in vitro effect on WSU-FSCCL cells by rituximab, AS-ODNs that down-regulate BCL-2 by targeting the immunoglobulin portions of the BCL-2-immunoglobulin fusion molecule, or a combination of the two. The combination is more effective than either agent alone in clearing DoHH2 cells from ascites in scid mice. Combination therapy with AS-BCL-2-ODNs and rituximab significantly prolongs survival in both the DoHH2 and WSU-FSCCL models. With higher and repeated doses, this combination could be curative. We conclude that the combination of rituximab and antisense-mediated down-regulation of BCL-2 has enhanced activity against human lymphoma, prolongs survival, and could cure mice bearing human lymphoma. This merits investigation in clinical trials.

Clinical Outcome of Lymphoma Patients After Idiotype Vaccination Is Correlated With Humoral Immune Response and Immunoglobulin G Fc Receptor Genotype

Purpose

The unique immunoglobulin idiotype (Id) expressed by each B-cell lymphoma is a target for immunotherapy. Vaccination with Id induces humoral and/or cellular anti-Id immune responses. However, the clinical impact of these anti-Id immune responses is unknown. We and others have previously reported that immunoglobulin G Fc receptor (FcγR) polymorphisms predict the clinical response of lymphoma patients to passive anti-CD20 antibody infusions. In this study, we tested whether anti-Id immune responses or FcγR polymorphisms associate with clinical outcome of patients who received Id vaccination.

Patients and Methods

We analyzed 136 patients with follicular lymphoma who had received Id vaccination. The anti-Id immune responses were measured and FcγRIIIa and FcγRIIa polymorphisms were determined and correlated with clinical outcome for these patients.

Results

Patients who mounted humoral immune responses had a longer progression-free survival (PFS) than those who did not (8.21 v 3.38 years; P = .018). Patients with FcγRIIIa 158 valine/valine (V/V) genotype also had a longer PFS than those with valine/phenylalanine (V/F) or phenylalanine/phenylalanine (F/F) genotypes (V/V, 8.21 v V/F, 3.38 years; P = .004; v F/F, 4.47 years; P = .035). Multivariate analysis using the Cox proportional hazards model showed that V/V genotype and humoral immune responses were independent positive predictors for PFS.

Conclusion

This study is the first to identify the predictive value of FcγR polymorphism on clinical outcome in patients who received active immunotherapy with tumor antigen vaccines. Our results imply that the antibodies induced against a tumor antigen are beneficial and that FcγR-bearing cells mediate an antitumor effect by killing antibody-coated tumor cells.

Prediction of survival in follicular lymphoma based on molecular features of tumor-infiltrating immune cells

BACKGROUND

Patients with follicular lymphoma may survive for periods of less than 1 year to more than 20 years after diagnosis. We used gene-expression profiles of tumor-biopsy specimens obtained at diagnosis to develop a molecular predictor of the length of survival.

METHODS

Gene-expression profiling was performed on 191 biopsy specimens obtained from patients with untreated follicular lymphoma. Supervised methods were used to discover expression patterns associated with the length of survival in a training set of 95 specimens. A molecular predictor of survival was constructed from these genes and validated in an independent test set of 96 specimens.

RESULTS

Individual genes that predicted the length of survival were grouped into gene-expression signatures on the basis of their expression in the training set, and two such signatures were used to construct a survival predictor. The two signatures allowed patients with specimens in the test set to be divided into four quartiles with widely disparate median lengths of survival (13.6, 11.1, 10.8, and 3.9 years), independently of clinical prognostic variables. Flow cytometry showed that these signatures reflected gene expression by nonmalignant tumor-infiltrating immune cells.

CONCLUSIONS

The length of survival among patients with follicular lymphoma correlates with the molecular features of nonmalignant immune cells present in the tumor at diagnosis.

The pattern and frequency of t(14;18) translocation and immunophenotype in Asian follicular lymphoma

AIMS

Follicular lymphoma is frequently associated with t(14;18)(q32;q21) translocation. This study was undertaken to determine the pattern of Bcl-2, CD10 and Bcl-6 expression in relation to t(14;18) translocation in follicular lymphoma from a cohort of a multi-ethnic Asian population.

METHODS AND RESULTS

Sixty-two cases of follicular lymphoma were retrieved for immunohistochemistry, and t(14;18) translocation analysis by polymerase chain reaction and fluorescent in-situ hybridization techniques. Bcl-2 expression was present in 74% of the cases. CD10 expression was also relatively low (61%), with decreasing frequency of expression in high-grade tumours. Bcl-6 protein was expressed in most of the tumours (88%) regardless of the tumour grade. The t(14;18) translocation was detected in 46 cases (74%) with an extremely high rate of t(14;18) translocation in ethnic Indian cases (100%).

CONCLUSION

The frequency of t(14;18) translocation in this series of follicular lymphomas was higher when compared with previous Asian reports, but in accordance with European and North American findings. CD10 expression is strongly associated with a t(14;18) translocation event, but the overall CD10 expression was relatively low, possibly due to the high proportion of high-grade tumours in the series. t(14;18) translocation was not associated with Bcl-2 or Bcl-6 expression.

The role of idiotype vaccines in the treatment of human B-cell malignancies

Twelve years after the first formal demonstration that it is possible to vaccinate a cancer patient against an antigen derived from his/her own tumor, idiotype vaccines are now well into Phase III clinical trials for the treatment of follicular lymphoma. Meanwhile, their potential has also begun to be explored in other non-Hodgkin's lymphoma settings, such as that of mantle cell lymphoma. Another well known field of potential application for idiotype vaccines is that of multiple myeloma. However, the currently available results, even with the advent of dendritic cells, seem to be less promising than those obtained in lymphoma, to such an extent that idiotype vaccines are currently tested in multiple myeloma patients in the context of more aggressive therapeutic strategies.

Human monoclonal antibodies produced in transgenic BABκ,λ mice recognising idiotypic immunoglobulins of human lymphoma cells

Clonal idiotypic immunoglobulins of follicular lymphomas can be isolated by somatic fusion procedures. Idiotypic IgMs (Id-IgM) were isolated from two patients and used to immunise a strain of mice, deficient in mouse antibody production and engineered with yeast artificial chromosomes (YAC) containing fragments of the human immunoglobulin (Ig) micro/delta heavy chain and kappa/lambda light chain loci. Sequence analysis showed that hybridomas prepared from spleen cells of immunised mice expressed exclusively one of the six VH genes (VH1-2) present in the YAC transgene with different D/J rearrangements, and secrete fully human monoclonal antibodies (mAb) that recognised the tumour-specific IgM proteins. Further studies of the reactivity of the monoclonal anti-human Id-IgM antibodies revealed that they are specific for the individual protein of each patient and probably react with idiotypic determinants. In one case studied, the antibody recognised specifically the lymphoma cell expressing the corresponding idiotypic IgM and lysed those cells in the presence of complement. This is the first example of a human monoclonal antibody with such characteristics and may be of further use in the therapy of patients with B cell malignancies.

Autologous lymphoma vaccines induce human T cell responses against multiple, unique epitopes

The clonotypic surface Ig receptor expressed by malignant B cells, idiotype, is a tumor-specific antigen and an attractive target for active immunotherapy. While Ab's specific for tumor idiotype have been well described in patients with B cell malignancies, the precise antigenic epitopes in human idiotype recognized by autologous T cells remain largely unknown. We report here that T cell lines generated from lymphoma patients actively immunized with idiotype protein specifically recognized multiple, unique immunodominant epitopes in autologous tumor idiotype. Synthetic peptides corresponding to hypervariable, but not framework, regions of Ig heavy chain specifically stimulated CD4(+) and CD8(+) T cells to proliferate and secrete proinflammatory cytokines in an MHC-associated manner. Detailed analysis revealed a minimal determinant of an immunodominant epitope, comprising critical residues at the amino terminus that may be a product of somatic hypermutation. Association of idiotype-specific T cell responses with previously documented molecular remissions in idiotype-vaccinated patients suggests that the newly identified T cell epitopes may be clinically relevant. Such antigenic epitopes may serve as candidates for novel peptide-vaccine strategies, and as tools to selectively expand tumor antigen-specific T cells for adoptive immunotherapy and for monitoring T cell immunity in vaccinated patients.

Haematogones in the peripheral blood of adults: a four-colour flow cytometry study of 102 patients

Haematogones have been extensively characterized in bone marrow, but not in the peripheral blood (PB). We studied 102 PB samples from adult patients with a sensitive flow cytometry method. Sixty-six of 102 samples (65%) contained detectable haematogones, ranging from 0.01% to 1.3% of white blood cells (median 0.06%, mean 0.13%). Of 66 cases with complete blood count data, 51 had absolute haematogone counts of 0.00037-0.105 x 10(9)/l (median 0.0054 x 10(9)/l, mean 0.012 x 10(9)/l). PB haematogones belonged exclusively to the most mature maturational stage. These findings have implications for PB analysis of minimal residual disease in acute lymphoblastic leukaemia and follicular lymphoma.

[Active immunotherapy in the treatment of haematological neoplasias]

The continuous search for therapeutic approaches that improve the conventional treatments of neoplasms, together with an improved understanding of the immune system, has led in recent years to the development of Immunotherapy. Basically, a distinction can be made between two forms of immunotherapy: passive immunotherapy, which consists in the transfer of antibodies or cells previously generated in vitro that are directed against the tumour, and active immunotherapy, which attempts to activate in vivo the immune system and induce it to elaborate a specific response against the tumor antibodies. Hematological neoplasms, specifically some B lymphomas, express in their membrane an immunoglobulin that is considered a specific antigen of the tumour, which is why these diseases have become the ideal target for immunotherapy treatments. There are many alternatives, ranging from protein vaccines, which have already shown clinical benefits, to those of the second generation, which make use of the new techniques of molecular biology to increase the efficacy of the vaccines and obtain their production in a quicker and less costly way, but with which there are not yet definitive clinical results.

[Clinical and hematological aspects of follicular lymphoma]

A comprehensive clinical-and-laboratory examination of patients with non-Hodgkin's malignant lymphomas revealed a lack of correspondence between results of histological and immunophenotypical investigations. The most characteristic feature appeared to be the presence of CD10, CD11a, and CD35 antigens. Absence of CD95 antigen on tumour cells is regarded as an unfavourable prognostic sign in patients with follicular lymphomas as is presence of CD10 antigen on the above cells.

Active immunotherapy in follicular lymphoma

The antigen receptors expressed by follicular lymphomas represent tumor-specific antigens ("idiotypes"). In murine models, vaccination with tumor-derived idiotype in a variety of formulations can induce protective lymphoma-specific immunity. Phase II clinical trials in follicular lymphoma have also demonstrated idiotype-specific immune responses. Clinical data from these trials indicate sustained progression-free survival, disappearance of minimal residual disease, and even frank lymphoma regression in some cases. Phase III trials to prove the beneficial effects of active immunotherapy are currently being conducted. Additional research efforts focus on the most efficacious vaccination route and on the development of convenient methods to manufacture individual idiotype vaccines.

Follicular lymphoma cell lines, an in vitro model for antigenic selection and cytokine-mediated growth regulation of germinal centre B cells

In the periphery, B cells differentiate in germinal centres (GCs) of secondary lymphoid organs. Isolated GC cells die quickly in vitro by apoptosis. Therefore, cell lines originating from follicular lymphomas, which are the malignant counterparts of GC B cells, would provide a stable in vitro model to study the immunobiology of GC B cells. We have established three novel human follicular lymphoma cell lines that were characterized with special reference to immunophenotypic features, response to B-cell receptor (BCR) triggering, response to cytokines and cytokine mRNA expression. One of the cell lines, HF-1A3, has a phenotype of a centrocyte. It expresses surface immunoglobulin G (sIgG) and dies by apoptosis following BCR cross-linking. Co-stimulation with interleukin-6 (IL-6), IL-15 or interferon-gamma (IFN-gamma) rescues HF-1A3 cells from BCR-induced apoptosis. The second cell line, HF-28, also represents phenotypically an IgG+ centrocyte. Ligation of its BCR leads to the cell-cycle arrest at G1 instead of apoptosis. HF-28 cells express both CD45RA and RO isoforms, which is unusual in B lymphocytes apart from plasma cells, thus suggesting a transition to plasma cell phenotype. The third cell line, HF-4.9, which phenotypically represents an sIgM+ centroblast, responds by proliferation to BCR cross-linking. These cell lines offer a unique in vitro model to study antigenic selection and cytokine-mediated growth regulation of human GC B cells.

HLA-DO. A useful marker to distinguish florid follicular hyperplasia from follicular lymphoma by flow cytometry

HLA-DO expression is regulated during B-cell development and activation. To determine whether the level of HLA-DO expression is a helpful marker in the differential diagnosis between florid follicular hyperplasia and follicular lymphoma, we analyzed single-cell suspensions from 29 lymph node specimens by 4-color flow cytometry. Of the 29 specimens, 7 were from patients with florid follicular hyperplasia, in which the clonality of the germinal center B cells (GCBCs) was indeterminate by flow cytometric immunophenotyping. The remaining 22 cases were follicular lymphomas; neoplastic cells in 2 of these cases lacked expression of surface immunoglobulin light chains. The level of HLA-DO expression in the reactive CD10+ GCBCs in florid follicular hyperplasia was markedly down-regulated compared with the CD10- polytypic B cells of the same specimens. In contrast, the level of HLA-DO expression in the CD10+ neoplastic cells in all cases of follicular lymphomas was similar to that of the CD10- polytypic B cells, thus higher than the reactive CD10+ GCBCs. This difference was confirmed by immunohistochemical staining. Our results suggest that HLA-DO is a useful marker to differentiate florid follicular hyperplasia from follicular lymphoma by flow cytometry, particularly when clonality of the CD10+ B cells is in question.

Pharmacokinetic study of patients with follicular or mantle cell lymphoma treated with rituximab as 'in vivo purge' and consolidative immunotherapy following autologous stem cell transplantation

BACKGROUND

Little is known about the pharmacokinetics of rituximab in an autologous stem cell transplant (ASCT) setting.

PATIENTS AND METHODS

We evaluated serum rituximab levels in 26 patients with follicular or mantle cell lymphoma treated with a combination of ASCT and immunotherapy. Patients received nine infusions of rituximab (375 mg/m(2)): one dose as an 'in vivo purge' prior to stem cell collection, and two 4-week cycles at 8 and 24 weeks following ASCT. Pre- and post-infusion serum rituximab levels were measured during the purging dose, with doses 1 and 4 of both sets of maintenance rituximab cycles, and 12 weeks and 24 weeks following treatment.

RESULTS

Rituximab levels were detectable after the first infusion, and peaked at a mean concentration of 463.8 micro g/ml after the final dose. Levels remained detectable 24 weeks after completion of treatment. There was a trend toward higher rituximab levels in patients with follicular lymphoma. Serum concentrations achieved during the maintenance cycles were similar to levels observed in patients with measurable lymphoma treated during 'the pivotal trial'. No correlation was observed between serum rituximab levels achieved in the minimal disease state and the risk of later clinical relapse, nor with the ability to achieve a molecular remission following ASCT.

CONCLUSIONS

The finding that patients treated in minimal disease states and at the time of active disease both achieve similar final serum rituximab concentrations after four infusions suggests that the pharmacokinetics are complex, and may not necessarily correlate with disease burden. The precise factors influencing rituximab clearance in patients with lymphoma are unresolved, and this remains an area of active research.

Safety of yttrium-90 ibritumomab tiuxetan radioimmunotherapy for relapsed low-grade, follicular, or transformed non-hodgkin's lymphoma

PURPOSE

Radioimmunotherapy (RIT) with yttrium-90 ((90)Y)-labeled anti-CD20 antibody ((90)Y ibritumomab tiuxetan; Zevalin, IDEC Pharmaceuticals Corporation, San Diego, CA) has a high rate of tumor response in patients with relapsed or refractory, low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma (NHL). This study presents the safety data from 349 patients in five studies of outpatient treatment with (90)Y ibritumomab tiuxetan.

PATIENTS AND METHODS

Patients received rituximab 250 mg/m(2) on days 1 and 8, and either 0.4 mCi/kg (15 MBq/kg) or 0.3 mCi/kg (11 MBq/kg) of (90)Y ibritumomab tiuxetan on day 8 (maximum dose, 32 mCi). Patients were observed for up to 4 years after therapy or until progressive disease.

RESULTS

Infusion-related toxicities were typically grade 1 or 2 and were associated with rituximab. No significant organ toxicity was noted. Toxicity was primarily hematologic, with nadir counts occurring at 7 to 9 weeks and lasting approximately 1 to 4 weeks depending on the method of calculation. After the 0.4-mCi/kg dose, grade 4 neutropenia, thrombocytopenia, and anemia occurred in 30%, 10%, and 3% of patients, respectively, and after the 0.3-mCi/kg dose, these grade 4 toxicities occurred in 35%, 14%, and 8% of patients, respectively. The risk of hematologic toxicity increased with degree of baseline bone marrow involvement with NHL. Seven percent of patients were hospitalized with infection (3% with neutropenia) and 2% had grade 3 or 4 bleeding events. Myelodysplasia or acute myelogenous leukemia was reported in five patients (1%) 8 to 34 months after treatment.

CONCLUSION

Single-dose (90)Y ibritumomab tiuxetan RIT has an acceptable safety profile in relapsed NHL patients with less than 25% lymphoma marrow involvement, adequate marrow reserve, platelets greater than 100,000 cells/ micro L, and neutrophils greater than 1,500 cells/ micro L.

Re-entry of tumour B cells into the cycle of somatic mutation and isotype switching in follicular lymphoma

Sequencing of the immunoglobulin (Ig) gene transcripts of the tumour B cells in lymph node (LN) and bone marrow (BM) from a follicular lymphoma (FL) patient associated with multiple myeloma identified two dominant clones. One of the clones, present in both LN and BM, had somatic mutations and extensive clonal diversity. Among the diversified clones, two dominant populations of identical sequences (group I and II) were present. Group II was a descendant population of group I and had nine more somatic mutations. Group I contained micro-, delta-, gamma- and alpha-expressing clones. Group II clones contained mainly micro- and delta-expressing clones. These findings showed that somatic mutation and isotype switching occurred repeatedly in this patient.

Evolution of classic Hodgkin lymphoma in correlation to changes in the lymphoid organ structure of vertebrates

In order to integrate evolutionary concepts into lymphoma research we mapped features of classic Hodgkin lymphoma (a disease which has been recently described to be derived from germinal center B-cells) onto a phylogenetic tree of vertebrates. Secondly, we matched the phylogenetic occurrence of classic Hodgkin lymphoma to the changes in the lymphoid organ structure during vertebrate evolution. According to our analysis, classic Hodgkin lymphoma evolved exclusively at the developmental stage of mammals. Interestingly the appearance of Hodgkin lymphoma is correlated to the evolution of germinal centers in mammals. This lends some credit to the hypothesis that genes specific to the germinal center reaction are involved in the pathogenesis of Hodgkin lymphoma. However, as evolution did not stop at the developmental stage of the mammalian stem-species, to a certain extent species with specific differences of classic Hodgkin lymphoma can be expected. One such difference is that classic Hodgkin lymphoma occurs with a significantly higher frequency in humans than in all other mammals. This could be partially due to Epstein-Barr virus (EBV) infection in approximately 40%-50% of Hodgkin disease cases, that is associated with an expression of the EBV-encoded oncogen LMP-1. In conclusion we propose that the mapping of lymphoma related characteristics onto a phylogenetic tree is a valuable new tool in lymphoma research.