First-line and maintenance treatment with rituximab for patients with indolent non-Hodgkin's lymphoma

The chimeric human-mouse anti-CD20 monoclonal antibody rituximab has durable single-agent activity in patients with relapsed and refractory indolent non-Hodgkin's lymphoma. The focus of this report is a phase II trial evaluating the efficacy of single-agent rituximab as first-line therapy in patients with indolent lymphoma and scheduled maintenance treatment in prolonging duration of remission. Patients received a 4-week course of standard rituximab (375 mg/m(2) intravenously weekly x 4). Those achieving objective response or stable disease then received maintenance courses of standard rituximab every 6 months, for a maximum of four rituximab courses. Of 62 patients entered in the trial, 61% had follicular lymphoma while 39% had small lymphocytic lymphoma (SLL). At 6 weeks, 28 of 60 evaluable patients (47%) had an objective response. The response rate improved to 73% (37% complete response) following maintenance rituximab therapy and was similar in patients with follicular lymphoma and SLL (76% v 70%, respectively). Median progression-free survival for the entire group was 34 months. Single-agent therapy was well tolerated and maintenance rituximab was administered without grade 3/4 toxicity. Because of the higher activity of rituximab in this study compared with previous results in patients with relapsed or refractory SLL, a second phase II trial of identical design but limited to patients with SLL and chronic lymphocytic leukemia was initiated. Forty-four patients entered this second trial and, at present, 27 continue to receive maintenance courses of rituximab. The current response rate is 56% (8% complete responses). In summary, rituximab appears highly active as first-line single-agent therapy for indolent non-Hodgkin's lymphoma and responses may be improved with maintenance courses of rituximab. Results suggest a higher response rate to rituximab when used as first-line compared with second/third-line treatment, particularly in the subset of patients with SLL and chronic lymphocytic leukemia. Further follow-up will provide important information regarding the impact of first-line and maintenance rituximab on progression-free survival in patients with indolent non-Hodgkin's lymphoma.

Changes in lymphocyte subsets in children with newly diagnosed type 1 diabetes mellitus

The aim of this study was to assess changes in selected peripheral blood lymphocyte subsets in children and adolescents with newly diagnosed type 1 diabetes mellitus (DM) and determine the correlation between these changes and other immunological markers. The study involved a group of 39 patients aged 2-14 years and a control group. The number of T- and B-lymphocytes and the number of CD4, CD8, CD4/HLA-DR, CD8/HLA-DR, CD5/CD20 subsets were measured by flow-cytometry using monoclonal antibodies. Islet cell antibodies (ICA) and antibodies to glutamic acid decarboxylase (GADA) were assessed. In both the diabetic and control groups the number of T-and B-lymphocytes were within normal limits. In patients with DM, the percentage of CD5+/CD20+ cells was significantly increased compared with the control group (p < 0.0001). ICA were positive in 80% of patients and GADA in nearly 65%. A positive correlation between the CD5/CD20 subset and ICA and GADA was found. In patients with a high percentage of CD5+/CD20+ lymphocytes, a higher percentage of activated subsets (CD4/HLA DR and CD8/ HLA DR) was detected.

IN CONCLUSION

CD5/ CD20 lymphocyte subsets are a good additional marker of autoimmunological processes in DM.

Successful treatment of gastrointestinal follicular lymphoma with rituxan and combination chemotherapy

The clinical course of follicular lymphoma (FL) is well known. Although it is a chemosensitive disease, thereby allowing substantial palliation, recurrence is the rule; only a small subset who presents with limited stage disease is cured. Multiple attempts have been made over the past two decades to improve the survival of patients with FL, and a large number of phase III trials have been reported. These have included a variety of different therapeutic interventions, such as combination chemotherapy, recombinant interferons, new cytotoxic drugs, and immunologic agents. Most studies have not demonstrated that the use of a particular therapy convincingly prolongs survival. Follicular lymphoma cells express CD20 and are associated in most cases with the t(14:18) chromosomal translocation. Rituximab is a chimeric monoclonal antibody directed against the B-cell CD20 antigen, which has been utilized for the therapy of B-cell non-Hodgkin's lymphoma. Rituximab was shown to be active in FL, and studies of its effectiveness in combination with cytotoxic chemotherapy to increase the response rate are forthcoming.

Immunochemotherapy in indolent non-Hodgkin's lymphoma

Non-Hodgkin's lymphomas (NHLs) comprise a diverse group of lymphatic malignancies of primarily B-cell origin, which are steadily increasing in prevalence worldwide. Of these, the indolent NHLs, although initially responsive to a variety of therapeutic regimens, have a continuous relapsing nature and are essentially incurable. Consequently, novel and innovative treatments are urgently required to prolong overall survival in patients with this disease. Rituximab, a human-mouse chimeric monoclonal antibody that mobilizes host effector mechanisms to destroy B cells expressing the CD20 antigen, has proven single-agent efficacy in NHL. There is a powerful rationale for combining rituximab with conventional chemotherapeutic agents to improve the outcome in NHL. A study evaluating the efficacy of rituximab plus cyclophosphamide/doxorubicin/vincristine/prednisone (CHOP) immunochemotherapy has been conducted in 40 patients diagnosed with indolent NHL. The overall response rate was 95% (38 of 40 patients) and 22 patients (55%) experienced a complete response. No unexpected toxicity was observed with the combination therapy. Median time to progression is not reached after 50 months of follow-up. Using a highly sensitive polymerase chain reaction technique, it was also shown that rituximab plus CHOP resulted in the elimination of bcl-2-positive lymphoma cells. A further study assessing whether or not similar efficacy can be achieved using rituximab combined with fludarabine chemotherapy has provided very encouraging early results to date, with an initial overall response rate of 93% in 30 treated patients and a complete response rate of 80%. Clearance of bcl-2-positive cells, as observed in the CHOP study, has also been achieved in these patients. The combination of rituximab with conventional chemotherapeutic agents such as CHOP appears to be a viable treatment option for indolent NHL. Ongoing and planned studies will lead to the optimal use of rituximab for the treatment of NHL.

[Development of monoclonal antibody therapy for malignant lymphoma]

Lymphomas are among the tumors most responsive to chemotherapeutic agents and radiation therapy. Despite chemotherapeutic and radiological advances, tumor cell resistance still remains a problem, and the toxicity of chemotherapy and radiation therapy limits their potential. Less toxic therapies for lymphoma have been continued to search for effectiveness. Since the discovery of the hybridoma technology by Kohler and Milstein in 1975, utilizing antibodies as targeted therapy for lymphoma has been investigated for many years. After 20 years of clinical trials, monoclonal antibody therapy of lymphoma enters the new millennium ready for 'prime time'. Investigators' early enthusiasm was dampened by problems with tumor targeting, HAMA, and allergic reactions, but important advances in molecular biology and chelation chemistry have led to new and improved reagents. Rituximab(IDEC-C2B8) has already been approved by the FDA in USA and the Ministry of Welfare and Labour in Japan for relapsed CD20-positive lymphomas and indolent B-cell lymphoma including mantle cell lymphoma, respectively. Ibritumomab tiuxetan and iodine-131 anti-B1 antibody have an excellent anti-lymphoma profile, and both appear to have higher response rates than rituximab. Results from the rituximab vs. ibritumomab tiuxetan phase III trial clearly favor the latter especially in %CR. Radiolabeled Lym-1, T101, LL2, and anti-Tac data will be forthcoming. Continued refinements of immunotoxins will establish their possible therapeutic role, and a variety of antibody conjugates including drugs, prodrugs, nonprotein toxins, and other agents, will continue to be studied in the clinic. Bispecific antibodies for lymphoma are also in early clinical testing. Over the next 10 years, many of the major advances in lymphoma therapy will be antibody-based.

Emerging information on the use of rituximab in chronic lymphocytic leukemia

Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA) is a chimeric monoclonal antibody that targets mature B cells in most lymphoid B-cell malignancies. While rituximab was approved by the US Food and Drug Administration for the treatment of recurrent B-cell lymphoma, initial studies suggested that it had less activity in small lymphocytic lymphoma, the nodal counterpart of chronic lymphocytic leukemia (CLL). Two studies have now investigated the activity of higher-dose and more intensive therapy with rituximab in CLL. They have shown a dose-response relationship and a higher response rate than previously seen in the lower-dose studies. This is presumably caused by the overcoming of lower antigen density on CLL cells compared with lymphoma cells, and the shorter half-life of rituximab in small lymphocytic lymphoma. There is now evidence that CD20 is shed into the plasma in patients with CLL, which may explain the shorter half-life of the antibody in small lymphocytic lymphoma/CLL. The higher dose may then be effective in overcoming this so-called "antigen sink." Toxicity was uncommon except in previously untreated patients and those with atypical forms of CLL such as mantle cell lymphoma and prolymphocytic leukemia. There is now evidence in vitro of additive or synergistic activity of rituximab with a variety of chemotherapeutic agents including fludarabine and cyclophosphamide. Combinations of fludarabine with rituximab or these two drugs combined with cyclophosphamide have given very high complete response rates in series of patients with both previously untreated and treated CLL. It is apparent that rituximab is playing a significant role in the management of patients with CLL as salvage therapy and is a potential potentiating agent for combined chemoimmunotherapy strategies for front-line or relapsed patients with CLL.

Yttrium 90 ibritumomab tiuxetan radioimmunotherapy for relapsed or refractory low-grade non-Hodgkin's lymphoma

The treatment of malignant lymphoma has improved over the past 20 years, but the majority of patients are not cured. New modalities using targeted therapy based on new information in molecular biology and immunology hold promise for better outcomes with less toxicity. We review data on the use of radiolabeled monoclonal antibodies directed against the CD20 antigen on malignant B cells. We discuss the major radionuclides available, iodine 131 ((131)I), tositumomab, and yttrium 90 ((90)Y) ibritumomab tiuxetan (Zevalin; IDEC Pharmaceuticals, San Diego, CA) and present data on new approaches in labeling antibodies that have facilitated their use. Clinical trial data with the yttrium-labeled antibodies are discussed. The use of dosimetry as a means for predicting toxicity is discussed, and the questions of long-term toxicity (late effects) are addressed. These targeted approaches to the treatment of malignancy, and lymphoma in particular, hold great promise.

Synergism between cytosine-guanine oligodeoxynucleotides and monoclonal antibody in the treatment of lymphoma

Synthetic oligodeoxynucleotides containing unmethylated cytosine-guanine dinucleotides (CpG ODN) are potent immunostimulatory agents that can activate various immune cell subsets. We have found that CpG ODN show a variety of effects that could be useful in enhancing the efficacy of antibody therapy of lymphoma. In a mouse model, CpG ODN alone had no effect on survival of animals inoculated with lymphoma. In contrast, CpG ODN plus monoclonal antibody (MAb) was more effective at inhibiting tumor growth than MAb alone or MAb plus control ODN. Cytosine-guanine ODN plus MAb cured mice with a large tumor burden that could not be cured with MAb therapy alone. We also evaluated the effects of CpG ODN on the phenotype of human malignant B cells. Cytosine-guanine ODN upregulated the expression of a number of antigens, including CD20. The upregulation of CD20 was most extensive in cells that had low baseline expression of this antigen. We conclude that CpG ODN enhances the efficacy of MAb in a murine lymphoma model, most likely by activating effector cells, and upregulates expression of CD20 on primary human malignant B cells. Given the effects of CpG ODN on both target antigen expression and effector-cell function, further evaluation of the combination of CpG ODN plus rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA) and CpG ODN plus other MAbs is warranted.

Rituximab: mechanism of action and resistance

Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA)-mediated killing of CD20-positive tumor cells is likely caused by a combination of immune-mediated effects including complement-mediated lysis and antibody-dependent cell-mediated cytotoxicity and direct effects induced by CD20 ligation. In vivo, the clearance of damaged or preapoptotic cells through specific receptors for phosphatidylserine translocated to the outer cell membrane may also be important. Direct effects, including growth inhibition and apoptosis, have been shown in vitro; however, their contribution to the clinical effect is not known. Currently, most data suggest that the predominant effector mechanism is antibody-dependent cell-mediated cytotoxicity, with a minor role of complement. With treatment, resistance to rituximab-mediated killing may emerge. Little is known regarding the molecular pathogenesis of this resistance. In rare cases, the CD20 antigen may be lost. Complement-resistance proteins may also increase, but it is not clear that this is the reason for loss of sensitivity. A better understanding of these mechanisms should allow combination therapy with agents capable of augmenting antibody-based killing.

The role of rituximab and chemotherapy in aggressive B-cell lymphoma: a preliminary report of dose-adjusted EPOCH-R

Accumulating evidence suggests that the ability to activate apoptotic pathways may be an important determinant of chemotherapy sensitivity and presents a potentially important new therapeutic strategy. Monoclonal antibodies against the CD20 antigen directly induce apoptosis and may serve to modulate the threshold for chemotherapy-induced apoptosis. Rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA), a monoclonal antibody against CD20, was combined with dose-adjusted EPOCH (infusional etoposide/vincristine/doxorubicin/bolus cyclophosphamide/prednisone) chemotherapy and tested in 38 untreated or relapsed poor-prognosis aggressive lymphomas. Twenty-three patients were untreated. Of these patients, all had large B-cell histologies, a median age of 52 years, Eastern Cooperative Oncology Group performance status > or = 2 in 30%, and high-intermediate or high International Prognostic Index scores in 61%. Fifteen patients had relapsed or refractory lymphomas. These patients had received a median of two (range, one to four) prior regimens, 67% had aggressive histologies, and 60% had high-intermediate or high International Prognostic Index scores. Complete remissions were achieved in 85% and 64% of untreated and previously treated patients, respectively; additionally 42% of patients with disease refractory before therapy achieved complete remission. At a median follow-up of 12 months, progression-free and overall survival in the previously untreated group was 85% and 79%, respectively, and no patient in complete remission has relapsed. These results suggest that rituximab may modulate the sensitivity of B-cell lymphomas to chemotherapy.

Conceptual aspects of combining rituximab and Campath-1H in the treatment of chronic lymphocytic leukemia

Monoclonal antibody-based therapy has emerged as a novel approach in the treatment of hematologic malignancies. The safety and tolerability of monoclonal antibodies make these compounds attractive and easy to administer, even in elderly, heavily pretreated patients. Chronic lymphocytic leukemia is an incurable disease with few therapeutic options once patients fail purine analogue-based therapy. Two monoclonal antibodies have shown activity in this disease. The first is rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA), a chimeric human-mouse anti-CD20 antibody. The second is Campath-1H, a humanized form of a rat antibody active against CD52. We hypothesize that combining both antibodies in patients who have failed conventional therapies and express both CD20 and CD52 might have enhanced efficacy and therapeutic benefit. This concept is being explored at our institution in the context of a phase I/II clinical trial. The outcome and feasibility of this combination opens the way for future combination therapies using novel biologic agents.

Advances in classification and therapy of indolent B-cell malignancies

Advances in our understanding of normal B-cell differentiation have allowed for improved classification and therapy of B-cell malignancies. B-cell neoplastic diseases may be classified more accurately according to the differentiation stages of presumed normal B-cell counterparts. These advances have challenged the notion that chronic lymphocytic leukemia represents a malignancy of naive CD5 B cells. Analyses of immunoglobulin genes and gene expression patterns through microarray have defined at least two types of chronic lymphocytic leukemia that differ in their tendency toward disease progression. Nevertheless, these types still share more in common than they do with other lymphoid malignancies, and both may be derived from memory-type B cells. Advances in immune therapy are revolutionizing the approach to therapy. B-cell surface differentiation antigens constitute tissue-specific targets for passive immune therapy. Since the US Food and Drug Administration approval of rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA) for use in the treatment of follicular lymphoma, monoclonal antibody therapy is being considered for all types of B-cell malignancies. The ability to transform leukemia and lymphoma B cells into effective antigen-presenting cells through CD40 ligation allows for autologous immune recognition of neoplastic cells. Together, active and passive immune approaches have potential for effective treatment of patients with these diseases.

Rituximab, a chimaeric anti-CD20 monoclonal antibody, in the treatment of hairy cell leukaemia

The introduction of first alpha-interferon and later the purine analogues has revolutionized the treatment of hairy cell leukaemia (HCL). However, there are still some patients that initially or eventually fail to respond and, thus, there is a need for alternative treatment modalities. We have treated 11 HCL patients (eight relapsing and three newly diagnosed) with a chimaeric monoclonal antibody, rituximab, in a dose of 375 mg/m2 once a week for 4 weeks. The response rate was seven out of eleven (64%) with six complete remissions and one partial remission, all which have lasted between 0 and 34 months (median 14 months). Rituximab appears promising in the treatment of HCL and warrants further studies.

Survival and clonal expansion of mutating "forbidden" (immunoglobulin receptor-deficient) epstein-barr virus-infected b cells in angioimmunoblastic t cell lymphoma

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) is a peculiar T cell lymphoma, as expanding B cell clones are often present besides the malignant T cell clones. In addition, large numbers of Epstein-Barr virus (EBV)-infected B cells are frequently observed. To analyze the differentiation status and clonal composition of EBV-harboring B cells in AILD, single EBV-infected cells were micromanipulated from lymph nodes of six patients with frequent EBV(+) cells and their rearranged immunoglobulin (Ig) genes analyzed. Most EBV-infected B cells carried mutated Ig genes, indicating that in AILD, EBV preferentially resides in memory and/or germinal center B cells. EBV(+) B cell clones observed in all six cases ranged from small polyclonal to large monoclonal expansions and often showed ongoing somatic hypermutation while EBV(-) B cells showed little tendency for clonal expansion. Surprisingly, many members of expanding B cell clones had acquired destructive mutations in originally functional V gene rearrangements and showed an unfavorable high load of replacement mutations in the framework regions, indicating that they accumulated mutations over repeated rounds of mutation and division while not being selected through their antigen receptor. This sustained selection-free accumulation of somatic mutations is unique to AILD. Moreover, the survival and clonal expansion of "forbidden" (i.e., Ig-deficient) B cells has not been observed before in vivo and thus represents a novel type of viral latency in the B cell compartment. It is likely the interplay between the microenvironment in AILD lymph nodes and the viral transformation that leads to the survival and clonal expansion of Ig-less B cells.

Lymphocyte predominance Hodgkin disease is characterized by recurrent genomic imbalances

Single-cell polymerase chain reaction (PCR) has been used as a tool to demonstrate clonality and B-cell origin of Reed-Sternberg (RS) cells in Hodgkin disease (HD). An analogous approach was used to investigate genomic imbalances in a (cyto)genetically poorly characterized subentity: lymphocyte predominance Hodgkin disease (LPHD). Nineteen cases of LPHD were selected for a comparative genomic hybridization (CGH) study. CGH was performed with degenerate oligonucleotide primed-PCR (DOP-PCR)-amplified DNA from 4-5 microdissected CD20+ malignant cells. All analyzed cases revealed a high number of genomic imbalances (average 10.8 per case), involving all chromosomes but the excluded 19, 22, and Y, indicating a high complexity of LPHD. The majority of detected aberrations were recurrent. Gain of 1, 2q, 3, 4q, 5q, 6, 8q, 11q, 12q, and X, and loss of chromosome 17 were identified in 36.8% to 68.4% of the analyzed cases. Some of them have also been found in non-Hodgkin lymphoma (NHL), and possibly represent secondary changes associated with disease progression. Gain of 2q, 4q, 5q, 6, 11q, however, are much more rarely observed in NHL and could be more specifically associated with LPHD. Particularly interesting is a frequent overrepresentation of chromosome arm 6q, a region usually deleted in NHL. Rearrangement of the BCL6 gene (3q27) demonstrated by cytogenetics and fluorescence in situ hybridization in 2 cases in this study suggests its contribution in pathogenesis of LPHD. In conclusion, the data show a consistent occurrence of genomic alterations in LPHD and highlight genomic regions that might be relevant for development and/or progression of this lymphoma entity.

Correlation of marrow dose estimates based on serial pretreatment radiopharmaceutical imaging and blood data with actual marrow toxicity in anti-CD20 yttrium-90 monoclonal antibody radioimmunotherapy of non-Hodgkin's B-cell lymphoma

The purpose of this study was to investigate whether marrow radiation absorbed dose estimates predict haematotoxicity following radioimmunotherapy with an yttrium-90 labelled anti-CD20 monoclonal antibody in non-Hodgkin's B-cell lymphoma (NHL). Radiopharmaceutical data from 12 NHL radioimmunotherapy patients were analysed retrospectively using three methods of marrow radiation absorbed dose estimation based on serial pretreatment indium-111 labelled anti-CD20 monoclonal antibody activity versus time data (0-144 h): (i) lumbar spine (LS) image counts; (ii) blood clearance (BL); and (iii) whole body (WB) activity. Linear regressions were performed between the methods, and between each method and the 0-6 month post-treatment platelet and white blood cell count nadir and absolute drop in count (ADC). For the range of yttrium-90 activities (740-1547 MBq), absorbed dose estimates (mean +/- sigma) were: LS, 142+/-50 cGy (range 62-233 cGy); BL, 89+/-21 cGy (range 63-140 cGy); and WB, 54+/-10 cGy (range 36-63 cGy). The LS and BL marrow estimates differed significantly (P <0.003), with a correlation coefficient r of 0.36 (P = NS), while WB correlated significantly with both LS (r = 0.50, P < 0.05) and BL (r = 0.58, P < 0.05). The range of r with platelet nadir and ADC was -0.20 < or = r < or = 0.01, except for WB with ADC (r = 0.38) (all P = NS). Values of r for white blood cell nadir were unexpectedly positive, being 0.13 for BL and 0.29 for LS (P = NS), and 0.60 for WB (P < 0.025). Values of r for white blood cell ADC were 0.36 for BL and -0.26 for LS (P = NS), and 0.50 for WB (P < 0.05). These results indicate that different commonly employed methods of estimating marrow radiation absorbed dose may yield significantly differing results, which may not correlate with actual radiation toxicity. Therefore, caution must be exercised in relying on these results to predict haematotoxicity.

Characterization of lymphocyte subsets in rhesus macaques during the first year of life

Establishing reliable phenotypic data sets from the analysis of peripheral blood lymphocytes of normal animals is required to assess disease states. The rhesus macaque animal model is well established with respect to adult animals, but limited data are available that characterizes lymphocyte subsets in normal neonates. To address this, we used four-color flow cytometric analysis to follow phenotypic changes in 29 normal rhesus animals through their first ten months of life. From birth to 44 wk of age, the white cell count and absolute lymphocyte count were both elevated compared to adults. CD4+ cells constituted over 80% of all T cells at birth, a percentage that declined gradually over the first 12 wk of life, coincidental with increases in the percentages of CD8+ T cells, CD3-8+ natural killer cells and CD20+ B cells. This difference in relative frequency of CD4 and CD8 results in a significant skewing of CD4:CD8 ratio from 0.7:1 in adults to 3.5:1 in neonates. In addition, the predominant population of T lymphocytes consisted of CD45RA+CD62L+ naive cells. This subset continues to be the predominant phenotype for at least the first year of age. After birth the expression of activation markers (CD25) increased particularly on CD4+ T cells, although these levels generally reached a frequency similar to that observed in adults between 12 and 20 weeks after birth. These results are similar to those seen in humans and further confirm the reliability of the rhesus macaque animal model to study human diseases.

[Immunophenotype characteristics of blood lymphocytes in patients with lymphogranulomatosis]

The blood lymphocyte immunophenotype was studied in patients with lymphogranulomatosis including those having been exposed to the Chernobyl spectrum radionuclide radiation in the doses up to 75 sGy. It is shown that in both groups of patients, there tends to be a decline in indices for T- and EK-cell immunity, that comes to be the most apparent in radiation-associated lymphogranulomatosis. The data obtained provide scientific explanation of more aggressive course of the disease in such patients and of difficulty in treatment.

Epstein-Barr virus is present in neoplastic cytotoxic T cells in extranodal, and predominantly in B cells in nodal T non-Hodgkin lymphomas

Epstein-Barr virus (EBV)-positive T non-Hodgkin lymphomas (T-NHLs) have been described, but it is at present unknown how EBV infects T lymphocytes. It has been postulated that cytotoxic T cells (CTLs) or natural killer (NK) cells can be infected by EBV during the killing of an EBV-infected target cell. The objective of this study was therefore to determine whether the neoplastic cells in EBV-positive T-NHLs (n=221) of various locations have a cytotoxic phenotype. To identify EBV-harbouring cells, combinations were used of EBV-encoded RNA (EBER) in situ hybridization (RISH) and immunohistochemistry for T- and B-cell markers and the cytotoxic proteins TIA-1 and granzyme B. EBV was detected in the neoplastic cells of all nasal T-NHLs (n=9), 5/34 gastrointestinal (GI) T-NHLs, and 2/6 lung T-NHLs, but not in primary cutaneous T-NHLs (n=103). Moreover, EBV was found in the neoplastic cells of 2/48 nodal anaplastic large cell lymphomas (ALCLs), but not in neoplastic T cells of other nodal T-NHLs. However, 5/17 nodal peripheral T-NHLs not otherwise specified (PTCLs NOS) and 1/4 T-prolymphocytic leukaemias did contain EBV-positive non-T cells. Double staining revealed that in EBV-positive extranodal T-NHLs (n=16), the EBER-positive cells had a cytotoxic phenotype (TIA-1- and/or granzyme B-positive). In nodal non-ALCL T-NHLs, the EBER-positive cells were not positive for TIA-1 or granzyme B, nor did they express CD3, CD21 or HECA452. Instead, most of these cells expressed the B-cell marker CD20. These PTCLs NOS with EBER-positive cells showed features of AILD-like T-NHL. It is concluded that neoplastic cells of EBV-positive extranodal T-NHLs always have a cytotoxic phenotype, supporting the view that EBV can infect CTLs. In nodal non-ALCL T-NHL, EBV is only found in T-NHL with AILD-like features and is present in B cells, where it may contribute to the outgrowth of a malignant B-cell clone.

Multicenter phase II study of iodine-131 tositumomab for chemotherapy-relapsed/refractory low-grade and transformed low-grade B-cell non-Hodgkin's lymphomas

PURPOSE

This multicenter phase II study evaluated the efficacy, dosimetry methodology, and safety of iodine-131 tositumomab in patients with chemotherapy-relapsed/refractory low-grade or transformed low-grade non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Patients received a dosimetric dose that consisted of 450 mg of anti-B1 antibody followed by 35 mg (5 mCi) of iodine-131 tositumomab. Serial total-body gamma counts were then obtained to calculate the patient-specific millicurie activity required to deliver the therapeutic dose. A therapeutic dose of 75 cGy total-body dose (attenuated to 65 cGy in patients with platelet counts of 101,000 to 149,000 cells/mm(3)) was given 7 to 14 days after the dosimetric dose.

RESULTS

Forty-five of 47 patients were treated with a single dosimetric and therapeutic dose. Twenty-seven patients (57%) had a response. The response rate was similar in patients with low-grade (57%) or transformed low-grade (60%) NHL. The median duration of response was 9.9 months. Fifteen patients (32%) achieved a complete response (CR; 10 CRs and five clinical CRs), including five patients (50%) with transformed low-grade NHL. The median duration of CR was 19.9 months, and six patients have an ongoing CR. Treatment was well tolerated, with the principal toxicity being hematologic. The most common nonhematologic toxicities that were considered to be possibly related to the treatment included mild to moderate fatigue (32%), nausea (30%), fever (26%), vomiting (15%), infection (13%), pruritus (13%), and rash (13%). Additionally, one patient developed human-antimouse antibodies.

CONCLUSION

Iodine-131 tositumomab produced a high overall response rate, and approximately one third of patients had a CR despite having chemotherapy-relapsed or refractory low-grade or transformed low-grade NHL.

Intrasinusoidal bone marrow infiltration revealing intravascular lymphomatosis

Intravascular lymphoma is a rare, often fatal disease characterized by a widespread intravascular proliferation of neoplastic lymphoid cells. Dermatological and bizarre neurological manifestations usually predominate. We report a case of intravascular lymphomatosis with an exceptional clinical presentation showing splenomegaly combined with early bone marrow involvement. The diagnosis was made on bone marrow biopsy examination using both immunohistochemistry and molecular biology analysis. We stress the histopathological features of bone marrow involvement by intravascular lymphoma which allow the prompt recognition of this disease. Early systemic chemotherapy, which represents the only chance of remission in such an aggressive disease, can then be initiated.