MALT lymphoma and extranodal diffuse large B-cell lymphoma are targeted by aberrant somatic hypermutation.

Recently, a novel mechanism introducing genetic instability, termed aberrant somatic hypermutation (ASHM), has been described in diffuse large B-cell lymphoma. To further investigate whether ASHM also occurs in mucosa-associated lymphoid tissue type (MALT) lymphoma, we studied the mutation profile of PIM1, PAX5, RhoH/TTF, and c-MYC in 17 MALT lymphomas and 17 extranodal diffuse large B-cell lymphomas (DLBCLs) still exhibiting a low-grade MALT lymphoma component (transformed MALT lymphoma). Mutations in one or more genes were detected in 13 (76.5%) of 17 cases of MALT lymphomas and in all of 17 (100%) cases of extranodal DLBCL. A total of 100 sequence variants were found in 30 of 34 cases, 28 in the MALT lymphomas and 72 in extranodal DLBCL. Further, in PIM1 and c-MYC some of the mutations were found to affect coding exons, leading to amino acid exchanges, thus potentially altering gene function. Expression levels of activation-induced cytidine deaminase (AID), an enzyme essential for somatic hypermutation (SHM), was associated with the mutational load. These data indicate that aberrant SHM is associated with extranodal DLBCL and MALT lymphoma, likewise. By mutating regulatory and coding sequences of the targeted genes, ASHM may represent a major contributor to their pathogenesis.

Treatment of rheumatoid arthritis in the 21st century: targeting B-lymphocytes.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by persistent inflammation of synovial tissue. Although the initiating event of RA is still unknown, recent research has demonstrated the importance of the increased production of tumor necrosis factor (TNF) alpha in the perpetuation of the inflammatory process of this disease. Targeting this molecule with soluble receptors, i.e., etanercept, or antibodies, like infliximab or adalimumab, a new class of highly effective anti rheumatic drugs has been developed. Unfortunately, not all patients respond sufficiently to TNF blockade and some of the patients become unresponsive to TNF-blocking agents. Targeting B-lymphocytes in these patients has opened a new therapeutic window. It has been demonstrated that B-lymphocytes have an important impact in the pathophysiology of RA. These cells produce not only a variety of autoantibodies, but directly stimulate autoaggressive T lymphocytes in the synovium. Furthermore, B-lymphocytes produce a variety of proinflammatory cytokines that also activate monocytes and synoviocytes. Several placebo-controlled clinical trials have demonstrated the efficacy of B-lymphocyte-directed therapy in patients that have responded poorly to conventional disease-modifying drugs or TNF blockade. In addition, several other B-cell specific antigens are potential targets in different autoimmune diseases.

Receptor revision and atypical mutational characteristics in clonally expanded B cells from the cerebrospinal fluid of recently diagnosed multiple sclerosis patients.

PURPOSE: To determine whether cerebrospinal fluid (CSF) B cells exhibit clonal expansion in patients recently diagnosed with multiple sclerosis (MS). CSF B cell clonal expansion was detected early in the disease process. Evidence of receptor revision was present in at least one MS patient who had been recently diagnosed with MS. Targeting of mutations to RGYW/WRCY motifs within CDRs was nominally observed in the CSF B cell clones despite the high mutational frequencies (MF). These observations are consistent with the presence of intense specific B cell stimulation and expansion in the CNS of MS patients early in the disease process.

Durable molecular response to imatinib mesylate following nonmyeloablative allogeneic stem-cell transplantation for persisting myeloid blast crisis in chronic myeloid leukemia.

We report a chronic myeloid leukemia (CML) patient in chronic phase (CP) who developed blast crisis (BC) under imatinib mesylate administered in a dose reduced and non-continuous fashion because of hematologic intolerance. The patient underwent nonmyeloablative stem-cell transplant from a matched unrelated donor, but failed to achieve full donor chimerism and antileukemic response resulting in persistence of advanced disease. Complete hematologic, cytogenetic and molecular responses were attained 5 weeks after readministration of regularly dosed imatinib and two-step nested RT-PCR confirmed molecular remission throughout a 6 month follow-up period. This is the first case demonstrating that imatinib mesylate is a highly effective and safe treatment option to induce durable molecular remission in patients with CML who remain in myeloid blast crisis after nonmyeloablative allogeneic stem-cell transplantation.

Treatment of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type with cladribine: a phase II study.

PURPOSE: As chemotherapy has not been extensively studied in patients with lymphoma of the mucosa-associated lymphoid tissue (MALT), we initiated a prospective study to evaluate the activity of the nucleoside analog cladribine (2-chlorodeoxyadenosine [2-CdA]) in this disease. PATIENTS AND METHODS: Patients with histologically verified MALT-type lymphoma were enrolled. 2-CdA was administered at a dose of 0.12 mg/kg body weight on 5 consecutive days, as a 2-hour infusion. Cycles were repeated every 4 weeks for a maximum of six cycles. RESULTS: Nineteen patients with gastric and seven patients with extragastric MALT lymphoma were enrolled. All patients were chemotherapy-naive, and two had been locally irradiated before systemic relapse of the lymphoma. A total of 102 cycles was administered to our patients (median number of cycles per patient, four). All 25 assessable patients responded to treatment: 21 patients (84%) achieved complete remission (CR) and four patients achieved partial remission. All patients (100%) with gastric presentation, but only three patients (43%) with extragastric presentation, achieved CR. Toxicities were moderate and mainly hematologic and required dose reduction and/or premature discontinuation of therapy in only three cases. Two patients died from vascular events, one shortly after the first cycle because of myocardial infarction and the other from stroke 3 months after the second course. Three patients relapsed after 13, 18, and 22 months and one patient showed progressive disease after 15 months. At present, 24 patients are alive at a median follow-up time of 32 months. CONCLUSION: Our data demonstrate that 2-CdA is highly effective in inducing CR in 84% of patients with MALT-type lymphoma.

Rituximab (anti-CD20 monoclonal antibody) as consolidation of first-line CHOP chemotherapy in patients with follicular lymphoma: a phase II study.

Advanced stages of follicular lymphoma are deemed incurable by conventional approaches. Immunotherapy with the humanised monoclonal anti-CD20 antibody rituximab represents a new therapeutic option. The aim of our study was to determine the effectiveness and safety of rituximab in the consolidation setting of first-line treated patients with follicular lymphomas. Thus the goal was first to reduce tumour burden using the CHOP regimen as induction treatment followed by consolidation with rituximab administered on a standard 4 wk schedule at a dosage of 375 mg m-2 body surface area. Between August 1998 and April 2001, 41 patients were enrolled in the study. All patients were evaluable with regard to tumour response and toxicity. The overall remission rate in the intent-to-treat analysis was 100%. On subgroup analysis, 20 [83% (95% CI: 63-95%)] of the 24 patients with grade 1 or 2 histology entered complete remission (CR), in 10 cases (42%) after additional rituximab therapy. Rituximab thus led to CR in 10/14 patients [71% (95% CI: 42-92%)] who had merely achieved partial remission (PR) with CHOP. Of 16 evaluable patients with grade 3 histology (excluding one patient achieving CR on CHOP who refused further treatment with rituximab), 15 [94% (95% CI: 63-97%)] achieved CR, 13 (81%) of these while still receiving CHOP. Two of the three patients achieving only PR on CHOP entered CR following rituximab. Thirty-four patients (83%) continued to be in remission during a median follow-up period of 24.3 (9-40) months. Our data suggest that the use of rituximab for consolidation after CHOP may improve CHOP-induced remission and thus increase the CR rate. Furthermore, it was accompanied by a reduced rate of infusion-related side-effects.

Inflammation, immune reactivity, and angiogenesis in a severe combined immunodeficiency model of rheumatoid arthritis.

Severe combined immunodeficiency (SCID) mice were engrafted with rheumatoid arthritis (RA) synovium and evaluated to determine whether RA synovial morphology and function were maintained in the RA-SCID grafts. The four major components of RA synovitis, inflammation, immune reactivity, angiogenesis, and synovial hyperplasia persisted in RA-SCID grafts for 12 weeks. Retention of chronic inflammatory infiltrates was demonstrated by histological evaluation and by immunohistology for CD3, CD20, and CD68. Staining for CD68 also revealed that the grafts had undergone reorganization of the tissue, possibly as a result of fibroblast hyperplasia. Immune and inflammatory components were confirmed by the detection of human immunoglobulins and human interleukin-6 in serum samples obtained from grafted animals. Human blood vessels were detected by dense expression of CD31. Small vessels persistently expressed the vitronectin receptor, alpha v beta 3, a marker of angiogenesis. All vessels expressed VAP-1, a marker of activated endothelial cells. Finally, the grafts retained the ability to support immigration by human leukocytes, as demonstrated by the functional capacity to recruit adoptively transferred 5- (and -6)-carboxyfluorescein diacetate succinimidyl ester-labeled T cells. T cells entering the RA-SCID grafts became activated and produced interferon-gamma, as detected by reverse transcriptase-polymerase chain reaction analysis. These studies demonstrate that the RA-SCID model maintains many of the phenotypic and functional features of the inflamed RA synovium.