Rituximab therapy for hairy cell leukemia: a retrospective study of 41 cases.

The purine analogs (PAs) cladribine and pentostatin have transformed the prognosis of hairy cell leukemia (HCL). However, some patients still relapse after PAs, or fail to reach an optimal response, and new agents are needed to further improve treatment outcome. We retrospectively studied 41 HCL patients from 10 centers in France and Belgium, who received 49 treatment courses with the anti-CD20 monoclonal antibody rituximab. Most of the patients were treated at relapse (84 % of cases) and rituximab was combined to a PA in 41 % of cases. Overall, response rate is 90 % including 71 % complete hematologic responses (CHRs). Frontline treatment, combination therapy, and absolute neutrophil count were associated with response in multivariate analysis. Three-year relapse-free and overall survivals are 68 and 90 %, respectively. When combined to a PA, rituximab yields a 100 % response rate, even beyond frontline therapy. In contrast, response rate is only 82 % (59 % CHR) when rituximab is used alone. In this latter setting, relapse rate is 56 % and median time to relapse is 17.5 months. All eight patients who were treated two times with the antibody responded again to re-treatment. We confirm the high efficacy of the combination rituximab + PA. However, when rituximab is used as monotherapy, response rate is lower and the high relapse rate is a concern. Prospective clinical trials are needed to confirm the superiority of the combination rituximab + PA over PA alone, both as frontline therapy and at relapse.

TLR9 Ligand (CpG Oligodeoxynucleotide) Induces CLL B-Cells to Differentiate into CD20(+) Antibody-Secreting Cells.

B-cell chronic lymphocytic leukemia (CLL) is the most frequent adult leukemia in the Western world. It is a heterogeneous disease characterized by clonal proliferation and the accumulation of CD5(+) mature B lymphocytes. However, the normal counterpart from which the latter cells arise has not yet been identified. CD27 expression and gene expression profiling data suggest that CLL cells are related to memory B-cells. In vitro, memory B-cells differentiate into plasma cells when stimulated with CpG oligodeoxynucleotide (CpG). The objective of the present study was therefore to investigate the ability of CpG, in the context of CD40 ligation, to induce the differentiation of CLL B-cells into antibody-secreting cells (ASCs). CD20(+)CD38(-) CLL B-cells were stimulated with a combination of CpG, CD40 ligand and cytokines (CpG/CD40L/c) in a two-step, 7-day culture system. We found that the CpG/CD40L/c culture system prompted CLL B-cells to differentiate into CD19(+)CD20(+)CD27(+)CD38(-)ASCs. These cells secreted large amounts of IgM and had the same shape as plasma cells. However, only IgMs secreted by ASCs that had differentiated from unmutated CLL B-cells were poly/autoreactive. Class-switch recombination (CSR) to IgG and IgA was detected in cells expressing the activation-induced cytidine deaminase gene (AICDA). Although these ASCs expressed high levels of the transcription factors PRDM1 (BLIMP1), IRF4, and XBP1s, they did not downregulate expression of PAX5. Our results suggest that CLL B-cells can differentiate into ASCs, undergo CSR and produce poly/autoreactive antibodies. Furthermore, our findings may be relevant for (i) identifying the normal counterpart of CLL B-cells and (ii) developing novel treatment strategies in CLL.

Phorbol myristate acetate, but not CD40L, induces the differentiation of CLL B cells into Ab-secreting cells.

In this study, we investigated the capacity of chronic lymphocytic leukemia (CLL) B cells to undergo terminal differentiation into Ig-secreting plasma cells in T cell-independent and T cell-dependent responses. We used a two-step model involving stimulation with phorbol myristate acetate (PMA) and CD40L, together with cytokines (PMA/c and CD40L/c), for 7 days. We describe immunophenotypic modifications, changes in the levels of mRNA and protein for transcription factors and morphological and functional events occurring during the differentiation of CLL B cells into antibody-secreting cells (ASCs). The induction of differentiation differed significantly between the CD40L/c and PMA/c culture systems. The PMA/c culture system allowed CLL B cells to differentiate into IgM-secreting cells with an immunophenotype and molecular profile resembling those of preplasmablasts. By contrast, CD40L/c-stimulated cells had a phenotype and morphology similar to those of activated B cells and resembling those of the CLL B cells residing in the lymph node and bone marrow. These data suggest that the CLL B cells are not frozen permanently at a stage of differentiation and are able to differentiate into ASCs as appropriate stimulation are provided. The data presented here raise questions about the molecular processes and stimulation required for CLL B-cell differentiation and about the inability of CD40 ligand to induce differentiation of the CLL B cells.

Mast Cell Leukaemia: c-KIT Mutations Are Not Always Positive.

Mast cell leukemia (MCL) is a rare and aggressive disease with poor prognosis and short survival time. D816V c-KIT mutation is the most frequent molecular abnormality and plays a crucial role in the pathogenesis and development of the disease. Thus, comprehensive diagnostic investigations and molecular studies should be carefully carried out to facilitate the therapeutic choice. A MCL patient's case with rare phenotypic and genotypic characteristics is described with review of major clinical biological and therapeutic approaches in MCL.

First identification of a point mutation at position -83 (G>A) of the beta-globin gene promoter.

We report the first identification of a point mutation located within the promoter region of the beta-globin gene at position -83 (G>A) and associated with the common heterozygous deletional alpha-thalassemia (alpha-thal) (-alpha(3.7)/alphaalpha). The patient was an adult male from Gabon belonging to the Obamba sub ethnic group, who was referred to our clinics for a mild microcytic anemia with a Hb A(2) level at the upper limit of the normal value (3.5%). This observation is a new example of alpha- and beta-thal co-inheritance with a normal Hb A(2) level, and illustrates a potential source of pitfall in screening for alpha- and beta-thal carriers.

Thalidomide in advanced mastocytosis.

Mastocytosis is an acquired orphan disease characterized by the abnormal accumulation of mast cells responsible for organ failure and systemic symptoms. Cytoreductive drugs have been shown to be effective, but have rarely resulted in complete or long-term remission. We report two patients with advanced systemic mastocytosis (SM) who were treated successfully with thalidomide, given at the maximal tolerated dosage. B and C-findings as well as clinical symptoms rapidly improved. After a follow-up of more than 1 year, the patients remained in partial remission. Thalidomide seems to be an active drug in advanced SM. However, clinical trials are warranted to define its efficacy and safety profiles.

Multi-drug resistance mediated by P-glycoprotein overexpression is not correlated with ZAP-70/CD38 expression in B-cell chronic lymphocytic leukemia.

ZAP-70 and CD38 expression can identify B-cell chronic lymphocytic leukemia with an inferior clinical outcome. Many groups have investigated the meaning of the expression of these two proteins and the correlation with the bad prognosis in B-CLL. But nobody has investigated the relation between the multidrug resistance mediated by Pgp overexpression (MDR1) and ZAP-70/CD38 coexpression. Forty-one untreated and stage A patients, either ZAP-70(+)CD38(+) or ZAP-70(-)CD38(-), were tested to determine the MDR1 status. MDR1 was observed in 41% of CLL ZAP-70(+)CD38(+) and in 37% of CLL ZAP-70(-)CD38(-). The difference was not significant (p = 0.745). Patients with ZAP-70 and CD38 positive CLL can not be candidates for MDR1 antagonists.