Gérard Sébahoun

Romiplostim safety and efficacy for immune thrombocytopenia in clinical practice: 2-year results of 72 adults in a romiplostim compassionate-use program

Romiplostim, a thrombopoietic agent with demonstrated efficacy against immune thrombocytopenia (ITP) in prospective controlled studies, was recently licensed for adults with chronic ITP. Only France has allowed romiplostim compassionate use since January 2008. ITP patients could receive romiplostim when they failed to respond to successive corticosteroids, intravenous immunoglobulins, rituximab, and splenectomy, or when splenectomy was not indicated. We included the first 80 patients enrolled in this program with at least 2 years of follow-up. Primary platelet response (platelet count ≥ 50 × 10(9)/L and double baseline) was observed in 74% of all patients. Long-term responses (2 years) were observed in 47 (65%) patients, 37 (79%) had sustained platelet responses with a median platelet count of 106 × 10(9)/L (interquartile range, 75-167 × 10(9)/L), and 10 (21%) were still taking romiplostim, despite a median platelet count of 38 × 10(9)/L (interquartile range, 35-44 × 10(9)/L), but with clinical benefit (lower dose and/or fewer concomitant treatment(s) and/or diminished bleeding signs). A high bleeding score and use of concomitant ITP therapy were baseline factors predicting romiplostim failure. The most frequently reported adverse events were: arthralgias (26%), fatigue (13%), and nausea (7%). Our results confirmed that romiplostim use in clinical practice is effective and safe for severe chronic ITP. This trial was registered at www.clinicaltrials.gov as #NCT01013181.

Gaucher disease and multiple myeloma

Gaucher disease (GD) is the most frequent lysosomal storage disease and corresponds to an inherited deficiency of glucocerebrosidase. Due to excessive accumulation of glucocerebroside in bone marrow, both cytopenia and bone lesions may occur. The incidence of malignant disorders has been evoked in non-neuronopathic type I GD. More particularly, many case reports have been published that describe the association between GD and multiple myeloma (MM). Here, we first deal with diagnosis criteria that allow to distinguish between bona fide Gaucher celles and the so-called pseudo or pseudo-pseudo Gaucher cells. We then analyse relevant case reports and recent articles that provide convincing data regarding GD and MM association and suggest physiopathological links between the two disorders.

Differential expression of natural killer cell activating receptors in blood versus bone marrow in patients with monoclonal gammopathy.

In monoclonal gammopathies (MG) and multiple myeloma (MM), normal natural cytotoxicity receptors (NCR) expression (NCR1/NKp46, NCR2/NKp44, NCR3/NKp30) is observed in natural killer (NK) cells. Nonetheless, except in plasma cell leukemia, few tumor plasmocytes are present in PB, while NK studies have been performed on peripheral blood (PB). For this reason we focused our attention on NK from bone marrow (BM). Our study demonstrates that the down‐regulation of NCR3/NKp30 is only detectable in NK from BM but not in PB, and shows a drastic decrease of both NKG2D and CD244/2B4/p38 expression in NK from BM in comparison with PB. In conclusion, our data more precisely describe the mechanism of immune escape of MG/MM from innate immunity since we show a drastic down regulation of 3 major activating NK receptors (NCR3/NKp30, NKG2D and CD244/2B4/p38) at the site of tumor, i.e BM, that was undetectable in PB. Further studies regarding immune regulatory drugs in MG/MM will imperiously require the assessment of immune cell status not only in PB but also in BM to obtain more relevant data regarding anti‐tumor efficacy.

Expression of natural killer cell activating receptors in patients with chronic lymphocytic leukaemia

Recent advances in chronic lymphocytic leukaemia (CLL) treatment, more particularly through upfront use of anti‐CD20 monoclonal antibodies, have prolonged patient progression‐free survival. Nonetheless, apart from allogeneic stem cell transplantation, no curative treatment is available. One possible explanation for the lack of cure in CLL could be a defective immune anti‐tumour response. As the result of abnormal HLA class I molecule expression, CLL cells escape from specific T‐lymphocyte immunity but should be the target for the innate natural killer (NK) cell‐mediated immune response. Defective NK cytotoxicity as the result of decreased expression of the natural cytotoxicity receptors (NCRs) NKp30/NCR3, NKp44/NCR2 and NKp46/NCR1 has been described in haematological malignancies such as acute myeloid leukaemia. This prompted us to focus our attention on NCR expression on NK cells from patients with CLL. Although we failed to detect any difference between CLL patients and healthy age‐matched controls, a precise analysis of clinical data showed a correlation between decreased NCR expression and poor prognosis factors such as low haemoglobin level, high (> 30 × 109 per litre) lymphocyte count or elevated C‐reactive protein. Together, these observations support the rationale for restoration of normal NK cell functions in patients with CLL, putatively through the use of immune therapy protocols that already have demonstrated some benefit in acute myeloid leukaemia such as interleukin‐2 plus histamine dihydrochloride.

Peripheral T-cell lymphoma gene expression profiling and potential therapeutic exploitations

Peripheral T‐cell lymphomas constitute a heterogeneous group with regard to diagnosis, treatment and prognosis. Efforts have been made to combine novel techniques with cytology and immunochemistry in order to more precisely define these entities. Molecular profiling has contributed to novel insights in the biology of T‐cell lymphoma. Regarding anaplastic large cell lymphoma, low expression T‐cell receptor signalling and high STAT3 target signatures have been associated with the ALK‐positive subgroup. Gene expression profiling differentiates angioblastic T‐cell lymphoma from other T‐cell malignancies, suggests that the normal counterpart of lymphoma cells are follicular helper T cells, and supports the involvement of vascular endothelial growth factor deregulation in its physiopathology. In peripheral T‐cell lymphoma unspecified, gene profiling suggests the normal counterpart of tumour cells are activated CD4+ or CD8+ T‐lymphocytes, delineates prognostic groups depending on the proliferative signature, and suggests therapeutic options aimed at regulating nuclear factor‐κB and platelet‐derived growth factor receptor‐α phosphorylation. Gene expression profiling of primary cutaneous T cell lymphomas highlighted the importance of abnormal methylation patterns, suggested a pivotal role for JUNB/AP‐1, and defined a predictive model for response to interferon‐α. In conclusion, gene expression profiling is beginning to change the pathological classification, the prognosis profiles and the therapeutic approach in T‐cell lymphomas.

A new heterozygous mutation in GP1BA gene responsible for macrothrombocytopenia

Michelle D. Catalina* Rukhsana Aslam Edwin R. Speck Richard F. Francovitch John W. Semple Division of Haematology and Transfusion Medicine, Lund University, Lund, Sweden, Protalex Inc., Florham Park, NJ, USA, The Toronto Platelet Immunobiology Group, Toronto, ON, Canada, Keenan Research Centre for Biomedical Science at St. Michael’s Hospital, Toronto, ON, Canada, Departments of Pharmacology, Medicine, Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada, and Canadian Blood Services, Toronto, ON, Canada. E-mail: john_w.semple@med.lu.se

Eradication of T315I mutation in chronic myeloid leukemia without third-generation tyrosine kinase inhibitor: a case report

We report the case of a patient bearing a T315I-mutant chronic myeloid leukemia resistant to nilotinib, successfully treated with omacetaxine and then with dasatinib. After 9 months of nilotinib, the patient achieved a major molecular response but relapsed 3 months later due to the T315I mutation. Because third-generation tyrosine kinase inhibitor was not available and the patient refused bone marrow transplantation, he received two cycles of omacetaxine. This treatment had been stopped after two cycles because of clinical intolerance, but a major molecular response and total disappearance of the T315I clone was obtained. Treatment with dasatinib was then started and after 34-month follow-up the patient is still in major molecular response, thus suggesting that eradication of the T315I mutation could be achieved without third-generation tyrosine kinase inhibitors.

Effects of 5-azacytidine on natural killer cell activating receptor expression in patients with refractory anemia with excess of blasts

Epigenetic drugs modify DNA methylation and are used in refractory anemia with excess of blasts (RAEB). These drugs may reactivate anti-oncogene expression and restore a normal phenotype instead of inducing antitumor toxicity, although they also have immunosuppressive effects on T-lymphocytes [1] In RAEB and acute myeloid leukemia, a defect in natural killer (NK) cell cytotoxicity has been shown, which relies on abnormal expression of activating receptors. Previous study has shown that 5-azacytidine impaired mRNA synthesis and induced apoptosis in NK cells [2]. In this study we investigated the effect of the demethylating drug 5-azacytidine (Vidaza(®)) on NK receptors with the hypothesis that demethylation of the promoters of activating NK receptor genes induces gene reactivation and thus may increase their expression.

Distribution of lymphocyte subpopulations in patients with polycythemia vera

Polycythemia vera (PV) is a disease with slow development. Nonetheless, the immune response is unable to eliminate the uncontrolled proliferating hematopoietic cells, leading to treatment of patient by phlebotomy and/or cytotoxic drugs. In addition, a higher incidence of cancers is observed in PV patients, independently of treatment. These observations argue for an impaired immune response in PV. In order to investigate this hypothesis, we studied the distribution of lymphocyte subpopulations in PV, and showed a significant decrease in T, TCR γ/δ and B cells together with an increase in natural killer (NK) cells.

Natural killer cells in patients with polycythemia vera.

Natural killer cells (NK) are pivotal cells of innate immunity. They are potent antileukemic cytotoxic effectors. A defect in their cytotoxicity has been described in some hematopoietic malignancies such as acute myeloid leukemia, multiple myeloma and myelodysplastic syndromes. This defect is at least partially linked to a decreased or absent expression of some activating NK cells molecules, more particularly the so-called natural cytotoxicity receptors. In the present study, we more particularly focused our attention on NK cells of polycythemia vera, a myeloproliferative disease characterized by the presence of mutated JAK2 tyrosine kinase. The polymerase chain reaction analysis of NK cells from patients showed that they expressed the mutated form of JAK2. In polycythemia vera the proportion of NK was increased compared to healthy donors. The proliferative and cytotoxic abilities of NK cells from patients were similar to healthy donors. Expression of activating or inhibitory receptors was comparable in patients and donors, with nonetheless an imbalance for the inhibitory form of the CD158a,h couple of receptors in patients. Finally, the transcriptomic profile analysis clearly identified a discriminant signature between NK cells from patients and donors that could putatively be the consequence of abnormal continuous activation of mutated JAK2.