ALBERT

Description: Follicular lymphoma (FL) grades 1 and 2 are regarded as a distinct disease entity, whereas data suggest that FL grade 3 might be an inhomogeneous tumor category. To define the biologic spectrum of FL, 89 follicular lymphomas were studied for their cytologic composition, antigen expression, mitotic and proliferation indices, cytogenetics, and clinical data. In contrast to the homogeneous appearance of FL grades 1 and 2 (29 and 33 cases, respectively), 2 types of FL grade 3 were recognized. Eleven cases of FL 3a displayed structural features similar to those of FL 1 and 2 and were composed of centroblasts and centrocytes, whereas 16 cases of FL 3b, with (n = 4) or without (n = 12) a diffuse large B-cell lymphoma component (DLBL) (FL 3b ± DLBL), consisted exclusively of blasts. In contrast to FL 3a, FL 3b ± DLBL were CD10+ in only 50% of cases and displayed plasmacytoid differentiation in 44% of cases.  Although FL3a was t(14;18)+ in 8 of 11 (73%) cases, only 2 of 16 (13%) FL3b ± DLBLs harbored this translocation. In contrast, chromosomal breaks at 3q27 were encountered in 7 of 16 (44%) FL 3b ± DLBL in contrast to only 2 of 11 (18%) FL 3a, and the spectrum of secondary aberrations in FL 3b ± DLBL was similar to that of diffuse large B-cell lymphoma. We conclude, therefore, that FL grade 3 is a heterogeneous disease group and that the distinction proposed in the new World Health Organization classification between FL 3a (with centrocytes) and FL3b (without centrocytes) is of biologic, and possibly clinical, importance.

Description: Crystal-storing histiocytosis (CSH) is a rare event in disorders associated with monoclonal gammopathy. The intracellular crystal formation is almost always accompanied by the expression of κ light chains. However, the exact mechanism for the storage has not been clarified until now. We report a case of generalized CSH in a 73-year-old man who presented with IgA κ paraproteinemia and paraproteinuria. The initially observed CSH in the bone marrow biopsy was associated with the clinical and pathomorphologic features of a monoclonal gammopathy of undetermined significance. The progression of disease could not be affected by steroid therapy and the patient died of septic shock 7 months after detection of CSH. At the time of autopsy there was evidence for multiple myeloma and generalized CSH. Two-dimensional gel electrophoresis of liver tissue combined with immunoblotting revealed the massive storage of heavy chains of α type and light chains of κ type, each in a monoclonal pattern. Analysis of the stored κ light chain by nanoelectrospray-ionization mass spectrometry indicated that it belongs to the variable κI variability subgroup. We identified some unusual amino acid substitutions including Leu59, usually important for hydrophobic interactions within a protein, at a position where it has never been previously described in plasma cell disorders. In conclusion, we present the first case of CSH with molecular identification of the stored κ subgroup and detection of unusual amino acid substitutions. Our results suggest that conformational alterations induced by amino acid exchanges represent a crucial pathogenic factor in CSH.

Description: Abstract 1308 Pediatric patients undergoing hematopoietic stem cell transplantation (HSCT) are at high risk of acquiring fungal infections. Post-transplant immune deficiency, immunosuppressive medication, viral infections, and acute graft-versus-host disease (GvHD) are known risk factors for fungal infections especially with Aspergillus spp. and Candida spp. Thus, antifungal prophylaxis early after transplantation is indicated, but data for pediatric patients under twelve years of age is scarce. Oral antifungal prophylaxis with extended spectra azoles, e. g. voriconazole or itraconazole, is preferentially used in pediatric patients after allogeneic HSCT, while only few studies have been published. Under either one prophylaxis, break-through invasive fungal infections were still observed in our center. In adults, another broad-spectrum triazole, posaconazole, showed activity against Candida spp., Aspergillus spp., Cryptococcus spp., Zygomycetes, Fusarium spp. Based on these data pediatric BMT patients received oral prophylaxis using posaconazole in our clinic, and we retrospectively assessed the safety, feasibility, and initial data on efficacy. The patient group consisted of sixty pediatric patients (median of age 6.0 years) early after high dose chemotherapy and allogeneic HSCT for hemato-oncological malignancies and inborn errors of metabolism. 31 patients (51.7%) received a T cell-depleted graft. Posaconazole was commenced after discharge from the BMT unit. The observation period was defined as the time from treatment start of posaconazole till the end of oral antimycotic prophylaxis with posaconazole with a maximum of 200 days after transplant. The dosage of posaconazole given on the basis of adult dosage of 200 mg three times per day (tid) and was adapted according to the weight of the pediatric patients accordingly. Twenty-eight of the sixty pediatric patients received 5 mg per kg body weight twice a day (bid) (5 mg/kg BW bid) in an oral suspension, and thirty-two pediatric patients received 4 mg/kg BW tid. Pediatric patients, who received posaconazole 4 mg/kg BW tid had more stable trough levels in the morning (median 377 μg/L, mean 390±137.1 μg/L) in comparison to patients, who received posaconazole 5 mg/kg BW bid (median 134 μg/L, mean 217±187.9 μg/L). Both regimens were well tolerated without severe side effects. There was no decline in white blood cell counts, granulocytes, platelets, the number of CD3 positive T cells, CD4 positive T cells and CD16/56 positive NK cells during treatment with posaconazole. There were no adverse effects on the organ functions of any of the 60 pediatric patients due to the administration of posaconozole. After start of posaconazole we observed an increase in the liver parameters AST (baseline value smaller than 39 U/L) in 3 (5%) out of sixty pediatric patients amount equivalent to 2 × baseline values, in 14 (23.3%) patients amount equivalent 3 × baseline and ALT in 9 (15%) pediatric patients amount equivalent to 2 × baseline, in 14 patients amount equivalent to 3 × baseline of 39 U/L. The increase of liver parameters occurred in 83% of cases within the first fourteen days after start of posaconazole and normalized by day twenty-six after discontinuation of the drug. The analysis of cyclosporine A (CsA) whole blood concentrations was performed in a total of 28 pediatric patients, who were treated with CsA during the observation period with posaconazole. There was a statistically significant, but moderate increase of CsA blood concentrations by 28% on days 2 to 6 (p

Description: The FIP1L1-PDGFRA positive myeloproliferative syndrome (MPS) represents a distinct clinicobiological entity with constitutively enhanced tyrosine kinase activity of the fusion protein and excellent response to treatment with imatinib. Most patients are initially diagnosed as idiopathic hypereosinophilic syndrome or chronic eosinophilic leukemia (CEL). A prominent clinical feature besides eosinophilia is the male predominance. However, the natural clinical course remains to be elucidated. Here we report on five male FIP1L1-PDGFRA positive patients (median age 58, range 46–64 years) with various subtypes of acute myeloid leukemia (AML) according to the FAB classification (M0, n=2; M2, n=1; M4eo, n=1; acute eosinophilic leukemia, n=1). All patients had a history of pronounced eosinophilia for a median interval of 6 mo (range 2–186) indicating the presence of a CML-like chronic phase disease evolving to blast crisis or secondary AML. One patient relapsed six years after conventional chemotherapy of a secondary FIP1L1-PDGFRA positive eosinophilia-associated AML M0 with typical features of CEL. Three patients had additional cytogenetic aberrations at diagnosis of AML similar to those frequently observed during clonal evolution of CML (trisomy 8, n=2; trisomy 9, n=1). All five patients received imatinib (100–300 mg/day) for a median time of 12 mo (range 1–23); three patients as monotherapy, one patient after one course and another patient after two courses of intensive chemotherapy. Three AML patients have been treated for more than 3 mo (12+, 18+, and 23+ mo) and are currently free of relapse. All three patients achieved a rapid complete hematological remission, defined as a complete clearance of blasts, normalization of peripheral blood and bone marrow eosinophil count, and a complete molecular remission 4, 5, and 14 mo, respectively, after start of treatment as determined by nested RT-PCR for the FIP1L1-PDGFRA transcript. In all cases treatment with imatinib was well tolerated. We conclude that the occurrence of the FIP1L1-PDGFRA fusion gene seems to be associated with a chronic phase disease which may progress to secondary AML. Therefore, all patients presenting with an eosinophilia-associated AML and normal karyotype should be screened for the cytogenetically invisible FIP1L1-PDGFRA fusion gene by RT-PCR and/or fluorescence in situ hybridization, in addition to the commoner CBFB-MYH11 fusion. Patients with a FIP1L1-PDGFRA positive MPS are excellent candidates for treatment with imatinib even if they present with secondary AML.

Description: Sixty-four cases of mantle cell (centrocytic) non-Hodgkin's lymphomas have been analyzed for their cytomorphologic features, proliferation indices, bcl-1 rearrangements, p53 expression patterns, and DNA content by both interphase cytogenetic and DNA flow cytometric analyses. According to cytomorphology, three subtypes were recognized: a common, a lymphoblastoid, and a pleomorphic variant of mantle cell lymphoma (MCL). Blastoid MCL subtypes were characterized by distinctly elevated mitotic counts (57 and 51/10 HPF v 21/10 high-power fields in common MCL), proliferation indices (58% and 53% v 27% in common types, respectively; P 〈 .001), frequent bcl-1 rearrangements at the major translocation cluster locus (59% v 40%), and overexpression of p53 (21% v 6%). However, the most interesting finding was a striking tendency of blastoid MCL subtypes to harbor chromosome numbers in the tetraploid range (36% of lymphoblastoid and 80% of pleomorphic types v 8% of common variants, P 〈 .001), a feature clearly separating these neoplasms from other types of B-cell non-Hodgkin's lymphoma and possibly being related to cyclin D1 overexpression. Our data indicate that, although characterized by a uniform immunophenotype and common biologic background, MCL shows a broad spectrum of morphologic features ranging from small cell to blastoid types and that the morphologic spectrum is mirrored by distinct biologic features.

Description: Background: The accurate detection of cytogenetic abnormalities in Acute Myeloid Leukemias (AML) and Myelodysplastic Syndromes (MDS) play an important role in prognostic value and often assist in therapeutic choice. The most commonly used genetic test for the diagnostics of these conditions is karyotype (KT), which is able to detect frequent non-random chromosomal abnormalities. However, this technique requires metaphases and offers low resolution (5Mb), which may lead to the loss of clinically important smaller genomic rearrangements. Therefore, a complementary technique is sometimes needed. FISH, for example, is a highly reliable technique, it can be performed in interphases, has higher resolution, and can detect balanced translocations (important for prognosis mainly in AML), although it is very expensive. As an alternative method, MLPA is usually less costly, is able to evaluate more genomic regions at once and is performed with genomic DNA, which is convenient for biological material availability. On the other hand, it is not able to detect balanced translocations due to its semi-quantitative PCR-based method. The aim of this study was to evaluate MLPA as a complementary technique to KT, and to compare the outcomes of MLPA and FISH panels for the high resolution detection of common unbalanced genetic alterations in MDS and AML. Methods: A total of 23 samples from patients diagnosed with MDS (n=16)/AML(n=6) were tested for KT and MLPA. 20 metaphases were analyzed in G-banding KT. MLPA (Kits P144 and P145, MRC-Holland) was performed with genomic DNA extracted from bone marrows. A subset of 10 samples was tested for FISH MDS/AML panel (PML/RARA, CBFB/MYH11, RUNX1/RUNX1T1, MLL rearrangement, del5q, del7q, de17p and del20q, Cytocell), and the outcomes were compared to MLPA. Reagent costs were also compared between MLPA and FISH techniques. Results: Outcomes from KT and MLPA were mostly concordant: 91.3% of samples had either concordant or partially concordant results (considering "partially concordant" when MLPA could detect smaller genetic alterations not achieved by KT). Discordance between KT and MLPA occurred in two cases: (i) MLPA detected a deletion of RUNX1 gene (chr 21) in a previously normal KT, and (ii) MLPA showed different abnormalities than those in a complex KT case, with low mitotic index. When comparing regions that are notoriously related to MDS/AML (-5/del5q, -7/del7q, +8, del11q, del13q, del17p, del20q and del21q), all results were concordant between MLPA and KT. Comparison of MLPA and FISH was performed with 10 samples, of which 4 were negative for genetic alterations and 6 were positive. 90% of samples had concordant results, and 10% (one sample) showed extra genetic alterations in MLPA (del7q; del11q and del20q). This is expected since MLPA analyzes more genetic regions then FISH MDS/AML panel at once. Genomic regions accessed both by MLPA and FISH included -7, +8, del17p, del21q. Regarding financial expenses (cost of commercial MDS/AML panels and additional reagents), MLPA costs approximately U$280.00 (considering test sample plus internal controls), while FISH costs U$555.00 (values were converted from quotes provided by regional distributors and converted to dollars). Conclusions: MLPA results are equivalent to FISH for the detection of MDS/AML frequent unbalanced genetic alterations. Both techniques are reliable as complementary molecular biology tests for KT. Moreover, MLPA is a friendly and less expensive technique for the detection of high resolution genomic unbalanced abnormalities, frequently adding extra information to KT results. Nevertheless, it is important to notice that only FISH can detect balanced translocations with significant prognostic value in AML. Disclosures No relevant conflicts of interest to declare.

Description: A large unmet medical need exists for safer antithrombotic drugs because all currently approved anticoagulant agents interfere with hemostasis, leading to an increased risk of bleeding. Genetic and pharmacologic evidence in humans and animals suggests that reducing factor XI (FXI) levels has the potential to effectively prevent and treat thrombosis with a minimal risk of bleeding. We generated a fully human antibody (MAA868) that binds the catalytic domain of both FXI (zymogen) and activated FXI. Our structural studies show that MAA868 traps FXI and activated FXI in an inactive, zymogen-like conformation, explaining its equally high binding affinity for both forms of the enzyme. This binding mode allows the enzyme to be neutralized before entering the coagulation process, revealing a particularly attractive anticoagulant profile of the antibody. MAA868 exhibited favorable anticoagulant activity in mice with a dose-dependent protection from carotid occlusion in a ferric chloride–induced thrombosis model. MAA868 also caused robust and sustained anticoagulant activity in cynomolgus monkeys as assessed by activated partial thromboplastin time without any evidence of bleeding. Based on these preclinical findings, we conducted a first-in-human study in healthy subjects and showed that single subcutaneous doses of MAA868 were safe and well tolerated. MAA868 resulted in dose- and time-dependent robust and sustained prolongation of activated partial thromboplastin time and FXI suppression for up to 4 weeks or longer, supporting further clinical investigation as a potential once-monthly subcutaneous anticoagulant therapy.

Description: Immunoglobulin variable heavy chain gene (VH) mutation status and VDJ rearrangement structure were analyzed in 141 patients with mantle cell lymphoma (MCL) and correlated with biologic and clinical characteristics; 29% of the MCLs displayed mutated VH using a 98% germline homology cutoff. Striking differences occurred in the VH mutation subgroups with respect to the use of specific V genes. Rearrangements involving V4-34 and V3-21 were almost exclusively unmutated, whereas rearrangements using V4-59 and V3-23 were typically mutated. Significant association occurred between mutated VH with shorter CDR3 lengths and the use of JH4b. V3-21 and V4-59 were involved in highly characteristic rearrangements, implying that antigen specificity might have been involved in MCL development. There was no evidence for isotype switch recombination or Bcl-6 expression in any MCL. ZAP70 expression was not different in VH-mutated or -unmutated MCL. Although the deletions 11q– and 17p– showed a balanced distribution, an overrepresentation was observed for trisomies +3q, +8q, and tetraploidy in the VH-unmutated subgroup and +12q in the VH-mutated subgroup. Clinically, mutated VH was associated with a higher rate of complete remission, but there was no correlation between VH mutation status and other clinical characteristics or overall survival.

Description: FTY720, a potent immunomodulatory drug in phase 2/3 clinical trials, induces rapid and reversible sequestration of lymphocytes into secondary lymphoid organs, thereby preventing their migration to sites of inflammation. As prerequisite for its function, phosphorylation of FTY720 to yield a potent agonist of the sphingosine-1-phosphate receptor S1P1 is required in vivo, catalyzed by an as-yet-unknown kinase. Here, we report on the generation of sphingosine kinase 2 (SPHK2) knockout mice and demonstrate that this enzyme is essential for FTY720 phosphate formation in vivo. Consequently, administration of FTY720 does not induce lymphopenia in SPHK2-deficient mice. After direct dosage of FTY720 phosphate, lymphopenia is only transient in this strain, indicating that SPHK2 is constantly required to maintain FTY720 phosphate levels in vivo.

Description: We show here for the first time that pluripotent hematopoietic stem cells express the CD4 antigen. CD4+ cells isolated from mouse marrow repopulated all hematopoietic lineages in both the long-term repopulation assay and the competitive repopulation assay. This finding indicates that the CD4+ population contains primitive stem cells with extensive repopulation capacity. Interestingly, the CD4- population had significant life-sparing activity, even though this population was depleted of long-term repopulating stem cells when compared with CD4+ cells. The majority of the cells that respond to the stroma in Whitlock- Witte cultures with B-cell differentiation were recovered in the CD4- population. Thus, this bone marrow (BM)-derived B-cell precursor lacks CD4, which is in contrast to myeloid precursors and thymus-derived lymphoid precursors that reportedly express CD4. We show further that the CD4 molecule expressed on BM cells is similar in molecular weight and epitope makeup to the CD4 antigen found on thymocytes. Detection of CD4 on BM cells is dependent on using high concentrations of antibodies. Thus, it is not surprising that expression of CD4 on pluripotent stem cells has been missed previously. Taken together, our data suggest that the CD4 molecule may play an important role in lineage definition in early hematopoietic differentiation.