Gelatinous bone marrow transformation due to extensive weight loss in median arcuate ligament syndrome.

A 34-year-old man was referred to the outpatient clinic because of progressive abdominal pain, weight loss and pancytopenia. His body mass index (BMI) had fallen to 14.2 kg/m2 A CT angiography (CTA) showed narrowing of the truncus coeliacus with poststenotic dilation, and duodenal biopsy revealed ischaemia establishing a rare diagnosis: median arcuate ligament syndrome (MALS). This explained the postprandial pain and minimal intake. Further pancytopenia workup was performed. The bone marrow displayed gelatinous marrow transformation (GMT), a rare disorder of unknown pathogenesis, which has been associated with severe malnutrition. The final diagnosis was pancytopenia secondary to GMT due to severe malnutrition caused by MALS. The abnormalities in the bone marrow may be reversible by restoring nutritional status. This case emphasises the awareness of GMT in patients with weight loss, malnutrition and cytopenias. To our knowledge, this is the first report demonstrating an association between pancytopenia and MALS.

Ixazomib, Daratumumab, and Low-Dose Dexamethasone in Frail Patients With Newly Diagnosed Multiple Myeloma: The Hovon 143 Study.

PURPOSE: Frail patients with newly diagnosed multiple myeloma have an inferior outcome, mainly because of a high discontinuation rate due to toxicity. We designed a phase II trial specifically for frail patients, evaluating the efficacy and tolerability of ixazomib-daratumumab-low-dose-dexamethasone (Ixa-Dara-dex). METHODS: Sixty-five patients, who were frail according to the International Myeloma Working Group frailty index, were treated with nine induction cycles Ixa-Dara-dex followed by maintenance with Ixa-Dara for a maximum of 2 years. RESULTS: The overall response rate on induction therapy was 78%. After a median follow-up of 22.9 months, median progression-free survival (PFS) was 13.8 months and 12-month overall survival (OS) was 78%. Median PFS and 12-month OS were 21.6 months and 92% in patients who were frail based on age > 80 years alone, versus 13.8 months and 78%, and 10.1 months and 70% in patients who were frail based on additional frailty parameters either ≤ 80 or > 80 years of age, respectively. In 51% of patients, induction therapy had to be discontinued prematurely, of which 6% because of noncompliance to study treatment, 9% because of toxicity, and 9% because of death (8% within 2 months, of which 80% because of toxicity). Quality of life improved during induction treatment, being clinically meaningful already after three induction cycles. CONCLUSION: Ixa-Dara-dex lead to a high response rate and improved quality of life. However, treatment discontinuation because of toxicity and early mortality, negatively influencing PFS and OS, remains a concern in frail patients. The outcome was heterogeneous across frail subpopulations. This should be taken into account in the design and interpretation of future studies in frail patients, to pave the way for more precise treatment guidance.

The expression of the peripheral cannabinoid receptor CB2 has no effect on clinical outcome in diffuse large B-cell lymphomas.

BACKGROUND: The peripheral cannabinoid receptor (CB2) is mainly detected on B cells in the germinal centers (GCs) of the immune system, using an antibody directed against the extra cellular N-terminal domain of the receptor. We retrospectively investigated the CB2 receptor expression in diffuse large B-cell lymphomas (DLBCL) and its clinical relevance for treatment outcome. PATIENTS AND METHODS: We have constructed a tissue micro-array (TMA) using lymphoma tissue of a large cohort of patients with DLBCL (N = 104) who were treated with CHOP. RESULTS: Forty-five out of 79 evaluable cases (57%) were CB2 positive. The expression of CB2 receptors was variably present in both the germinal center B cell (GCB) (n = 31) and the non-GCB/activated B-cell (ABC) (n = 43) DLBCL subtypes. CB2 positivity was not associated with a different outcome in this patient cohort (CR; P = 0.87, EFS; P = 0.32, DFS; P = 0.06 and OS; P = 0.18). Implementation of CB2 expression in the Hans algorithm using the markers CD10, BCL6, and MUM1 did not result in added prognostic value (all P-values >0.1). CONCLUSIONS: We hypothesize that although CB2 is normally expressed in GCs, the expression in one of the malignant counterparts such as DLBCL is aberrant. This may be an explanation for the absence of prognostic relevance for the expression of this protein.

Prognostic relevance of immunohistochemical subclassification of diffuse large B-cell lymphoma in two prospective phase III clinical trials.

PURPOSE: Until now molecular biologic techniques have not been easily used in daily clinical practice to stratify patients for therapeutic purposes. Therefore, we have investigated the prognostic relevance of the immunohistochemical (IHC) germinal center B-cell (GCB) versus non-GCB diffuse large B-cell lymphoma (DLBCL) subtypes. PATIENTS AND METHODS: We have analyzed tumor samples from patients treated in 2 prospective multicenter phase III trials, ie HOVON 25 (patients≥65 years, n=153) and HOVON 26 (patients<65 years, n=144) using whole sections (WS) or tissue microarray (TMA). CD10, BCL6, and MUM1 were applied in a specific IHC algorithm. The effect on clinical outcome using WS or TMA and variations in cut-off levels of these markers was also investigated. RESULTS: The GCB subtype was not associated with a better OS in either trial. Small differences were observed in the HOVON 25 trial between techniques, with TMA showing a better outcome for GCB than did WS. Variation of cut-off levels in the specific algorithm did not improve the prediction of clinical outcome. CONCLUSION: We did not observe a consistent predictive power of the GCB and non-GCB classification by IHC in this large series of DLBCL patients treated with CHOP. This underscores the need to determine the biologic variation and the standardization of the protein expression levels and to further study the relevance of prognostic IHC classifications, preferably in phase III clinical trials.

The expression of the peripheral cannabinoid receptor on cells of the immune system and non-Hodgkin's lymphomas.

The peripheral cannabinoid receptor CB2 is expressed highly on normal human B-lymphocytes. C-terminal specific anti-CB2 antibody recognises a non-phosphorylated inactive receptor on naïve and resting B-lymphocytes. Another, N-terminal specific CB2 antibody, primarily recognises B-cells present in the germinal centres of secondary follicles in lymph nodes. We hypothesise that N-terminal specific CB2 antibody recognises activated CB2 receptors. In this study, we showed using these antibodies, that expression of CB2 is generally absent on T-lymphocytes in reactive, non-malignant human lymphoid tissues. Applying single and dual immunohistochemistry, CD23(+) follicular dendritic cells and a small but significant subpopulation of CD68(+) macrophages showed positive staining with the N-terminal specific CB2 antibody but not with the C-terminal specific CB2 antibody. This may indicate the presence of an active CB2 receptor on these cells with possible involvement in immunomodulation. In contrast to the low expression on normal T-cells, abundant levels of CB2 protein were present on T-non-Hodgkin's lymphomas (NHL). Moreover, in many B-NHL, high CB2 protein expression was found as well. In contrast to the distinct expression patterns in normal immune tissues using the two different CB2 antibodies, NHL specimens in general stained positively with both. We conclude that CB2 receptor expression pattern may be abnormal in NHL.

The peripheral cannabinoid receptor Cb2, frequently expressed on AML blasts, either induces a neutrophilic differentiation block or confers abnormal migration properties in a ligand-dependent manner.

Cb2, the gene encoding the peripheral cannabinoid receptor, is located in a common virus integration site and is overex-pressed in retrovirally induced murine myeloid leukemias. Here we show that this G protein-coupled receptor (GPCR) is also aberrantly expressed in a high percentage of human acute myeloid leukemias. We investigated the mechanism of transformation by Cb2 and demonstrate that aberrant expression of this receptor on hematopoietic precursor cells results in distinct effects depending on the ligand used. Cb2-expressing myeloid precursors migrate upon stimulation by the endocannabinoid 2-arachidonoylglycerol and are blocked in neutrophilic differentiation upon exposure to another ligand, CP55940. Both effects depend on the activation of G(alphai) proteins and require the mitogen-induced extracellular kinase/extracellular signal-regulated kinase (MEK/ERK) pathway. Down-regulation of cyclic adenosine monophosphate (cAMP) levels upon G(alphai) activation is important for migration induction but is irrelevant for the maturation arrest. Moreover, the highly conserved G protein-interacting DRY motif, present in the second intracellular loop of GPCRs, is critical for migration but unimportant for the differentiation block. This suggests that the Cb2-mediated differentiation block requires interaction of G(alphai) proteins with other currently unknown motifs. This indicates a unique mechanism by which a transforming GPCR, in a ligand-dependent manner, causes 2 distinct oncogenic effects: altered migration and block of neutrophilic development.

Distinct expression profiles of the peripheral cannabinoid receptor in lymphoid tissues depending on receptor activation status.

Using two distinct anti-CB2 receptor Abs, we investigated the expression patterns of the peripheral cannabinoid receptor CB2 in human secondary lymphoid organs. Immunohistochemical analysis using an N-terminal specific anti-CB2 Ab revealed high protein expression in the germinal centers (GCs) of secondary follicles. A C-terminal specific anti-CB2 Ab, which only recognizes a nonphosphorylated inactive receptor, showed positivity in the mantle zones (MZs) and marginal zones (MGZs) of the secondary follicles where resting cells reside, and in the primary follicles. In contrast, no positivity was observed in GCs using the C-terminal Ab, suggesting that active CB2 receptors are mainly present on cells in the GCs. Dual immunohistochemical analysis revealed that B lymphocytes express the CB2 protein abundantly. In contrast to B cells in the MZ or MGZ, CB2-expressing cells in the GCs coexpress the costimulatory membrane protein CD40, which is mainly expressed in the GCs and at very low levels in the MZs and MGZs and the proliferation marker Ki-67. Using the human Raji B cell line as a model, we demonstrate in a transwell assay that moderate migration occurs upon stimulation of the CB2 receptor with the endocannabinoid 2-arachidonoylglycerol, which is enhanced by CD40 costimulation. Our findings, that GC-related cells express active CB2 and that CB2-dependent migration requires CD40 costimulation, suggest that CB2 is involved in B cell activation.

Identification, characterization, and function of a novel oncogene: the peripheral cannabinoid receptor Cb2.

By means of retroviral insertional mutagenesis, we identified a novel common virus integration site (cVIS) (Evi11) in murine leukemias, and demonstrated that Cb2, encoding the peripheral cannabinoid receptor, is the potential proto-oncogene located in that region. Cb2 is a 7-transmembrane G protein-coupled receptor (GPCR), which is normally expressed on B lymphocytes. Using transwell assays we observed strong migration of Cb2-expressing cells upon stimulation with 2-arachidonoylglycerol (2-AG), a potent endocannabinoid. Overexpression of Cb2 receptor on murine myeloid precursor cells causes a block of neutrophilic differentiation, a major characteristic of myeloid leukemia. Intriguingly, we could not detect functional Cb2 receptors on normal murine bone marrow precursor cells. Furthermore, analysis of human acute myeloid leukemia (AML) samples revealed the presence of CB2 mRNA transcripts in several cases. Furthermore, migration could be induced by 2-AG when analyzed in one of the patient samples. Our data suggest that the initially identified cVIS, Evi11, encodes for a murine onco-protein and that human CB2 may be involved in certain cases of human AML as well.