ALBERT

Description: CD74 is a cell-surface receptor for the cytokine macrophage migration inhibitory factor. Macrophage migration inhibitory factor binding to CD74 induces its intramembrane cleavage and the release of its cytosolic intracellular domain (CD74–ICD), which regulates cell survival. In the present study, we characterized the transcriptional activity of CD74–ICD in chronic lymphocytic B cells. We show that following CD74 activation, CD74–ICD interacts with the transcription factors RUNX (Runt related transcription factor) and NF-κB and binds to proximal and distal regulatory sites enriched for genes involved in apoptosis, immune response, and cell migration. This process leads to regulation of expression of these genes. Our results suggest that identifying targets of CD74 will help in understanding of essential pathways regulating B-cell survival in health and disease.

Description: The combination of fludarabine, cyclophosphamide and rituximab (FCR) is still currently regarded as the standard regimen for treatment of physically fit patients with chronic lymphocytic leukemia (CLL). This therapy can be associated with significant toxicity, and patient adherence to the protocol may often be difficult outside of clinical trials. This retrospective study aimed to evaluate the efficacy and safety of FCR therapy in the real life setting, with particular focus on the influence of dose reduction on treatment outcome. A total of 132 CLL patients (≤70 years of age) treated with FCR as frontline therapy from 10 medical centers, were reviewed. The majority of patients were males (73.5%, n=97) and younger than 60 years (78%, n=103). Eleven patients had Binet stage A (8.3%), 72 (54.5%) were stage B and 49 (37.1%) had Binet stage C. Results of FISH analysis were available for 99 patients, with high risk cytogenetics of del(11q) in 21 patients (21.2%) and del(17p) in 9 cases (9.1%). The majority (56.5%, n=74) received rituximab at a dose of 500mg/m2 and the rest 375mg/m2. Almost half of the patients (49.2%, n=65) were given a reduced dose of chemotherapy (

Description: CD74 is an integral membrane protein that was thought to function mainly as an MHC class II chaperone. However, CD74 was recently shown to have a role as an accessory-signaling molecule. Our studies demonstrated that CD74 regulates B-cell differentiation by inducing a pathway leading to the activation of transcription mediated by the NF-κB p65/RelA homodimer and its coactivator, TAFII105. Here, we show that CD74 stimulation with anti-CD74 antibody leads to an induction of a signaling cascade resulting in NF-κB activation, entry of the stimulated cells into the S phase, elevation of DNA synthesis, cell division, and augmented expression of BCL-XL. These studies therefore demonstrate that surface CD74 functions as a survival receptor.

Description: Rituximab is a chimerical human/mouse monoclonal anti-CD20 antibody successfully applied in B-cell lymphoproliferative disorders. The suppression of B-lymphocytes may induce hypogammaglobulinemia and increased risk for infection. These complications are rarely observed as a result of monotherapy with rituximab but have been often noted following combination with aggressive chemotherapy or in the setting of autologous stem cell transplantation (ASCT). In an attempt to study the role of rituximab in induction of hypogamma, we analyzed the frequency of this phenomenon, its possible causes, infectious complications and infection-related mortality in lymphoma patients treated with different chemotherapy regimens with or without rituximab. We analyzed 136 patients who received rituximab concurrently with chemotherapy (R-Chemo) and 46 patients who were treated with chemotherapy only, with follow-up period of up to five years. Following R-Chemo, 17 cases (12.5%) of severe hypogamma (defined as 6 doses of rituximab were given. Moreover, rituximab in 〉8 doses leaded to severe hypogamma in 50% of patients compared to 11.8% in patients treated with

Description: Abstract 3437 Poster Board III-325 Previously, we have shown that Allicin, the highly active compound of freshly crushed garlic, produced by the reaction of the enzyme Alliinase with its substrate Alliin, induced the apoptotic killing of B-CLL cells in vitro. In addition, we also reported that generation of Allicin in situ on the surface of B-CLL cells by targeting Alliinase to the cell surface of the CD20+ cells by Rituximab, resulted in the eradication of primary B-CLL in a human-mouse chimeric model, denoting the marked anti-CLL potential of combining these two different molecules, with different mechanism of action, into a single drug entity (Arditti et al., Mol Cancer Ther 2005;4(2)325-331). Indeed, monotherapeutic approaches, even if effective, are usually not sufficient to fully eradicate B-CLL and the most effective therapeutic protocols require the utilization of more than one agent. With this in mind, we took advantage of the high reactivity of Allicin, with SH-containing compounds, and created novel chimeric compounds by the combination of Allicin with 6-Mercapto-Purine (6MP) and 6MP-riboside (6MPR), both SH-containing purine analogs used for decades for the treatment of hematologic malignancies. The resulting novel compounds, S-Allyl-6MP (SA-6MP) and S-Allyl-6MPR (SA-6MPR), were examined against primary B-CLL cells obtained from the peripheral blood of patients at Binnet stage C. In our in vitro assays, Annexin-V staining indicated that SA-6MP acted in a dose dependent manner, inducing the apoptotic death of 37.9% and 95.2% of plated CD19+CD5+ B-CLL cells (10.9% in untreated cells) incubated for 16 h at 37 °C in the presence of 50 uM or 100 uM, respectively. As expected, the original 6MP compound had no impact on the viability of plated B-CLL cells (9.7% and 8.7%) at doses of up to 150 uM. In preliminary in vivo experiments, we compared the anti-BCLL activity of SA-6MP with that of SA-6MPR and the original 6MP compound on primary B-CLL cells from 5 different patients (Binnet stage C) in a human-SCID/Beige mouse model. Following the engraftment of the human B-CLL cells, mice were treated with i.p. injections of 2.5 mg/kg body weight of SA-6MP, SA-6MPR, or 6MP on a daily basis throughout 7 consecutive days, after which, the engraftment of primary B-CLL cells was examined by the recovery of CD45+CD19+CD5+ from injected mice. An additional group of mice injected with vehicle (1% DMSO) was also examined as a control. In close similarity to our in vitro results, engraftment of primary B-CLL cells was considerably reduced following treatment with SA-6MP (〉90% reduction), as compared with treatment with the original 6MP drug. In addition, the chimeric riboside 6MP derivative, SA-6MPR, induced a potent anti-BCLL effect comparable to that of SA-6MP. In summary, our results in vitro and in vivo suggests that combining the pro-apoptotic effects of Allicin with the antiproliferative effects of 6MP or 6MPR is superior to the effect of either of the purine analogs alone. This approach may be evaluated at first instance in B-CLL patients with refractory disease. Disclosures No relevant conflicts of interest to declare.

Description: Scientific background: Increasing evidence points to the crucial role of malignant lymphoma interaction with the tumor microenvironment. Our previous investigations indicated that the stromal cytokine activin A induces apoptotic death of myeloma cells due to its antagonism with the growth promoting effect of interleukin-6. Activin A is a homodimer of the ßA inhibin polypeptide chain. Like other transforming growth factor (TGF)ß superfamily members, it is a pleiotropic molecule, which is widely expressed. It has initially been studied in the reproductive system, but has also been implicated in the regulation of hemopoiesis; it is an erythroid differentiation factor and is expressed within the bone marrow microenvironment. Activin A functions are tightly regulated by the competitive inhibitor inhibin A (a heterodimer, /ßA) and the binding inhibitors, follistatins. We previously showed that abundance of activin A was restrictive for B cell production in vitro and that within human nasal polyps activin A expression was widespread but absent from foci of B lineage cells. We were therefore interested to find out whether activin A plays a role in the occurrence of BM (bone marrow) involvement in malignant lymphomas. Materials and methods: The patient population consisted of 17 patients with lymphoma and 3 patients without lymphoma served as controls. Paraffin embedded sections were prepared and immunohistochemical staining was performed using an antibody to the bA chain. The slides were reviewed by team of 5 investigators and graded separately. Results: Out of 17 lymphoma cases, 10 patients showed BM involvement. In patients with BM involvement the level of activin A was significantly decreased in the area surrounding the lymphoid infiltrate (Fig 1a). This was seen uniformly in all the patients except for one. The level of activin A in the rest of the BM was similar to the level seen in specimens of reactive BM. In all 7 patients that had no BM involvement we found a diffuse staining for activin A (similar to what we saw in patients with reactive BM) (Fig.1b). Discussion: It is interesting that only some of the patients with malignant lymphomas have BM involvement. This could stem from a difference in the migratory abilities of the lymphoid cells, which is unlikely, or from a difference in their ability to home and flourish in the BM microenvironment. We have demonstrated that activin A, is significantly down regulated in the vicinity of the lymphoid infiltrate in the BM, as opposed to what occurs in normal inflammatory BM. This suggests that an interaction between the lymphoma cell and the BM microenvironment leads to down-regulation of activin A expression and possibly promotes the survival of the lymphoid cells. Figure 1: low power view of activin staining in the vicinity of the involved BM (a) and uninvolved BM (b). Figure 1:. low power view of activin staining in the vicinity of the involved BM (a) and uninvolved BM (b).

Description: Background: The Israel National Cancer Registry (INCR) is a population based, national passive tumor registry established in 1960. Reporting by hospitals, laboratories, and other providers has been mandatory in Israel since 1982 and most cancer cases are registered on the basis of pathology reports and hospital records. In some hematopoietic malignancies where the diagnosis was not based on tissue pathology and patients initially received no inpatient treatment, cases may not have been reported to the registry, or reporting to the INCR may have been delayed, resulting in an underestimation of the true burden of disease. One diagnosis for which there is particular concern in this regard is CLL/SLL and here we used active surveillance to estimate the true incidence of CLL/SLL in Israel. Here we present the interim results Methods: We attempted to estimate the incidence of CLL in Israel more accurately,recognizing the fact that the exact incidence may never be known. The Israel Chronic Lymphocytic Leukemia Study Group, working with the Israel Center for Disease Control of the Ministry of Health, actively documented new cases of CLL/SLL in Israel for calendar years 2011 and 2012. All flow cytometry laboratories in Israel provided lists of patients with B cell clones. Israeli hematologists diagnosing CLL were asked to verify which of the B cell clones indicated a diagnosis of CLL, SLL, PLL or MBL and to fill out an internet-based reporting form. Diagnoses based on flow cytometry were verified by medical record review. Cases identified through active surveillance were pooled with cases known to INCR in order to estimate the true annual incidence of CLL/SLL and assess the completeness of the INCR data. Results: We identified 432 and 396 CLL/SLL cases for 2011 and 2012, respectively of whom 57.4% were males. The average age was 68.8. The corresponding age-adjusted[1]incidence rates per 100,000 (ASR) were 4.26 for 2011 and 3.79 for 2012. In comparison, the INCR registered 295 new CLL cases in 2011 (ASR=2.78) and 232 in 2012 (ASR=2.19), 54.5% of them males. The average age at diagnosis was 69.9. These data indicate a gap between true and reported incidence (1.48 and 1.60/100,000 in 2011 and 2012, respectively). However, it should be noted that the INCR will be fully updated for 2012 only by the beginning of 2015. Of active surveillance cases, 157 (2011) and 152 (2012) were registered in the INCR. Most cases missing in the INCR were diagnosed based on flow cytometry, peripheral blood samples and FISH (85.9% in 2011, 89.8% in 2012) without histo-pathological confirmation. Of the CLL/SLL cases existing in the INCR dataset for 2011-12 but not detected by active surveillance (138 in 2011; 80 in 2012), most (76.8% in 2011, 63.8% in 2012) had been diagnosed earlier and the remainder were coded as diagnoses other than CLL/SLL. Omitting these cases from the INCR dataset substantially increased the observed gaps in the true and the registered annual incidence of CLL/SLL (from 1.48 to 2.80 per 100,000 in 2011 and from 1.60 to 2.37 per 100,000 in 2012). Conclusions: The true incidence of CLL is unknown, but it is clear that there is under reporting to cancer registries. Completeness of CLL/SLL data requires accurate reporting of cases by hematologists and other care providers in the community. In Israel, this issue has been addressed by publishing updated guidelines for mandatory reporting stressing the requirement for reporting of hematologic malignancies. [1] Age-adjustment made on the basis of the world standard population Disclosures Ruchlemer: Roche: Research Funding.

Description: Introduction: Although the spleen is involved in about a third of patients with non-Hodgkin's lymphoma (NHL), primary splenic diffuse large B-cell lymphoma (PS-DLBCL) is rare having a reported incidence of less than 1% of all NHL. Most of the described series include small numbers of patients before the rituximab era and the role of splenectomy treatment in addition to immuno-chemotherapy is unknown. Methods: Data were retrospectively collected for 87 patients (pts) with PS-DLBCL treated in 7 medical centers in Israel during the years 1982-2013. Patients presenting with systemic disease with splenic involvement or those having a diagnostic biopsy from other nodal or extranodal disease were excluded. Results: The mean age was 59.6 years (range, 24-89 years); 57.5% were male. Abdominal pain was reported in 61 pts (81%), B symptoms in 49 pts (59%), ECOG performance status 0 - 1 in 85%. Stage I disease was recorded in 28%, II in 33%, III in 18%, and IV in 21%. Thrombocytopenia (

Description: Introduction: Ibrutinib, an irreversible inhibitor of Bruton's tyrosine kinase, is an established therapeutic agent in a variety of B-cell lymphoproliferative disorders. Ibrutinib induces platelet dysfunction and concurrent treatment with ibrutinib and warfarin was shown to significantly increase the risk of bleeding. The current study was designed to investigate the safety of direct oral anticoagulants (DOACs) in patients receiving ibrutinib, considering their expanding employment together with the lack of data regarding their safety in patients receiving ibrutinib. Methods: We conducted a retrospective cohort study to evaluate risks of major bleeding in patients with B-cell lymphoproliferative disorders (CLL, MCL, DLBCL, MZL or WM) that were treated with ibrutinib and DOACs but without concurrent antiplatelet therapy, between January 2010 and October 2018 in 5 participating centers. Patient medical charts were reviewed for demographic parameters, comorbidities, ibrutinib dosage, DOACs dosage (including the adjustment for renal function), blood count and chemistry tests, bleeding site and grade. Results: The study included 30 patients, median age at starting concurrent administration of ibrutinib and DOACs was 71.58 years (range 50.9-88.2). Most patients were treated for CLL (n=18, 60%) and MCL (n=8, 26%). The most common daily doses of ibrutinib were 420 mg and 560 mg in 63.3% and 30% of patients respectively. None of the patients received an additional antiplatelet agent. Twenty-three patients were treated with apixaban (76.7%), 4 with rivaroxaban (13.3%) and 3 (10%) with dabigatran. The main indications for DOACs were atrial fibrillation and VTE (venous thromboembolism). The median follow-up after initiation of the ibrutinib-DOAC combination was 13.4 months (range 1.8-47.9 months). Bleeding was reported in 22 patients (73.3%), mostly mucocutaneous (n=12, 40%) and gastrointestinal tract (n=7, 23.3%), followed by CNS bleeding (n=4, 13.3%). Mucocutaneous bleedings were all grade 1-2 and gastrointestinal tract and CNS bleeding events were grade 1-4. Major bleeding events, defined as grade 3 or 4, occurred in 5 patients (16.6%) and did not result in death of any of the patients. The median time for bleeding following ibrutinib-DOAC initiation was 5.6 months. Over a follow-up period of 21 months of combined treatment, the incidence of bleeding events (of all grades) increased to 75% (Figure 1). Incidence of bleeding events (including all grades) was quite similar between all DOAC subtypes (73.9% with apixaban, 75% with rivaroxaban and 66.7% with dabigatran). No statistically significant predictors for increased risk of bleeding in patients receiving ibrutinib combined with DOACs were detected. Ibrutinib was stopped in 8 patients (26.7%) due to grade 1 to 4 bleeding events and was re-initiated in 6 patients, resulting in recurrent grade 3 and 4 bleeding events in 2 patients. Conclusions: Concurrent administration of DOACs and ibrutinib appears to be feasible. However, risk of bleeding is not neglectable, and treatment resumption in patients that experienced a significant bleeding event should be considered with caution. Disclosures Arnason: Celgene/Juno: Consultancy; Regeneron Pharmaceuticals, Inc.: Consultancy. Herishanu:Roche: Honoraria; AbbVie: Honoraria; Janssen: Honoraria.