ALBERT

Description: Abstract 2962 Background: Multiple myeloma (MM) is characterized by clonal proliferation of malignant plasma cells (PCs) in the bone marrow (BM) compartment. Interaction of plasma cells with the BM stromal cells (BMSCs) is critical for homing, growth and drug resistance acquisition of the malignant PCs. However, the functional significance of other cellular components of the MM milieu, which includes osteoclasts and immune effector cells, is less clear. Both MM-derived and stromal cell-produced factors, including cytokines and chemokines, are believed to participate in the cross-talk between the MM and stroma leading to disease progression. Aim and Results: We hypothesized an important role for CXCL12 (SDF-1) chemokine and its receptor CXCR4 in MM-stroma interactions and microenvironment formation. We now show that MM cell lines ARH77 and RPMI8226 and primary MM cells may produce high amounts of CXCL12 and co-express CXCR4 receptor. Co-culture of the MM cells with BMSCs significantly up-regulated both CXCR4 cell-surface expression and CXCL12 secretion by the MM cells. Enhanced CXCR4 signaling in the MM cells upon the interaction with BMSCs promoted the survival and proliferation of the cells in an autocrine way. Moreover, the paracrine effect of increased CXCL12 production on immune cell migration was tested. We found, that conditioned medium (CM) produced by MM cells cultured with BMSCs specifically attracted increased numbers of CXCR4-expressing PB CD14+ cells. Furthermore, CXCR4 inhibition, using neutralizing antibodies toward CXCR4, inhibited the MM-induced migration of CD14+ monocytes, suggesting the possible role of CXCR4/CXCL12 axis in monocyte recruitment to the site of the disease. We next examined the functional consequence of MM-macrophage interaction. We saw that PB-generated macrophages induced the proliferation of MM cells, even more effectively than BMSCs. Furthermore, co-culture with macrophages strongly increased the expression of various pro-inflammatory and pro-angiogenic factors by MM cells, including CCL2 (MCP-1), CCL4 (MIP1a), IL-1b, IL-8 and VEGF. Interestingly, expression of IL-10 by MM cells was also up-regulated following the interaction with macrophages, suggesting the possible reciprocal effect of MM-produced factors on macrophage phenotype polarization. Conclusion: Taken together, our findings demonstrate that interaction of MM with BM stromal cells positively regulates the expression of CXCR4 and CXCL12 by MM cells, affecting both MM proliferation and CXCR4-dependent monocyte recruitment. The migrated monocytes may in turn interact with MM cells, support their growth and activate cytokine release, therefore producing favorable pro-inflammatory and pro-angiogenic environment and promoting disease progression. Overall, our data provide the basis for future targeting MM-BMSCs and MM-macrophage interactions with anti-CXCR4 agents as a therapeutic strategy to improve the outcome of patients with MM. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction: Ruxolitinib has been shown in two randomized clinical trials (RCTs) to be effective in alleviating systemic symptoms and effecting a reduction in spleen size in patients with myelofibrosis (MF). However, JAK2 allele burden is not significantly impacted by this drug and there is no consistent salutary effect on marrow fibrosis or definite improvement in overall survival. Currently, the goals of Ruxolitinib treatment remain palliative. We sought to determine the efficacy and tolerability of Ruxolitinib in a cohort of unselected patients with MF treated in routine clinical practice. Methods: MF patients treated with Ruxolitinib for at least 3 months in 13 participating centers that are members of the Israel Myeloproliferative Neoplasm (MPN) Working Group were identified. The following demographic and clinical data were analyzed: the form of MF [primary (PMF), post polycythemic myelofibrosis (PPVMF), post essential thrombocytosis myelofibrosis (PETMF)], duration of MPN, indication for treatment, initial dose, dose reduction, hematologic toxicity, response to therapy and withdrawal of treatment. Results: One hundred and two patients from 13 centers that began Ruxolitinib between January 2012 and April 2014 were identified. Ninety three patients who were treated for more than 3 months were included in the analysis. Median age at diagnosis was 59 years (range 25-84), 57 % were males. PMF was the diagnosis in 44 patients (47.3%), PPVMF in 29 (31.2%) and PETMF in 17 (18.3%). The median duration of disease was 5 years (range 3 months-35 years) for the entire cohort. Median age at Ruxolitinib initiation was 67 years (range 32-84). Seventy two (78.3%) patients received cytoreductive therapies for MF prior to Ruxolitinib. Indications for treatment were constitutional symptoms only in 14 patients (15%), symptomatic splenomegaly only in 6 patients (6%) and both in 71 patients(76%). Two patients received Ruxolitinib for other indications (non-constitutional symptoms and refractory thrombocytosis). The median initial dose of Ruxolitinib was 30 mg per day (range 10-40mg). Median duration of Ruxolitinib therapy was 11 months (range 3-31 months). Eighty two patients (88.2%) responded to therapy, 76 (84.4%) patients had improvement in constitutional symptoms and 60 patients (70.6%) had reduction in spleen length. While on Ruxolitinib, 60 patients (64%) had a nadir hemoglobin level of less than 10g/dL, 43 patients (46%) had a nadir platelet count of less than 100 x 109/µL and in 12 of them (12.9%) a platelet nadir was less than 50 x 109/µL. Twenty one patients (22.6%) needed packed red blood cell (PRBC) transfusion in the 2 months preceding Ruxolitinib initiation and they received a median of 2.5 units (range 1-8), while 27 patients (29.1%) needed PRBC transfusion in the first 2 months after starting treatment and they received a median of 4 units (range 1-8). Thirty five patients required dose reduction of Ruxolitinib and 14 (15.2%) discontinued their therapy. Univariate analysis revealed that response to Ruxolitinib occurred in patients with a lower white blood cell (WBC) count (median 9.7 x 103/µL vs 21.5 x 103/µL; P=0.033), a greater degree of splenomegaly (median 12 vs 4 cm below costal margin; P=0.001) and hepatomegaly (median 4 vs 0 cm below costal margin; P=0.011). In multivariate analysis, the degree of splenomegaly was found to be predictive of response to treatment (odds ratio=1.263, p=0.03 and 95% CI=1.08-1.476) while there was a trend to improved response in patients with a lower WBC (p=0.074). Conclusions: The present analysis of a cohort of MF patients treated with Ruxolitinib in routine clinical practice has demonstrated the efficacy and tolerability of this drug outside of a highly monitored RCT setting. Data of this sort are currently sparse, and emanate mainly from single-center reports. Our study performed in 13 academic and community hospitals provides real-life evaluation of the utility of Ruxolitinib and factors associated with response to treatment. Disclosures No relevant conflicts of interest to declare.

Description: Introduction The therapeutic options for diffuse large cell B cell lymphoma (DLBCL) patients (pts) that fail to respond/relapse after≥2 treatment regimens are limited. The SCHOLAR-1 study reported an overall response/ complete remission (ORR/CR) rates of 26%/ 7% with a median overall survival (OS) of 6.3 months in chemorefractory and early relapsing DLBCL pts. Polatuzumab vedotin (Pola) is a conjugated antibody that delivers the microtubule inhibitor MMAE to CD79b-expressing cells. Polatuzumab administered in combination with Bendamustine-Rituximab (P-BR) has been recently approved by the FDA for pts with relapsed/refractory (R/R) DLBCL that failed to respond≥2 prior therapies. The current study investigated the tolerability and efficacy of Pola mainly with BR, in DLBCL pts, treated through a compassionate program after failing ≥2 prior regimens. Methods Data of all pts with consecutive R/R DLBCL, treated with Pola-BR or Pola-R (2-8 cycles) in 11 Israeli centers between 6/2018 and -5/2019 were analyzed. Inclusion criteria for this study were: R/R DLBCL (denovo and transformed follicular lymphoma [t-FL]), age ≥ 18 years, ≥ 2 prior treatments. We evaluated pt characteristics, treatment details and toxicities, overall response and CR rates, progression free survival (PFS) and OS. Cox regression model was used to define factors affecting outcomes. Results 34 patients- (denovo DLBCL, n=24 and t-FL, n=10 ⌈50% -non CGB and 50% - GCB type⌉) were included. Median age at Pola administration was 65.5 (range 60-72) years. Stage ≥3 disease was recorded in 88% and IPI ≥3 in 73.5%. Median prior lines was 3 (range 3-5); including anthracyclines and rituximab in 100% and cisplatin-based regimens in 91%. 32% relapsed after ASCT and 9% after CART infusion. 53% had primary refractory disease, 29% had refractory relapse and 18% had prior sensitive relapse. 22 pts received Pola-B, mostly with Rituximab (n=19), and 12 received Pola-R. In 5 pts, Pola-based regimen was used as a bridge for Allo SCT (all responded CR, n=4 and PR, n=1) and in 6 as a bridge to CARTs (all responded CR n=1, PR n=2, SD n=3). Median number of Pola B cycles was 3 (3-5) and median Pola-R cycles was 4 (3-6). Median B dose per cycle was 90 mg/m2 (45-90). GCSF was used in 47%. Early treatment discontinuation due to progressive disease (PD) occurred in 8 (23%) of the entire cohort: 23% of Pola-B pts and 25% of Pola-R pts. Safety: Hematological AEs grade 3-4, reported with Pola- B vs Pola-R were: neutropenia (45.5.% vs 33%), thrombocytopenia (25% vs 8%) and anemia (23% vs 17%). Infections were recorded in 41% and 36% of Pola-B pts and Pola-R respectively. Neutropenic fever was reported in 36% in Pola-B pts and none in Pola-R. Pulmonary infections were recorded in 33.3% and 27.3% of Pola-B and Pola-R pts respectively, resulting in death in one pt. Peripheral neuropathy occurred in 18% of Pola- B pts (grade ≤2) vs 8% with Pola -R. Hospitalization due to AEs was recorded in 41% of Pola-B vs 25% of Pola-R. Pola dose reduction due to AE was reported in 1 pt (8%) in the Pola-R. Efficacy: ORR for the entire cohort was 65%, including 38% CRs and 27% PRs. 12% pts attained SD and 23% experienced PD. ORR was higher in non-GCB than in GCB pts 80% vs 43% (p=0.036). Median follow up of the entire cohort from Pola administration was 4.4 months (range 0.6-11.4). 6 months projected OS and PFS were 83% and 63%, respectively. Post Pola treatment in pts that failed to respond/Relapsed post pola: 8 patients had PD; 3 died from progression, 1-CART, 1-Allo SCT, 2-paliative care and 1-unknown. Additional 5 pts progressed during follow up; 4-CART and 1-palliative care. 1 patient continues Pola treatment after achieving SD. Univariate analysis for factors predicting PFS and OS GCB type (HR-1.816, P=0.055), Primary refractory vs relapsed disease (HR-1.507, p=0.049) and a higher number of prior lines since diagnosis (HR-1.35, p=0.079) tended to be associated with shorter time to progression. T-FL vs denovo DLBCL was associated with decreased OS (p=0.008). Data of 60 patients, including pts treated recently, therefore, not evaluable at the time of abstract submission, would be presented at ASH. Conclusions The toxicity of Pola-based regimen was relatively low. Pola based treatment provided an encouraging PFS and OS in pts with R/R DLBCL that failed to respond ≥2 prior therapies, treated in a real-life setting. Primary refractory disease, higher number prior lines and t-FL vs denovo DLBCL were associated with inferior outcome. Figure Disclosures Herishanu: Roche: Honoraria; AbbVie: Honoraria; Janssen: Honoraria.

Description: Chronic lymphocytic leukemia (CLL) occurs in older individuals with a median age at diagnosis of 72 years. In recent years, there has been considerable progress in the frontline therapy of elderly/physically unfit patients with CLL. The German CLL11 trial showed that addition of obinutuzumab to chlorambucil (G-Clb) prolongs progression free survival (PFS) and overall survival (OS) compared to chlorambucil alone or in combination with rituximab. More recently, obinutuzumab together with ibrutinib or venetoclax were shown to be superior to G-Clb with regard to PFS, but there was no advantage in terms of OS. In this retrospective, multinational and multicenter co-operative study the European Research Initiative on CLL (ERIC) and the Israeli CLL Study Group (ICLLSG) evaluated the efficacy of frontline treatment with G-Clb in patients with CLL, in a "real-world" setting. Our analysis excluded CLL patients with documented del(17p) or TP53 mutations since they are no longer treated with chemotherapy. Results: A total of 437 treatment-naïve patients with CLL from 51 medical centers located in 13 countries were included. The median age of this patient population was 75.9 years; 59.7% were men, median CIRS total score was 8 and estimated creatinine clearance 61.1 mL/min. Seventy four patients had Binet stage A (17.2%), 167 (38.8%) stage B and 190 (44.1%) stage C. Results of FISH and IGHV mutational status were available for 332 and 115 patients, respectively. High-risk cytogenetics, del(11q) was documented in 18.7% patients and IGHV-unmutated gene in 64.4%. The vast majority of patients were treated with G-Clb (N=408) and the rest with obinutuzumab monotherapy (G-monotherapy, N=29). The clinical overall response was 86.5%, including clinical complete and partial responses in 41.6% and 45.8% of cases, respectively. The median observation time was 14.1 months (m) and the median PFS of the entire cohort was 27.6m (95% CI, 24.2-31.0). The PFS for G-Clb was significantly better than G-monotherapy (P=0.001; HR=0.38, 95% CI: 0.22-0.67), being the 2-year PFS estimates 61.8% and 52.8%, respectively. The median PFS was significantly shorter for patients with del(11q) (19.2m) compared to those with normal FISH (not reached, P

Description: Essential thrombocythemia (ET) is associated with an increased risk for thrombo-hemorrhagic complications. The presence of the JAK2V617F mutation, found in approximately 50% of ET patients, has been associated with increased indices of platelet (PLT) activation suggesting its casual role in thrombus formation. Mutations in CALR were recently described in the majority of JAK2V617F negative ET patients, and are associated with a decreased rate of thrombotic events. This has led us to hypothesize that CALR mutations have a different influence on PLT activation compared to JAK2V617F. To evaluate the PLT activation state, surface expression of two PLT activation markers - p-selectin (CD62P) and PAC1 was studied using specific antibodies. MFI was analyzed by flow cytometry at baseline, as well as following ADP addition to PLT rich plasma. Monocyte-platelet aggregates were studied in whole blood samples by gating CD45+/CD14+ cells and calculating the percentage of CD41+ cells in the monocytes population. The immature PLT fraction (IPF) was analyzed with the XE-5000 hematology analyzer (Sysmex UK Ltd., Milton Keynes, UK), and the absolute number of immature PLT (nIP) was calculated from the total PLT count. Low risk ET patients (N-13, M/F-5/8) and healthy controls (N-10, M/F-4/6) are included in this analysis. JAK2V617F and CALR mutations were present in 8 and 5 patients, respectively; low dose aspirin (range 75-100mg) was taken by 85% of patients and 90% of controls. Median PLT count in CALR mutated, JAK2V617F mutated and healthy subjects was 913, 579 and 247 K/uL, respectively (p=0.0002), and it was higher in CALR compared to JAK2V617F positive patients (p=0.09). Both patient subgroups had a lower baseline MFI of p-selectin and PAC1 compared to healthy controls (p-selectin: 2.8, 3 and 4.5 for JAK2V617F [p=0.01], CALR [p=0.05] and controls; PAC1: 3, 3.3 and 5.2 for JAK2V617F [p=0.01], CALR [p=0.02] and controls, respectively) with no difference between CALR and JAK2V617F mutated patients. CALR compared to JAK2V617F mutated patients had higher median number of immature PLT (30 and 10.6 K/uL, p=0.04), and a higher fraction of monocyte- platelet aggregates (90 and 58%, p=0.05). nIP and monocyte- platelet aggregates were also significantly higher in CALR mutated but not in JAK2V617F mutated patients compared to healthy controls. Interestingly, there was no difference in post ADP PLT activation (post/baseline ratio) between ET patients and healthy controls. Finally, there were correlations between the PLT counts and nIP (R=0.8, p