Abstract: Background: The BCL-2 inhibitor venetoclax in combination with an anti-CD20 monoclonal antibody (rituximab or obinutuzumab) has demonstrated superior outcomes and manageable safety as compared to chemo-immunotherapy in phase III clinical trials for chronic lymphocytic leukemia (CLL). Moreover, venetoclax-based regimens induced high rates of undetectable minimal residual disease (uMRD). Prospective data on the effectiveness of venetoclax-based regimens specifically with regard to achieving uMRD in a real-world setting are still lacking. Here we report the first interim analysis for efficacy and safety of an ongoing nationwide real-world study of venetoclax based therapy for CLL/small lymphocytic lymphoma (SLL). Method: A prospective observational nationwide multicenter study. Treatment-naïve (TN) and relapsed/refractory (R/R) CLL/SLL patients were enrolled in 13 medical centers in Israel. The primary endpoint was clinical response, per physician assessment 12-months after the initiation of venetoclax treatment. Key secondary endpoints included progression free survival (PFS), overall survival (OS) and uMRD as assessed at a central laboratory by 8-color flow-cytometry. Results: Between February 10, 2019, and Jun 17, 2021 (data cut), 199 CLL/SLL patients were enrolled from 13 medical centers in Israel to receive venetoclax based therapy. The study included 83 TN and 116 R/R evaluable CLL/SLL patients with a median age of 69 years (range, 34-85) and 70.5 years (range, 25-91), respectively (Table 1). R/R patients had received a median of one prior therapy with a range up to 8, of these patients 60 (51.7%) were previously treated with a B-cell receptor inhibitor (BCRi) including ibrutinib in 52 (44.8%) and idelalisib in combination with rituximab in 6 (5.2%). TN patients had been treated with venetoclax in combination with obinutuzumab (92.8%) or rituximab (4.8%) and R/R patients received either venetoclax with rituximab (60.3%) or obinutuzumab (9.5%), venetoclax monotherapy (25.8%) or triple therapy with venetoclax, rituximab and ibrutinib in 5 (4.3%). Dose escalation of venetoclax to the recommended dose of 400 mg daily was achieved in 80.7% (n=67) of TN and 81% (n=94) of R/R patients. The median duration of ramp-up was 38 and 42 days in TN and R\R patients, respectively. Prior to therapy, tumor lysis syndrome (TLS) risk was considered high in 12% and 29.3% of TN and R/R patients, respectively (Table 1). Laboratory TLS occurred in one TN patient and 4 R/R patients, whereas 3 of the R/R patients experienced clinical TLS. Nineteen TN and 75 R/R patients had a follow-up of at least 12 months or discontinued study prematurely. The 12-month overall response rate (ORR) for TN and R/R patients was 89.5% [complete response (CR) 13 (68.4%), partial response (PR) 4 (21.1%)] and 73.3% [CR 37 (49.3%), PR 18 (24%)] , respectively. In the R/R cohort, the 12-month ORR among assessed patients was 67.6% (25/37) in BCRi-exposed versus 85.7% (30/35) in BCRi-naïve patients. At 12 months, peripheral blood uMRD ( & lt;0.01%) was achieved in 12 out of 14 (85.7%) TN and 26 out of 38 (68.4%) R/R evaluated patients. At a median follow-up of 5.1 months (range, 0.5-15.6) for TN and 10.1 months (range, 0-25.7) for R/R patients, the median PFS and OS, for both cohorts have not been reached. The estimated 12-month PFS was 90.9% for TN and 81.1% for R/R patients. For R/R patients with prior exposure to BCRi, the estimated 12-month PFS was 69.6% versus 94.8% in BCRi-naïve patients (figure 1). Grade ≥3 adverse events (AEs) were reported in 34.9% of TN patients and 43.9% R/R patients. The most frequent grade ≥3 AEs documented were neutropenia (TN: 19.2% and R/R 17.2%), infections (TN: 4.8% and R/R: 21.5%) and febrile neutropenia (TN: 2.4% and in R/R: 2.6%). COVID-19 occurred in 7 patients including one death. At the time of data cut, 10 deaths occurred, one TN and 9 R/R patients. Causes for death included infections (5 patients), disease progression (2 patients), acute myeloid leukemia/ myelodysplastic syndrome (2 patients) and a soft-tissue sarcoma (1 patient). Conclusions: This first interim analysis of our ongoing prospective real-world study of venetoclax-based treatment for TN and R/R CLL/SLL, demonstrates high efficacy together with a high proportion of undetectable MRD levels and a favorable toxicity profile. These efficacy results are comparable to those reported in previous Phase III clinical trials for CLL, with no new safety signals. Figure 1 Figure 1. Disclosures Herishanu: AbbVie: Consultancy, Honoraria, Research Funding; Janssen: Honoraria; Roche: Honoraria; AstraZeneca: Honoraria. Goldschmidt: AbbVie: Consultancy, Research Funding. Itchaki: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Levi: AbbVie: Consultancy, Research Funding. Aviv: AbbVie: Honoraria, Research Funding. Fineman: AbbVie: Research Funding. Dally: AbbVie: Honoraria, Research Funding. Tadmor: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Ruchlemer: AbbVie: Consultancy, Honoraria, Research Funding. Abadi: AbbVie: Honoraria, Research Funding. Shvidel: AbbVie: Honoraria, Research Funding. Braester: AbbVie: Honoraria, Research Funding. Cohen: AbbVie: Current Employment, Current equity holder in publicly-traded company. Frankel: AbbVie: Current Employment, Current equity holder in publicly-traded company. Ofek: AbbVie: Current Employment, Current equity holder in publicly-traded company. Berelovich: AbbVie: Current Employment, Current equity holder in publicly-traded company. Grunspan: AbbVie: Current Employment, Other: May hold equity. Benjamini: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding.

Abstract: Decreased absolute lymphocyte counts (ALCs) following frontline therapy for chronic lymphocytic leukemia may be associated with disease control, even in patients without evidence of minimal residual disease. We studied the prognostic significance of ALCs during the first year following treatment with fludarabine, cyclophosphamide, and rituximab (FCR). We evaluated 99 patients who achieved a partial response without lymphocytosis ( 〈 4.0 × 10 3 cells/μL) or better after FCR. Absolute lymphocyte counts were recorded at 3‐, 6‐, 9‐, and 12‐month posttreatment and correlated with overall survival (OS) and event‐free survival (EFS). For each time point, analyses were limited to patients without lymphocytosis, so as to avoid possible biases from undocumented disease progressions. Lymphopenia (ALC  〈  1.0 × 10 3 cells/μL) at 3 m after FCR (69% of patients n = 68), was associated with a longer OS (5y OS 91% vs 64%, P  = .001), as were ALC ≤ 2 × 10 3 cells/μL at 6 m (5y OS 85% vs 48%, P  = .004) and ALC ≤ 1.8 × 10 3 cells/μL at 9 m (5y OS 93% vs 54%, P  = .009). A normal‐range ALC (≤4 × 10 3 cells/μL) at 12 m was also associated with a 91% 5y OS. Higher ALCs (but without lymphocytosis) were associated with shorter EFS (median EFS 27 months for ALC  〉  1.8 vs not reached for ALC ≤ 0.7 at 9 months, P   〈  .0001). In conclusion, lower ALC levels in the first few months following frontline FCR therapy were associated with longer OS and EFS. Possible explanations may be that lower ALCs reflect deeper clonal suppression or protracted T reg depletion. Absolute lymphocyte count levels may be a cheap and widely available prognostic marker, though the added value for clinical practice is the minimal residual disease era needs to be explored.

Abstract: 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 ( 〈 90% of the indicated dosage), while 23% (n=30) received 2/3 or less. Primary chemotherapy dose reduction was most commonly in accordance with the treating physician's judgment, while secondary dose modifications and less chemotherapy cycles were initiated mainly because of hematological toxicity. Most patients had a clinical complete response (69.8%, n=90) while only 10 (7.8%) failed to respond. Partial or non- responders were more commonly associated with lower pretreatment hemoglobin levels and platelet counts, Binet stage C, and presence of del(17p) and had also received lower doses of chemotherapy (p=0.024). The rituximab dose administered was not associated with differences in response rates (p=0.7). Reducing the dose of chemotherapy (≤2/3) was associated with an increase in risk of disease progression (HR 4.1, 95% CI 2.3-7.0, p 〈 0.0001), resulting in a decrease in median progression free survival (PFS) from 46.9 months (for those receiving the full dose), to 15.8 months for patients given a reduced dose. In a multivariate analysis of PFS only a reduced dose of chemotherapy (≤2/3) and del(17) retained statistical significance, p=0.004 and p 〈 0.0001, respectively. The median overall survival for the entire cohort was 99.5 months (95% CI 78.5-120.5). Del(17p) and failure to respond to treatment were independently associated with a worse overall survival (HR=9.2, 95% CI 2.0-41.8, p=0.004 and HR=15.1, 95% CI 3.2-72.0, p-0.001, respectively). The most commonly recorded severe adverse events included, at least one episode of infection or neutropenia in 25.8% and 24.2% of patients, respectively. Treatment related DAT+ autoimmune hemolysis occurred in 6.0% of the cases, late-onset neutropenia in 8.1%, Richter's transformation in 3% and therapy related MDS/AML in 2.3% of patients. In conclusion, it is apparent that outside of clinical trials treating physicians tend more readily to reduce doses of chemotherapy. Reduced doses of fludarabine and cyclophosphamide but not of rituximab, is significantly associated with a shorter PFS. Disclosures No relevant conflicts of interest to declare.

Abstract: To evaluate disease characteristics and long‐term outcomes in patients requiring second‐line treatment following fludarabine, cyclophosphamide, and rituximab ( FCR ), for relapsed/refractory disease (R/R), or following discontinuation due to toxicities. Method A retrospective analysis of 126 chronic lymphocytic leukemia patients treated with frontline FCR : 63 received second‐line treatment (41 relapsed, nine refractory [ SD / PD ], 13 prior toxicity). Time to next treatment ( TTNT ) was calculated from beginning FCR to initiation of second‐line therapy. Overall and event‐free survival was calculated from initiation of salvage treatment ( OS 2/ EFS 2). Results Median follow‐up for the entire cohort was 67 and 37 months from second‐line therapy. TTNT   〈  24 months was associated with shorter OS 2 and EFS 2 similar to those observed with primary refractory disease ( OS 2 19 and 23 months; EFS 2 12 and 9 months for TTNT   〈  24 months and SD / PD , respectively). TTNT  ≥ 24 months (71% chemotherapy‐based second‐line), had longer OS 2 and EFS 2 (48 and 20 months). Among the 13 patients receiving second‐line therapy after discontinuing FCR due to toxicity EFS 2 was 41 months (59 months from initiation of FCR ). Conclusion With limitations of sample size and treatment heterogeneity, patients progressing 〈 24 months following FCR have poor outcomes, similar to refractory patients, while longer remissions are indicative of a chemoimmunotherapy sensitive disease. Patients who discontinue FCR for toxicities may achieve excellent outcomes with subsequent treatment.

Abstract: Richter's syndrome (RS) is the rare development of an aggressive lymphoid malignancy in a patient with pre‐existing chronic lymphocytic leukemia (CLL). Data on RS is sparse and mostly derived from case reports or small series of patients and only a few larger cohorts have been published. The purpose of this large retrospective study was to summarize our national experience with RS in CLL, examine possible risk factors, and analyze relevant demographic, laboratory and clinical parameters, including results of therapy and outcome. We first evaluated data obtained from 119 patients with RS diagnosed during 1971–2010 from 12 medical centers in Israel. The final cohort summarized consisted of 81 patients with RS who developed only diffuse large B‐cell lymphoma (DLBCL) after exclusion all cases with insufficient data and those who were not DLBCL. Median overall survival from time of diagnosis of RS was 8 months; after applying the Richter score, patients could be stratified into three prognostic groups, while all other clinical and laboratory parameters evaluated had no prognostic significance. Prior therapy for CLL had no impact on RS survival ( P  = 0.8) and patients with therapy “naïve” RS and those who had already received chemotherapy prior to developing RS, had the same survival. The addition of rituximab to chemotherapy for RS improved 2 years overall survival from 19% in the chemotherapy alone arm to 42% ( P value of 0.001). Although prognosis of patients with RS remains dismal, this retrospective observation provides support for the use of chemo‐immunotherapy in DLBCL‐RS. Am. J. Hematol. 89:E218–E222, 2014. © 2014 Wiley Periodicals, Inc.

Abstract: In recent years, considerable progress has been made in frontline therapy for elderly/physically unfit patients with CLL. The combination of obinutuzumab and chlorambucil (O‐Clb) has been shown to prolong progression free survival (PFS, median PFS‐31.5 months) and overall survival (OS) compared to chlorambucil alone. More recently, obinutuzumab given in combination with either ibrutinib or venetoclax improved PFS but not OS when compared to O‐Clb. In this retrospective multinational, multicenter co‐operative study, we evaluated the efficacy and safety of frontline treatment with O ± Clb in unfit patients with CLL, in a “real‐world” setting. Patients with documented del (17p13.1)/ TP53 mutation were excluded. A total of 437 patients (median age, 75.9 years; median CIRS score, 8; median creatinine clearance, 61.1 mL/min) were included. The clinical overall response rate was 80.3% (clinical complete and partial responses in 38.7% and 41.6% of patients, respectively). Median observation time was 14.1 months and estimated median PFS was 27.6 months (95% CI, 24.2‐31.0). In a multivariate analysis, high‐risk disease [del (11q22.3) and/or IGHV‐unmutated], lymph nodes of diameter  〉  5 cm, obinutuzumab monotherapy and reduced cumulative dose of obinutuzumab, were all independently associated with shorter PFS. The median OS has not yet been reached and estimated 2‐year OS is 88%. In conclusion, in a “real‐world” setting, frontline treatment with O‐Clb achieves PFS comparable to that reported in clinical trials. Inferior outcomes were noted in patients with del (11q22.3) and/or unmutated IGHV and those treated with obinutuzumab‐monotherapy. Thus, O‐Clb can be still considered as legitimate frontline therapy for unfit CLL patients with low‐risk disease.

Abstract: The incidence of systemic diffuse large B cell lymphoma (DLBCL) concurrently involving the central nervous system (CNS) at diagnosis, is very low and data regarding the clinical course of these patients are scarce. We investigated characteristics, efficacy of treatment regimens including consolidative autologous stem cell transplantation and outcome of patients presenting with concomitant systemic and CNS DLBCL. The records of 44 patients, diagnosed between 2004 and 2017, who fulfilled the inclusion criteria, were retrospectively reviewed. CNS involvement was diagnosed as solely parenchymal in 41%, solely leptomeningeal in 43%, and paranchymal with leptomeningeal in 11% of the patients. Induction regimens were anthracycline‐based combined with high‐dose methotrexate (HD‐MTX) in 80% (n = 35) of patients, anthracycline‐based combined with intrathecal MTX in 3, cytarabine‐based (without antracyclines) in 2, HD‐MTX in 1 and palliative in three. Five of 41 patients treated with chemotherapy died of treatment‐related toxicity, all due to infections. Nineteen patients had consolidative autologous transplantation. Overall response rate following induction was 80% (complete responses 66% and partial responses 15%). All relapses (n = 11) occurred within less than 2 years. Within a median follow‐up of 26.8 months, 3‐years projected overall survival (OS) and progression free survival rates for the entire cohort were 56% ± 8.3 and 42% ± 8.9, respectively. In multivariate analysis, RCHOP‐HD MTX‐based induction [HR = 0.228, (0.054‐0.964)], administration of 3.5 g/m 2 MTX [HR = 0.735 (0.620‐0.871)], and attaining CR following induction [HR = 0.185, (0.051‐0.667)] predicted longer OS. RCHOP‐HD MTX can provide prolonged remissions in DLBCL patients presenting with concomitant systemic and CNS involvement whereas role of autograft remains uncertain.