Abstract: e20072 Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyper-inflammatory syndrome with distinct clinical and laboratory features. In adults, HLH is often associated with underlying malignancy, most commonly hematologic malignancies (HM). HLH occurs in 1% of adults with HM and overall survival can be low as 10-20%. Abnormal serum levels of the inflammatory markers sCD25 and ferritin are diagnostic criteria for familial HLH. However, because these reactants are often elevated in malignancy, appropriate levels for diagnosis in HM-HLH are unknown. In this study, we establish optimal sCD25 and ferritin levels for the diagnosis of HM-HLH in adults. Methods: Patients from three centers in Israel and Japan with HM-HLH and HM in whom sCD25 testing was performed were studied. The diagnosis of HLH was according to the HLH 2004 diagnostic criteria. Initial (at HLH presentation) and the maximum ferritin levels were analyzed. Sensitivity, specificity, and optimal cutoffs were calculated by receiver operating characteristic (ROC). Results: 62 patients with HM's without HLH and 40 patients with HM-HLH were included. The distribution of ages and HM subtypes was similar between groups (mostly B cell, T/NK cell, and Hodgkin's lymphoma). The median sCD25 concentration in HM was 1776 U/ml versus 8077 U/ml in HM-HLH. The median initial/ maximum ferritin levels were 190/202 ng/ml for the HM group and 2267/4515 ng/ml for the HM-HLH group. Both sCD25 and ferritin were very sensitive but nonspecific. sCD25 〉 2400 U/ml had a sensitivity/specificity of 95%/65%, while initial ferritin 〉 500 ng/ml had a sensitivity/specificity of 95%/75%. ROC analysis demonstrated optimal confirmatory cutoff values (maximizing specificity) of 〉 10,056 ng/ml for sCD25 (sensitivity/specificity 47%/95%). While initial ferritin demonstrated a cutoff of 〉 5231 ng/ml (sensitivity/specificity 22.5%/95%, AUC = 0.88) the maximum ferritin performed better with the cutoff of 〉 5748 ng/ml (sensitivity/specificity 45%/95%, AUC = 0.92). Conclusions: Our data suggest that the current HLH 2004 criteria of ferritin 〉 500 ng/ml and sCD25 〉 2400 U/ml are effective screening criteria for the complication of HLH in HM patients. sCD25 〉 10,000 U/ml and initial ferritin 〉 5,200 ng/ml are highly specific. Patients with suspected HM- HLH should have serial ferritin testing which increases specificity of this test. Future prospective studies are needed to confirm these findings.

Abstract: 7563 Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may accompany hematologic malignancies (HM). The diagnosis of HLH in patients with HM (HM-HLH) is confounded by a number of factors: the most commonly used HLH-2004 diagnostic criteria are derived from studies in infants while the Hscore used in adults is not specific for HMs; moreover, most parameters in these scoring systems may reflect features of the underlying HM rather than HLH associated inflammation; and finally specific diagnostic cutoff values for laboratory abnormalities in HM-HLH have not been defined. We therefore conducted a study to optimize the HLH-2004 laboratory thresholds for the diagnosis of HM-HLH. Methods: A multi-center retrospective study in adult patients with HM in whom testing for HLH was performed. HM-HLH was defined as fulfillment of 5/8 HLH-2004 diagnostic criteria. We established the optimal diagnostic cutoff levels for HLH-2004 laboratory parameters using receiver operating curves (ROC) and combined the best performing parameters into a combined index, using binary logistic regression. We then created a clinical decision tree using a Classification and Regression Tree (CART) analysis with all available parameters, using cross validation. We also determined the prognostic value of our combined diagnostic tool. Results: 225 adults were analyzed (112 with HM-HLH per HLH-2004 and 113 with HM only). 35% of patients were evaluated for HLH routinely upon HM diagnosis. Soluble CD25 (sCD25) and ferritin best discriminated HM-HLH from HM, with an area under the curve (AUC) of 0.83 for each. ROC analysis demonstrated an optimal cutoff of 〉 4190 U/mL for sCD25 (sensitivity/specificity 91%/69%) and an optimal cutoff of 〉 2636 ng/ml for ferritin (sensitivity/specificity 64%/86%) for HM-HLH. We term the combination of elevated sCD25 and ferritin using optimized cutoff levels the ‘optimized HLH inflammatory’ (OHI) index. This OHI index was highly specific for the diagnosis of HM-HLH (specificity of 92%, sensitivity 79%). CART analysis demonstrated that OHI index positivity was sufficient to diagnose HM-HLH. In patients without a positive OHI index an Hscore 〉 168 and either splenomegaly or triglycerides 〉 279 ng/dL can still diagnose HM-HLH. By following this decision pathway, approximately 92% of patients were accurately classified based on HLH-2004. Furthermore, the OHI was better (odds ratio (OR) 7.9; 95% confidence interval (CI) 4.2-14.6) than Hscore 〉 169 (OR 5.5; CI 3.9-9.6) and 〉 5/8 HLH-2004 (OR 5.3; CI 3-9.3) at predicting mortality at 1 year. Conclusions: The OHI index derived here is a simple tool that can accurately diagnose HLH and predict mortality in patients with hematologic malignancies. Some patients may not need full HLH workup before intervening with therapy that is HLH directed and not only malignancy directed.

Abstract: Background: Low blood ALT, Alanine aminotransferase activity and high FRAIL (Fatigue, Resistance, Ambulation, Illnesses and Loss of Weight) questionnaire scores were previously shown to be associated with frailty and increased risk of mortality. We aimed to correlate these tools with mortality and each other in patients hospitalized in an internal medicine department. Methods: This is a prospective study in a large tertiary hospital. We assessed the predictive value for clinical outcomes of both low ALT blood activity and the pre-frail and frail categories of the “FRAIL” questionnaire. Results: During a 15 months study, 179 consecutive patients were recruited, of whom 20 died. When all study participants were divided to three groups according to admission ALT levels (below 10 IU/L, 11 to 19 IU/L and above 20 IU/L) we found a statistically significant difference in the rate of mortality: 4 patients died within the group of ALT 〈 10 IU/L, 14 patients died in the group of 10 IU/L 〈 ALT 〈 19 IU/L and in the group of patients with ALT 〉 20 IU/L, only 2 patients died (p = 0.042). A higher score on the FRAIL questionnaire was associated, with statistical significance, with higher risk of mortality (p = 0.029). There was a significant correlation (p = 0.038) between blood ALT activity and the pre-frailty and frailty classifications by the FRAIL Questionnaire. Conclusions: Both the FRAIL questionnaire and blood ALT activity are simple and practical tools for frailty assessment and risk stratification of patients hospitalized in the internal medicine department. Both tool’s results also correlate with each other.

Abstract: Histiocytic sarcoma (HS) is a rare, malignant, and aggressive subtype of histiocytosis. We present an unusual case of aggressive HS presenting in the gastrointestinal tract and gallbladder that progressed after several lines of chemotherapy with a leukemic phase. We review the clinical, pathological, and molecular characteristics of HS in this case and review the literature on HS involving the digestive system as well as on overt leukemic phase of this disease. HS is often diagnosed at an advanced stage, and mortality is high. We discuss the therapeutic approach to patients with HS. We highlight the role of overexpression and somatic alterations in the RAF-MEK-ERK pathway in the pathogenesis of HS and discuss potential targeted approaches to treat these rare tumors.

Abstract: Primary central nervous system lymphoma (PCNSL) is a rare disease with an incidence of 0.4/per 100,000 person‐years. As there is a limited number of prospective randomized trials in PCNSL, large retrospective studies on this rare disease may yield information that might prove useful for the future design of randomized clinical trials. We retrospectively analyzed the data of 222 newly diagnosed PCNSL patients treated in five referral centers in Israel between 2001 and 2020. During this period, combination therapy became the treatment of choice, rituximab has been added to the induction therapy, and consolidation with irradiation was largely laid off and was mostly replaced by high‐dose chemotherapy with or without autologous stem cell transplantation (HDC‐ASCT). Patients older than 60 comprised 67.5% of the study population. First‐line treatment included high‐dose methotrexate (HD‐MTX) in 94% of patients with a median MTX dose of 3.5 g/m 2 (range 1.14–6 g/m 2 ) and a median cycle number of 5 (range 1–16). Rituximab was given to 136 patients (61%) and consolidation treatment to 124 patients (58%). Patients treated after 2012 received significantly more treatment with HD‐MTX and rituximab, more consolidation treatments, and autologous stem cell transplantation. The overall response rate was 85% and the complete response (CR)/unconfirmed CR rate was 62.1%. After a median follow‐up of 24 months, the median progression‐free survival (PFS) and overall survival (OS) were 21.9 and 43.5 months respectively with a significant improvement since 2012 (PFS: 12.5 vs. 34.2 p  = 0.006 and OS: 19.9 vs. 77.3 p  = 0.0003). A multivariate analysis found that the most important factors related to OS were obtaining a CR followed by rituximab treatment and Eastern Cooperative Oncology Group performance status. The observed improvement in outcomes may be due to multiple components such as an intention to treat all patients regardless of age with HD‐MTX‐based combination chemotherapy, treatment in dedicated centers, and more aggressive consolidation with the introduction of HDC‐ASCT.

Abstract: Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyper-inflammatory syndrome which may occur in adults with hematologic malignancies (HM). The diagnosis of HLH in this context (HM-HLH) is hindered by a number of factors. First, the currently used HLH 2004 diagnostic criteria are derived from pediatric patients commonly with HLH-associated genetic lesions, a very different population than adults with cancer. Second, most parameters used for diagnosis of HLH are directly impacted by the underlying HM and may reflect the presence of the malignant clone itself rather than an inflammatory process. Finally, appropriate diagnostic cutoff values for laboratory abnormalities in HM-HLH have not been defined. In this study we determine the diagnostic value of the laboratory components of the HLH 2004 diagnostic criteria and establish optimal cutoffs for the diagnosis of HM-HLH in HM patients. Methods: This is a multicenter, retrospective study of adult patients with a hematologic malignancy in whom sCD25 was measured because of clinically suspected HM-HLH or as part of routine screening of patients with a newly diagnosed hematologic malignancy, between January 2012 and March 2020. We considered patients fulfilling the five of eight of the HLH 2004 diagnostic criteria to have HM-HLH. Patients fulfilling fewer than five criteria were assigned to the HM group. These cohorts were well balanced in terms of disease distribution. We established the optimal cutoffs for laboratory parameters used for the diagnosis of HM-HLH using receiver operating curves (ROC) in a discovery cohort and tested their performance in a validation cohort. In order to improve the results obtained using the individual ROC, we then created a combined ROC using parameters demonstrating the highest individual performance (highest area under the curve (AUC)), in order to develop a diagnostic index. Finally, we examined the performance of each parameter in each cohort by using a contingency table and Chi-square and Fisher's exact test to determine the positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and likelihood ratio (LR) of disease for each parameter. Results: 212 adults with HM with or without HLH in whom testing for HLH was performed were included in the study. HMs were: B cell lymphoma (41%), T cell lymphoma (26%), Hodgkin lymphoma (9%), acute myeloid leukemia (8%), myelodysplastic syndrome (8%), myeloproliferative neoplasms (5%) and chronic lymphocytic leukemia (4%). 99 (47%) patients had HM-HLH. Despite considerable overlap in laboratory values between the patient groups, all parameters apart from fibrinogen were able to distinguish HM-HLH from HM alone, with ferritin and sCD25 having the greatest discriminatory power. ROC analysis revealed an optimal cutoff value of & gt;5,600 U/mL for sCD25 (sensitivity/specificity 76%/78%, AUC=0.83) and & gt;1,300 ng/ml for ferritin (sensitivity/specificity 76%/76%, AUC=0.83). Combining the two markers to create a novel inflammatory index (HM-INFL) yielded superior diagnostic ability (AUC =0.86). Using HLH 2004 cutoff levels the HM-INFL index had a sensitivity of 94% and NPV of 94% and when using the optimal cutoff levels, it had a specificity of 92% and PPV of 90% (Table 1). Conclusions: HM-INFL is an index comprising only ferritin and sCD25. Using the original HLH 2004 cutoffs the index is an effective screening tool. Using our newly defined cutoff levels obtained by ROC analysis it is highly specific and can be used as a confirmatory test for the diagnosis of HLH in HM patients. These findings also support the hypothesis that HLH in the context of HM is an inflammatory condition associated with immune dysregulation. Disclosures Miller: Foundation Medicines, Inc.: Consultancy. Daver:Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees. Jordan:Sobi: Consultancy.

Abstract: To characterize risk factors for the development of post‐transplant erythrocytosis (PTE), and its long‐term effect on mortality, graft failure, and thrombosis. Methods Retrospective study including all kidney transplant recipients in Rabin Medical Center (RMC) during the years 2005‐2014. The primary outcome was a composite outcome of all‐cause mortality or graft failure at the end of follow‐up. Secondary outcomes included death censored graft loss, venous thromboembolism, major adverse cardiovascular events, and mortality. A matched control group was also evaluated. Univariate and multivariate time‐varying Cox model analyses were conducted for outcome evaluation. Results A total of 1304 patients were included, 169 of whom were diagnosed with PTE (12.9%). PTE was associated with male gender, higher glomerular filtration rate (GFR), and polycystic kidney disease. PTE was found to be associated with a reduced risk of the primary outcome (HR 0.355, CI 95% 0.151‐0.89, P  = .027) in a univariate time‐varying Cox analysis, but was not associated with the composite outcome in a multivariate analysis. There was no difference in the primary outcome when the PTE group was compared with the matched control. Conclusion PTE was not found to be associated with long‐term outcomes of graft failure and poor survival.

Abstract: Surface antigens are commonly used in flow cytometry assays for the diagnosis of multiple myeloma (MM). Some of these are directly involved in MM pathogenesis or interactions with the microenvironment, but most are used for either diagnostic or prognostic purposes. In a previous study, we showed that in-vitro, CD24-positive plasma cells exhibit a less tumorigenic phenotype. Here, we assessed the prognostic importance of CD24 expression in patients newly diagnosed with MM as it correlates to their clinical course. Immunophenotyping by flow cytometry of 124 patients uniformly treated by a bortezomib-based protocol was performed. The expression of CD24, CD117, CD19, CD45, and CD56 in bone marrow PCs was tested for correlations to clinical parameters. None of the CD markers correlated with the response rates to first-line therapy. However, patients with elevated CD24+ expression on their PCs at diagnosis had a significantly longer PFS (p = 0.002) and OS (p = 0.044). In contrast, the expression of CD117, CD56, or CD45 was found to have no prognostic value; CD19 expression was inversely correlated with PFS alone (p 〈 0.001) and not with OS. Thus, elevated CD24 expression on PCs appears to be strongly correlated with survival and can be used as a single-surface antigenic prognostic factor in MM.