Tadmor, Tamar

Abstract Hairy cell leukemia (HCL) and HCL variant (HCLv) are distinct, rare, and chronic splenic B-cell lymphomas/leukemias that partially overlap in clinicopathologic presentation but differ in genetic basis, prognosis, and management. HCL is caused by the BRAF-V600E kinase–activating mutation in >95% of the patients, usually has excellent responses to chemotherapy with purine analogues, and is also amenable to BRAF inhibitor–based targeted treatments. In contrast, HCLv lacks BRAFV600E mutation, requires combined therapy with purine analogues in addition to rituximab, and generally shows less durable responses. Here, an international team of hematologists, experts on these rare diseases, was convened by the Hairy Cell Leukemia Foundation to update the previous guidelines (published in 2017) by providing a summary of current methods to diagnose and manage patients with HCL and HCLv as well as a prospective on newer targeted therapies to further improve outcomes.

Abstract Introduction FD Ibr+Ven is approved as first-line (1L) treatment (tx) for CLL/SLL in 78 countries across Asia, Europe, the Middle East, and South America, plus Australia, Canada, and New Zealand. Clinical trials with up to 5.5 years (yrs) of follow-up have demonstrated progression-free and overall survival benefits of 1L FD Ibr+Ven in pts with CLL/SLL (Wierda WG, ASH 2024; Jacobs R, EHA 2024). Despite established clinical benefits, there is a lack of RW evidence on the effectiveness and tolerability of FD Ibr+Ven outside of clinical trial settings. Here we present pooled data from REALITY-WW and REALITY-2 to understand the usage, factors for therapy decision, clinical response, and safety of FD Ibr+Ven in routine clinical practice. Methods REALITY-WW and REALITY-2 are prospective observational cohort studies. REALITY-WW is an international study; REALITY-2 is conducted in Germany. Both included previously untreated pts with CLL/SLL from hospitals and medical institutions where Ibr+Ven was routinely used. The decision to start FD Ibr+Ven was made prior to and independent of pt enrollment. Pts aged ≥18 yrs with a confirmed diagnosis of CLL/SLL requiring 1L tx per iwCLL 2018 criteria received 3 cycles of Ibr, followed by 12 cycles of FD Ibr+Ven orally (Ibr, 420 mg/d; Ven, 5-week ramp-up to 400 mg/d). Primary end point was overall response rate (ORR) per iwCLL 2018 criteria. Secondary end points and outcomes of interest included tx-emergent adverse events (TEAEs), tumor lysis syndrome (TLS) risk, and factors associated with physician decision to initiate FD Ibr+Ven in routine clinical practice. Results At data cutoff (REALITY-WW: May 2025; REALITY-2: March 2025), 129 pts from both studies received FD Ibr+Ven (REALITY-WW, 81; REALITY-2, 48). The median (range) time on study was 6.4 (0.1-19.0) months (mo). Median (range) age was 65.0 (37.0-87.0) yrs, with 46.5% of pts aged <65 yrs and 53.5% of pts aged ≥65 yrs; 62.8% were male. Median (range) time from diagnosis to FD Ibr+Ven initiation was 38.1 mo (0.1-238.0) and median (range) duration of tx was 6.0 mo (0.1-15.9) for Ibr and 3.2 mo (0.1-8.4) for Ven. A Cumulative Illness Rating Scale score of >6 was observed in 12.6% of pts, with a higher score in pts aged ≥65 vs <65 yrs (18.0% vs 6.9%). TP53 mutations were seen in 7.4% of pts; 52.8% had an unmutated IGHV status. ORR was assessed in the 44 pts with ≥ 1 post-baseline assessment in REALITY-WW. Of these, 39 showed a response by the end of 6 tx cycles (3 cycles of Ibr + 3 cycles of FD Ibr+Ven) and 5 had stable disease. ORR at 6 mo per iwCLL 2018 criteria (partial response [PR] with lymphocytosis [PR-L] or better) was 88.6% (95% CI, 79.3-98.0), including complete responses in 29.5%, PR in 34.1%, and PR-L in 25.0% pts. Among 129 treated pts, TEAEs were reported in 61.2%; diarrhea was the most common TEAE (14.0%). Serious TEAEs and grade 3/4 TEAEs were reported in 12.4% and 8.5% of pts, respectively. The most common grade 3/4 TEAE was myocardial infarction (1.6%). Dose reduction was observed in 13.2% (Ibr) and 2.3% (Ven) of pts, mainly due to tx-associated TEAE/toxicity/TLS. Rates of TEAEs leading to discontinuation, dose reduction, and interruption of ≥1 study tx were 4.7%, 10.9%, and 20.9%, respectively. At baseline (n=129), 18.6%, 45.0%, and 14.7% of pts had high, intermediate, and low TLS risk, respectively, while 20.2% were not assessed and 1.6% had missing data. After the 3-cycle Ibr lead-in, the distribution shifted to 9.3%, 24.8%, and 24.0%, respectively, with 14.7% not assessed and 27.1% missing. There were no TEAEs of TLS and no hospitalizations due to TLS. Seven pts (6 aged ≥65 yrs and 1 <65 yrs) were hospitalized prophylactically for TLS. Prophylactic hospitalization was observed in 8.5% (11/129) of pts with high or medium TLS risk and impaired renal function for whom the Ven ramp-up was initiated; no pts were hospitalized due to laboratory/clinical TLS during the Ven ramp-up period. Physician questionnaire responses (n=126) indicated the most common factors associated with decision to initiate FD Ibr+Ven were administration route advantage (91.3%), overall health status (87.3%), anticipated superior efficacy of tx (84.1%), and general risk factors such as high tumor burden/genetic risk factors (81.0%). Conclusions Overall findings suggest that FD Ibr+Ven is an effective and safe tx for pts with CLL/SLL in a RW population, including those aged ≥65 yrs. Data with longer follow-up will be presented at the meeting.

Abstract Background Red blood cell distribution width (RDW) is an easily accessible diagnostic test that is underutilized as a prognostic marker, despite substantial supporting evidence in cancer, cardiovascular diseases, and helathy individuals (Pilling et al. PLoS One 2028;13:e0203504). The association between increased RDW and incident acute myeloid leukemia (AML) has long been suggested in healthy volunteers (Abelson et al. Nature 2019;559:400). We looked into a similar phenomenon in patients with polycythemia vera (PV) or essential thrombocythemia (ET) in large discovery and validation cohorts. Methods A machine learning (ML) approach was used to identify baseline clinical and laboratory parameters that were predictive of leukemic transformation (LT) and develop a predictive model in a large discovery cohort of PV and ET, obtained from electronic medical records of the Maccabi Healthcare Services (MHS; Tel-Aviv, Israel). Receiver operating characteristic (ROC) curve analysis was utilized to determine the optimal cutoff points for RDW and other continuous variables. Mayo Clinic databases (Rochester, MN, USA) for patients with PV and ET were utilized as validation cohorts. Identification of study patients in the latter was according to the International Consensus Classification (Arber et al. Blood 2022; 140:1200) while in the discovery cohort was based on presence of ICD-9 codes associated with documentation of disease-specific driver mutations or treatment records that are consistent. Statistical analyses were performed using the R statistical software 4.4.2 (November, 2024) (Foundation for Statistical Computing, Vienna, Austria) or JMP Pro 18.0.0 software (SAS Institute, Cary, NC, USA). Results The discovery cohorts from Israel included 4,592 patients with PV (median age 63 yesrs; 53% males) and 5,968 with ET (median age 61 yesrs; males 40%). The validation cohorts from the Mayo Clinic included 633 PV (median 65 years; 51% males) and 634 ET (median 60 years; females 64%) patients that were informative for RDW. In the discovery cohorts, median follow-up (incident AML) was 6.1 years (N=186; 4.1%) in PV and 6.1 years (N=85; 1.4%) in ET. The corresponding values for the validation cohorts were 6.6 years (N=24; 3.8%) in PV and 7.0 years (N=22; 3.5%) in ET. Discovery cohort analyses Covariate-adjusted Cox regression analysis was utilized to estimate associations between LT and several clinical variables followed by machine learning pipeline to predict LT in a given timeframe. Conversion from continuous to binary variables was accompliched by ROC analysis. Shapley Additive exPlanations (SHAP) application enabled selection of top-ranked features that included RDW >15.5 (HR 3.2, 1.1-9.5; p=0.03), age >60 years (HR 2.9, 1.4-5.9; p<0.01), and LDH >1.5 x UNL (HR 4.0 (1.6-10.0; p<0.01). A similar analysis in ET also identified RDW >15.5 (p<0.01), age >60 years (p=0.01) as well as male sex (p=0.03) as independent risk factors for LT. Subseqent risk models based on these risk factors were externally validated and enabled robust risk stratification with 10-20 year AUCs rangening from 0.75 to 0.81. Validation cohorts analyses The indpendent predictive value of increased RDW observed in the discovery cohort was confirmed in the validation cohorts for both PV and ET and further gender-specified: female/male RDW ≥16.4/15.8 in PV (HR 7.9, 1.9-33.8) and ≥16.1/14.4 in ET (HR 5.1, 2.2-11.9). Also confirmed were the additional prognostic contributions of age ≥60 years (HR 3.8, 1.3-10.9) and LDH >1.5 x UNL (HR 3.9, 1.6-9.4), in PV, while no other clinical risk factor showed RDW-independent prognostic relevance in ET. The prognostic impact of RDW in ET was most apparent in females (p<0.01), as opposed to males (p=0.32) while the effect was equally significant in PV. In multivariable analysis that included previously recognized high risk mutations in PV (SRSF2) and ET (SF3B1), both RDW and mutations sustained significance (p<0.05). Conclusion The current study identifies higher RDW as a key risk factor for LT in both PV and ET, independent of other clinical or genetic risk factors. Possible underlying mechanisms include increased RDW as a marker of long-term pre-leukemic clones with sub-clinical ineffective erythropoiesis or an associated pro-leukemic inflammatory state.

ABSTRACT Survival prediction models in essential thrombocythemia (ET) include the International Prognostic Scoring System (IPSET) and the more recently introduced triple‐A (AAA) prognostic score. The latter enlists age and absolute neutrophil (ANC) and lymphocyte (ALC) counts as risk variables. In the current study, a Mayo Clinic discovery cohort of 658 patients with ET was used to identify AAA‐independent risk variables. Accordingly, multivariable analysis‐derived HRs (95% CI) were 15.7 (8.4–29.5) for age > 70 years (8 points); 4.2 (2.3–7.5) for age 50 to 70 years (2 points); 1.8 (1.2–2.5) for ANC ≥ 8 × 10 9 /L (1 point); 1.4 (1.03–1.9) for ALC < 1.7 × 10 9 /L (1 point); 1.8 (1.2–2.6) for absolute monocyte count (AMC) ≥ 0.5 × 10 9 /L (1 point); 1.8 (1.2–2.3) for male sex (1 point); 1.8 (1.3–2.4) for arterial hypertension (1 point); and 1.6 (1.2–2.3) for arterial thrombosis (1 point). HR‐weighted scoring enabled a 4‐tiered risk classification: ultra‐low (0–1 points; N = 94; median survival 42.7 years), low (2–4 points; N = 297; 23 years), intermediate (5 points; N = 66; 17.3 years), and high (6–14 points; N = 201; 10.8 years). Time‐dependent predictive performance at 20/25 years favored AAA + (AUC 0.92/0.91) vs. AAA (0.86/0.86) vs. IPSET (0.81/0.84). The AAA + risk model was subsequently validated by two external cohorts from Israel ( N = 5968) and Italy ( N = 682). In the cohort from Israel, disease‐specific mortality was assessed by comparing observed survival to an age‐ and sex‐matched reference population, which suggested near‐normal life expectancy in ultra‐low risk patients. The current study highlights host‐related factors as the primary determinants of longevity in ET and provides a composite risk score (AAA + ) that is based on complete blood count‐derived parameters and host‐related factors. Predictive performance of the new model was shown to be superior to that of IPSET and AAA.

Abstract BACKGROUND: The study of rare diseases is limited by the uncommon nature of the conditions as well as the widely dispersed patient populations. Current rare disease registries such as the National Organization of Rare Diseases utilize centralized platforms for data collection; however because of their broad nature, these do not always capture unique, disease specific elements. Hairy Cell Leukemia (HCL) is a rare leukemia globally with approximately 900 new cases diagnosed in the US each year. The HCL Foundation undertook creation of a Patient Data Registry that collects data from multiple HCL Centers of Excellence (COE) around the globe to better understand the complications, treatment outcomes, disease subtypes, comorbid conditions, epidemiology, and quality of life of patients with HCL. METHODS: Investigators at The Ohio State University Department of Biomedical Informatics and Division of Hematology in collaboration with the HCL Foundation developed a Patient Data Registry (PDR) for the longitudinal capture of high quality research data. This system differs from other registries in that it uses a federated( rather than centralized) architecture, wherein data is queried and integrated in an on-demand manner from local registry databases at each participating site. Further, the data collected for use in the registry combines both automated exports from existing electronic health records (EHRs) as well as additional data entered via a set of web-based forms. All manually entered data comes from source documents, and data provenance spanning electronic and manually entered data is maintained via multiple technical measures. Patients may be enrolled at HCL COE, or, if they do not have access to a COE they may enroll via a web-based portal (www.hairycellleukemia.org). At this time due to regulatory requirements the web-based portal is available to US patients only. All data are de-identified (see Figure 1: De-Identification Workflow) which reduces regulatory burden and increases opportunities for data access and re-use. End users have access to data via a project-specific query portal. RESULTS: The Patient Data Registry has been deployed at The Ohio State University, Royal Marsden Hospital, and MD Anderson Cancer Center, and is undergoing deployment at the University of Rochester. Up to 25 international HCL COE may participate. In addition, US patients are actively entering the registry via the web-based portal. To date, 227 patients have been consented to the registry with 119 of these being via the web-based entry point. CONCLUSION: We created an international and web-based patient data registry which will enable researchers to study outcomes in HCL in ways not previously possible given the rarity of the disease. This work was made possible by research funding from the Hairy Cell Leukemia Foundation. Figure De-Identification Workflow Figure. De-Identification Workflow Disclosures Andritsos: Hairy Cell Leukemia Foundation: Research Funding. Anghelina:Hairy Cell Leukemia Foundation: Research Funding. Lele:Hairy Cell Leukemia Foundation: Research Funding. Burger:Pharmacyclics: Research Funding. Delgado:Gilead: Consultancy, Honoraria; Novartis/GSK: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Infinity: Research Funding. Jones:AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lozanski:Beckman Coulter: Research Funding; Genentech: Research Funding; Stemline Therapeutics Inc.: Research Funding; Boehringer Ingelheim: Research Funding. Montserrat:Morphosys: Other: Expert Testimony; Vivia Biotech: Equity Ownership; Gilead: Consultancy, Other: Expert Testimony; Pharmacyclics: Consultancy; Janssen: Honoraria, Other: travel, accommodations, expenses. Parikh:Pharmacyclics: Honoraria, Research Funding. Park:Genentech/Roche: Research Funding; Amgen: Consultancy; Juno Therapeutics: Consultancy, Research Funding. Robak:Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Tam:janssen: Honoraria, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Heckler:Hairy Cell Leukemia Foundation: Research Funding. Payne:Hairy Cell Leukemia Foundation: Research Funding.

AbstractHairy cell leukemia is an uncommon hematologic malignancy characterized by pancytopenia and marked susceptibility to infection. Tremendous progress in the management of patients with this disease has resulted in high response rates and improved survival, yet relapse and an appropriate approach to re-treatment present continuing areas for research. The disease and its effective treatment are associated with immunosuppression. Because more patients are being treated with alternative programs, comparison of results will require general agreement on definitions of response, relapse, and methods of determining minimal residual disease. The development of internationally accepted, reproducible criteria is of paramount importance in evaluating and comparing clinical trials to provide optimal care. Despite the success achieved in managing these patients, continued participation in available clinical trials in the first-line and particularly in the relapse setting is highly recommended. The Hairy Cell Leukemia Foundation convened an international conference to provide common definitions and structure to guide current management. There is substantial opportunity for continued research in this disease. In addition to the importance of optimizing the prevention and management of the serious risk of infection, organized evaluations of minimal residual disease and treatment at relapse offer ample opportunities for clinical research. Finally, a scholarly evaluation of quality of life in the increasing number of survivors of this now manageable chronic illness merits further study. The development of consensus guidelines for this disease offers a framework for continued enhancement of the outcome for patients.