Chanan‐Khan, Asher

*Drs. Yifan Zhai and Sikander Ailawadhi are co-corresponding authors Background R/R MM is an incurable condition, with virtually inevitable relapse. AL amyloidosis is a rare disease that may cause serious illness and even death. Lisaftoclax is a novel, potent, selective BCL-2 inhibitor under clinical development for treatment of patients with hematologic malignancies or solid tumors, and has shown clinical antitumor benefits. In a previous study on chronic lymphocytic leukemia, lisaftoclax was shown to require only a short (daily vs weekly) dose ramp-up to mitigate tumor lysis syndrome and was associated with a low incidence of adverse events (AEs) (Ailawadhi et al. J Clin Oncol 2021;39:abstract 7502; Davids et al. Blood 2022;140[suppl 1]:2326-2328). Methods This multicenter study evaluated lisaftoclax combined with pomalidomide and dexamethasone (Arms A and C) or daratumumab, lenalidomide, and dexamethasone (Arm B) in patients with R/R MM (Arm A and B) or R/R amyloidosis (Arm C). Eligible patients had an ECOG performance status ≤ 2; ≥ 1 prior line of therapy; and adequate organ function. Patients with R/R amyloidosis also needed confirmed symptomatic organ involvement, in addition to purpura and/or carpal tunnel syndrome. Lisaftoclax was administered orally daily (QD) at 5 dose levels (400, 600, 800, 1,000, and 1,200 mg) without ramp-up in repeated 28-day cycles. Pomalidomide, daratumumab, and lenalidomide were administered per label use. Dexamethasone 40 mg (20 mg for patients aged > 75 years) was administered on Days 1, 8, 15, and 22 of 28-day cycles. Study objectives were safety and efficacy assessments of the combination treatments. Results As of July 3, 2023, a total of 30 patients were enrolled: 22 in Arm A at dose levels of 400 (n = 3), 600 (n = 4), 800 (n = 3), 1,000 (n = 6), and 1,200 mg (n = 6); 3 in Arm B at 600 mg; and 5 in Arm C at 400 (n = 1) and 600 mg (n = 4). A total of 66.7% of patients were male, and the median (range) age was 70.5 (24-88) years, with 66.7% of patients above the age of 65. The median (range) lines of prior therapies was 4 (1-19), and median (range) time from diagnosis to first dose was 5.2 (1-29) years. The median (range) number of treatment cycles was 4 (1-19). A total of 18 patients were triple-class-exposed, 7 had received pomalidomide, and 3 harbored t(11;14) at baseline. A total of 19 patients reported experiencing any-grade lisaftoclax treatment-related adverse events (TRAEs), including neutropenia or nausea (16.7% each); and thrombocytopenia, leukopenia, abdominal distension, constipation, or diarrhea (6.7% each). Seven patients experienced grade ≥ 3 TRAEs, including neutropenia (10%) and febrile neutropenia, iron deficiency anemia, thrombocytopenia, prolonged electrocardiogram QT interval, and acute kidney injury (3.3% each). Two patients experienced lisaftoclax-related serious AEs, of which 1 was febrile neutropenia and 1 acute kidney injury. In Arm B, 1 patient experienced a dose-limiting toxicity (prolonged QT interval). A total of 12 patients discontinued treatment because of disease progression (n = 8), an AE (n = 1), noncompliance (n = 1), and investigator/patient decision (n = 2). In Arm A, 21 patients with R/R MM were evaluable, of whom 9 experienced a partial response (PR) and 5 a very good PR (VGPR). The overall response rate (ORR [PR or better]) was 66.7%, with a median (range) time to response of 1.2 (1-3) months. After a median (range) time to response of 1.4 (1-2) months, 2 patients with R/R MM in Arm B achieved a PR (n = 1) or VGPR (n = 1). In Arm C, 3 patients with R/R amyloidosis achieved a hematologic VGPR; the ORR was 60%; the median (range) time to response was 0.9 (1-1) month; and 1 patient experienced organ function improvement. Conclusion Lisaftoclax, combined with novel therapeutic regimens, was well tolerated and has demonstrated preliminary antitumor activity in patients with AL amyloidosis or R/R MM. Internal study identifier: APG-2575-MU101; clinical trial registration: NCT04942067.

Introduction: Waldenström macroglobulinemia (WM) is a rare B-cell lymphoma that may be preceded by an asymptomatic IgM-monoclonal gammopathy of undetermined significance (MGUS). The mechanisms underlying the progression from IgM-MGUS to WM remain to be fully elucidated; however, the stepwise accumulation of genomic abnormalities has been suggested as a potential driver. Currently, the role of epigenetic regulation of DNA remains underexplored in this disease spectrum. Aberrant DNA methylation is a hallmark of oncogenesis that plays an important role in hematologic malignancies. The aim of this study was to assess differential DNA methylation in WM compared to IgM-MGUS and identify hyper- and hypomethylated pathways that may alter key cellular functions. Methods: This study included 15 patients with WM and 6 with IgM-MGUS. Bone marrow samples were prospectively collected and CD19+ and/or CD138+ B cells were positively selected. Subsequently, genome-wide DNA methylation analysis was performed. CpG methylation ratios were segmented into 200-bp regions and differentially methylated regions (DMRs) comparing WM to IgM-MGUS were identified. DMRs with a Q-value <0.05 and absolute methylation difference of ≥20% were considered significant and utilized for analysis. DMRs were annotated according to genomic regions of interest (promotors, 3'UTR, 5'UTR, introns, exons, CpG islands, CpG shores). Next, genes with significant promotor hyper- or hypomethylation were assessed using the Ingenuity Pathway Analysis. Pathways with a corrected p-value<0.05 were considered statistically significant and a Z-value was calculated based on the degree of differential methylation. Results: Genome-wide DNA methylation analysis revealed a significant number of DMRs (n= 15691, hyper: 8248; hypo: 7443) in WM compared to IgM-MGUS. Assessing genomic regions, promotors (hyper: 1379; hypo: 2403), introns (hyper: 1548; hypo: 2292), CpG shores (hyper: 587; hypo: 849) and 3'UTR (hyper: 66; hypo: 193) regions were observed to have a significantly greater number of hypomethylated DMRs (all comparisons, p<0.001) in WM compared to IgM-MGUS (Figure A). While exons (hyper: 1686; hypo: 1378), CpG islands (hyper: 2128; hypo: 82), and 5'UTR (hyper: 854; hypo: 246) regions had a significantly greater number of hypermethylated DMRs (all comparisons, p<0.001) (Figure A). Next, promotor methylation-based pathway analysis revealed differential methylation of multiple cellular pathways important in WM pathogenesis (Figure B). These included pathways involved in intracellular signaling and the regulation of cellular proliferation, such as the STAT3 and CXCR4 pathways which were hypomethylated, and the PTEN signaling pathway which was hypermethylated. Of interest, we have previously demonstrated the transcription factor, STAT3, to have an increased expression in WM and to be implicated in IgM secretion (Elsawa, 2011). Next, multiple cytokine signaling pathways were observed to be hypomethylated in WM compared to IgM-MGUS including members of the interleukin (IL) family (IL-1, IL-8, IL-15, IL-23), VEGF, and TGF-β. Of relevance, previous studies have demonstrated the elevation of IL-8, IL-15, and increased expression of angiogenic cytokines, including VEGF, in patients with WM (Lewicki, 2010; Anagnostopoulos, 2007). Furthermore, our group has also shown miRNA-based epigenetic regulation of IL-8 and IL-15 in WM compared to IgM-MGUS (Chohan, 2023). Lastly, several pathways critical in the regulation of the cell structure and the extracellular matrix (ECM) were found to be hypomethylated including the FGF, actin cytoskeleton, PAK, and FAK signaling pathways. Of note, the FGF/FGFR axis has been demonstrated to be dysregulated in WM, and its targeting has been shown to halt WM cell growth (Sacco, 2021). Conclusions: This study demonstrates differential DNA methylation of key genomic regions in WM compared to IgM-MGUS. Promotor methylation-based analysis reveals hypomethylation of several important cellular pathways involved in cytokine signaling, cell structure/ECM, and intracellular signaling. These results underscore the influence of epigenetics in the IgM-gammopathy disease spectrum and suggest the potential role of aberrant DNA methylation underlying the malignant progression from IgM-MGUS to WM.

Introduction: Chronic lymphocytic leukemia and small lymphocytic lymphoma (CLL/SLL) are the most prevalent types of leukemia in the United States. Given the emergence of novel CLL/SLL therapies, it is important to understand real-world treatment characteristics and unmet needs. The objectives of this retrospective cohort study were to examine patient characteristics, treatment patterns, and associated outcomes for patients with CLL/SLL, overall, and by CLL and SLL, respectively. Methods: A retrospective study was conducted using Symphony Integrated Dataverse (IDV ®), a comprehensive, longitudinal, open-claims database, and integrated electronic medical record data. Patients aged ≥18 years with ≥1 diagnosis for CLL or SLL and who initiated a first-line or second-line treatment between January 1, 2020, and December 31, 2022 (index period) were included in the study. Index date was defined as the date of treatment initiation. Patients were required to be continuously enrolled for 365 days prior to the index date and ≥90 days following the index date. Patient data were included until patients were lost to follow-up or to the end of the study period (March 31, 2023). Treatment patterns were examined with the following treatment regimens and stratified by line of therapy: chemotherapy (including bendamustine-based and other chemotherapy), anti-CD20-based, Bruton tyrosine kinase inhibitors (BTKiibrutinib- and acalabrutinib-based), and venetoclax-based therapy. Zanubrutinib use was not captured in the BTKi treatment category as its CLL/SLL indication approval date (January 19, 2023) was outside the index period. Discontinuation rate was defined as the percentage of patients who discontinued their current treatment regimen within 90 days. Healthcare resource utilization was measured by number of outpatient visits, inpatient visits, and other medical/hospital services per patient per month (PPPM) during the treatment regimen. Results:There were 17,748 and 5,667 patients with CLL/SLL who initiated a first-line or second-line treatment regimen during the index period, respectively. The most frequently used treatment regimens in first line were BTKi (49.9%), followed by anti-CD20 (26.1%), venetoclax (15.4%), and chemotherapy (8.6%). BTKi continued to be the predominant treatment (49.6%) in second line, followed by venetoclax (30.9%), chemotherapy (10.4%), and anti-CD20 (9.2%). First-line patients treated with BTKi regimens were older and Medicare-insured when compared with patients receiving venetoclax-based regimens (65+ years: 77.1% vs 66.9%, P-value <0.001; Medicare: 61.7% vs 53.0%, P-value <0.001). Patients receiving BTKi had significantly lower discontinuation rates compared with other treatment regimens during both first and second lines of therapies (Figure 1). Mean PPPM outpatient visits, inpatient visits, and other medical/hospital services were less frequent with BTKi therapies vs other treatment regimens across both lines of therapy (Table 1). Of the 17,748 patients initiating first line of therapy, 13.3% had SLL while the remaining 86.7% had CLL. The proportion of patients with SLL vs CLL decreased in second line and second line or later (8.0% vs 92.0% and 6.8% vs 93.2%, respectively). Treatment discontinuation rate in SLL patients was higher than that in CLL patients in first line (32.41% and 25.08%, respectively); however, discontinuation rates became comparable with later lines of therapy. Across all lines of therapy, healthcare resource utilization was significantly higher in SLL patients than CLL patients. Median PPPM outpatient visits were 1.02 for SLL and 0.67 for CLL. Median PPPM for other medical/hospital services was 0.7 for SLL and 0.23 for CLL. Conclusions: BTKi therapy, the primary treatment regimen across first- and second-line therapies, has significantly lower discontinuation rate and healthcare resource utilization compared with other treatment regimens. Further studies are needed to evaluate real-world clinical outcomes of CLL/SLL regimens to support evidence-based treatment decisions.

Introduction: Chronic lymphocytic leukaemia (CLL) is the most common leukaemia type. In 2020, there were an estimated 207,463 people living with CLL, with an annual incidence of approximately 4.9 per 100,000 in the United States (US). Zanubrutinib is a Bruton tyrosine kinase inhibitor that is FDA-approved and an NCCN preferred and recommended treatment of CLL. In the phase 3 ALPINE trial (NCT03734016), zanubrutinib elicited a significantly higher overall response rate and significantly longer progression-free survival (PFS) than ibrutinib. This study aimed to compare zanubrutinib versus ibrutinib in Relapsed/Refractory (R/R) CLL by calculating the number needed to treat (NNT) to avoid one progression or death and associated incremental costs. Methods:A health-economic model was developed to evaluate the number of R/R CLL patients needed to be treated to avoid a progression or death from the US payer perspective. Payer blend was assumed with 40% Commercial and 60% Medicare payer mix. Clinical efficacy data were extracted from the ALPINE trial. Final analysis result of 24-month PFS (79.5% for zanubrutinib and 67.3% for ibrutinib) was used for the base-case analysis in the model. Treatment, adverse event management, other medical resource use, and subsequent treatment costs were considered in the model. The NNT, incremental cost per treated patient, and incremental cost per additional patient with progression or death were captured. Deterministic sensitivity analyses were conducted to assess parameter uncertainties and explore key model drivers. Scenario analyses were conducted to test the impact of different PFS estimates. Results: The base-case results fromthe NNT model showed that for every 8 patients treated with zanubrutinib, 1 event of progression or death would be avoided compared to using ibrutinib. The total costs per patient treated with zanubrutinib and ibrutinib are $370,558 and $430,150, respectively, with a cost savings of $59,593 associated with using zanubrutinib (Table). Drug costs and PFS have the greatest impact on the incremental cost per patient. Varying the PFS scenarios, including adjustment with drug interruption, COVID death, or treatment discontinuation, change the NNT from 8 to 12, and are associated with cost savings of $58,179 to $67,153 per zanubrutinib-treated patient in a 24-month time frame. Applying the model result to a hypothetical scenario of a clinical practice of 100 patients treated with zanubrutinib versus ibrutinib suggest that approximately 13 patients will avoid disease progression events or death. Conclusions: The NNT model suggests thatusing zanubrutinib to treat R/R CLL patients, compared to ibrutinib, will result in more favorable clinical and economic outcomes in the US.

Background: The treatment landscape for chronic lymphocytic leukemia (CLL) is evolving at a rapid pace, with development of several targeted therapies. The real-world applicability of clinical trial effectiveness is markedly influenced by treatment choices, the specific characteristics of patients' diseases, their overall health, and individual preferences. However, there is limited evidence to understand the impact of multiple treatment options on real-world effectiveness in CLL in routine clinical practice. This study aimed to characterize recent real-world treatment sequencing patterns and associated time to next treatment among patients with CLL in the United States. Methods: This retrospective observational study included patients diagnosed with CLL (≥18 years at diagnosis) from January 1, 2018, through January 1, 2023, who received ≥1 treatment after initial diagnosis. Patients were sourced from the ConcertAI RWD360 dataset, a real-world de-identified dataset >6 million patients from across the United States derived from various electronic health record systems and integrated with a large administrative open claims dataset. Patients were followed through the end of the record or death, whichever occurred first. Patients were classified into the following treatment categories: chemotherapy (including bendamustine-based and other chemotherapy), anti-CD20-based, Bruton tyrosine kinase inhibitor (BTKi)-based (ibrutinib, acalabrutinib, or zanubrutinib), and venetoclax-based therapy. Demographic and clinical characteristics, treatment sequencing pattern, and time to next treatment were examined across lines of therapy for each treatment category. Kaplan-Meier analysis was used to estimate median time to next treatment. Results: The study included 3,431 patients with CLL (median age: 69 years; male: 63.8%). There was a significant variation in average age among the 4 treatment groups ( P<0.0001). Compared with the overall population, patients who received anti-CD20-based therapy were slightly older (median age: 71 years), while patients who received venetoclax-based therapy were relatively younger (median age: 67 years). Patients were primarily treated in community rather than academic settings (76.4% vs 21.3%). First-line patients were most commonly treated with BTKi (60.1%), venetoclax (16.0%), and anti-CD20 (15.4%) regimens. Among patients who initiated BTKi therapies, zanubrutinib use (2.6%) was limited; this may be due to the recent approval date (January 2023). Among CLL patients, 35.0% received second-line treatment and BTKi stayed dominant (35.7%), followed by anti-CD20 (29.6%) and venetoclax (25.8%) therapies. From first- to second-line therapy, the prevailing sequencing pattern was from either one BTKi to another BTKi (23.5%), venetoclax to anti-CD20 (13.2%), or BTKi to an anti-CD20 (9.7%). From second- to third-line therapy, patients most frequently switched from anti-CD20 to venetoclax (24.6%), anti-CD20 to BTKi (13.3%), or one BTKi to another BTKi (12.6%). From third- to fourth-line therapy, the predominant sequencing pattern was from venetoclax to anti-CD20 (21.3%), anti-CD20 back to venetoclax (20.6%), or one BTKi to another BTKi (11.6%). Median time to next treatment in first line was significantly longest for patients receiving BTKi (53.9 months) and shortest for patients treated with venetoclax (7.7 months) ( P<0.0001) (Figure 1). Median time to next treatment in second line was not reached among patients using BTKi, while it was significantly shorter for those on venetoclax and anti-CD20 (10.4 months and 1.5 months, respectively; P<0.0001) (Figure 2). Conclusions: This studydemonstrated unique treatment sequencing patterns among patients with CLL in the real-world setting.As the most commonly used regimen, BTKi therapy was shown to have significantly improved time to next treatment compared with other treatment regimens in first and second lines of therapies. Future studies with extended follow-up are needed to allow for assessment of newer treatments and enable evaluation of long-term clinical outcomes.

AbstractIntroductionHealth information technology (HIT) has the potential to improve healthcare delivery and engagement. Studying racial‐ethnic disparities in HIT engagement will help understand and overcome challenges to healthcare utilization.MethodsWe undertook a patient‐reported survey among patients with lymphoid malignancies at two campuses of Mayo Clinic, Florida to explore HIT‐related disparities. Variables between Whites and non‐Whites, and non‐Whites from the two campuses were compared.ResultsThe survey was completed by 1004 respondents, with 71% whites, 27% non‐Whites (race‐ethnicity not reported by 2%). Non‐Whites included 30% responders at the main campus and 64% at an inner‐city campus. Whites were significantly older and had higher education, while non‐Whites had lesser access to a computer. Only 51% of non‐Whites were registered to use electronic medical records (EMR) as compared to 72% Whites (p < 0.001) and significantly lesser number of non‐Whites even knew that EMR existed (81% vs. 92%, p < 0.001). Encouragingly, a higher number of non‐Whites wanted to engage in EMR. Non‐Whites from the main campus were older, more educated and had more access to a computer as compared to those from the inner‐city campus. Similar disparate factors were noted among minorities from the two campuses, suggesting impact of socioeconomic backgrounds on EMR usage among non‐Whites. Linguistic barriers were more striking among inner‐city campus non‐Whites.ConclusionsNon‐Whites continue to struggle with suboptimal utilization of the healthcare system and barriers related to integration in HIT, including disparities representing socioeconomic differences. Efforts need to be made at several levels to help racial‐ethnic minorities overcome awareness, access, and linguistic barriers to HIT utilization.

Abstract ELEVATE-RR demonstrated noninferior progression-free survival and lower incidence of key adverse events (AEs) with acalabrutinib vs ibrutinib in previously treated chronic lymphocytic leukemia. We further characterize AEs of acalabrutinib and ibrutinib via post hoc analysis. Overall and exposure-adjusted incidence rate was assessed for common Bruton tyrosine kinase inhibitor–associated AEs and for selected events of clinical interest (ECIs). AE burden scores based on previously published methodology were calculated for AEs overall and selected ECIs. Safety analyses included 529 patients (acalabrutinib, n = 266; ibrutinib, n = 263). Among common AEs, incidences of any-grade diarrhea, arthralgia, urinary tract infection, back pain, muscle spasms, and dyspepsia were higher with ibrutinib, with 1.5- to 4.1-fold higher exposure-adjusted incidence rates. Incidences of headache and cough were higher with acalabrutinib, with 1.6- and 1.2-fold higher exposure-adjusted incidence rate, respectively. Among ECIs, incidences of any-grade atrial fibrillation/flutter, hypertension, and bleeding were higher with ibrutinib, as were exposure-adjusted incidence rates (2.0-, 2.8-, and 1.6-fold, respectively); incidences of cardiac events overall (the Medical Dictionary for Regulatory Activities system organ class) and infections were similar between arms. Rate of discontinuation because of AEs was lower for acalabrutinib (hazard ratio, 0.62; 95% confidence interval, 0.41-0.93). AE burden score was higher for ibrutinib vs acalabrutinib overall and for the ECIs atrial fibrillation/flutter, hypertension, and bleeding. A limitation of this analysis is its open-label study design, which may influence the reporting of more subjective AEs. Overall, event-based analyses and AE burden scores demonstrated higher AE burden overall and specifically for atrial fibrillation, hypertension, and hemorrhage with ibrutinib vs acalabrutinib. This trial was registered at www.clinicaltrials.gov as #NCT02477696.

Abstract Introduction: Cytokines are protein factors that regulate diverse cellular processes. The malignant progression of immunoglobulin M monoclonal gammopathy of undetermined significance (IgM-MGUS) to Waldenstrom macroglobulinemia (WM) is in part cytokine mediated, and we have previously shown IL-6 mediates IgM secretion in WM via the JAK/STAT pathway. Cytokine signaling can be epigenetically modulated by micro-RNAs (miRs). We aimed to identify the role of miRs in the regulation of inflammatory cytokine pathways between these diseases. Methods: Bone marrow samples of patients with IgM-MGUS (n=7) and WM (n=25) were prospectively collected and sorted for CD19+ and/or CD138+ malignant cells. Total RNA extraction and sequencing were performed, miR and mRNA profiling was conducted, and differential expression was calculated between WM and IgM-MGUS using a log2 fold change (FC)&gt;0.5 and ←0.5, false discovery rate&lt;0.05. Experimental differentially expressed miR-mRNA pairing was performed, and pairs were filtered for correlated expression (i.e., upregulated miR/downregulated mRNA, and vice-versa). Filtered pairs were analyzed using the Ingenuity Pathway Analysis to identify pathways between WM and IgM-MGUS with absolute activation Z-score ≥1. Results: We identified 34 differentially expressed miRs experimentally targeting 1132 mRNAs. Pathway analysis showed overall miR-based inactivation of inflammatory cytokine signaling pathways in WM compared to IgM-MGUS, especially of the interleukin (IL) family: IL-2, IL-6, IL-8, IL-9, IL-15, and IL-17. Underlying multiple pathways was upregulation of miRs-146a, 150, 194, all targets of Signal Transducer and Activator of Transcription 1 (STAT1), observed to be downregulated. Of relevance, miR-146a has been previously shown to be an inhibitor of inflammatory cytokines, including IL-6. Next, we observed upregulation of miR-142 which targets phosphoinositide-3-kinase regulatory subunit 6 (PIK3R6), observed to be downregulated. Both the STAT and PIK3 families are important cytokine signal transducers, and we have previously shown the PI3k-AKT-IkB-p65 pathway induces expression of IL-6 via a GLI2-mediated mechanism. We additionally observed granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling to be inactivated in WM. Here, miR-19b and miR-30e were upregulated, both target CSF 2 receptor subunit beta (CSF2RB), found to be downregulated. CSF2RB is the common receptor subunit of GM-CSF, IL-3, and IL-5. Conclusion: Our study identifies multiple cytokines pathways involved in inflammation and the tumor microenvironment to be potentially inactivated by differentially expressed miRs in WM compared to IgM-MGUS. Downregulation of these pathways and targeting of the STAT and PIK3 family indicates a possible miR-based negative feedback loop to down-modulate inflammatory cytokine signaling in WM. Citation Format: Karan Chohan, Jonas Paludo, Surendra Dasari, Jithma P. Abeykoon, Prashant Kapoor, Esteban Braggio, Michelle K. Manske, Aneel Paulus, Craig B. Reeder, Sikander Ailawadhi, Asher A. Chanan-Khan, Robert A. Kyle, Morie A. Gertz, Anne J. Novak, Stephen M. Ansell. Micro-RNA induced inactivation of inflammatory cytokine signaling pathways in Waldenstrom macroglobulinemia compared to IgM-MGUS. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3811.

7569 Background: B-cell lymphoma 2 inhibitors (BCL-2i) are well tolerated and effective in treating B-cell lymphoproliferative disorders such as CLL. Investigational agent lisaftoclax is a novel, oral, highly selective and potent BCL-2i. Preclinical data show a strong synergistic effect of lisaftoclax plus ibrutinib in an ibrutinib-insensitive PDXWM1 model. Methods: This global, open-label, multicenter study evaluates the safety and efficacy of lisaftoclax alone and combined with ibrutinib or rituximab in pts with WM. Pts were enrolled in 3 arms: Arm A (lisaftoclax), BTKi-resistant/intolerant pts; Arm B (lisaftoclax plus ibrutinib), treatment-naïve pts; and Arm C (lisaftoclax plus rituximab), BTKi-naïve relapsed/refractory pts. Lisaftoclax was escalated from 400 to 1,200 mg using a modified toxicity probability interval design. A 3-day ramp-up was used for pts at high TLS risk. Primary objectives were pharmacokinetics (PK), safety, and efficacy assessments; responses were assessed per IWWM criteria. Results: As of January 25, 2023, 46 pts were enrolled (Arm A [n = 14]; up to 1,000 mg; Arm B [n = 24]; up to 1,200 mg; Arm C [n = 8]; up to 800 mg). Baseline characteristics are shown in the table. Median (range) treatment duration was 6 (1-18; Arm A), 14 (1-27; B), and 8 (2-26; C) months. Overall response rates (ORRs) were: Arm A, 25% (median time to response [MTTR], 4.3 months); Arm B, 90.9% (MTTR, 1.9); Arm C, 37.5% (MTTR, 4.4). No significant difference was observed between pts with and without CXCR4-mut. At 1,200 mg, 1 DLT (grade 3 clinical TLS), due to pre-existing renal impairment, was reported. At 1,000 mg, 1 grade 3 laboratory TLS occurred in Arm B because of dehydration and active symptomatic therapies; abnormal electrolytes resolved after 1 day of drug interruption, without recurrence. Grade ≥ 3 lisaftoclax-related AEs included neutropenia (13%), leukocytopenia (4.3%), anemia (2.2%), weight loss (2.2%), and septic shock (2.2%). Ventricular arrhythmias were not observed. Only 1 pt required dose reduction (due to neutropenia). MTD has not been reached. A total of 14 pts discontinued study treatment because of disease progression (n = 5) and AE (n = 1). Lisaftoclax plus ibrutinib showed a PK exposure comparable to ibrutinib alone, indicating no potential DDI. Conclusions: Lisaftoclax alone or combined with ibrutinib/rituximab demonstrated measurable effects in pts with naïve or BTKi-treatment-failed WM. Internal study identifier: APG2575WU101. *SA and ML are co-first authors. Clinical trial information: NCT04260217 . [Table: see text]