Waldenstrom's Macroglobulinemia Research Articles

Updated efficacy and safety results of BCL-2 inhibitor lisaftoclax (APG-2575) alone or combined with ibrutinib or rituximab in patients (pts) with Waldenström macroglobulinemia (WM).

7078 Background: Lisaftoclax is a novel, oral, highly selective, potent BCL-2 inhibitor in development. In an ibrutinib-resistant patient-derived WM xenograft/preclinical model, lisaftoclax + ibrutinib has a strong synergistic effect. This report provides updated efficacy and safety data of lisaftoclax-based therapies (including combinations with ibrutinib) in pts with WM. Methods: In this global, open-label, phase 1b/2 multicenter study, pts with WM were enrolled in 3 arms: Arm A (lisaftoclax) included BTKi-resistant/intolerant pts; Arm B (lisaftoclax + ibrutinib), treatment-naïve pts; and Arm C (lisaftoclax + 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 risk of tumor lysis syndrome (TLS). Objectives were efficacy, safety, and pharmacokinetics (PK) assessments (responses assessed per IWWM criteria). Results: As of January 25, 2024, 46 pts were enrolled and treated at doses of up to 1,000 (Arm A), 1,200 (Arm B), and 800 mg (Arm C; Table). The median (range) treatment duration was 11 (1-28; Arm A), 23.5 (1-34; B), and 11.5 (5-33; C) months. Objective response rates (PR, VGFR, CR) were: 41.7% (Arm A), 90.9% (B), and 37.5% (C). In Arm A, pts with wild-type CXCR4 (n = 7) had better overall response to lisaftoclax than the CXCR4mut group (n = 3). No significant difference was observed between pts with/without CXCR4mut in Arms B and C. In Arm B, 1 DLT (grade 3 clinical TLS due to preexisting renal impairment) was reported at 1,200 mg; 1 grade 3 laboratory TLS, primarily attributed to dehydration and concomitant symptomatic therapies, occurred at 1,000 mg; abnormal electrolytes resolved after 1 day of drug interruption, without recurrence. Grade ≥ 3 lisaftoclax-related AEs included neutropenia (15.2%), thrombocytopenia (4.3%), decreased leukocytes (4.3%), TLS (4.3%), anemia (2.2%), weight loss (2.2%), and septic shock (2.2%). Ventricular arrhythmia was not observed. One pt required dose reduction because of neutropenia. The MTD was not reached. Lisaftoclax + ibrutinib showed a PK exposure comparable to lisaftoclax or ibrutinib alone, indicating no potential drug-drug interactions. Conclusions: Lisaftoclax alone and combined with ibrutinib or rituximab was well tolerated and demonstrated measurable effects in pts with naïve or BTKi-treatment-failed WM. (CT.gov: NCT04260217; Internal ID: APG2575WU101) *Co-first authors: ML and SA. Clinical trial information: NCT04260217 . [Table: see text]

A phase IIA clinical trial to evaluate a reversible Bruton’s tyrosine kinase inhibitor (BTKi) HBW-3220 capsules in patients with relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL).

e19042 Background: This clinical study is to evaluate HBW-3220, a novel BTKi with an improved in vitro profile than the existing non-covalent drugs pirtobrutinib (approved) and nemtabrutinib (Phase III). HBW-3220 shows superior inhibition against BTK wild-type and several common mutants, such as C481S, C481R, T474I, T316A, and L528W (enriched in pirtobrutinib resistance), and hematopoietic cell kinase (HCK, a key contributor to BTKi resistance due to kinase-defective BTK). Methods: This phase IIA clinical study is conducted in R/R B-NHL patients who had received two or more prior lines of treatment. The dose escalation study adopts accelerated titration and a "3+3" design, with a daily single dose of 15, 30, 60, 90, 120, or 150 mg. During the dose escalation phase, the sponsor and investigators determine whether to expand the cohort of the previous dose based on the existing data. Adverse events (AEs) are assigned according to NCI Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Response assessment is based on iwCLL 2018 guidelines for chronic lymphocytic leukemia (CLL), IWWM-7 consensus for Waldenstrom macroglobulinemia (WM), and Lugano 2014 guidelines for all other lymphomas, including small lymphocytic lymphoma (SLL), diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and follicular lymphoma (FL). Results: 29 patients have been enrolled, and the dose escalation study has been completed. No dose-limiting toxicity (DLT) occurred in any patient, implicating good tolerability. Adverse events (AEs), similar to other BTKis, were mostly Grade 1 or 2, including fever (36%), diarrhea (32%), headache (18%), anemia (39%), infectious pneumonia (18%), decreased neutrophils count (39%), decreased platelet count (29%), increased alanine aminotransferase (21%), etc. Drug-related Grade 3 AEs included decreased neutrophil count (n=3, 11%), increased lymphocyte count (n=2, 7%), and infectious pneumonia (n=2, 7%). 23 patients underwent at least 1 response assessment. The overall response rate (ORR) in CLL/SLL (all with prior irreversible BTKi treatment, and 4 of them with additional BCL2 inhibitor treatment), MZL, MCL, and DLBCL patients were 83% (5/6), 50% (2/4), 40% (2/5) and 33% (1/3), respectively. Among the ORR, 90% (9/10) were in the 90 mg and above dose group, regardless of previous BTKi treatment history or mutation status of p53 and BTK. After oral administration, the drug exposures showed dose-dependent increases. The time to maximum plasma concentration (Tmax) was 2 hours, and the elimination half-life (T1/2) was 19 hours. Conclusions: The current data show that HBW-3220 is well tolerated with no DLT occurred at daily doses up to 150 mg, displaying most promising efficacy in patients with CLL/SLL, MZL, and MCL. Clinical trial information: ChiCTR2200062537.

Simplified Risk Stratification Model for Patients With Waldenström Macroglobulinemia.

Patients with Waldenström macroglobulinemia (WM) have disparate outcomes. Newer therapies have emerged since the development of International Prognostic Scoring System, and MYD88L265P mutation is now frequently assessed at diagnosis, warranting reexamination of the prognostic parameters. We reviewed records of 889 treatment-naïve patients with active WM, consecutively seen between January 01, 1996, and December 31, 2017, to identify clinical predictors of overall survival (OS) in univariate analyses. Patients with complete data for the parameters significant on the univariate analyses (n = 341) were included in a multivariable analysis to derive a prognostic model, subsequently validated in a multi-institutional cohort. In the derivation cohort (n = 341), age (hazard ratio [HR], 1.9 [95% CI, 1.2 to 2.1]; P = .0009), serum lactate dehydrogenase (LDH) above upper limit of normal (HR, 2.3 [95% CI, 1.3 to 4.5]; P = .007), and serum albumin <3.5 g/dL (HR, 1.5 [95% CI, 0.99 to 2.3]; P = .056) were independently prognostic. By assigning a score of 1 point each to albumin <3.5 g/dL (HR, 1.5) and age 66-75 years (HR 1.4) and 2 points for age >75 years (HR, 2.6) or elevated LDH (HR, 2.3), four groups with distinct outcomes were observed on the basis of the composite scores. Five-year OS was 93% for the low-risk (score 0), 82% for low-intermediate risk (score 1), 69% for intermediate-risk (score 2), and 55% for the high-risk (score ≥3; P < .0001) groups. In the validation cohort (N = 335), the model maintained its prognostic value, with a 5-year OS of 93%, 90%, 75%, and 57% for the four groups, respectively (P < .0001). Modified Staging System for WM (MSS-WM), utilizing age, albumin, and LDH is a simple, clinically useful, and externally validated prognostic model that reliably risk-stratifies patients with symptomatic WM into four groups with distinct prognosis.

Waldenstrom Macroglobulinemia Recurrence with Bing–Neel Syndrome Presentation

Bing–Neel syndrome (BNS) is a rare condition that may occur in patients with Waldenstrom macroglobulinemia (WM) and is caused by lymphoplasmacytic infiltration into the central nervous system. BNS is an extramedullary manifestation of WM which may present with various neurological signs and symptoms that make the diagnosis difficult to achieve. We present a case of BNS in a 60-year-old patient diagnosed 6 years after recovering from Waldenstrom’s macroglobulinemia. We observed the patient for a secondary generalized focal motor seizure. Unenhanced brain CT revealed slight hyperdensity of left parietal subarachnoid spaces. The MRI of the brain and spinal cord showed leptomeningeal enhancement in both parietal lobes. The presence of monoclonal bands (light chain k and IgM) was found in cerebrospinal fluid, leading to the diagnosis of BNS. The patient started treatment with ibrutinib and remains clinically stable during a 1-year follow-up. However, the MRI showed the appearance of a new subcortical left parietal lesion. BNS is an extremely rare presentation of WM that should be recognized and considered early in the presence of unexplained neurological symptoms in patients with a history of WM, even if the patient appears to have recovered.

Unexpectedly high levels of 25-hydroxycholecalciferol in a patient with waldenstrom macroglobulinemia

Unexpectedly high levels of 25-hydroxycholecalciferol in a patient with waldenstrom macroglobulinemia

Optimizing BTK Inhibition in Waldenström Macroglobulinemia.

Bruton tyrosine kinase (BTK) inhibitors have become a standard of care in the treatment of patients with Waldenström macroglobulinemia (WM) and are the only medications approved by the FDA to treat these patients. As more patients with WM are treated with BTK inhibitors in the United States and worldwide, it is essential to optimize this therapy by selecting the patients who are more likely to benefit from it, and by managing the unique adverse effects associated with these agents. Herein, we propose a genomic-driven approach to selecting patients with WM who are more likely to experience fast, deep, and durable responses to BTK inhibitors, and provide practical strategies for managing adverse effects, including BTK inhibitor dose reductions, switching to other BTK inhibitors, and abandoning BTK inhibitor therapy. Ongoing clinical trials are evaluating covalent and noncovalent BTK inhibitors alone and in combination, as well as BTK degraders, with exciting results, making the horizon for BTK-targeting therapies in WM bright and hopeful.

A phase II study of ibrutinib in combination with ixazomib in patients with Waldenström macroglobulinaemia.

This phase II study evaluated time-limited (24 cycles) treatment with ibrutinib and ixazomib in newly diagnosed (NDWM; n = 9) and relapsed/refractory (RRWM; n = 12) Waldenström macroglobulinaemia (WM). The overall response rate (ORR) was 76.2% (n = 16) in 21 evaluable patients with no patient achieving a complete response (CR). The median duration of treatment was 15.6 months, and after a median follow-up time of 25.7 months, the median progression-free survival (PFS) was 22.9 months. While the primary end-point was not met (CR rate at any time) and 28.5% discontinued treatment due to toxicity, ibrutinib plus ixazomib led to a clinically meaningful ORR and PFS. Combined Bruton's tyrosine kinase (BTK) and proteasome inhibition merits further evaluation in WM.

Impact of the presence and number of chromosomal abnormalities on the clinical outcome in Waldenström Macroglobulinemia: a monocentric experience.

The prognostic and predictive role of specific gene mutations in Waldenström Macroglobulinemia (WM) is well-ascertained whereas the clinical impact of chromosome aberrations is far less known. Recent work has provided initial evidence for an adverse prognostic impact of some aberrations, such as del(6q), while other studies suggest a possible relationship between some clinical features (e.g. advanced age and/or inflammatory status) and specific cytogenetic abnormalities. To add to the still limited knowledge on WM cytogenetics and its clinical implications, we herein report our experience in a cohort of WM patients across 23years. Based on our retrospective study, we found that abnormal karyotype was more represented in older patients and maintained a statistically significant independence from other molecular, clinical, and biological features related to WM. The presence and number of cytogenetic aberrations correlated with inferior overall and progression-free survival outcomes regardless of the type of single chromosome aberration. Our data suggests that the role of the altered karyotype deserves to be further clarified especially in elderly WM patients, in whom cytogenetic abnormalities and disease biology appear to be characterized by a higher degree of complexity.

Baseline immunoglobulin G and immune function in non-Hodgkin lymphoma: a retrospective analysis.

Non-Hodgkin's lymphoma (NHL) encompasses a diverse group of lymphoma subtypes with a wide range in disease course. Previous studies show that hypogammaglobulinemia in treatment-naïve patients is associated with poorer survival in high grade B-cell non-Hodgkin's lymphomas, though it is not known how this applies across all B-cell lymphoid malignancies. We conducted a retrospective study of immunoglobulin levels and clinical outcomes including survival, hospitalization, and infection rates in patients diagnosed with B-cell non-Hodgkin lymphomas of all grades at our institution. Two-hundred twenty-three adults (aged = 18 years) with available pre-treatment IgG levels were selected, with hypogammaglobulinemia defined as IgG< 500 mg/mL. For this analysis, we grouped DLBCL (n=90), Primary CNS (n=5), and Burkitt lymphoma (n=1) together as high-grade, while CLL (n=52), mantle cell (n=20), marginal zone (n=25), follicular (n=21), and Waldenstrom macroglobulinemia (n=5) were low-grade. The incidence of hypogammaglobulinemia in our cohort of both high and low-grade lymphoma patients was 13.5% (n=30). Across all NHL subtypes, individuals with baseline IgG< 500 mg/dL showed an increased rate of hospitalization (4.453, CI: 1.955-10.54, p= 0.0005) and higher mortality (3.325, CI: 1.258, 8.491, p= 0.013), yet no association in number of infections when compared with those with IgG=500 mg/dL. There was a higher hospitalization rate (3.237, CI: 1.77-6.051, p=0.0017) in those with high-grade lymphoma with hypogammaglobulinemia when compared with low-grade. There was no statistically significant difference in individuals who were alive after three years in those with baseline IgG<500 mg/dL. Our study is the first to analyze incidence of hypogammaglobulinemia at the time of diagnosis of NHL as a potential biomarker of interest for future outcomes including hospitalization and infection.

Early progression is associated with worse survival in patients with Waldenström’s macroglobulinemia

Early progression of disease within 24 months (POD24) of diagnosis is associated with inferior overall survival (OS) in follicular lymphoma, but its prognostic role in Waldenström’s macroglobulinemia (WM) is still unclear. Here, we performed a retrospective analysis of 373 patients pooled from the database of the Chinese Registration Network for WM (CRNWM) to determine the outcomes of early progressors. POD24 occurred in 98 evaluable patients (26.3%). The median OS in patients with POD24 was 40 months (95%CI: 15.2–64.0), which was significantly shorter than that without POD24 (156 months, 95%CI: 123.6–188.4; HR: 6.587, 95% CI 4.392–9.881, P < 0.0001). Moreover, subgroup analysis showed that POD24 still maintained its predictive ability of inferior OS in patients treated with rituximab or bortezomib-based treatment. Patients with a very high-risk rIPSSWM stage were more likely to have POD24 (P = 0.020). In conclusion, POD24 was associated with poorer survival and may represent a useful endpoint in future prospective clinical trials.

A phase 2, open-label study of ibrutinib plus rituximab in Japanese patients with Waldenstrom’s macroglobulinemia

Ibrutinib is a first-in-class Bruton kinase inhibitor against B-cell neoplasms including Waldenström macroglobulinemia (WM). This study evaluated the efficacy and safety of ibrutinib-rituximab in Japanese patients with WM. Patients received ibrutinib 420 mg orally once daily plus weekly rituximab 375 mg/m2 IV (8 infusions total). The primary end point was major response rate (MRR; PR or better) by Independent Review Committee assessment. Secondary endpoints were progression-free survival (PFS), safety, pharmacokinetics, and biomarkers. Primary analysis was conducted in 16 patients [baseline, treatment naïve: 8 (50.0%); relapsed/refractory WM: 8 (50.0%)] who received ibrutinib-rituximab, after all patients completed Week 57 or end of treatment. At primary analysis, MRR was 87.5% [14/16 patients; 95% CI: 61.7, 98.4%; p < 0.0001 (null hypothesis: 32% response rate)]. At final analysis (median study intervention duration: 34.4 months, median follow-up: 35.0 months), MRR was unchanged at 87.5%, but VGPR [6/16 (37.5%)] and PR [8/16 (50.0%)] improved. Prior treatment status did not affect response. At final analysis, median PFS was not reached [36-month PFS rate: 86% (95% CI: 55, 96%)]. No critical safety signals were reported. This study demonstrated a positive benefit/risk profile of ibrutinib-rituximab in Japanese patients with WM, consistent with the iNNOVATE study.

Abstract CT144: Safety and efficacy of HMPL-523 (Syk inhibitor) in patients with relapsed or refractory lymphoma

Abstract Background: HMPL-523, a selective oral Syk inhibitor, demonstrated encouraging benefit-risk profile in 2 Phase 1 (P1) studies in relapsed/refractory (R/R) lymphoma patients (pts) in USA/Europe (NCT03779113) and China (NCT02857998). In the 16 response-evaluable pts in the dose-escalation portion (Part 1) of study NCT03779113, 4 responses were noted, including complete responses (CRs) in R/R hodgkin lymphoma (HL) and follicular lymphoma (FL) pts (Strati et al. Blood 2021). Here, we report the results from the dose expansion portion (Part 2) of the study NCT03779113. Methods: Safety and efficacy of HMPL-523, at the recommended phase 2 dose (RP2D) of 700 mg QD, was evaluated in lymphoma pts who have exhausted all approved therapy options. Treatment emergent adverse events (TEAEs) were assessed per NCI CTCAE v5.0. Responses were assessed by investigators at weeks 8, 16, and 24, and then every 12 weeks. Results: As of 14 July 2023, 47 pts were enrolled in the Part 2 [25 HL, 9 Peripheral T cell lymphoma (PTCL), 7 Chronic lymphocytic leukemia (CLL), 2 each of FL and Mantle cell lymphoma (MCL), and 1 each with Marginal zone lymphoma (MZL) and Waldenström's macroglobulinemia (WM)]. Median age was 57 (Range:21-93) years, 55% were males, 85% were Caucasian, 47% had ECOG status of 1, 81% were disease stage ≥3 and 17% had B-symptoms at study entry. Median prior lines of therapy was 4 (range 1 - 12); 86% of CLL pts were prior BTK treated and 88% of HL pts had both a PD-1 inhibitor and Brentuximab vedotin. With a median drug exposure of 2.9 months, the overall response rate (ORR) among 41 efficacy evaluable pts was 26.8% and disease control rate (DCR) was 65.9% [4 CR (9.8%), 7 PR (17.1%) and 16 SD (39.0%)]. The median time-to-response was 1.9 months. Among HL pts (N=24), ORR was 25.0% and DCR was 66.7% [2 CR (8.3%), 4 PR (16.7%) and 10 SD (41.7%)]. Among PTCL pts (N=7), ORR and DCR were 42.9% [2 CR (28.6%) and 1 PR (14.3%)]. The median duration of response (DOR) was not reached for HL pts and was 5.7 months (2.0 - NR) in PTCL. Two pts (one each with HL and PTCL) with disease control were taken off treatment to be consolidated with allogenic stem cell transplant. At cut-off, 1 pt each with CLL (N=5 ) and WM (N=1) demonstrated a PR. Serious TEAEs occurred in 18 pts (38.3%), of which 4 (8.5%) were considered treatment-related (TRAE). Grade≥3 TRAEs were noted in 15 pts (31.9%); the most common Grade≥3 TRAEs (&amp;gt;5%) were alanine aminotransferase increase 4 (8.5%) and febrile neutropenia 3 (6.4%). Dose interruption due to TEAEs occurred in 23 pts (48.9%) and dose reduction in 4 pts (8.5%). Two pts (4.3%), 1 each with TEAE of thrombocytopenia and pruritis had drug discontinued. Conclusion: HMPL-523 was well tolerated at the RP2D of 700 mg QD in R/R lymphoma pts. Encouraging proof of activity was demonstrated in heavily pre-treated HL and PTCL pts. Additional studies are needed to evaluate the value of SYK-inhibitor as either monotherapy or combination in these high unmet-need population. Citation Format: Paolo Strati, Eva Gonzalez-Barca, Daniel Morillo, Sairah Ahmed, Dominik Chraniuk, Sirpa Leppa, Fatima de la Cruz Vicente, Piotr Centkowski, Rathi N. Pillai, Shivani Nanda, Alisha Khullar, Marjo Hahka-Kemppinen, Vijayvel Jayaprakash, Giuseppe Gritti. Safety and efficacy of HMPL-523 (Syk inhibitor) in patients with relapsed or refractory lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT144.

Abstract CT156: A Phase I study evaluating AC676, an innovative BTK chimeric degrader, in patients with relapsed and refractory B-cell malignancies

Abstract Study Background Bruton tyrosine kinase (BTK) is a key signaling molecule that plays a central role in B-cell receptor transduction. The development of drugs that inhibit BTK has transformed the management of patients with B-cell malignancies. However, therapy using covalent BTK inhibitors such as ibrutinib, and non-covalent inhibitors such as pirtobrutinib, can still result in resistance, primarily due to the development of mutations in BTK including residues C481 and L528. AC676 was designed as a chimeric degrader to target and degrade BTK using Accutar's proprietary Protein-Protein Interaction Targeting Chimeras (PPI-TAC) platform. By effectively linking a BTK ligand to the cereblon E3-ligase recruiting ligand, AC676 brings BTK in proximity to cereblon, thereby inducing subsequent ubiquitination and degradation of BTK. AC676 degrades BTK proteins irrespective of mutations; including C481, kinase dead L528 and others, and thus may be effective for the treatment of patients who progress on both covalent and non-covalent BTK inhibitors. Notably, it is also effective in cell lines expressing gain of function PLCG2 mutants, suggesting that it removes BTK’s scaffolding function. AC676 does not degrade cereblon neo-substrates, so neutropenia is not expected to be an on-target effect. This abstract describes an ongoing first in human Phase 1 trial of AC676. Study Description AC676-001 is a Phase 1 dose-escalation study of AC676 administered orally once daily as monotherapy in patients with relapsed and refractory B-cell malignancies. Approximately 60 patients may be enrolled. Eligible patients must be ≥ 18 years, and have one of the following histologically confirmed relapsed or refractory disease types: Chronic lymphocytic leukemia and small lymphocytic lymphoma, Diffuse large B cell lymphoma - non-GCB subtype, Follicular lymphoma, Mantle cell lymphoma, Marginal zone lymphoma, Lymphoplasmacytic lymphoma including Waldenstrom macroglobulinemia. Patients must have received at least two prior systemic therapies or have no other standard of care therapies to provide significant clinical benefit. Patients must have measurable disease per disease-specific response criteria and Eastern Cooperative Oncology Group performance status≤ 1. Dose-escalation will begin with an accelerated titration phase, followed by a standard 3+3 phase. AC676 is administered orally once daily on a 28 day per cycle schedule at doses ranging from 50mg to 600mg. The primary objective of the study is to evaluate the safety and tolerability of AC676. Secondary objectives include the evaluation of anti-tumor activity and the pharmacokinetic profile following single and multiple doses. Study enrollment began in April 2023 with three sites currently open in the United States (NCT05780034). Citation Format: Jennifer Woyach, Michael Tees, Nancy Mota, Gladys Brown, Su Young Kim, Manish R. Patel. A Phase I study evaluating AC676, an innovative BTK chimeric degrader, in patients with relapsed and refractory B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT156.

Ibrutinib (Imbruvica)

&#x0D; CADTH reimbursement reviews are comprehensive assessments of the clinical effectiveness and cost-effectiveness, as well as patient and clinician perspectives, of a drug or drug class.&#x0D; The assessments inform non-binding recommendations that help guide the reimbursement decisions of Canada's federal, provincial, and territorial governments, with the exception of Quebec.&#x0D; This review assesses ibrutinib (Imbruvica), 140 mg capsule, oral.&#x0D; Indication: For the treatment of adult patients with:&#x0D; &#x0D; Waldenström macroglobulinemia (WM) as a monotherapy or in combination with rituximab&#x0D; Previously untreated active chronic lymphocytic leukemia (CLL), including patients with 17p deletion&#x0D; CLL who received at least one prior therapy, in combination with bendamustine and rituximab&#x0D; Relapsed or refractory mantle cell lymphoma (MCL)&#x0D; marginal zone lymphoma (MZL) who require systemic therapy and have received at least one prior anti-CD20-based therapy&#x0D; Steroid-dependent or refractory chronic graft vs. host disease (cGVHD)&#x0D; &#x0D; &#x0D;

Bruton Tyrosine Kinase Inhibition: an Effective Strategy to Manage Waldenström Macroglobulinemia.

The treatment of Waldenström macroglobulinemia (WM) has evolved over the past decade. With the seminal discoveries of MYD88 and CXCR warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) mutations in WM cells, our understanding of the disease biology and treatment has improved. The development of a new class of agents, Bruton tyrosine kinase inhibitors (BTKi), has substantially impacted the treatment paradigm of WM. Herein, we review the current and emerging BTKi and the evidence for their use in WM. Clinical trials have established the role of covalent BTKi in the treatment of WM. Their efficacy is compromised among patients who harbor CXCR4WHIM mutation or MYD88WT genotype. The development of BTKC481 mutation-mediated resistance to covalent BTKi may lead to disease refractoriness. Novel, non-covalent, next-generation BTKi are emerging, and preliminary results of the early phase clinical trials show promising activity in WM, even among patients refractory to a covalent BTKi. Covalent BTK inhibitors have demonstrated meaningful outcomes in treatment-naïve (TN) and relapsed refractory (R/R) WM, particularly among those harboring the MYD88L265P mutation. The next-generation BTKi demonstrate improved selectivity, resulting in a more favorable toxicity profile. In WM, BTKi are administered until progression or the development of intolerable toxicity. Consequently, the potential for acquired resistance, the emergence of cumulative toxicities, and treatment-related financial burden are critical challenges associated with the continuous therapy approach. By circumventing BTK C481 mutations that alter the binding site to covalent BTKi, the non-covalent BTKi serve as alternative agents in the event of acquired resistance. Head-to-head comparative trials with the conventional chemoimmunotherapies are lacking. The findings of the RAINBOW trial (NCT046152), comparing the dexamethasone, rituximab, and cyclophosphamide (DRC) regimen to the first-generation, ibrutinib are awaited, but more studies are needed to draw definitive conclusions on the comparative efficacy of chemoimmunotherapy and BTKi. Complete response is elusive with BTKi, and combination regimens to improve upon the efficacy and limit the treatment duration are also under evaluation in WM.

Use of Vonicog Alpha and Acquired von Willebrand Syndrome, a New Approach: A Case Report.

Therapeutic management of acquired von Willebrand syndrome (AVWS) can be challenging, particularly in cases of AVWS associated with monoclonal IgM such as Waldenström macroglobulinemia (WM) where several therapeutic options may be ineffective. Here, we describe the case of an 88-year-old patient who developed AVWS during follow-up for WM. The presence of a severe bleeding symptomatology not controlled by several therapies (plasma-derived von Willebrand factor, plasmapheresis) led us to introduce a supplementation with recombinant von Willebrand factor, vonicog α (Veyvondi, Takeda, Japan), starting at a dose of 50 IU/kg/d. This supplementation allowed clinical (no further bleeding) and biological (hemoglobin level, von Willebrand factor parameters) improvements. Because of the persistence of bleeding risk factors, the treatment was maintained at a prophylactic dose (20 UI/kg three times a week), without recurrence of bleeding events for a period of 9 months.

Abstract 6044: EPriL: A platform for the rapid identification of degraders of inhibitor-resistant kinases

Abstract Heterobifunctional kinase degraders (HKDs) are an important new class of therapeutic modalities, of which the first have recently entered clinical trials. HKDs are small molecules that comprise a kinase-of-interest binding moiety and an E3 ligase binding moiety connected via a spacer. HKDs are excellently suited to target kinases that have a scaffolding function, or that are resistant against conventional inhibitors. A HKD brings a kinase and an E3 ligase in proximity forming a ternary complex leading to ubiquitin-dependent catalytic degradation of the kinase of interest. This ternary complex formation is unique for each kinase which can make HKDs highly specific. To discover novel HKDs, we have developed a platform called Energetically Privileged Ligands (EPriLs), which is based on a macrocycle scaffold that binds non-covalently in the kinase ATP pocket with near-covalent affinity, and allows binding to kinases that have acquired known inhibitor resistance mutations. The macrocyclic structure allows attachment of E3 ligase ligands with multiple exit vectors. With the EPriL platform, we have developed novel HKDs for various clinically relevant kinase targets, including Bruton’s Tyrosine Kinase (BTK). BTK inhibitor drugs are used as first line treatment for chronic lymphocytic leukemia (CLL), Waldenström macroglobulinemia (WM) and as second line treatment for mantle cell lymphoma (MCL). Despite their great success in the clinic, many patients on BTK inhibitors relapse eventually, mostly because of the emergence of resistance mutations in the BTK protein. These include BTKC481S, which abrogates binding of covalent drugs, and BTKT474I, BTKL528W and BTKV416L which preclude binding of non-covalent inhibitors like pirtobrutinib. HKDs can combat resistance by degrading such BTK variants, and by removing the scaffold function of BTK. BTK degraders such as NX-5948 and NX-2127 are currently in clinical Phase 1. To show the applicability of the EPriL platform for the discovery of novel BTK degraders, we screened a library of more than 100 EPriL HKDs for biochemical binding to BTK, and tested their propensity to induce degradation of HiBiT-tagged BTKWT, BTKC481S and BTKT474I in HEK293 cell lines. The degrading activity of hits was verified through western blot on the BTK-dependent DLBCL cell line TMD8. The best degraders - based on potency and efficacy - were tested in cell proliferation assays on a panel of TMD8 BTK mutant cell lines. In these lines, endogenous BTK was mutated by CRISPR to BTKC481S, BTKT474I, BTKL528W or BTKV416L. Several BTK degraders had potent (&amp;lt; 20 nM IC50) antiproliferative activity on most TMD8 lines, including difficult-to-target variants such as BTKV416L and BTKL528W. The unique binding mode of the EPriL scaffold thus translates to broad activity on resistance variants, while its selectivity ensures minimal degradation of off-target tyrosine kinases as observed for other degraders. Citation Format: Michelle Muller, Jos de Man, Joost C. Uitdehaag, Freek van Cauter, Sander van Gemert, Milan Hoffmann, Yvonne G. van Mil, Winfried R. Mulder, Martine B. Prinsen, Jan Gerard Sterrenburg, Diep Vu, Joeri de Wit, Erik Ensing, Rogier C. Buijsman. EPriL: A platform for the rapid identification of degraders of inhibitor-resistant kinases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6044.

From Biological Activity to Stereoselectivity: A Portrait of Molecular and Mechanistic Profiles of the Therapeutic Potential of G-1 and LNS8801 as GPER-1 Activator in the Treatment of Waldenström’s Macroglobulinemia

Therapeutic activation of G protein-coupled estrogen receptor 1 (GPER-1) shows promise for treating Waldenström's Macroglobulinemia (WM). Recently, the selective small-molecule agonist G-1 or its enantiomer LNS8801 were reported as potent GPER-1 pharmacological activators, however, the molecular events surrounding their chirality towards GPER-1 is still unexplored. This study aimed to explore the molecular events surrounding the chirality of the selective small-molecule agonists G-1 and LNS8801 towards GPER-1. Molecular docking and dynamics simulations revealed strong binding affinities and key amino acid residues involved in the activation process. The results revealed favourable binding affinities of -29.87kcal/mol, and -28.09kcal/mol for G-1 and LNS8801 towards GPER-1, respectively. Per-residue energy decomposition and time-dependent analysis proved that Arg253 and Arg254 are key amino acid residues in binding these activators towards GPER-1. The activators affected stability, flexibility, and structure of GPER-1. G-1 exhibited greater rigidity when bound to GPER-1 compared to LNS880. This study's findings illuminate chirality and the potential for optimizing the enantiomer ratio to enhance inhibitory effects. These results could also reveal the molecular specifics and binding mechanism of the G-1 and its enantiomer LNS8801 with GPER-1, laying the basis for the rational design of enhanced chiral molecules against WM.

Abstract 4813: Demographic, treatment, and survival patterns in Hispanic vs. non-Hispanic patients with lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia: A national retrospective analysis from the National Cancer Database

Abstract Background: Lymphoplasmacytic lymphoma (LPL) is a rare type of non-Hodgkin B cell lymphoma. Waldenstrom macroglobulinemia (WM) is a form of LPL that presents with overproduction of IgM monoclonal protein. The understanding and treatment of LPL/WM has improved. However, few studies analyze LPL/WM in Hispanic (HI) patients specifically. This study aims to evaluate demographics, treatment, and survival patterns in HI vs. Non-Hispanic (NH) patients with LPL/WM. Methods: Data were analyzed on LPL/WM patients in the US reported to the NCDB from 2004-2019. Demographic and treatment characteristics were compared between ethnic groups. Kaplan-Meier and Cox regression analyses were used to compare overall survival (OS) between HI and NH. Multivariate analysis and propensity score matching were performed with adjustment for age, stage, co-morbidity score, insurance status, type of facility and great circle distance (GCD). Results: 17,915 patients were identified. 92% were NH, 3% were HI. Most patients were male in both NH and HI (p = 0.120). The median age at diagnosis for HI was 68 vs. 71 for NH (p &amp;lt; 0.001). Most HI and NH were white (87% HI, 91% NH p &amp;lt; 0.001). More HI were uninsured (8% HI, 1% NH p &amp;lt; 0.001) and were less likely to have government sponsored insurance (60% HI, 66% NH p &amp;lt; 0.001). Regarding income, most NH (42%) were in the $63,000+ bracket while most HI were in the $48,000-$62,999 bracket. Regarding education, reported in percent quartiles with no high school degree, most HI (41%) were in the &amp;gt; 21% bracket while most NH (35%) were in the 7-12.9% bracket (p &amp;lt; 0.001). Most HI (43%) were treated at academic/research programs; most NH were treated at comprehensive community cancer programs (38.4%, p &amp;lt; 0.001). Regarding comorbidities score, 9% of HI scored ≥ 2 vs 8% of NH (p 0.029). Regarding GCD, the median distance in miles between the patient’s residence and the hospital that reported the case, HI lived at a median of 6.7 miles vs 9 miles for NH (p &amp;lt; 0.001). Regarding treatment, 68% of HI were given treatment vs. 62% of NH (p &amp;lt; 0.001). There was no difference in mortality between HI vs. NH (30 day mortality p = 0.322; 90 day mortality p = 0.217). On survival analysis, the survival probability at 2, 5 and 10 years of HI vs NH were 81% vs 83%, 69% vs 68%, and 52% vs 46%, respectively. The median survival time (MS) was 10.6 years for HI vs 9 years for NH. There was no OS difference between HI vs. NH (p = 0.47). On multivariate analysis, there were no independent variables associated with better or worse OS. The propensity matched analysis showed no MS difference between HI vs NH (8.96 y vs. 8.74 y). Conclusion: We identified ethnic differences in age, race, insurance, education, income, location of treatment, GCD, staging, and treatment patterns. However, there was no statistically significant ethnic difference in MS or OS. Citation Format: Maria Elena Fierro, Heidi Latiolais, Qianquian Liu, Joel Michalek, Adolfo Enrique Diaz Duque. Demographic, treatment, and survival patterns in Hispanic vs. non-Hispanic patients with lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia: A national retrospective analysis from the National Cancer Database [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4813.

Long-term results of Waldenström macroglobulinaemia treatment by bendamustine and rituximab: A study on behalf of the French Innovative Leukemia Organization (FILO).

The bendamustine-rituximab (BR) schedule is an efficient first-line therapy in Waldenström macroglobulinaemia (WM). A previous analysis of 69 patients who received this treatment confirmed a high response rate and good progression-free (PFS) and overall survival (OS). With a median follow-up of 76.1 months (95% confidence interval [CI] 69.9-80.6), 5-year outcome is still excellent at 66.63% (95% CI 56.09-79.17) for PFS and 80.01% (95% CI 70.82-90.41) for OS. The rate of secondary cancers is 17.66% (IQR 7.99-27.64) at 66 months. Relapsed patients who received ibrutinib as second-line clearly benefited from this schedule. This confirms current recommendations suggesting BR long-term efficacy as first-line option in WM.