Bruton Tyrosine Kinase Inhibitor Acalabrutinib Research Articles

Three-year cardiovascular and non-cardiovascular adverse events in patients with chronic lymphocytic leukemia or small cell lymphocytic lymphoma treated with Bruton tyrosine kinase inhibitors acalabrutinib or ibrutinib: a real-world analysis.

Bruton tyrosine kinase (BTK) inhibitors play an important role in targeted treatment of B-cell lymphoproliferative disorders. However, adverse events may limit the proper course of treatment in many patients. The purpose of this study is to compare the risk of cardiovascular and non-cardiovascular adverse events in patients with chronic lymphocytic leukemia (CLL) or small cell lymphocytic lymphoma (SLL) treated with the first-generation BTK inhibitor ibrutinib versus second-generation acalabrutinib, using real-world data from a collaborative multinational network. We used data from the network (TriNetX), which encompasses more than 100 healthcare organizations worldwide. We queried the database for patients aged ≥ 18 years with chronic lymphocytic leukemia or small-cell lymphomas treated with ibrutinib or acalabrutinib in the past ten years before the analysis. We used propensity score matching to balance the cohorts. The 3-year cumulative incidences and hazard ratios for the following outcomes were calculated: atrial flutter or fibrillation, other arrhythmias, heart failure, ischemic stroke or peripheral embolism, acute coronary syndrome, bleeding, and sepsis. We compared 2,107 patients in each group. Atrial fibrillation or flutter occurred in 150 (7.1%) patients with acalabrutinib and 310 (14.7%) patients with ibrutinib during the 3-year follow-up (hazard ratio, 0.68, 95% CI 0.55-0.84). New-onset hypertension occurred in 342 (16.3%) patients in the acalabrutinib group and 584 (27.7%) patients in the ibrutinib group (hazard ratio 0.81, 95% CI 0.66-0.98). Sepsis was diagnosed in 136 (6.5%) patients in the acalabrutinib group versus 239 (11.3%) patients in the ibrutinib group (hazard ratio 0.77, 95 CI 0.60-0.98). The two groups had no significant differences concerning the other adverse events. In a large retrospective cohort using real-world data from electronic medical registers, patients with CLL or SLL treated with acalabrutinib had a better cardiovascular and non-cardiovascular safety profile than those treated with ibrutinib, with lower risks of atrial flutter or fibrillation, new-onset arterial hypertension, and sepsis.

Cardiotoxicity from bruton tyrosine kinase inhibitors (BTKi)—an analysis of an administrative health claims database

BackgroundFirst generation Bruton tyrosine kinase inhibitors (BTKi) such as ibrutinib have been associated with cardiovascular toxicities. Newer generation BTKi (e.g.,acalabrutinib and zanabrutinib) have been associated with lower incidence of cardiotoxicity in clinical trials.ObjectiveGiven paucity in real-world data on the overall cardiac risk factor profile, especially with the newer BTKi, our study evaluated the incidence of cardiotoxicity with various BTKi among a large, commercially insured population of patients.MethodsWe performed a retrospective cohort analysis of all adults with a diagnosis of B-cell malignancy undergoing treatment with BTKi acalabrutinib and ibrutinib between January 2018 and June 2020 using Optum’s de-identified Clinformatics® Data Mart Database. We then identified patients who had pre-existing cardiac disease one year prior to starting BTKi. New incidence of atrial fibrillation/flutter, hypertension, bleeding, ventricular tachycardia/fibrillation and sudden cardiac death from the time of index presciption were compared with standard Chi Square or Student t-test where appropriate. Multivariate logistic regression models were also estimated to evaluate for confounding.ResultsA total of 1691 patients were included in the final analysis. 1595 (94%, median age 75 (19–90) years, 61% male gender) patients received ibrutinib, and 96 (6%, median age 73.5 (32–90) years, 62.5% male gender) patients received acalabrutinib. The median duration of drug exposure of ibrutinib was 238 (2-1084) days vs. 150 (30–870) days for acalabrutinib. There was lower new incidence of atrial fibrillation/flutter (4.6%-vs-17%, p = 0.013), hypertension (6.3%-vs-25%, p = NS), sudden cardiac arrest/death (0% vs. 1.5%, p = NS) in the acalabrutinib group compared to ibrutinib, of which only the lower incidence of atrial fibrillation/flutter was statistically significant. This was despite the finding of a higher prevalence of atrial fibrillation/flutter at baseline in patients receiving acalabrutinib.ConclusionsThere was lower incidence of new atrial fibrillation/flutter with acalabrutinib when compared to ibrutinib in a real-world cohort of patients.

Bruton's tyrosine kinase inhibition limits endotoxic shock by suppressing IL-6 production by marginal zone B cells in mice.

Sepsis is a systemic inflammatory response to a severe, life-threatening infection with organ dysfunction. Although there is no effective treatment for this fatal illness, a deeper understanding of the pathophysiological basis of sepsis and its underlying mechanisms could lead to the development of new treatment approaches. Here, we demonstrate that the selective Bruton's tyrosine kinase (Btk) inhibitor acalabrutinib augments survival rates in a lipopolysaccharide (LPS)-induced septic model. Our in vitro and in vivo findings both indicate that acalabrutinib reduces IL-6 production specifically in marginal zone B (MZ B) cells rather than in macrophages. Furthermore, Btk-deficient MZ B cells exhibited suppressed LPS-induced IL-6 production in vitro. Nuclear factor-kappa B (NF-κB) signaling, which is the downstream signaling cascade of Toll-like receptor 4 (TLR4), was also severely attenuated in Btk-deficient MZ B cells. These findings suggest that Btk blockade may prevent sepsis by inhibiting IL-6 production in MZ B cells. In addition, although Btk inhibition may adversely affect B cell maturation and humoral immunity, antibody responses were not impaired when acalabrutinib was administered for a short period after immunization with T-cell-independent (TI) and T-cell-dependent (TD) antigens. In contrast, long-term administration of acalabrutinib slightly impaired humoral immunity. Therefore, these findings suggest that Btk inhibitors may be a potential option for alleviating endotoxic shock without compromising humoral immunity and emphasize the importance of maintaining a delicate balance between immunomodulation and inflammation suppression.

Abstract 7586: TOX loss-of-function(TOXLOF)results in BCR hyperactivation andenhanced responses to BCR-targeting in diffuse large B cell lymphomas (DLBCL)

Abstract DLBCL originate from germinal center B cells (GCB). The ABC-DLBCL subtype, characterized by activation of B-cell receptor (BCR) signaling and downstream NF-kB pathway, carries a poor outcome. Up to 30% of ABC-DLBCL present TOXLOF mutations, suggesting that TOX function as a tumor suppressor. Our analysis of TOX expression along the germinal center B-cell differentiation program (naïve → GCB → plasma cells) showed that TOX expression paralleled NF-kB activity with highest levels in plasma cells (P<0.001, vs. either naïve and GCB). We thus propose that TOX acts as a transcriptional gatekeeper in GCB cells to prevent early activation of NF-kB thus enabling differentiation into plasma cells while restraining lymphomagenesis. We generated a conditional GCB TOX KO mouse model, induced the GC reaction with a T-cell antigen and found that TOX KO (vs. TOX WT, 10 mice per condition) had impaired differentiation of plasma cells (p<0.001) and hyperproliferative Ki67+ GCB cells (p<0.05). We then generated (by CRISPR) an isogenic TOXLOF ABC-DLBCL cell line (TMD8) and found upregulation of genes in the NF-kB pathway (q-value <0.05, vs. TMD8). Furthermore, TMD8-TOXLOF cells showed increased secretion of autocrine cytokines IL6 and IL10, and higher STAT3 phosphorylation (p<0.05 for all comparisons, vs. TMD8-TOXWT cells) all compatible with NF-kB activation. Tumor microenvironmental cues can hyperactivate BCR and downstream NF-kB in ABC-DLBCL. We thus implanted isogenic TMD8 cells in mice (n = 10) and determined pathway activation by phospho-flow. We found massive activation of SYK, BTK, PLCG2 (from the BCR) and p65 (from NF-kB) in TMD8-TOXLOF vs. TMD8-TOXWT tumors (all p<0.01), and vs. these cell lines cultured in vitro (all p<0.01). To determine whether these features can be therapeutically exploited, we conducted a viability screening using a panel of 20 clinical-phase targeted therapies relevant to ABC-DLBCL. We found that BTK inhibitor acalabrutinib (BCR pathway) and MALT1 inhibitor JNJ67690246 (NF-kB pathway) were 2-3 fold more active in TMD8-TOXLOF vs. TMD8-TOXWT cells (all p<0.05). We then xenografted isogenic TMD8 cells (n = 10 mice per condition) and, when tumors reached 150 mm3, we randomized mice to vehicle vs. acalabrutinib 30 mg/kg/day by oral gavage (human dose equivalent). Acalabrutinib was significantly more active in TMD8-TOXLOF tumors (vs. TMD8-TOXWT, p=0.0008), which translated into significantly prolonged survival (p<0.05). This acalabrutinib effect was accompanied by significant reduction of BTK, SYK and PLCG2 phosphorylation in TMD8-TOXLOF tumors (p<0.0001, all comparisons). Thus, TOXLOF leads to hyperactivation of the BCR and NF-kB signaling pathways in ABC-DLBCL cells, rendering them hypersensitive to BCR-targeted therapies, delineating a potential mechanism-based therapeutic approach for ABC-DLBCL TOXLOF patients. Citation Format: Eloisi Caldas Lopes, Maria Revuelta, Rossella Marullo, Leandro Cerchietti. TOX loss-of-function(TOXLOF)results in BCR hyperactivation andenhanced responses to BCR-targeting in diffuse large B cell lymphomas (DLBCL) [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 7586.

Abstract C139: The IRAK4 inhibitor emavusertib (CA-4948) synergizes with second generation BTK inhibitors acalabrutinib and zanubrutinib in MYD88-L265P mutated lymphoma cell lines

Abstract Background. IRAK4 is a protein kinase downstream the Toll-like receptor (TLR), activated through the adaptor protein MYD88, crucial for the signaling cascade that leads to NF-κB-mediated cytokine and survival factor expression. Somatic mutations in the gene coding for the adaptor protein MYD88 are common in lymphoid tumors. In particular, the MYD88-L265P mutations, known to sustain NF-κB activation, is specifically observed in a fraction of the activated B cell (ABC) diffuse large B-cell lymphomas (DLBCL), in the vast majority of lymphoplasmacytic lymphoma (LPL), and in rare marginal zone lymphomas (MZLs). So far, no success has been achieved to directly inhibit MYD88. Emavusertib (CA-4948) is an IRAK4 inhibitor, which has shown preclinical activity in ABC DLBCL and MZL models, especially in cases bearing the MYD88-L265P. We and others have shown synergism when combining emavusertib with the first generation BTK inhibitor ibrutinib. Clinical trials are on-going exploring emavusertib as single agent or in combination in patients with hematological cancers or solid tumors. Since ibrutinib is associated with possible toxicities that can outbalance its clinical efficacy, here, we have tested the combination of emavusertib with acalabrutinib and zanubrutinib, two 2nd generation BTK inhibitors that have shown improved safety profile in clinical trials. Methods. Cell lines were exposed to five increasing concentrations of each compound as single agent or in combination for 72 h, followed by MTT assay. The beneficial effect of the combinations compared to the single agents was considered both as synergism according to the Chou-Talalay combination index and as potency and efficacy according to the MuSyC algorithm. Results. Cell lines bearing the MYD88-L265P mutation and derived from ABC DLBCL (OCI-Ly-10, TMD8, HBL1) or MZL/LPL (Karpas-1718) were exposed to emavusertib, acalabrutinib or zanubrutinib as single agent or in combination. Synergism, defined as a median Chou-Talalay index < 0.9, was observed for both the combination of emavusertib plus acalabrutinib and for the combination of emavusertib plus zanubrutinib in all four cell lines. Based on the MuSyC algorithm, the synergistic activity of emavusertib was mainly due to an improved efficacy (i.e., maximal effect) rather than improved potency (i.e., minimal active dose) of the BTK inhibitors. Conclusions. In MYD88-L265P mutated lymphoma cell lines, synergism is observed combining the IRAK4 inhibitor emavusertib with the 2nd generation BTK inhibitors acalabrutinib and zanubrutinib. Our data sustain further clinical exploration of the combination of IRAK4 and BTK inhibitors for lymphoma patients. Citation Format: Francesca Guidetti, Alberto J. Arribas, Eleonora Cannas, Emanuele Zucca, Anastasios Stathis, Reinhard von Roemeling, Francesco Bertoni. The IRAK4 inhibitor emavusertib (CA-4948) synergizes with second generation BTK inhibitors acalabrutinib and zanubrutinib in MYD88-L265P mutated lymphoma cell lines [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C139.

CD19-Directed CAR T-Cells (CD19-CAR) Combined with Acalabrutinib Achieves Durable Remissions in Patients with Relapsed or Refractory (r/r) Mantle Cell Lymphoma (MCL)

Background: MCL is an aggressive non-Hodgkin lymphoma (NHL) subtype which remains incurable despite improvements in progression free survival with consolidative autologous transplant and the introduction of novel targeted therapies [Dreyling et al. Blood 2012]. CD19-directed chimeric antigen receptor (CAR) T-cell therapy (CD19-CAR) has shown durable disease control in r/r MCL, but current standard of care products are limited by high rates of grade 3+ immune-related toxicities [Wang et al. NEJM 2020]. We hypothesized that combining a naïve/stem-memory (T N/SCM) phenotype-enriched CD19-CAR T-cell product with the selective BTK inhibitor (BTKi) acalabrutinib would attenuate the rates of severe toxicities, improve durable remission rates, and obviate the need for indefinite use of acalabrutinib in r/r MCL. Methods: We conducted a phase 1 single center, prospective clinical trial (NCT04484012) evaluating a single infusion of T N/SCM-enriched CD19.28.z.EGFRt-CAR at a target dose of either 2x10 8 (DL1) or 5x10 8 (DL2) CAR+ cells (≤20% lower dose allowed) in combination with ongoing acalabrutinib 100 mg twice daily for patients with r/r MCL after at least 1 prior line of therapy. Patients were required to undergo at least 3 months but less than 7 months of treatment with a BTKi prior to enrollment without evidence of progression and with measurable disease per Lugano criteria. All patients were switched to acalabrutinib for protocol therapy prior to lymphodepletion, and planned to continue until day 180 post CD19-CAR infusion at which time all therapy would be discontinued. We report outcomes from the dose finding portion of the study. Descriptive statistics were utilized for baseline characteristics and survival analyses were calculated utilizing the Kaplan-Meier method. Investigator-assessed response rates were based on Lugano criteria. Minimal residual disease (MRD) status was determined using either multiparameter flow cytometry (FCM) or next-generation sequencing (NGS). Results: To date, 8 patients enrolled and have received CD19-CAR (n=4 at DL1; n=4 at DL2). Manufacturing was successful in 100% of patients. Median time from leukapheresis to product infusion was 53 days (range, 41-114). Treated patients were 75% male; with a median age of 63 years (range, 38-70); and median number of prior therapies of 2 (range, 2-3). All patients had bone marrow involvement, and had high risk features including progression of disease within 24 months (n=6), relapse after autologous HCT (n=2), TP53 mutations (n=6), Ki-67 ≥30% (n=4), and/or complex karyotype (n=1). Prior to enrollment, all patients had received BTKi (n=8 acalabrutinib) for a median of 6.1 months (range, 4.5-7.3). No BTK and PLC-γ mutations were detected in patients with available samples. The combination of acalabrutinib and CD19-CAR was well tolerated; 5 patients (63%; n=1 grade 2; n=4 grade 1) had cytokine release syndrome (CRS), with no severe cases. No patients (0%) had immune effector cell associated neurotoxicity syndrome (ICANS) [Figure 1A]. No patient required corticosteroids for toxicity management, and only 2 patients (n=2/5, 40%) required tocilizumab for CRS. There were no serious adverse events (SAEs), and no treatment discontinuations due to AEs observed. The best ORR was 88% [n=6 CR (75%); n=1 PR (13%)], with median time to best response of 28 days. In those 6 patients who achieved CR, 2 patients were FCM-MRD negative (<10 -4) and 2 were NGS-MRD negative (<10 -6) (n=4/6, 67%) [Figure 1B]. After a median follow-up of 18.5 months (range, 8.3-28.9), 5 of 6 patients remain in CR, while1 patient who achieved an initial CR relapsed at 9.2 months. At 1-year post-infusion, the cumulative incidence of relapse and NRM were 30% (95% CI, 3%-67%) and 0%, respectively. The 1-year PFS and OS were 70% (95% CI: 22%-92%) and 100%, respectively. Conclusion: The combination of CD19-CAR with acalabrutinib was well tolerated and effective, yielding an ORR 88% and MRD- rate 50% in a cohort of patients with high-risk MCL. Notably, CRS events were manageable and low grade, and no ICANS was observed. Enrollment is ongoing in the expansion cohort (DL2), and additional clinical and correlative analyses will be presented at the meeting.

A Matching-Adjusted Indirect Comparison of Acalabrutinib with and without Obinutuzumab Versus Zanubrutinib in Treatment-Naïve Chronic Lymphocytic Leukemia

Introduction The second-generation Bruton tyrosine kinase inhibitors acalabrutinib (acala) and zanubrutinib (zanu) have not been compared with each other in a head-to-head randomized controlled trial (RCT). Acala with and without obinutuzumab (obin) was evaluated in the ELEVATE-TN RCT in treatment-naïve patients with chronic lymphocytic leukemia (CLL). Zanu was evaluated in treatment-naïve patients with CLL/small lymphocytic leukemia (SLL) in cohorts 1 and 2 of the SEQUOIA RCT. We used an unanchored matching-adjusted indirect comparison (MAIC) to compare the efficacy and safety of acala ± obin versus zanu in patients with treatment-naïve CLL/SLL without del(17p). Datasets were derived from comprehensive individual patient data (IPD) from ELEVATE-TN and published aggregate data from cohort 1 in SEQUOIA. Methods In this unanchored MAIC, we weighted IPD for the acala + obin and acala monotherapy arms from ELEVATE-TN to match zanu baseline data from SEQUOIA. We excluded patients with del(17p) in ELEVATE-TN to match cohort 1 in SEQUOIA, which excluded patients with del(17p). Patients were matched based on variables considered prognostic and/or predictive of investigator-assessed progression-free survival (INV-PFS) in an exploratory multivariate Cox-regression analysis of ELEVATE-TN. These were age, ECOG status, Binet stage, bulky disease, B2 microglobulin, cytopenia, del(11q), trisomy 12, IGHV status,and TP53 mutation. The efficacy analysis assessed INV-PFS in randomized patients (acala + obin, n = 162; acala monotherapy, n = 163; zanu, n = 241) using the Oct 2021 data cut-off (DCO) for ELEVATE-TN and the Oct 2022 DCO for SEQUOIA (median follow-up 58 versus 44 months). Pseudo-IPD for INV-PFS for zanu were obtained from Kaplan-Meier curves. The safety analysis assessed the incidence of adverse events (AEs) and reported the odds ratios (ORs) of AEs in treated patients (acala + obin, n = 162; acala monotherapy, n = 162; zanu, n = 240). To compare the incidence of AEs, the ELEVATE-TN Sep 2020 DCO was used to match the median follow-up from the SEQUOIA Oct 2022 DCO (47 versus 44 months). Results In the efficacy analysis, the acala + obin and acala monotherapy effective sample sizes (ESSs) post-matching were 124 (76%) and 105 (64%), respectively. Matching had little impact on acala + obin and acala monotherapy INV-PFS (Figure 1). Post-matching, 36-month INV-PFS was higher with acala + obin (95%; 95% CI: 90-97) than with zanu (84%; 95% CI: 79-88). The MAIC-weighted Cox hazard ratio (HR) found INV-PFS to be superior with acala + obin versus zanu (HR: 0.41; 95% CI: 0.23-0.74; Figure 1). No evidence of a difference between acala monotherapy post-matching and zanu was found when looking at 36-month INV-PFS (86%; 95% CI: 78-91 versus 84%; 95% CI: 79-88; HR: 0.91; 95% CI: 0.53-1.56). In the safety analysis, the acala + obin and acala monotherapy ESSs post-matching were 123 (76%) and 103 (64%), respectively. There were no significant differences in the odds of having most types of AE with acala + obin versus zanu, except for higher odds of having any grade neutropenia (OR: 2.19; 95% CI: 1.33-3.60) and arthralgia (OR: 2.33; 95% CI: 1.37-3.96). Acala monotherapy showed lower odds of having any grade hypertension (OR: 0.44, 95% CI: 0.20-0.99; Figure 2) and no significant differences in the odds of having other types of AEs versus zanu. Conclusions In this MAIC of ELEVATE-TN and SEQUOIA evaluating patients with treatment-naïve CLL/SLL without del(17p), acala + obin had a longer INV-PFS versus zanu, while there was no evidence of a difference between acala monotherapy and zanu. Acala + obin and acala monotherapy generally had similar safety profiles to zanu. However, acala monotherapy was associated with lower odds of any grade hypertension versus zanu, while acala + obin was associated with higher odds of any grade neutropenia and arthralgia versus zanu. Although the results of MAIC analyses can only be hypothesis-generating, these results address an important data gap by systematically comparing these two commonly used regimens where randomized, prospective data are not available.

A Phase 2 Study of Acalabrutinib, Umbralisib, and Ublituximab (AU2) in Treatment-Naïve and Relapsed or Refractory Chronic Lymphocytic Leukemia (CLL)

Background Targeting the B-cell receptor (BCR) signaling pathway is highly effective for the treatment of CLL. However, attainment of undetectable minimal residual disease (uMRD) is infrequent with current BCR targeting strategies. Here, we report results of a phase 2 study testing time-limited dual BCR inhibitor therapy with a BTK inhibitor acalabrutinib and a PI3Kδ inhibitor umbralisib. With the goal of enhancing depth of remission, a glycoengineered anti-CD20 antibody ublituximab was initiated during Cycle (C) 7. Methods In this investigator-sponsored trial, eligible patients with treatment-naïve (TN) or relapsed or refractory (RR) CLL received up to 24 cycles of AU2 (NCT04624633). Each cycle was 28 days. Daily oral doses of acalabrutinib (100mg BID) and umbralisib (800mg QD) began on C1 Day (D) 1. Ublituximab IV began on C7 for 6 cycles (D1, 2, 8, and 15 of C7, D1 of C8-12). Treatment was stopped after C12 if patients achieved complete response (CR) by IWCLL criteria, while all others continued acalabrutinib and umbralisib until C24. In March 2023, umbralisib was withdrawn from drug development, and those who were receiving study therapy at the time continued acalabrutinib alone until C24. The primary endpoint was the CR rate after C24. MRD was assessed in peripheral blood (PB) and bone marrow (BM) using multi-color flow cytometry at 10 -4. Results The study enrolled 29 patients from December 2020 to January 2022. The median age at enrollment was 63 years (range 40-77). Most patients were male (62%), had TN CLL (72%), and had unmutated IGHV (79%). RR CLL patients had a median of 1 prior line of therapy, most frequently (88%) with chemoimmunotherapy. Genetic alterations were commonly observed at study enrollment, including deletion 17p or TP53 mutation (21%), deletion 11q or ATM mutation (38%), trisomy 12 (24%), and mutations of NOTCH1(45%), SF3B1 (24%), and RAS/RAF pathway (21%). 7% had complex karyotype defined as ≥3 abnormalities. At a median follow-up of 23 months (range 2-29), with 7 patients still receiving therapy prior to reaching C24, there were no deaths, Richter's transformations, or CLL progression events on the study. The rates of CR, BM uMRD, and PB uMRD at best response were 30%, 44%, and 67%, respectively (Table 1). There were no statistically significant differences in CR and uMRD rates between TN and RR groups at best response. CR and BM uMRD rates improved during the second year of therapy (CR rate: 11% after C12, 28% after C24; BM uMRD rate: 22% after C12, 39% after C24). PB uMRD occurred earlier than BM uMRD, and the rate (44%) remained unchanged between C12 and C24. After completion of study therapy, PB MRD was monitored every 3 months. Five patients had MRD conversion at the end of therapy or shortly after treatment cessation. Median time from the last uMRD to detectable MRD (dMRD) in PB was 3 months (range 3-6). Most (80%, n=4/5) patients with MRD conversion had partial response or dMRD in BM at best response. Two patients stopped treatment early (due to the diagnosis of second cancer and G4 transaminitis, in 1 patient each). In addition, 7 (24%) patients stopped umbralisib between C15-19 due to discontinuation of drug supply; these patients remained on acalabrutinib monotherapy until C24. All others completed up to 24 cycles of treatment including 3 (10%) patients who stopped therapy per protocol after C12 once CR was achieved. Dose reduction of umbralisib (38%) was more common than acalabrutinib (7%) and was most frequently due to diarrhea (21%) and transaminitis (14%). Only 2 (7%) patients required temporary dose reduction of acalabrutinib to avoid drug-drug interaction. Notable adverse events included diarrhea or colitis (76%, 10% Grade 3 or higher [G≥3]), bruising (69%, 0% G≥3), transaminitis (62%, 17% G≥3), COVID-19 infection (55%, 7% G≥3), hypertension (52%, 10% G≥3), rash (24%, 0% G≥3), and pneumonitis (7%, 3% G≥3). One (3%) patient had Pneumocystis jirovecii pneumonia while being off of mandatory prophylaxis due to non-compliance. None had atrial fibrillation. Conclusions Dual inhibition of the BCR signaling pathway with up to 2 years of AU2 provided a time-limited treatment option for TN and RR CLL patients. Immune-related adverse events were frequently observed and required dose reduction of umbralisib in 38% of the patients but most were then able to stay on therapy. Longer follow-up is required to determine durability of remission off therapy.

BET inhibition targets ABC-DLBCL constitutive B-cell receptor signaling through PAX5.

B-cell receptor (BCR) signaling is essential for the diffuse large B-cell lymphoma (DLBCL) subtype that originates from activated B-cells (ABCs). ABC-DLBCL cells are sensitive to Bruton tyrosine kinase intervention. However, patients with relapsed or refractory ABC-DLBCL had overall response rates from 33% to 37% for Bruton tyrosine kinase inhibitors, suggesting the evaluation of combination-based treatment for improved efficacy. We investigated the efficacy and mechanism of the bromodomain and extraterminal motif (BET) inhibitor AZD5153 combined with the Bruton tyrosine kinase inhibitor acalabrutinib in ABC-DLBCL preclinical models. AZD5153 is a bivalent BET inhibitor that simultaneously engages the 2 bromodomains of BRD4. Adding AZD5153 to acalabrutinib demonstrated combination benefits in ABC-DLBCL cell line and patient-derived xenograft models. Differential expression analyses revealed PAX5 transcriptional activity as a novel downstream effector of this drug combination. PAX5 is a transcription factor for BCR signaling genes and may be critical for perpetually active BCR signaling in ABC-DLBCL. Our analyses further indicated significant alterations in BCR, RELB/alternative NF-κB, and toll-like receptor/interferon signaling. Validation of these results mapped a positive-feedback signaling loop regulated by PAX5. We demonstrated that AZD5153 decreased PAX5 expression, whereas acalabrutinib disruption of BCR signaling inhibited PAX5 activation. Furthermore, several interferon levels were decreased by AZD5153 and acalabrutinib in tumors. Adding interferon-beta1 (IFNβ1) to cells treated with acalabrutinib partially rescued PAX5 activation. Our results demonstrate that AZD5153 enhances the efficacy of acalabrutinib through PAX5 and BCR mechanisms that are critical for ABC-DLBCL.

Ibrutinib impairs IGF-1-dependent activation of intracellular Ca handling in isolated mouse ventricular myocytes.

The Bruton tyrosine kinase (BTK) inhibitor Ibrutinib is associated with a higher incidence of cardiotoxic side effects including heart failure (HF). Ibrutinib is capable of inhibiting PI3K/Akt signaling in neonatal rat ventricular cardiomyocytes when stimulated with insulin-like growth factor 1 (IGF-1). We therefore hypothesized that Ibrutinib might disrupt IGF-1-mediated activation of intracellular Ca handling in adult mouse cardiomyocytes by inhibiting PI3K/Akt signaling. Isolated ventricular myocytes (C57BL6/J) were exposed to IGF-1 at 10 nmol/L in the presence or absence of Ibrutinib (1 µmol/L) or Acalabrutinib (10 µmol/L; cell culture for 24 ± 2 h). Intracellular Ca handling was measured by epifluorescence (Fura-2 AM) and confocal microscopy (Fluo-4 AM). Ruptured-patch whole-cell voltage-clamp was used to measure ICa. Levels of key cardiac Ca handling proteins were investigated by immunoblots. IGF-1 significantly increased Ca transient amplitudes by ∼83% as compared to vehicle treated control cells. This was associated with unaffected diastolic Ca, enhanced SR Ca loading and increased ICa. Co-treatment with Ibrutinib attenuated both the IGF-1-mediated increase in SR Ca content and in ICa. IGF-1 treated cardiomyocytes had significantly increased levels of pS473Akt/Akt and SERCA2a expression as compared to cells concomitantly treated with IGF-1 and Ibrutinib. SR Ca release (as assessed by Ca spark frequency) was unaffected by either treatment. In order to test for potential off-target effects, second generation BTK inhibitor Acalabrutinib with greater BTK selectivity and lower cardiovascular toxicity was tested for IGF1-mediated activation of intracellular Ca handling. Acalabrutinib induced similar effects on Ca handling in IGF-1 treated cultured myocytes as Ibrutinib in regard to decreased Ca transient amplitude and slowed Ca transient decay, hence implying a functional class effect of BTK inhibitors in cardiac myocytes. Inhibition of BTK by Ibrutinib impairs IGF-1-dependent activation of intracellular Ca handling in adult ventricular mouse myocytes in the face of disrupted Akt signaling and absent SERCA2a upregulation.

SOHO State of the Art Updates and Next Questions | Infections in Chronic Lymphocytic Leukemia Patients: Risks and Management.

Although chronic lymphocytic leukemia (CLL) is a malignancy characterized by accumulation of tumor cells in the blood, bone marrow, lymph nodes and secondary lymphoid tissues, the hallmark of the disease and the major cause of death for patients with CLL is actually immune dysfunction and associated infections. Despite improvement in treatment based on combination chemoimmunotherapy and targeted treatment with BTK and BCL-2 inhibitors leading to longer overall survival for patients with CLL, the mortality due to infections have not improved over the last 4 decades. Thus, infections are now the main cause of death for patients with CLL, posing threats to the patient whether during the premalignant state of monoclonal B lymphocytosis (MBL), during the watch & wait phase for treatment naïve patients, or upon treatment in terms of chemoimmunotherapy or targeted treatment. To test whether the natural history of immune dysfunction and infections in CLL can be changed, we have developed the machine learning based algorithm CLL-TIM.org to identify these patients. The CLL-TIM algorithm is currently being used for selection of patients for the clinical trial PreVent-ACaLL (NCT03868722), testing whether short-term treatment with the BTK inhibitor acalabrutinib and the BCL-2 inhibitor venetoclax can improve immune function and decrease the risk of infections for this high-risk patient population. We here review the background for and management of infectious risks in CLL.

Differential Regulation of GPVI-Induced Btk and Syk Activation by PKC, PKA and PP2A in Human Platelets.

Bruton's tyrosine kinase (Btk) and spleen tyrosine kinase (Syk) are major signaling proteins in human platelets that are implicated in atherothrombosis and thrombo-inflammation, but the mechanisms controlling their activities are not well understood. Previously, we showed that Syk becomes phosphorylated at S297 in glycoprotein VI (GPVI)-stimulated human platelets, which limits Syk activation. Here, we tested the hypothesis that protein kinases C (PKC) and A (PKA) and protein phosphatase 2A (PP2A) jointly regulate GPVI-induced Btk activation in platelets. The GPVI agonist convulxin caused rapid, transient Btk phosphorylation at S180 (pS180↑), Y223 and Y551, while direct PKC activation strongly increased Btk pS180 and pY551. This increase in Btk pY551 was also Src family kinase (SFK)-dependent, but surprisingly Syk-independent, pointing to an alternative mechanism of Btk phosphorylation and activation. PKC inhibition abolished convulxin-stimulated Btk pS180 and Syk pS297, but markedly increased the tyrosine phosphorylation of Syk, Btk and effector phospholipase Cγ2 (PLCγ2). PKA activation increased convulxin-induced Btk activation at Y551 but strongly suppressed Btk pS180 and Syk pS297. PP2A inhibition by okadaic acid only increased Syk pS297. Both platelet aggregation and PLCγ2 phosphorylation with convulxin stimulation were Btk-dependent, as shown by the selective Btk inhibitor acalabrutinib. Together, these results revealed in GPVI-stimulated platelets a transient Syk, Btk and PLCγ2 phosphorylation at multiple sites, which are differentially regulated by PKC, PKA or PP2A. Our work thereby demonstrated the GPVI-Syk-Btk signalosome as a tightly controlled protein kinase network, in agreement with its role in atherothrombosis.

Bruton's Tyrosine Kinase inhibition by Acalabrutinib does not affect early or advanced atherosclerotic plaque size and morphology in Ldlr-/- mice

Atherosclerosis is characterized by the accumulation of lipids and immune cells, including mast cells and B cells, in the arterial wall. Mast cells contribute to atherosclerotic plaque growth and destabilization upon active degranulation. The FcεRI-IgE pathway is the most prominent mast cell activation route. Bruton's Tyrosine Kinase (BTK) is involved in FcεRI-signaling and may be a potential therapeutic target to limit mast cell activation in atherosclerosis. Additionally, BTK is crucial in B cell development and B-cell receptor signaling. In this project, we aimed to assess the effects of BTK inhibition on mast cell activation and B cell development in atherosclerosis.In human carotid artery plaques, we showed that BTK is primarily expressed on mast cells, B cells and myeloid cells. In vitro, BTK inhibitor Acalabrutinib dose-dependently inhibited IgE mediated activation of mouse bone marrow derived mast cells. In vivo, male Ldlr−/− mice were fed a high-fat diet for eight weeks, during which mice were treated with Acalabrutinib or control solvent. In Acalabrutinib treated mice, B cell maturation was reduced compared to control mice, showing a shift from follicular II towards follicular I B cells. Mast cell numbers and activation status were not affected. Acalabrutinib treatment did not affect atherosclerotic plaque size or morphology. In advanced atherosclerosis, where mice were first fed a high-fat diet for eight weeks before receiving treatment, similar effects were observed.Conclusively, BTK inhibition by Acalabrutinib alone did neither affect either mast cell activation nor early- and advanced atherosclerosis, despite the effects on follicular B cell maturation.

The BTK inhibitor acalabrutinib reduces or eliminates clinical reactivity during oral challenge to peanut in allergic adults

The BTK inhibitor acalabrutinib reduces or eliminates clinical reactivity during oral challenge to peanut in allergic adults

Experience of using acalabrutinib therapy in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma

Introduction. Thanks to scientific advances and discoveries in the study of tumor cell biology, new effective drugs for the treatment of chronic lymphocytic leukemia/ small lymphocytic lymphoma have emerged. Currently, there are drugs with different application points at the molecular level. One such drug is acalabrutinib, which is a selective second-generation inhibitors of Bruton tyrosine kinase and has a more favorable toxicity profile.Objective. To evaluate the efficacy of acalabrutinib in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma.Materials and methods. Since February 2020 acalabrutinib (100 mg 2 p/day orally) has been administered to 7 patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (mean age 64 years) at the Hematology Research Center. Six patients received acalabrutinib in 1st-line therapy and one patient received acalabrutinib in 2nd-line therapy. The mean comorbidity index (CIRS) of the patients was 10 points (range, 8 to 14). Most patients had at least one of the adverse prognostic factors - IGHV nonmutated gene status, TP53 gene aberration (del17p13 and/or TP53 gene mutation), complex karyotype disorders.Results. All patients achieved partial remission of the disease (overall response 100% in the form of regression of B-symptoms, lymphocytic leukocytosis, splenomegaly) at the control period of treatment with acalabrutinib +12 months. The most frequent adverse events when taking acalabrutinib were the occurrence of headache in the first month of taking the drug, spontaneous subcutaneous hematomas. No hematologic toxicity, infectious complications, or cardiac complications were noted. At a median follow-up of 34 months, no patient showed disease progression.Conclusions. The selective Bruton tyrosine kinase inhibitor acalabrutinib has demonstrated high efficacy in patients with adverse risk factors, good tolerability and minimal toxicity, including in comorbid patients.

Changes in the T Helper Cell Compartment during Treatment with the BTK Inhibitor Acalabrutinib

Interactions with T helper cells are part of the supportive lymph node microenvironment promoting chronic lymphocytic leukemia (CLL) cell growth and survival. Treatment of CLL patients with ibrutinib, the first-in-class BTK inhibitor, induces profound changes in the T cell compartment, with normalization of elevated T cell numbers and plasma cytokine levels, and diversification of the T cell receptor (TCR) repertoire (Yin Q et al., J Immunol 2017). Acalabrutinib, a second generation BTK inhibitor, is more selective for BTK, with less off-target effects towards other kinases, including IL-2-inducible T cell kinase (ITK), an important kinase for T cell signaling. To characterize acalabrutinib effects on T cell numbers and function in patients with CLL, we analyzed serial samples from 12 acalabrutinib-treated CLL patients at baseline, after 1 week, and after 1, 3, 6, and 12 months of continuous acalabrutinib treatment (with monthly Obinutuzumab added during months 3-9) in an ongoing Phase 2 trial (NCT04505254). Six age-matched healthy donors (HD) were analyzed for comparison. T cell subsets were characterized by flow cytometry. Functional T cell response were assessed after stimulation with phorbol myristate acetate and ionomycin, and proliferation by Ki-67 expression. Prior to treatment, untreated CLL patients had elevated numbers of CD4+ (1864±32/ml) and CD8+ (2533±452/ml, mean T cells which normalized after 12 months of therapy (CD4+ 514±65/ml, p<0.01; and CD8+ 747±271/ml, p<0.05). Two key subsets, T follicular helper cells (Tfh) and T regulatory cells (Tregs), also decreased significantly after 12 months of treatment (Tfh from 2.9±0.4% to 0.2±0.1%, p<0.05; and Tregs from 2.4±0.4% to 0.9±0.2%, p<0.05). Next, we analyzed expression of Tfh and Treg surface markers and found significant down-modulation of CD69 (on Tfh from 20±3.7% to 3.3±0.6%, p<0.001; on Tregs from 10±1.8% to 1.7±0.5%, p<0.01), ICOS (on Tfh from 33±2.6% to 13±1.6%, p<0.01), PD-1 (on Tregs from 7.8±1.3% to 1.2±0.3%, p<0.01), and CTLA-4 (on Tfh from 16±3.2% to 3.8±1.0%, p<0.05; on Tregs from 14±1.5% to 3.1±0.7%, p<0.001) after 12 months of treatment. Additionally, this therapy resulted in reduced cytokine production by Tfh and Tregs when compared to baseline samples, as quantified by flow cytometry after cytoplasmatic staining. For example, induced IL-21 expression decreased from 23±1.3% in baseline samples to 12±0.5% after 12 months, p<0.05 (for comparison, 5.7%±1.3% in HD), IL-10 decreased from 7.3±1.1% to 0.9±0.2% at 12 months, p<0.05 (0.9%±0.1% in HD), and TGFb (from 6.2±0.9% to 0.8±0.2% at 12 months, p<0.01 (1.6%±0.5% in HD). Moreover, circulating Tfh cells from pre-treatment samples expressed higher levels of the co-stimulatory molecule CD40L upon restimulation at baseline compared to after 12 months of treatment and the levels in HD (from 23.0±1.6% to 11.0±1.1% at 12 months, p<0.05; versus 3.8%±1.0% in HD, p<0.001). Looking at Ki-67 expression, we noted, as expected, a significant decrease in CLL cell proliferation from 3.9±0.8% down to 0.8±0.6% after 1 month of therapy (p<0.001), similar data were seen at later time points. Interestingly, Tregs also had reduced Ki-67 expression, down from 16±0.6% to 7.3±0.9% after 6 months (p<0.01) and to 7.9%±1.1% after 12 months of therapy (p<0.05). Collectively, the reduction in T cells and T helper cell subset numbers, along with changes in surface activation markers, and reduced cytokine and Ki-67 expression suggest that an activated pre-treatment T helper cell compartment normalizes during continuous acalabrutinib therapy. These findings are reminiscent of the T cell data from patients receiving ibrutinib therapy, suggesting that off-target effects of the BTK inhibitor may not dictate T helper cell changes, and these may rather be due to activation by the CLL clone, which diminishes as the underlying disease responds to treatment.

MAJIC: a phase III trial of acalabrutinib+venetoclax versus venetoclax+obinutuzumab in previously untreated chronic lymphocytic leukemia or small lymphocytic lymphoma.

Here we describe the rationale and design of MAJIC, a phase III, prospective, multicenter, randomized trial comparing the combination of the BTK inhibitor acalabrutinib plus the BCL2 inhibitor venetoclax versus the combination of venetoclax plus obinutuzumab as frontline treatment for chronic lymphocytic leukemia or small lymphocytic lymphoma. In both treatment arms, disease response (assessed by International Workshop on Chronic Lymphocytic Leukemia criteria) and minimal residual disease will be used to guide therapy duration, with all patients ultimately discontinuing treatment after a maximum of 2years. The primary end point is progression-free survival. Key secondary end points include rates of undetectable minimal residual disease, overall response and overall survival. This study will address key unanswered questions in frontline chronic lymphocytic leukemia/small lymphocytic lymphoma therapy by investigating the optimal duration of finite treatment and identifying the optimal venetoclax doublet regimen.

Cardiotoxicity of BTK inhibitors: ibrutinib and beyond

Introduction The development of Bruton’s Tyrosine Kinase (BTK) inhibitors has transformed the treatment of B-cell malignancies and other non-malignant conditions. Management of the unique cardiotoxic profile of these agents requires prompt recognition and a multi-disciplinary approach. Areas Covered The increasing indications and addition of newer agents to clinical practice and emergence of BTK inhibitor-related cardiac adverse events have complicated the management decisions for utilization of this class of therapy. We review the incidence, mechanisms, and management approaches for BTK inhibitor-related atrial fibrillation, hypertension, and ventricular arrhythmias. Expert Opinion The newer BTK inhibitor acalabrutinib represents a new standard of care in front-line chronic lymphocytic leukemia (CLL) given the results of the ELEVATE-RR trial demonstrating comparable efficacy and a more favorable toxicity profile especially with regards to cardiac adverse events as compared to ibrutinib. Often not recognized by clinicians, BTK inhibitor-induced hypertension is common and can be severe, requiring prompt recognition and initiation or adjustment of anti-hypertensive medications to prevent major adverse cardiac outcomes. Novel BTK inhibitors in development are being designed to overcome the patterns of resistance from first-generation agents and to minimize off-target kinase activity, with promising toxicity profiles in early trials.

New Treatment Options for Newly-Diagnosed and Relapsed Chronic Lymphocytic Leukemia.

The better understanding of the biology of chronic lymphocytic leukemia (CLL) gained over the past decade has led to the development and introduction of several targeted drugs, with an demonstrable improvement in the prognosis for this currently incurable condition. Currently, Bruton's tyrosine kinase (BTK) inhibitors, phosphoinositide 3-kinase (PI3K) inhibitors, venetoclax, and CD20 monoclonal antibodies are the key elements in the treatment of both previously untreated and relapsed/refractory CLL patients. Ibrutinib was the first BTK inhibitor approved for clinical use, and showed excellent efficacy and an acceptable safety profile. Following this, the better-tolerated second-generation irreversible BTK inhibitors acalabrutinib and zanubrutinib have been introduced for the treatment of lymphoid malignancies, and acalabrutinib was approved for CLL. When used as single drugs, BTK inhibitors are given continuously until unacceptable toxicity or disease progression; however, when combined with venetoclax and/or CD20 antibodies, they induce deeper response and can be given for a limited time. Recently, promising new reversible BTK inhibitors pirtobrutinib and nemtabrutinib were discovered, and these seem to be more active and better tolerated than their irreversible predecessors. However, they are in an early phase of development and are not currently approved for CLL. The phosphatidylinositol 3-kinase (PI3K) inhibitors idelalisib and duvelisib are highly effective in patients with relapsed CLL, including high-risk disease. The major limitations for their use are adverse events, mostly of autoimmune origin (hepatitis, enteritis/colitis, and pneumonitis). Otherwise, cellular therapies like allogeneic hematopoietic stem cell transplantation and chimeric antigen receptor (CAR) T cells and bispecific monoclonal antibodies offer promise for patients who have failed BTK inhibitors and venetoclax treatment. In the coming years, it is likely that novel targeted therapies will replace immunochemotherapy regimens in most patients.

The highly selective Bruton tyrosine kinase inhibitor acalabrutinib leaves macrophage phagocytosis intact.

Not available.