Selective Btk Inhibitor Research Articles

Abstract 5438: FCN-589, a novel, potent and selective BTK inhibitor, targets BTK C481S for the treatment of B-cell malignancies

Abstract Bruton’s tyrosine kinase (BTK) is a member of the Tec family of non-receptor tyrosine kinases and plays critical roles in B-cell receptor (BCR) signaling. BTK is often overexpressed in B-cells of patients with hematological malignancies. BTK inhibition blocks BCR signals, prevents B-cell activation and malignant B-cell growth, and induces apoptosis. Early irreversible BTK inhibitors such as ibrutinib, which covalently binds to the cysteine residue (C481) of BTK, are effective against B-cell malignancies and have received approval for various B-cell lymphomas and leukemia including mantle cell lymphoma and chronic lymphocytic leukemia, but their effectiveness is often limited by toxicities from off-target inhibition of the Tec (e.g., ITK/TEC) and EGFR family (e.g., EGFR/HER2/HER4). Acquired resistance mutations in the C481 binding site are known to cause clinical resistance to irreversible BTK inhibitors, which accounts for over half of progression in patients received ibrutinib. There is thus unmet medical need for a novel BTK inhibitor with improved safety profile efficacious against C481 mutation. Here we introduce FCN-589, a novel and orally active next-generation BTK inhibitor. FCN-589 shows potent kinase activities against wild-type (WT) BTK and the most common resistant mutation BTK C481S with single-digit nanomolar IC50 and improved selectivity over clinically significant off-targets such as TRK and ITK compared with nemtabrutinib (MK-1026, ARQ 531), another BTK C481S inhibitor in development. FCN-589 exhibits remarkable anti-proliferating potency against a panel of human B-cell malignancies-derived cancer cell lines. FCN-589 is over 30x more potent against follicular lymphoma cells (DOHH2) and activated B-cell subset of diffuse large B-cell lymphoma (DLBCL) cells (OCI-LY10 and Ri-1), and about 4x more potent against germinal center B-cell like subset of DLBCL cells (SU-DHL-4) compared with ARQ 531. In HEK-293 cell line ectopically expressing WT or BTK C481S, FCN-589 markedly inhibits p-BTK expression with superior activity compared with ARQ 531. Consistently, FCN-589 shows significant and superior anti-tumor activities in mice xenograft models derived from human non-Hodgkin’s lymphomas compared with ARQ 531 and ibrutinib. In non-clinical studies, FCN-589 exhibits good pharmacokinetic (PK) and safety properties. In particular, FCN-589 has longer T1/2 in both rats and dogs, displays improved CYP450 inhibition profile, and is less plasma protein bound compared with ARQ 531. Overall, FCN-589 is a novel next-generation BTK inhibitor targeting WT and BTK C481S. FCN-589 possesses potent in vitro and in vivo anti-cancer activities with better selectivity against clinically significant off-targets and exhibits favorable PK and safety profiles compared with ARQ 531. FCN-589 has potential to be a more effective and safer option for patients with B-cell malignancies. Citation Format: Shu Lin, Haohan Tan, Qihong Liu, Yunling Wang, Bin Liu, Zhifu Li, Zhifang Chen, Xianlong Wang, Xingdong Zhao, Lihua Jiang, Xilei Wang, Tao Cheng, Jiashu Zhou, Weibo Wang. FCN-589, a novel, potent and selective BTK inhibitor, targets BTK C481S for the treatment of B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5438.

Clinical Application of Zanubrutinib in B-Cell Lymphoma --Review

Zanubrutinib is a highly selective second-generation BTK inhibitor developed in China and first approved by the U.S. Food and Drug Administration (FDA) as a novel antineoplastic drug. In recent years, with the birth of molecularly targeted drugs, the treatment of B-cell lymphoma have entered the era of targeted therapy, and immunotherapy has been widely accepted. Especially in some relapsed and refractory lymphomas, zanubrutinib has shown deep and sustained remissions and a favorable safety, which lays a foundation for precision therapy. In this review the clinical application and new progress for zanubrutinib in B-cell lymphoma was summarized briefly.

Zanubrutinib in relapsed/refractory mantle cell lymphoma: long-term efficacy and safety results from a phase 2 study

AbstractBruton tyrosine kinase (BTK) inhibitor is an established treatment for relapsed/refractory (R/R) mantle cell lymphoma (MCL). Zanubrutinib, a highly selective BTK inhibitor, is approved for patients with MCL who have received ≥1 prior therapy. We report the long-term safety and efficacy results from the multicenter, open-label, phase 2 registration trial of zanubrutinib. Patients (n = 86) received oral zanubrutinib 160 mg twice daily. The primary endpoint was the overall response rate (ORR), assessed per Lugano 2014. After a median follow-up of 35.3 months, the ORR was 83.7%, with 77.9% achieving complete response (CR); the median duration of response was not reached. Median progression-free survival (PFS) was 33.0 months (95% confidence interval [CI], 19.4-NE). The 36-month PFS and overall survival (OS) rates were 47.6% (95% CI, 36.2-58.1) and 74.8% (95% CI, 63.7-83.0), respectively. The safety profile was largely unchanged with extended follow-up. Most common (≥20%) all-grade adverse events (AEs) were neutrophil count decreased (46.5%), upper respiratory tract infection (38.4%), rash (36.0%), white blood cell count decreased (33.7%), and platelet count decreased (32.6%); most were grade 1/2 events. Most common (≥10%) grade ≥3 AEs were neutrophil count decreased (18.6%) and pneumonia (12.8%). Rates of infection, neutropenia, and bleeding were highest in the first 6 months of therapy and decreased thereafter. No cases of atrial fibrillation/flutter, grade ≥3 cardiac AEs, second primary malignancies, or tumor lysis syndrome were reported. After extended follow-up, zanubrutinib demonstrated durable responses and a favorable safety profile in R/R MCL. The trial is registered at ClinicalTrials.gov as NCT03206970.

Optimization of a novel piperazinone series as potent selective peripheral covalent BTK inhibitors

BTK is a tyrosine kinase playing an important role in B cell and myeloid cell functions through B cell receptor (BCR) signaling and Fc receptor (FcR) signaling. Selective inhibition of BTK has the potential to provide therapeutical benefits to patients suffering from autoimmune diseases. Here we report the design, optimization, and characterization of novel potent and highly selective covalent BTK inhibitors. Starting from a piperazinone hit derived from a selective reversible inhibitor, we solved the whole blood cellular potency issue by introducing an electrophilic warhead to reach Cys481. This design led to a covalent irreversible BTK inhibitor series with excellent kinase selectivity as well as good whole blood CD69 cellular potency. Optimization of metabolic stability led to representative compounds like 42, which demonstrated strong cellular target occupancy and inhibition of B-cell proliferation measured by proximal and distal functional activity.

Discovery and Preclinical Characterization of BIIB091, a Reversible, Selective BTK Inhibitor for the Treatment of Multiple Sclerosis.

Multiple Sclerosis is a chronic autoimmune neurodegenerative disorder of the central nervous system (CNS) that is characterized by inflammation, demyelination, and axonal injury leading to permeant disability. In the early stage of MS, inflammation is the primary driver of the disease progression. There remains an unmet need to develop high efficacy therapies with superior safety profiles to prevent the inflammation processes leading to disability. Herein, we describe the discovery of BIIB091, a structurally distinct orthosteric ATP competitive, reversible inhibitor that binds the BTK protein in a DFG-in confirmation designed to sequester Tyr-551, an important phosphorylation site on BTK, into an inactive conformation with excellent affinity. Preclinical studies demonstrated BIB091 to be a high potency molecule with good drug-like properties and a safety/tolerability profile suitable for clinical development as a highly selective, reversible BTKi for treating autoimmune diseases such as MS.

A Phase I Study Of The Oral Btk Inhibitor ONO-4059 In Patients With Relapsed/Refractory and High Risk Chronic Lymphocytic Leukaemia (CLL)

IntroductionThe B-cell receptor (BCR) pathway plays a central role in signal transduction pathways that regulate survival, activation, proliferation and differentiation of B-lineage lymphoid cells. Bruton's tyrosine kinase (Btk) is a critical kinase in BCR signal transduction and recent studies support that targeting Btk is effective in the treatment of B-cell malignancies. ONO-4059 is a highly potent and selective oral Btk inhibitor with an IC50 in the sub-nmol/L range that has demonstrated anti-tumour activity in several pre-clinical models (Yasuhiro T et al, AACR 2013). MethodsThis Phase I study was initiated to determine the safety, tolerability, dose-limiting toxicity (DLT), pharmacokinetics and pharmacodynamics of ONO-4059 given as monotherapy to patients with relapsed/refractory, high risk CLL for whom no therapy of higher priority was available. In this safety-driven, dose-escalating 3+3 design, ONO-4059 was administered as an oral, daily dose (flat dose) given continuously initially for up to 6 months, with the option of additional dosing up to 2 years. We present the safety and efficacy data on 16 evaluable patients, median age 67 yrs (range 40-77), with high risk cytogenetics (17p [38% (6/16)] or 11q [19% (3/16)], 12/16 displaying unmutated IgVH status, 8/16 displaying TP53 mutation), median baseline tumour burden 4,534mm2 [461-14,492 mm2]. Patients had received a median of 3 prior therapies [2-7], including fludarabine (16/16) and rituximab-containing therapy (13/16). Baseline median haematology parameters included hemoglobin 11.3 g/dL [8.5 -15.2], WBC 56.02 x 109/L [2.06-394.74], platelets 95.5 x 109/L [23-173], lymphocytes 50.6 x 109/L [0.5-390], neutrophils 2.46 x 109/L [0.5-11.1]. Patients were treated with ONO-4059 at doses ranging from 20mg-320mg (cohorts 1-5) and the study is currently ongoing with additional dose escalation cohorts to be completed. ResultsONO-4059 was found to be well tolerated, with no dose limiting toxicities (DLTs). A total of 15 ONO-4059-related Grade 1 (n=10) and 2 (n=5) adverse events were reported in 8 out of 16 patients, including one event of diarrhea (G2) and two events of rash (G1, G2). ONO-4059-related G3 or G4 haematological toxicities were infrequent and independent of dose; neutropenia (n=3 [G4 x1, G3 x 2]), febrile neutropenia (n=1 [G3]) occurring in 2 patients at the 20mg dose level only. Only one Grade 3 ONO-4059-related non-haematological event (pyrexia) was reported. Infection rate was low with only one event of bronchitis reported (G2, related). Three ONO-4059-related SAEs were reported in two patients (febrile neutropenia [G3] and pyrexia [G3] in one patient [20 mg]; rash [G2] in another [80 mg]). The pharmacokinetics of ONO-4059 reflects rapid absorption and elimination, a half-life of ∼6 hours, a dose dependent increase in exposure with no accumulation of ONO-4059 exposure and low inter- or intra-patient variability; with Btk occupancy in peripheral blood (as measured by phosphorylated Btk) being maintained for at least 24 hours across all dose levels.Responses have occurred across all dose levels. All patients experienced rapid reductions in lymphadenopathy observed early in treatment, between D1-D28 of the first cycle, accompanied by an increase in absolute lymphocyte count in some, but not all patients. Best overall response rate according to IWCLL criteria (including modified PR with lymphocytosis) was 70% [based on CT-scan and P/E for 7/10 evaluable patients]; with 2 PR, 5 PR with lymphocytosis (For 7 responding patients, median reduction of lymph nodes was 67% [Range 61%-79%]), 2 SD, 1 patient PD (possible Richter's). All patients showed an improvement in haematological parameters after ≥3 months on treatment. Patients (ONO-4059 20mg [1pt] and 40mg [1pt] respectively) who had grade 3 thrombocytopenia at study baseline had a significant improvement in platelet count (>100 x 109/L) with ONO-4059 treatment. To date, 15 of 16 patients remain on treatment with a median progression-free survival of 99 days [Range 8-268].In conclusion, ONO-4059 is a highly potent and selective oral Btk inhibitor with a favourable safety profile along with promising efficacy in this heavily pre-treated population, with responses observed in relapsed, refractory and 17p deleted patients. Disclosures:Salles:Janssen: Honoraria; Gilead: Honoraria; Celgene: Honoraria. Karlin:Janssen: Honoraria; Celgene: Honoraria. Morschhauser:ONO Pharma: Honoraria; Roche: Honoraria; Celgene: Honoraria; Mundipharma: Honoraria. Dyer:ONO Pharma: Honoraria, Research Funding. Hutchinson:ONO Pharma: Research Funding. Fegan:ONO Pharma: Honoraria. Cartron:ONO Pharma: Honoraria. Knurowski:ONO Pharma: Consultancy. Saunders:ONO Pharma: Consultancy; Pharmacyclics: Consultancy. Wright:ONO Pharma: Consultancy. Honda:ONO Pharma: Employment. Mazur:ONO Pharma: Consultancy. Yoshizawa:Ono Pharma: Employment. Kawabata:Ono Pharmaceutical Co., Ltd.: Employment. Birkett:Ono Pharma UK: Employment.

Distinct BTK inhibitors differentially induce apoptosis but similarly suppress chemotaxis and lipid accumulation in mantle cell lymphoma

BackgroundThe more selective second-generation BTK inhibitors (BTKi) Acalabrutinib and Zanubrutinib and the first-generation BTKi Ibrutinib are highlighted by their clinical effectiveness in mantle cell lymphoma (MCL), however, similarities and differences of their biological and molecular effects on anti-survival of MCL cells induced by these BTKi with distinct binding selectivity against BTK remain largely unknown.MethodsAlamarBlue assays were performed to define cytotoxicity of BTKi against MCL cells, Jeko-1 and Mino. Cleaved PARP and caspase-3 levels were examined by immunoblot analysis to study BTKi-induced apoptotic effects. Biological effects of BTKi on MCL-cell chemotaxis and lipid droplet (LD) accumulation were examined in Jeko-1, Mino and primary MCL cells via Transwell and Stimulated Raman scattering imaging analysis respectively. Enzyme-linked immunoassays were used to determine CCL3 and CCL4 levels in MCL-cell culture supernatants. RNA-seq analyses identified BTKi targets which were validated by quantitative RT-PCR (qRT-PCR) and immunoblot analysis.ResultsAcalabrutinib and Zanubrutinib induced moderate apoptosis in Ibrutinib high-sensitive JeKo-1 cells and Ibrutinib low-sensitive Mino cells, which was accompanied by cleaved PARP and caspase-3. Such effects might be caused by the stronger ability of Ibrutinib to upregulate the expression of pro-apoptotic genes, such as HRK, GADD45A, and ATM, in JeKo-1 cells than in Mino cells, and the expression of such apoptotic genes was slightly changed by Acalabrutinib and Zanubrutinib in both JeKo-1 and Mino cells. Further, Acalabrutinib, Zanubrutinib and Ibrutinib reduced MCL-cell chemotaxis with similar efficiency, due to their similar abilities to downmodulate chemokines, such as CCL3 and CCL4. Also, these three BTKi similarly suppressed MCL-cell LD accumulation via downregulating lipogenic factors, DGAT2, SCD, ENPP2 and ACACA without significant differences.ConclusionBTKi demonstrated differential capacities to induce MCL-cell apoptosis due to their distinct capabilities to regulate the expression of apoptosis-related genes, and similar biological and molecular inhibitory effects on MCL-cell chemotaxis and LD accumulation.

Simultaneous Global Phase I Studies of a Differentiated BTK Inhibitor, Dtrmwxhs-12, in Relapsed/Refractory Patients with Chronic Lymphocytic Leukemia and B-Cell Lymphomas

Simultaneous Global Phase I Studies of a Differentiated BTK Inhibitor, Dtrmwxhs-12, in Relapsed/Refractory Patients with Chronic Lymphocytic Leukemia and B-Cell Lymphomas

Orelabrutinib: First Approval.

Dysregulation of Bruton's tyrosine kinase (BTK) signalling has been linked to various B cell malignancies and autoimmune diseases. Orelabrutinib (®) is an orally administered, potent, irreversible and highly selective BTK-inhibitor being developed by InnoCare Pharma for the treatment of B cell malignancies and autoimmune diseases. In December 2020, orelabrutinib received its first approval in China for the treatment of patients with mantle cell lymphoma (MCL) or chronic lymphocytic leukaemia (CLL)/small lymphocytic lymphoma (SLL), who have received at least one treatment in the past. Clinical development of orelabrutinib for various indications is underway in the USA and China. This article summarizes the milestones in the development of orelabrutinib leading to this first approval.

Geniposide protects depression through BTK/JAK2/STAT1 signaling pathway in lipopolysaccharide-induced depressive mice

The purpose of this study was to investigate the antidepressant mechanism of GEN (geniposide) on depression mice induced by LPS. The mice were intragastrically treated with GEN (10 mg/kg/d or 40 mg/kg/d) or ibrutinib for continuous 7 days prior to LPS injection. The anxiety- and depression-like behaviors of mice were assessed via behavioral tests (sucrose preference test (SPT), tail suspension test (TST), forced swimming test (FST), and open-field test (OFT)). Microglial BV2 cells were treated with GEN or/and ibrutinib and stimulated with LPS. The productions of pro-inflammatory cytokines IL-6 and TNF-α in hippocampus, serum, and supernatant were detected by ELISA. The correlative proteins BTK, p-BTK, JAK2, p-JAK2, STAT1, p-STAT1, BDNF, TrkB, and p-TrkB were assessed through western blot. As a result, GEN ameliorated the anxiety- and depression-like behaviors of mice in behavioral tests. GEN treatment also regulated microglia polarization towards anti-inflammatory phenotype M2 and inhibited the production of pro-inflammatory cytokines IL-6 and TNF-α. In addition, with the application of ibrutinib, the selective inhibitor of BTK, it was proclaimed that the administration of GEN restrained the activation of JAK2/STAT1 pathway via attenuating the hyperphosphorylation of BTK both in mice and BV2 cells. Furthermore, it was also found that GEN activated BDNF/TrkB neuroprotective signaling pathway through the reduction of BTK phosphorylation. From the overall results, we suggested that GEN exerted a beneficial effect on LPS-induced depression in mice possibly through the modulation of BTK/JAK2/STAT1 signaling.

Updated Results from the Phase II Study of Orelabrutinib Monotherapy in Chinese Patients with Relapsed or Refractory Chronic Lymphocytic Leukemia/Small Cell Leukemia

Orelabrutinib (ICP-022) is a novel and highly selective irreversible BTK inhibitor. We previously reported that orelabrutinib had high bioavailability with ~100% BTK occupancy at 24 hours at 150 mg daily dosing regimen and demonstrated excellent safety and efficacy profiles at median follow-up of 8.7 months in a Phase I/II trial of refractory/relapsed (r/r) CLL/SLL (Chronic Lymphocytic Leukemia/Small Cell Leukemia). Here we present an updated analysis of efficacy and safety results from the clinical study of Orelabrutinib in Chinese patients with r/r CLL/SLL following extended treatment. This is an open-label, multicenter, phase II study with objectives to evaluate its safety and efficacy following an oral daily administration. The primary endpoint was objective response rate (ORR). The duration of response (DOR), progression-free survival (PFS) and safety were chosen as secondary endpoints. Response was assessed per 2008 IWCLL criteria with modification for partial remission (PR) with lymphocytosis (PR-L) (Hallek 2012) or the Lugano Classification (Cheson, 2014) for CLL and SLL, respectively. Results: A total of 80 patients with r/r CLL (n=70)/SLL (n=10) were enrolled. Eligible patients had relapsed after or were refractory to ≥1 prior treatment with median age of 60.0 (range, 36.0-78.0 years). There are 70% of patients for Rai stage 3-4 disease, 22.5% for 17p13.1 deletion [del(17p)] and/or TP53 mutation, 41.3% for unmutated immunoglobulin heavy chain variable region (IGHV) and 23.8% for 11q22.3 deletion [del(11q)]. The median follow-up time was 14.3 months (range, 0.2-21.6 months), and the last patient completed a minimum of 12 cycles of orelabrutinib treatment. Efficacy: The efficacy results presented here were evaluated by IRC (Independent review committee). Following a minimum of 12 cycles treatment, the ORR (PR-L or above) was 91.3% (95% confidence interval [CI]: 82.80 ~ 96.41%) with 10.0% of patients having complete response (CR), 63.8% PR and 17.5% PR-L. Median time for achieving first response was 1.87 months (range, 1.84 - 1.94 months). The median DOR and PFS were not reached. The estimated 12-month DOR was 77.1% (95% CI: 62.50-86.60%), PFS 81.1% (95% CI: 70.53 - 88.13%) and OS 86.3% (95% CI: 76.55 - 92.14%). Patients with Del(17p) and/or TP53 mutation achieved 100% ORR. The ORR is 94.7% for Del(11q)) and 93.9% for unmutated IGHV. Comparing to the first analysis results of which the median follow-up was 8.7 months, the CR rate had increased from 3.8% to 10.0%, and 8 patients with PR-L had converted to a deeper response. So, orelabrutinib showed a significant higher CR rate comparing to other BTK inhibitors at a similar treatment period and we anticipate a further increase of CR rate with longer duration of treatment. Safety: Most adverse events (AEs) were mild to moderate, similar to the first reported safety profiles at median follow-up of 8.7 months. Extended follow-up analysis did not reveal new safety nor toxicity concerns. The most frequent adverse events (AEs) of any cause/any grade were well characterized as hematological toxicities: thrombocytopenia, neutropenia, and anemia; upper respiratory tract infection, pneumonia and hypokalemia. No case of atrial fibrillation nor secondary malignancy was reported, no patient was observed for ≥3 hypertension and only one patient had ≥3 grade diarrhea. Major hemorrhage was reported in 2 patients, one with intracranial hemorrhage (65-year-old male patient with more than 10 years hypertension) and the other with vitreous hemorrhage which were resulted from posterior vitreous detachment that was assessed as unlikely related to the treatment of orelabrutinib. Once again, it has been further confirmed that orelabrutinib has excellent safety profiles following extended treatment. Conclusion: This updated and extended study further confirms that orelabrutinib is efficacious in treating r/r CLL patients with a higher CR rate, durable response and improved safety profiles. As a highly selective BTK inhibitor with favorable pharmacokinetic and pharmacodynamic properties, orelabrutinib provides a favorable therapeutic choice for patients with r/r CLL/SLL and a potential best candidate for combination therapy. Disclosures Zhu: Beijing InnoCare Pharma Tech Co., Ltd: Current Employment. Zhao:Beijing InnoCare Pharma Tech Co., Ltd: Current Employment. Zhang:Beijing InnoCare Pharma Tech Co., Ltd: Current Employment. Xu:Beijing InnoCare Pharma Tech Co., Ltd: Current Employment.

A Phase 1b-2 Study of KRT-232, a First-in-Class, Oral, Small Molecule Inhibitor of Murine Double Minute 2 (MDM2), in Combination with Acalabrutinib for the Treatment of Relapsed/Refractory (R/R) Chronic Lymphocytic Leukemia (CLL) or R/R Diffuse Large B-Cell Lymphoma (DLBCL)

A Phase 1b-2 Study of KRT-232, a First-in-Class, Oral, Small Molecule Inhibitor of Murine Double Minute 2 (MDM2), in Combination with Acalabrutinib for the Treatment of Relapsed/Refractory (R/R) Chronic Lymphocytic Leukemia (CLL) or R/R Diffuse Large B-Cell Lymphoma (DLBCL)

A randomized phase 3 trial of zanubrutinib vs ibrutinib in symptomatic Waldenström macroglobulinemia: the ASPEN study

AbstractBruton tyrosine kinase (BTK) inhibition is an effective treatment approach for patients with Waldenström macroglobulinemia (WM). The phase 3 ASPEN study compared the efficacy and safety of ibrutinib, a first-generation BTK inhibitor, with zanubrutinib, a novel highly selective BTK inhibitor, in patients with WM. Patients with MYD88L265P disease were randomly assigned 1:1 to treatment with ibrutinib or zanubrutinib. The primary end point was the proportion of patients achieving a complete response (CR) or a very good partial response (VGPR) by independent review. Key secondary end points included major response rate (MRR), progression-free survival (PFS), duration of response (DOR), disease burden, and safety. A total of 201 patients were randomized, and 199 received ≥1 dose of study treatment. No patient achieved a CR. Twenty-nine (28%) zanubrutinib patients and 19 (19%) ibrutinib patients achieved a VGPR, a nonstatistically significant difference (P = .09). MRRs were 77% and 78%, respectively. Median DOR and PFS were not reached; 84% and 85% of ibrutinib and zanubrutinib patients were progression free at 18 months. Atrial fibrillation, contusion, diarrhea, peripheral edema, hemorrhage, muscle spasms, and pneumonia, as well as adverse events leading to treatment discontinuation, were less common among zanubrutinib recipients. Incidence of neutropenia was higher with zanubrutinib, although grade ≥3 infection rates were similar in both arms (1.2 and 1.1 events per 100 person-months). These results demonstrate that zanubrutinib and ibrutinib are highly effective in the treatment of WM, but zanubrutinib treatment was associated with a trend toward better response quality and less toxicity, particularly cardiovascular toxicity.

Abstract CT132: Orelabrutinib, a potent and selective Bruton's tyrosine kinase inhibitor with superior safety profile and excellent PK/PD properties

Abstract Bruton's tyrosine kinase (BTK) as a therapeutic target for B-cell malignancies, including mantle cell lymphoma (MCL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and other non-Hodgkin's lymphomas (NHL), has been clinically validated. Orelabrutinib (ICP-022) is a novel, potent and highly selective BTK inhibitor with excellent pharmacokinetics/pharmacodynamics (PK/PD) properties distinguished from other BTK inhibitors. Here we report the results from preclinical studies, together with safety and PK/PD data in human healthy subjects. Orelabrutinib potently inhibits BTK enzymatic activity with an IC50 value of 1.6 nM. In KINOMEscan assay conducted in parallel at 1 μM against a panel of 456 kinases, orelabrutinib only targeted BTK with > 90% inhibition while ibrutinib inhibited additional many other kinases including EGFR, TEC and BMX, demonstrating orelabrutinib's superior kinase selectivity. In addition, orelabrutinib has a favorable PK profile with an ideal T1/2 (~1.5-4 h) and good oral bioavailability (~20-80%) as well as prolonged BTK target occupancy in preclinical PK/PD studies. The superior selectivity translates into improved safety profile and large safety window in the GLP toxicology studies in rats and dogs. A randomized dose-escalation phase I study in healthy subjects was conducted to evaluate the safety, tolerability, PK and PD profiles of orelabrutinib following single dose (20, 50, 100, 200 and 400 mg) and multiple doses (100 and 200 mg QD, 100 mg BID) escalation for 14 consecutive days. Safety: Orelabrutinib was safe and well tolerated in healthy subjects who received a single dose up to 400 mg or multiple doses up to 100 mg BID or 200 mg QD for 14 days. All treatment-emergent adverse events (TEAEs) reported during the study were mild or moderate in severity and resolved before the end of studies. Petechiae and headache were the most commonly reported treatment related TEAEs. No dose limiting toxicities (DLT) were encountered, and the maximum tolerated dose (MTD) was not reached. No serious TEAEs, TEAEs leading to treatment withdrawal, or serious TEAEs resulting in death were reported during this study. PK: Systemic exposure (both AUC and Cmax) was in a well dose proportional manner, indicating a good linear PK. The mean terminal T1/2 was approximately 4 hours across all cohorts. There was no drug accumulation in plasma after repeated dosing. No significant food effect was observed following co-administration with a standard high-fat, high-calorie meal. PD: Near complete (>99%) BTK occupancy was achieved at a dose of 50 mg or higher with small inter-subject variability, and the effect was sustained for 24 hours post dosing, which is consistent with the covalent binding mode of orelabrutinib. The Cmax that required to achieve complete (>99%) BTK occupancy (EC99) is ~300 ng/mL. In summary, orelabrutinib has superior selectivity, favorable PK, prolonged PD as well as a large safety window in both preclinical and clinical phase I studies. Therefore, orelabrutinib may offer an excellent option for the treatment of B-cell malignancies in avoid of the high frequency of adverse events (diarrhea, atrial fibrillation, bleeding, etc.) observed for ibrutinib and other BTK inhibitors. Orelabrutinib is currently under investigation with multiple phase II trials in patients with B-cell malignancies. Citation Format: Bin Zhang, Renbin Zhao, Ruixia Liang, Yingxiang Gao, Richard Liu, Xiangyang Chen, Zhengguang Lu, Zuopeng Wang, Liqin Yu, Sepehr Shakib, Jisong Cui. Orelabrutinib, a potent and selective Bruton's tyrosine kinase inhibitor with superior safety profile and excellent PK/PD properties [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT132.

Abstract 3023: Exposure versus efficacy/safety of acalabrutinib and its pharmacologically active metabolite, ACP-5862, for the treatment of chronic lymphocytic leukemia

Abstract Background: Acalabrutinib is a selective BTK inhibitor approved for the treatment of Mantle Cell Lymphoma. Relationship between plasma exposures to acalabrutinib and ACP-5862 versus clinical efficacy and safety were evaluated in subjects with B-cell malignancies, following administration of acalabrutinib monotherapy or in combination with obinutuzumab. Methods: Acalabrutinib and ACP-5862 exposures (AUC24h,ss) were generated using population pharmacokinetic (PK) analysis. To account for the contribution of ACP-5862 to overall activity, an exposure metric (total active AUC24h,ss) accounting for relative BTK potency and protein binding was estimated. Efficacy data from the pivotal Phase 3 study in previously untreated (PU) CLL subjects (n=274), who received acalabrutinib 100 mg twice daily (BID) as monotherapy or in combination, were included. Safety data pooled across 8 studies in PU or relapsed/refractory (R/R) subjects with B-cell malignancies (n=567), who received acalabrutinib 100, 175, 200, and 250 once daily or 100 mg and 200 mg BID as monotherapy or in combination, were included. Efficacy endpoints including best overall response rate (BOR), progression -free survival (PFS) and sum of products of the greatest perpendicular diameters (SPD) of index lesions were evaluated. Safety endpoints including all AEs Grade ≥2 in severity, and Grade ≥2 events of clinical interest such as, anemia, cardiac events, diarrhea, headache, hemorrhage, hepatic events, hypertension, infections, neutropenia, and thrombocytopenia were evaluated. Kaplan-Meier survival and logistic regression analyses were conducted for key efficacy and safety endpoints. Results: Median acalabrutinib/ACP-5862/total active AUC24h,ss were similar between responders versus non-responders, and across the 4 response categories (i.e. complete response, partial response, stable disease or progressive disease). No correlation between AUC24h,ss and PFS or SPD were noted. With the exception of Grade ≥2 anemia, no significant relationship between AUC24h,ss and safety outcomes was observed. Model-based analyses revealed baseline hemoglobin levels and line of therapy as highly significant predictors of Grade ≥2 anemia (p<0.0001) but not PK exposure (AUC24h,ss; p=0.08), indicating the lack of an exposure-dependent relationship. The results were consistent across acalabrutinib monotherapy or combination with obinutuzumab treatment arms. Conclusions: No clinically meaningful correlation between PK exposures and selected efficacy and safety outcomes was observed. In pivotal studies, the 100 mg BID acalabrutinib regimen demonstrated an acceptable safety profile and robust efficacy (consistent with ≥95% BTK occupancy over a dosing interval) in PU and R/R CLL. Overall, these data support a fixed 100 mg BID acalabrutinib dose for the treatment of subjects with CLL. Citation Format: Helena Edlund, Karthick Vishwanathan, Ming Yin, Rakesh Raman, Miné de Kock, Zhongqing He, Huan Liu, Marshall Baek, Nidal Al-Huniti, Joseph Ware, Shringi Sharma. Exposure versus efficacy/safety of acalabrutinib and its pharmacologically active metabolite, ACP-5862, for the treatment of chronic lymphocytic leukemia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3023.

Ibrutinib, but not zanubrutinib, induces platelet receptor shedding of GPIb-IX-V complex and integrin αIIbβ3 in mice and humans

AbstractThe Bruton's tyrosine kinase (Btk) inhibitor ibrutinib has proven to be efficacious in the treatment of B-cell chronic lymphocytic leukemia (B-CLL) and related diseases. However, a major adverse side effect of ibrutinib is bleeding, including major hemorrhages. The bleeding associated with ibrutinib use is thought to be due to a combination of on-target irreversible Btk inhibition, as well as off-target inhibition of other kinases, including EGFR, ITK, JAK3, and Tec kinase. In this study, we investigated the effects of ibrutinib vs zanubrutinib (a more selective Btk inhibitor) on platelet activation, glycoprotein expression, and thrombus formation. Ibrutinib, but not zanubrutinib, induced a time- and dose-dependent shedding of GPIb-IX complex and integrin αIIbβ3, but not of GPVI and GPV, from the platelet surface. The shedding of GPIbα and GPIX was blocked by GM6001 and TAPI-2, an ADAM17 inhibitor but not ADAM10 inhibitor. Ibrutinib but not zanubrutinib treatment of human platelets increased ADAM17 activation. Pretreatment of C57BL/6 mice with ibrutinib (10 mg/kg), but not zanubrutinib (10 mg/kg), inhibited ex vivo and in vivo thrombus growth over time. Platelets from ibrutinib-treated patients with CLL showed reduced GPIb-IX complex and integrin αIIbβ3 surface expression and reduced ex vivo thrombus formation under arterial flow, which was not observed in zanubrutinib-treated patients. In mice, ibrutinib, but not zanubrutinib, led to increased soluble GPIbα and soluble αIIb levels in plasma. These data demonstrate that ibrutinib induces shedding of GPIbα and GPIX by an ADAM17-dependent mechanism and integrin αIIbβ3 by an unknown sheddase, and this process occurs in vivo to regulate thrombus formation.

Preliminary Safety and Efficacy Results from a Phase 2 Study of Acalabrutinib, Venetoclax and Obinutuzumab in Patients with Previously Untreated Chronic Lymphocytic Leukemia (CLL)

Montegaard: Pharmacyclics: Consultancy; Janssen: Consultancy. Jacobson:Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel Expenses; Pfizer: Consultancy, Research Funding; Humanigen: Consultancy, Other: Travel Expenses; Bayer: Consultancy, Other: Travel Expenses; Precision Biosciences: Consultancy, Other: Travel Expenses; Celgene: Consultancy, Other: Travel Expenses. Jacobsen:Astra-Zeneca: Consultancy; Novartis: Research Funding; F. Hoffmann-LaRoche: Research Funding; Takeda: Honoraria; Pharmacyclics: Research Funding; Merck: Consultancy, Research Funding; Acerta: Consultancy. LaCasce:Seattle Genetics: Consultancy, Research Funding; BMS: Consultancy; Research to Practice: Speakers Bureau; Humanigen: Consultancy. Arnason:Regeneron Pharmaceuticals, Inc.: Consultancy; Celgene/Juno: Consultancy. Armand:Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Affimed: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Otsuka: Research Funding; Sigma Tau: Research Funding; Infinity: Consultancy; Genentech: Research Funding; Pfizer: Consultancy; ADC Therapeutics: Consultancy; Tensha: Research Funding. Brown:BeiGene: Consultancy; AbbVie: Consultancy; Catapult Therapeutics: Consultancy; Dynamo Therapeutics: Consultancy; Genentech/Roche: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Loxo: Consultancy, Research Funding; Novartis: Consultancy; Juno/Celgene: Consultancy; Acerta Pharma: Consultancy; AstraZeneca: Consultancy; Gilead: Consultancy, Research Funding; Pfizer: Consultancy; Pharmacyclics: Consultancy; Sunesis: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy, Research Funding; Sun Pharmaceuticals: Research Funding; Janssen: Honoraria; Teva: Honoraria; Morphosys: Other: Data safety monitoring board; Invectys: Other: Data safety monitoring board; Octapharma: Consultancy. Davids:AbbVie, Acerta Pharma, Adaptive, Biotechnologies, Astra-Zeneca, Genentech, Gilead Sciences, Janssen, Pharmacyclics, TG therapeutics: Membership on an entity's Board of Directors or advisory committees; AbbVie, Astra-Zeneca, Genentech, Janssen, MEI, Pharmacyclics, Syros Pharmaceuticals, Verastem: Consultancy; Acerta Pharma, Ascentage Pharma, Genentech, MEI pharma, Pharmacyclics, Surface Oncology, TG Therapeutics, Verastem: Research Funding; Research to Practice: Honoraria. Acalabrutinib, venetoclax, obinutuzumab - combination therapy for previously untreated CLL.

Ibrutinib Maintenance (I-M) Following Frontline Intensive Induction in Mantle Cell Lymphoma (MCL): Interim Safety, Response and Sequential MRD Evaluation

Ibrutinib Maintenance (I-M) Following Frontline Intensive Induction in Mantle Cell Lymphoma (MCL): Interim Safety, Response and Sequential MRD Evaluation

PRISM: A Platform Protocol for the Treatment of Relapsed/Refractory Aggressive Non-Hodgkin Lymphoma

PRISM: A Platform Protocol for the Treatment of Relapsed/Refractory Aggressive Non-Hodgkin Lymphoma

Ibrutinib inhibits antibody dependent cellular cytotoxicity induced by rituximab or obinutuzumab in MCL cell lines, not overcome by addition of lenalidomide

BackgroundThe Bruton’s Tyrosine Kinase (BTK)-inhibitor ibrutinib is highly active in mantle cell lymphoma (MCL) but may inhibit response to anti-CD20 antibody as previously shown in CLL models. We investigated how antibody-dependent cellular cytotoxicity (ADCC) induced by type I/II anti-CD20 antibodies was affected by treatment with ibrutinib in MCL. Furthermore, we investigated if lenalidomide, a potential sensitizer to anti-CD20 treatment, could prevent an inhibitory effect of ibrutinib.MethodsAnti-CD20 (rituximab/obinutuzumab) opsonized MCL cell lines were co-cultured with ibrutinib (± lenalidomide)—exposed effector cells, and analyzed for evaluation of cell death.ResultsCell death induced by rituximab was reduced with 75% at 0.5 µM ibrutinib and with 52% at 0.1 µM ibrutinib when induced by obinutuzumab, even by addition of lenalidomide. Moreover, obinutuzumab was associated with higher rate of cell death compared to rituximab.ConclusionIbrutinib negatively affects anti-CD20 induced cell death in MCL, not reversed by lenalidomide. Explorations of sequential administration and selective BTK-inhibitors may reveal the optimal combination of novel agents in MCL.