Irreversible Inhibitor Of Bruton Tyrosine Kinase Research Articles

Discovery of a novel BTK inhibitor S-016 and identification of a new strategy for the treatment of lymphomas including BTK inhibitor-resistant lymphomas.

Bruton's tyrosine kinase (BTK) has emerged as a therapeutic target for B-cell malignancies, which is substantiated by the efficacy of various irreversible or reversible BTK inhibitors. However, on-target BTK mutations facilitating evasion from BTK inhibition lead to resistance that limits the therapeutic efficacy of BTK inhibitors. In this study we employed structure-based drug design strategies based on established BTK inhibitors and yielded a series of BTK targeting compounds. Among them, compound S-016 bearing a unique tricyclic structure exhibited potent BTK kinase inhibitory activity with an IC50 value of 0.5 nM, comparable to a commercially available BTK inhibitor ibrutinib (IC50 = 0.4 nM). S-016, as a novel irreversible BTK inhibitor, displayed superior kinase selectivity compared to ibrutinib and significant therapeutic effects against B-cell lymphoma both in vitro and in vivo. Furthermore, we generated BTK inhibitor-resistant lymphoma cells harboring BTK C481F or A428D to explore strategies for overcoming resistance. Co-culture of these DLBCL cells with M0 macrophages led to the polarization of M0 macrophages toward the M2 phenotype, a process known to support tumor progression. Intriguingly, we demonstrated that SYHA1813, a compound targeting both VEGFR and CSF1R, effectively reshaped the tumor microenvironment (TME) and significantly overcame the acquired resistance to BTK inhibitors in both BTK-mutated and wild-type BTK DLBCL models by inhibiting angiogenesis and modulating macrophage polarization. Overall, this study not only promotes the development of new BTK inhibitors but also offers innovative treatment strategies for B-cell lymphomas, including those with BTK mutations.

Single-Cell RNA-Seq Analysis of Patient Myeloid-Derived Suppressor Cells and the Response to Inhibition of Bruton's Tyrosine Kinase.

scRNA-seq revealed characteristic gene expression patterns for MDSC from different patients with cancer and BTK inhibition led to the downregulation of multiple genes and pathways important to MDSC function and migration.

A Phase 1 Study Evaluating PRT2527, a Potent and Highly Selective CDK9 Inhibitor, As Monotherapy and in Combination with Zanubrutinib in Patients with Select Relapsed/Refractory B-Cell Malignancies

Background and Significance: PRT2527 is an investigational, potent, and highly selective cyclin-dependent kinase 9 inhibitor that is being developed for select relapsed or refractory (R/R) hematologic malignancies. CDK9, a key regulator of transcription elongation, has been studied as a potential target for therapy in transcriptionally addicted cancers that are dependent on oncogenic drivers with short half-lives. Although most of these drivers do not respond to direct inhibition, studies suggest that a subset of drivers, eg MYC, MYB, and MCL-1, may be targeted indirectly via CDK9 inhibition. Several nonselective CDK9 inhibitors have shown clinical activity in multiple tumor types, however, tolerability was poor (Mandal, et al. Cancers (Basel). 2021). PRT2527 has demonstrated high specificity and promising antitumor activity in preclinical studies, and a favorable tolerability profile in preliminary data from a Phase 1 study (NCT05159518) in adults with advanced solid tumors. These support further development of PRT2527 in hematologic malignancies as monotherapy and in combination with targeted agents. Combination of CDK9 inhibition and Bruton tyrosine kinase (BTK) inhibition may drive a durable response by enhancing apoptotic priming and shifting dependency toward CDK9 targets MCL1 and BFL1. Zanubrutinib (BGB-3111) is a highly selective, potent, irreversible BTK inhibitor that upregulates the proapoptotic signaling molecule BCL2 modifying factor, an endogenous inhibitor of BCL2, BCLXL, and BCLW (Kong, et al. ChemMedChem. 2018). PRT2527 as monotherapy or in combination with zanubrutinib may be an effective treatment option for select R/R hematologic malignancies. Study Design and Methods: PRT2527-02 is a phase 1, open-label, multicenter, dose-escalation and dose-confirmation study evaluating safety, tolerability, recommended phase 2 dose (R2PD), and preliminary efficacy of PRT2527 as monotherapy and in combination with zanubrutinib in patients (pts) with select R/R hematologic malignancies. Pts eligible to receive PRT2527 monotherapy include those with aggressive B-cell lymphoma subtypes, mantle cell lymphoma (MCL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) including Richter syndrome, and T-cell lymphoma subtypes. Pts eligible to receive PRT2527 in combination with zanubrutinib include those with aggressive B-cell lymphoma subtypes, MCL, and CLL/SLL including Richter syndrome. Eligibility criteria include having relapsed or become refractory to standard-of-care therapy, measurable disease or requirement for treatment in accordance with disease-specific criteria for the hematologic malignancies under study, an ECOG PS of 0 to 1, and adequate bone marrow, renal, and liver function. Dose escalation will comprise successive cohorts receiving escalating doses of intravenous (IV) PRT2527 monotherapy once weekly (qw) in a 21-day cycle (cycle ≥2); pts at high risk for tumor lysis syndrome (TLS) and those receiving IV PRT2527 qw in combination with oral zanubrutinib 320 mg may have a 28- or 35-day ramp-up period during cycle 1. Dose escalation and de-escalation decisions will be guided by the prespecified Bayesian optimal interval design method based on dose-limiting toxicities (DLTs) observed in cycle 1. Dose confirmation will consist of indication-specific cohorts receiving the RP2D of PRT2527; pts at high risk for TLS and those receiving combination therapy may have weekly ramp-up dosing to reach RP2D. PRT2527 treatment will continue until disease progression or unacceptable toxicity, whichever comes first. The primary endpoints include safety, tolerability, DLTs, and RP2D of PRT2527 monotherapy and in combination with zanubrutinib. Adverse events will be assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events v5.0. Secondary endpoints include objective response rate, duration of response, duration of complete response, and pharmacokinetic profile of PRT2527 monotherapy and in combination with zanubrutinib. For descriptive analyses, continuous variables will be summarized by mean, standard deviation, median, minimum, and maximum. Response rates will be calculated with the 95% confidence interval. Time-to-event data will be analyzed using the Kaplan-Meier method. The study is open to enrollment and registered at ClinicalTrials.gov (NCT05665530).

Orelabrutinib Monotherapy in Patients with Relapsed or Refractory Waldenström's Macroglobulinemia in a Single-Arm, Multicenter, Open-Label, Phase 2 Study: Long Term Follow-up Results

Background Orelabrutinib is a novel, small molecule, selective irreversible Bruton tyrosine kinase inhibitor, approved in China for the treatment of patients with relapsed/refractory (R/R) chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), mantle cell lymphoma (MCL), and marginal zone lymphoma (MZL). The previous publication of this study reported that orelabrutinib is highly active in R/R Waldenström's macroglobulinemia (WM), with a well-tolerated safety profile (EClinicalMedicine. 2022;52:101682). We present here the long-term results of this study. Methods This is a prospective, multicenter study of orelabrutinib in patients with WM who had at least one prior line of treatment (ClinicalTrials NO. : NCT04440059). Orelabrutinib was administered orally at a daily dose of 150 mg until disease progression or unacceptable toxicity. Genotyping using MYD88 L265P and CRCR4 S338X mutation were performed with qPCR assay. The primary endpoint was major response rate (MRR) assessed by the Independent Review Committee (IRC) according to IWWM-6 (Br J Haematol. 2013; 160: 171-176). Results Between August 2019 and December 2020, 66 R/R WM patients were assessed for eligibility. Forty-seven eligible patients were evaluated for efficacy at a median follow-up of 31.9 months (interquartile range: 28.0，36.5). As assessed by IRC, the MRR was 80.9%, and the overall response rate was 91.5%. The PFS rates was estimated as 72.1% at 36 months and the median PFS has not been reached. There is no significant difference in PFS across various MYD88 L265P and CRCR4 S338X genotype (P=0.69; Figure 1). The 30-months PFS rate in MYD88 L265P/CXCR4 NEG, MYD88 L265P/CXCR4 S338X, and MYD88 NEG/CXCR4 NEG were 86.2%, 75% and 75%, respectively. Most adverse events were Grades 1 or 2 (63.8%). The common grade 3 or higher adverse events occurred were neutropenia (10.6%), thrombocytopenia (8.5%), and pneumonia (6.4%). Treatment related serious adverse events were reported in 8.5% patients. Adverse events leading to discontinuation occurred in 4 patients (8.5%). One treatment-related death was reported (hepatitis B reactivation). Conclusions Results with longer follow-up continue to show that orelabrutinib has high, deep and durable response in patients with R/R WM. Data support the safety of long-term orelabrutinib treatment in R/R WM, with no new safety signals identified.

Structure of BTK kinase domain with the second-generation inhibitors acalabrutinib and tirabrutinib.

Bruton's tyrosine kinase (BTK) is the target of the therapeutic agent, Ibrutinib, that treats chronic lymphocyte leukemia (CLL), mantle cell lymphoma (MCL) and other B cell malignancies. Ibrutinib is a first in class, covalent BTK inhibitor that limits B-cell survival and proliferation. Designing new inhibitors of BTK has been an important objective for advancing development of improved therapeutic agents against cancer and autoimmune disorders. Based on the success of Ibrutinib, several second-generation irreversible BTK inhibitors have been developed that exhibit fewer off-target effects. However, the binding-mode and their interaction with Btk have not been experimentally determined and evaluated at atomic resolution. Here we determined the first crystal structure of the BTK kinase domain in complex with acalabrutinib. In addition, we report a structure of the BTK/tirabrutinib complex and compare these structures with previously solved structures. The structures provide insight in the superior selectivity reported for acalabrutinb and guide future BTK inhibitor development.

A Pilot Study Evaluating Acalabrutinib for the Treatment of Relapsed/Refractory Primary and Secondary Central Nervous System Lymphomas

Background: Primary central nervous system lymphoma (PCNSL) is a rare variant of extranodal non-Hodgkin lymphoma (NHL) that involves the brain, leptomeninges, eyes, and/or spinal cord without evidence of systemic disease. While frontline PCNSL is potentially curable, relapsed PCNSL has a dismal prognosis, particularly if the relapse is within 1 year of frontline therapy. Secondary central nervous system lymphoma (SCNSL) is defined as systemic NHL that has CNS involvement either concurrently or at relapse. There is no standard of care for relapsed CNS lymphoma. Recently, though, novel targeted agents have shown promise. Bruton's tyrosine kinase (BTK) is a key enzyme in the B-cell receptor (BCR) signaling pathway. In some B-cell NHL, BTK is essential for proliferation and survival. The BTK inhibitor (BTKi) ibrutinib is effective for the treatment of both primary and secondary CNS lymphomas with response rates of 68% (CR=45%) and 56% (CR=17%), respectively. Acalabrutinib is an irreversible BTKi that has been evaluated in NHL. Phase 2 trials of acalabrutinib in relapsed/refractory MCL reported an ORR of 80.6% with a CR rate of 39.5%. Importantly, there were no cases of atrial fibrillation and only 1 case of grade 3 or higher gastrointestinal hemorrhage. We hypothesize that acalabrutinib, a more selective BTKi, may be an effective treatment for relapsed CNS lymphomas with fewer complications. Study Design/Methods: This is a multicenter, open-label, single-arm, pilot study designed to investigate the antitumor effects of acalabrutinib in subjects with relapsed PCNSL or SCNSL that is open to accrual (NCT04548648). All subjects receive acalabrutinib 100mg every 12 hours until progression or discontinuation of treatment due to an adverse event. Prophylactic administration of the antifungal agent isavuconazole will be mandatory while subjects receive acalabrutinib. This decision is based on cases of invasive aspergillosis in studies evaluating ibrutinib. As a moderate CYP3A4 inhibitor, isavuconazole may increase acalabrutinib levels. Pharmacokinetic studies have shown that coadministration may increase acalabrutinib dosing 2- to 3-fold. We feel that this possible increase in concentration is reasonable given the need for blood-brain-barrier penetration. During the study, 15 evaluable subjects will be enrolled and treated. Response will be assessed via brain magnetic resonance imaging (MRI) after 2, 4, 6, 9, 12, 18 and 24 months. After 24 months, patients will require yearly MRIs for response assessment. The primary endpoint is overall response rate (ORR) at 2 months of therapy. Secondary endpoints include toxicity, complete response (CR) rate, progression free survival (PFS), duration of response (DoR), and overall survival (OS). Key inclusion criteria include: biopsy (can be from initial diagnosis) or MRI findings consistent with B-cell NHL in CNS; ocular and CSF involvement are allowed but there must be a parenchymal mass as well; at least one prior line of therapy; no systemic involvement; ECOG performance status < 2. Key exclusion criteria include: previous BTKi exposure; anticoagulation with warfarin; strong CYP3A4 inhibitor that cannot be stopped; severe hepatic insufficiency; inability to take oral medication. Correlative studies include blood and CSF pharmacokinetic studies of acalabrutinib and its active metabolite, ACP-5862 (collected on day 1 and 8 of cycle 1). Molecular testing will be performed on biopsy samples to evaluate the presence of mutations in the MYD88 and CXCR4 genes. Additionally, the utility of 82Rubidium as a positron emission tomography-radiotracer will be evaluated (at screening and prior to cycle 3 and cycle 7) in the first five subjects at the University of North Carolina who consent to this scan. Mental status and cognitive function will be evaluated with the mini-mental status examination (MMSE) at screening then every 6 months. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Efficacy and Safety of Lenalidomide, Anti-PD-1 Antibody Combined with Orelabrutinib or Rituximab in the Treatment of Patients with Relapsed/Refractory Diffuse Large B-Cell Lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma worldwide. Although most patients with DLBCL respond to first-line chemoimmunotherapy with R-CHOP, approximately 40% of patients will have relapsed or refractory disease. Currently, the second-line therapeutic regimen is chemoimmunotherapy followed by consolidative autologous hematopoietic stem cell transplantation (AHCT) for relapsed/refractory DLBCL (R/R DLBCL). However, the prognosis has remained poor. (Sawalha. J Pers Med. 2021). Thus, discovering effective treatment regimens for patients with R/R DLBCL has become extremely crucial. Recently, a combination regimen of lenalidomide, anti-programmed cell death protein-1 (PD-1) antibody, and rituximab demonstrated a good efficacy with an overall response rate (ORR) of 40% in R/R DLBCL (Sethi et al. Blood. 2019). Activation of the Bruton's tyrosine kinase (BTK)-mediated B-cell receptor (BCR) signaling pathway is a hallmark of DLBCL (Kapoor et al. Cell Death Dis. 2019). Orelabrutinib, a novel and potent irreversible BTK inhibitor, has shown encouraging efficacy with an ORR of 61.5% in combination with a new generation anti-CD20 antibody MIL62 in R/R DLBCL (Xu et al. Blood. 2020; Thus, we assessed the efficacy and safety of lenalidomide, anti-PD-1 antibody combined with orelabrutinib or rituximab in R/R DLBCL. Methods: This was a prospective, multicenter, single-arm, open-label, phase II study (ChiCTR2200056256). Patients aged 18 to 75 years were eligible if they had histologically confirmed R/R DLBCL, an Eastern Cooperative Oncology Group performance status of 0-2, adequate organ and bone marrow function, and survival time ≥ 6 months. Eligible patients received a combination regimen (21-day/cycle) of lenalidomide (10-25 mg, days 1-10, QD, oral), Tislelizumab (200 mg, day 1, intravenous), and orelabrutinib (150 mg, QD, oral) or rituximab (375 mg/m2, day 1, intravenous). The primary endpoint was ORR. Secondary endpoints included complete response (CR), progression-free survival (PFS), duration of response (DOR), time to response (TTR) and adverse events (AEs). Efficacy was assessed using Lymphoma Response to Immunomodulatory therapy Criteria (LYRIC, 2016). AEs were assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v 4.0. Results: Between August 2021 and March 2022, 9 patients (6 males; median age, 73 years, range 65-76) were enrolled. Among them, 8 patients were non-germinal center B-cell-like and 1 was unknown. Most patients had comorbidities (n=8, 88.9%), an Ann Arbor stage of III or IV (n=4, 44.4%), International Prognostic Index (IPI) ≥ 3 (n=4, 44.4%). All patients received lenalidomide, anti-PD-1 antibody combined with orelabrutinib regimen, and the median duration of treatment was 5 cycles (range 3-6). Among them, 4 patients (44.4%) received a second-line therapy, and 5 patients (55.5%) received ≥ third-line therapy. Before enrollment, 3 patients attained a CR as their best response during the previous therapies. Eight patients were included in the efficacy analysis. The ORR, CR and median TTR were 87.5%, 25.0%, and 2.45 months (range 1.97-2.73), respectively. Among them, 3 patients completed 6 cycles of therapy with ORR of 100% (Figure 1). The PFS and DOR were not completely mature due to the short follow-up period at the end of follow-up. Eight (80%) patients reported AEs. The most common hematological AEs were anemia (77.8%), platelet count reduced (55.6%), neutrophil count decreased (33.3%) and white blood cell count decreased (22.2%). Three patients (33.3%) discontinued treatment due to AEs (atrioventricular block, n=1; rash, n=2). In addition, the most common AEs were grade 1 or 2, and no grade 4 AEs. One patient died due to electrolyte disturbances and depression. Conclusion: Lenalidomide, anti-PD-1 antibody combined with orelabrutinib or rituximab regimen is effective and well-tolerated for patients with R/R DLBCL in this phase II study. This study provides a potential novel strategy for the treatment of R/R DLBCL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Thiotepa, Orelabrutinib, and Methotrexate Combined with or without the Rituximab Regimens in the Treatment of Patients with Central Nervous System Lymphoma

Background: Central nervous system lymphoma (CNSL) is a rare but lethal type of non-Hodgkin lymphoma (NHL), including primary CNSL (PCNSL) and secondary CNSL (SCNSL) (Zorofchian et al. Frontiers in Oncology. 2018). High-dose (HD) methotrexate (MTX, M)-based regimens followed by autologous stem cell transplantation (ASCT) or whole-brain radiotherapy (WBRT) (Young et al. Clin Lymphoma MyelomaLeuk. 2020) constitute the main therapeutic strategies. However, the outcome remains poor; nearly 50% of patients had relapsed disease, and 10%-15% were primary refractory (Dasgupta et al. Leuk Lymphoma. 2018; Sacks et al. Int J Stroke. 2018). Recently, several studies have shown that the B-cell receptor (BCR) signaling pathway is more susceptible to mutations in PCNSL (Zhang et al. EHA. 2022). Bruton tyrosine kinase (BTK) is a fundamental component in the BCR pathway. Orelabrutinib is a novel and potent irreversible BTK inhibitor with high cerebrospinal fluid (CSF) concentration and has shown efficacy in the treatment of CNSL (Wu et al. Invest New Drugs. 2022; Yang et al. Front Oncol. 2022; Zhang et al. HemaSphere. 2022). Thiotepa inhibits tumor growth by disrupting DNA bonds showing promising activity in CNSL. Thus, we conducted a retrospective study to evaluate the efficacy and safety of the thiotepa, orelabrutinib, and methotrexate combined with or without the rituximab (TOM±R) regimens in the treatment of patients with CNSL. Methods: Between March 2021 and March 2022, 13 patients with CNSL who received TOM±R regimens (thiotepa, 30-40 mg/m2, d4; orelabrutinib, 150 mg, daily; methotrexate, 3.5g/m2, d1; rituximab, 375mg/m2, d0; 21 days/cycle) as induction therapy was included in this retrospective study. Dose modification was administered in old patients or patients with renal impairment. After 4 to 6 cycles of the combination treatment, patients could receive consolidation therapy as ASCT or WBRT with or without afterward orelabrutinib maintenance. The primary endpoint was the best overall response rate (ORR) during the induction therapy according to the International PCNSL Collaborative Group (IPCG) standard, and the secondary endpoints included complete response (CR), partial response (PR), progression-free survival (PFS), and adverse events (AEs). Results: Thirteen patients (6 males; median age 58 years, range, 52-64) with histologically confirmed diffuse large B-cell lymphoma were included in this retrospective study, of whom 6 patients with PCNSL were treatment-naïve, 4 patients with PCNSL were first relapsed, and the rest 3 patients received their first treatment for SCNSL. Most patients had a history of Hepatitis virus infection (n=7), International Extranodal Lymphoma Study Group (IELSG) scores ≥ 2 (n=12), high-risk Memorial Sloan Kettering Cancer Center (MSKCC) score (n=11) and deep intracranial lesions (n=12).The median treatment cycle was 3 cycles (range, 2-9), and 7 patients received TOM+R. The ORR/CR and 6-month PFS rate was 92.3%/53.9% and 63.6% in all patients, 83.3%/66.7% and 66.7% in patients with PCNSL receiving first-line therapy, 100.0%/50.0% and 66.7% in patients with PCNSL receiving second-line therapy, and 100.0%/33.3% and 50% in patients with SCNSL receiving first-line therapy (Table 1). Among the 13 patients, 5 patients received orelabrutinib maintenance treatment, of whom 1 patient underwent WBRT and 1 patient underwent ASCT before orelabrutinib maintenance treatment. The ORR/CR and 6-month PFS rate of the 5 patients receiving orelabrutinib as maintenance treatment were 100%/80% and 100%, respectively (Figure 1). The most commonly reported AEs of all patients included leukopenia (53.9%) and pneumonia (15.4%). Grade 3-4 AEs included white blood cell count decreased (23.1%), thrombocytopenia (7.7%), fever (7.7%), and pneumonia (7.7%). No patients experienced severe AEs, and 1 patient died due to progressive disease. Conclusion: TOM±R regimens were effective and well-tolerated for patients with CNSL in this retrospective study. This combo regimens may provide a potential treatment strategy for patients with CNSL. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Novel 6-amino-1,3,5-triazine derivatives as potent BTK inhibitors: structure-activity relationship (SAR) analysis and preliminary mechanism investigation

Bruton's tyrosine kinase (BTK) is a promising drug target for the treatment of B-cell related malignancies. Irreversible inhibition of BTK by a covalent inhibitor has been proved to be a clinically effective therapy. However, most irreversible BTK inhibitors also inhibit other kinases including JAK3 and EGFR, leading to some adverse events. Herein, we reported the structure-based design and optimization of a series of irreversible BTK inhibitors bearing the 6-amino-1,3,5-triazine scaffold. Most of the synthesized compounds demonstrated considerable BTK inhibition and improved anti-proliferative activity against Raji and Ramos cells. Among them, compound C11 exhibited potent BTK inhibition (BTK IC50 = 17.0 nM) and a desirable selectivity profile especially over EGFR. Moreover, C11 effectively blocked activation of BTK and downstream signaling, arrested the cell cycle in G0/G1 phase and induced apoptosis in Raji cells. Its irreversible binding mode was further investigated by both molecular modeling and a washout experiment. Collectively, C11 is a novel selective irreversible BTK inhibitor worthy of further in-depth research.

Discovery of JNJ-64264681: A Potent and Selective Covalent Inhibitor of Bruton's Tyrosine Kinase.

Bruton's tyrosine kinase (BTK) is a Tec family kinase that plays an essential role in B-cell receptor (BCR) signaling as well as Fcγ receptor signaling in leukocytes. Pharmacological inhibition of BTK has been shown to be effective in treating hematological malignancies and is hypothesized to provide an effective strategy for the treatment of autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. We report the discovery and preclinical properties of JNJ-64264681 (13), a covalent, irreversible BTK inhibitor with potent whole blood activity and exceptional kinome selectivity. JNJ-64264681 demonstrated excellent oral efficacy in both cancer and autoimmune models with sustained in vivo target coverage amenable to once daily dosing and has advanced into human clinical studies to investigate safety and pharmacokinetics.

Evaluation of orelabrutinib monotherapy in patients with relapsed or refractory Waldenström's macroglobulinemia in a single-arm, multicenter, open-label, phase 2 study.

SummaryBackgroundOrelabrutinib is a novel, small molecule, selective irreversible Bruton tyrosine kinase inhibitor. The purpose of this study was to evaluate the efficacy and safety of orelabrutinib in patients with relapsed or refractory Waldenström's macroglobulinemia (R/R WM).MethodsThis is a prospective, multicenter study of orelabrutinib in patients with WM who had at least one prior line of treatment. Orelabrutinib was administered orally at a daily dose of 150 mg until disease progression or unacceptable toxicity. The primary endpoint was major response rate (MRR) assessed by the Independent Review Committee (IRC) according to IWWM-6. This study is registered with ClinicalTrials.gov, NCT04440059. This trial was also registered on Center for Drug Evaluation (www.chinadrugtrials.org.cn) in March 2019, with a number of CTR2019036.FindingsBetween August 2019 and December 2020, 66 R/R WM patients were assessed for eligibility. Forty-seven eligible patients were evaluated for efficacy at a median follow-up of 16.4 months (interquartile range: 12.5, 19.5). As assessed by IRC, the MRR was 80.9%, and the overall response rate was 89.4%. The median time to at least a minor response was 1.9 months. The PFS rates was 89.4% at 12 months. For patients with MYD88L265P/CXCR4NEG, MYD88L265P/CXCR4S338X, and MYD88NEG/CXCR4NEG mutations, the MRRs were 84.6%, 100%, and 25.0%. Most adverse events were Grades 1 or 2 (91.0%). The common grade 3 or higher adverse events occurring were neutropenia (10.6%), thrombocytopenia (6.4%), and pneumonia (4.3%). Serious adverse events (SAE) occurred in 10 patients (21.3%). One treatment-related death was reported (hepatitis B reactivation).InterpretationOrelabrutinib has shown good efficacy and manageable safety profiles in patients with R/R WM.FundingInnoCare Pharma.

Perioperative Bleeding Associated With Ibrutinib in Dermatologic Surgery: A Case-Control Study.

Ibrutinib, an irreversible Bruton tyrosine kinase inhibitor, has been associated with an increased risk of bleeding. There is a paucity of data on the risk of bleeding in patients on ibrutinib undergoing dermatologic surgery. To determine the frequency of bleeding complications associated with ibrutinib in patients undergoing dermatologic surgery. A retrospective, single-center, case-control study of patients on ibrutinib undergoing skin surgery between January 2013 and March 2020 compared with sex, disease, and age-matched control patients undergoing cutaneous surgeries. A total of 75 surgeries performed on 37 case patients and 116 surgeries performed on 64 control patients were included. Ibrutinib was associated with a statistically significant increased rate of bleeding events (6/75 [8%] vs 1/116 [0.8%], p -value = .02). Compared with ibrutinib patients who did not have a bleeding event, those on ibrutinib who suffered bleeding were all men, older (mean age 82.7 vs 73.0, p -value= .01), and had lower mean platelet counts (104.0 vs 150.5 K/μL, p -value = .03). Ibrutinib may be associated with increased risk of bleeding in patients with hematologic malignancies, particularly older men with lower platelet levels and on multiple anticoagulants. Transient discontinuation of ibrutinib should be considered for dermatologic surgeries.

Quantitative evaluation and pharmacokinetic characteristics of the irreversible BTK inhibitor zanubrutinib in mouse plasma using LC-MS/MS.

Zanubrutinib (BGB-3111) belongs to the class of irreversible inhibitors of Bruton's tyrosine kinase (BTK) for treating B-cell malignancies. A validated assay with excellent sensitivity, selectivity, and simplicity is required to measure plasma concentration and investigate its pharmacokinetics. The plasma of mice containing zanubrutinib and roxithromycin (internal standard) was processed with acetonitrile for protein precipitation. Then the supernatant was analyzed by high-performance liquid chromatography coupled with a triple quadrupole mass spectrometer using electrospray ionization in the positive mode. Zanubrutinib was given to mice intragastrically at 30 mg/kg to determine its pharmacokinetic parameters. The method was verified and showed good linearity in the range of 0.1-100 ng/mL. The method's sensitivity, accuracy, and precision were all within acceptable bounds. By this method, the pharmacokinetic profile of zanubrutinib in mouse plasma was measured.

Abstract 1400: AS-1763: a highly potent, noncovalent and next generation BTK inhibitor for the treatment of patients with B-cell malignancies having C481S mutation in BTK

Abstract Introduction: Bruton's tyrosine kinase (BTK) has been recently recognized as a validated drug target for the treatment of B-cell malignances. The emergence of clinical resistance to the first-generation covalent BTK inhibitors is, however, becoming a serious concern. Patients are reported to develop resistance during the treatment due to substitution of cysteine residue at position 481 with serine (C481S mutation) in BTK, which prevents the covalent binding of the first-generation irreversible BTK inhibitors, resulting in the loss of inhibitory activities. Therefore, there is a high unmet medical need for new therapeutic approaches to overcome the BTK C481S-mediated resistance. Material and methods: Compounds were tested in biochemical assays using recombinant human wildtype (WT) and C481S mutant BTKs. Cellular activity of AS-1763 was evaluated in human diffuse large B cell lymphoma (DLBCL) cell lines, OCI-Ly10 and its BTK[C481S] knock-in cells. The in vivo antitumor activity of AS-1763 was assessed in two tumor xenograft mouse models bearing WT or BTK [C481S] knock-in OCI-Ly10 cells. Results: We have discovered AS-1763 as an orally available, highly potent, selective and reversible BTK inhibitor. AS-1763 showed potent inhibitory activities for WT BTK (an activated form, BTK[A]) and the C481S mutant with sub-nanomolar IC50s (IC50 = 0.85 and 0.99 nM for BTK[A] and BTK[C481S], respectively). In cellular assays, AS-1763 exhibited strong antiproliferative activities for WT and BTK [C481S] knock-in OCI-Ly10 cells. AS-1763 demonstrated significant tumor growth inhibition and tumor regression in WT as well as BTK[C481S] knock-in OCI-Ly10 xenograft model. Conclusions: The preclinical data support the clinical development of AS-1763 in patients with B-cell malignancies both having WT and C481S mutation in BTK. The first-in-human Phase 1 clinical trial of AS-1763 in healthy volunteers (EudraCT 2020-005599-37) is currently ongoing, and the Phase 1b study in patients is expected to begin in 2022. Citation Format: Wataru Kawahata, Tokiko Asami, Takao Kiyoi, Takayuki Irie, Shigeki Kashimoto, Hatsuo Furuichi, Masaaki Sawa. AS-1763: a highly potent, noncovalent and next generation BTK inhibitor for the treatment of patients with B-cell malignancies having C481S mutation in BTK [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 1400.

Abstract CT532: Phase 1/2 results of ceralasertib (Cerala) as monotherapy or in combination with acalabrutinib (Acala) in high-risk relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL)

Abstract Introduction: Patients (pts) with CLL who relapse on therapies targeting B-cell receptor signaling pathways have limited treatment options. Cerala, a selective oral ATR inhibitor, has shown synergistic preclinical activity with a Bruton tyrosine kinase inhibitor (BTKi) in TP53- and ATM-defective CLL cells (Kwok et al. Blood. 2016;127:582-95). Acala is a selective, irreversible BTKi approved for CLL. This phase 1/2 proof-of-concept study investigated cerala alone and in combination with acala in high-risk R/R CLL. Methods: This multicenter, nonrandomized, open-label study (NCT03328273) enrolled adults with high-risk R/R CLL per iwCLL criteria and ECOG performance status ≤2. In Arm A, pts with TP53 mutation, del(17p), or del(11q) having exhausted available treatment options received cerala monotherapy (cohort 1: 160 mg BID continuously; cohort 2 [after ≥2 DLTs in cohort 1]: 160 mg BID 2 wk on/2 wk off). In Arm B, pts with del(11q) suitable for BTKi and cerala treatment per investigator judgment received acala 100 mg BID continuously alone for cycle 1 and acala 100 mg BID continuously + cerala 160 mg BID 1 wk on/3 wk off from cycle 2 onward. Primary objectives: safety and pharmacokinetics (PK). Secondary objective: activity—overall response rate (ORR), complete response rate, duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Pharmacodynamic changes were explored using novel multiple reaction monitoring-targeted mass spectrometry. Results: Eleven pts were treated (median age 64 y; median prior therapy lines 3). Pts in Arm A (n=8 [7 received prior BTKi]: cohort 1 n=5; cohort 2 n=3) received cerala for a median of 3.5 mo (range 0.5-7.7). Grade (G) ≥3 AEs in &amp;gt;1 pt were anemia (75%), thrombocytopenia (63%), and neutropenia (25%); 4 DLTs of G4 thrombocytopenia were reported (3 in 2 pts in cohort 1; 1 in 1 pt in cohort 2). No responses were observed in Arm A. At a median follow-up of 15.1 mo, median PFS was 3.8 mo (95% confidence interval [CI] 0.7-4.6); median OS was 16.9 mo (95% CI 6.6-not reached [NR]). All pts had baseline telomeres within a “fusogenic” range (negative prognostic indicator).In Arm B (n=3; all BTKi-naive), 2 pts received acala + cerala and 1 received acala only. Median (range) treatment duration was 7.2 mo (4.9-9.5) for cerala and 15.9 mo (9.7-18.4) for acala. No G≥3 AEs or DLTs were reported. ORR was 100% (all partial responses); median DOR was NR. At a median follow-up of 15.9 mo, median PFS and OS were NR. PK of acala and cerala were consistent with historical data, with no drug-drug interactions when combined; cerala did not affect BTK occupancy. Conclusions: Cerala monotherapy in BTKi-exposed, high-risk CLL pts showed limited clinical benefit. Acala + cerala was tolerable with preliminary clinical activity in pts with CLL and del(11q). The study terminated due to the evolving treatment landscape. Citation Format: Wojciech Jurczak, Nagah Elmusharaf, Christopher P. Fox, William Townsend, Amanda G. Paulovich, Shringi Sharma, Graeme Parr, Veerendra Munugalavadla, Fanny Krantz, Helen Yang, Emma Dean, Richa Manwani, Peter Hillmen. Phase 1/2 results of ceralasertib (Cerala) as monotherapy or in combination with acalabrutinib (Acala) in high-risk relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL) [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 CT532.

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.

Acalabrutinib: a bruton tyrosine kinase inhibitor for the treatment of chronic lymphocytic leukemia

ABSTRACT Introduction The first-in-class Bruton tyrosine kinase (BTK), ibrutinib, demonstrated remarkable activity in chronic lymphocytic leukemia (CLL). However, its toxicity profile renders it potentially inappropriate for use in patients with bleeding or cardiovascular disorders. In response to the high demand for a safer and efficient BTK inhibitor, with improved toxicity profile, acalabrutinib as a second-generation irreversible BTK inhibitor has been approved for the treatment of CLL. Areas covered This review examines the activity of acalabrutinib in treating treatment-naïve and relapsed refractory CLL and its toxicity profile when compared to ibrutinib and other drugs. It will examine the outcomes of the ELEVATE-TN, ASCEND, and ELEVATE-RR studies in detail, with a particular focus on the safety and efficacy of acalabrutinib. The strengths and weaknesses of this drug will be highlighted and future directions for research will be identified. Expert opinion In patients with CLL, acalabrutinib demonstrates a superior safety profile than ibrutinib and similar activity. In the first direct comparison of acalabrutinib with ibrutinib in relapsed/refractory CLL, acalabrutinib was found to demonstrate non-inferior progression-free survival, with fewer cardiovascular adverse events.

Zanubrutinib for the Treatment of B-cell Malignancies

Selective Bruton's tyrosine kinase (BTK) inhibition is an important therapeutic approach for B-cell malignancies. Ibrutinib, a first-in-class, oral, irreversible BTK inhibitor, has a toxicity profile attributed to off-target inhibition of kinases structurally related to BTK. A highly potent and selective next-generation BTK inhibitor, zanubrutinib, was designed to address intolerance and toxicity concerns associated with ibrutinib. Zanubrutinib provides complete and sustained BTK occupancy in peripheral blood mononuclear cells and lymph nodes, with reduced toxicity compared with ibrutinib. Zanubrutinib received accelerated approval in the USA for patients with previously treated mantle cell lymphoma (2019) and relapsed/refractory (R/R) marginal zone lymphoma (2021) and was approved for Waldenström's macroglobulinaemia (WM) in 2021. Key clinical trials evaluating the efficacy and safety of zanubrutinib include the ASPEN study in patients with WM (ClinicalTrials.gov identifier: NCT03053440), the ALPINE study in patients with R/R chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma (SLL; ClinicalTrials.gov identifier: NCT03734016) and the SEQUOIA study in treatment-naïve patients with CLL/SLL with and without del(17p) mutation (ClinicalTrials.gov identifier: NCT03336333). The more selective BTK binding profile, high potency, favourable pharmacokinetic and pharmacodynamic profile, and minimal cardiovascular toxicity of zanubrutinib compared with ibrutinib suggest that zanubrutinib may be an important treatment option when prescribed in accordance with guidelines.

Discovery of a potent BTK and IKZF1/3 triple degrader through reversible covalent BTK PROTAC development

Building on our previous work on ibrutinib-based reversible covalent Bruton's tyrosine kinase (BTK) PROTACs, we explored a different irreversible BTK inhibitor poseltinib as the BTK binder for PROTAC development. Different from ibrutinib, converting the irreversible cysteine reacting acrylamide group of poseltinib to a reversible covalent cyano-acrylamide group dramatically decreases the binding affinity to BTK by over 700 folds. Interestingly, one of the reversible covalent BTK PROTACs based on poseltinib with a rigid linker, dubbed as PS-RC-1, is highly potent (IC50 = ~10 nM) in Mino cells but not in other mantle cell lymphoma (MCL) cell lines, such as Jeko-1 and Rec-R cells. We showed that PS-RC-1 potently induces degradation of IKZF1 and IKZF3 but not BTK or GSPT1, accounting for its toxicity in Mino cells. We further decreased the molecular size of PS-RC-1 by shrinking the BTK binding moiety and developed PS-2 as a potent BTK and IKZF1/3 triple degrader with high specificity.

Targeted Treatment of Chronic Lymphocytic Leukemia: Clinical Utility of Acalabrutinib

In chronic lymphocytic leukemia (CLL), a deeper understanding of the disease biology led over the last decade to the development and clinical use of different targeted drugs, including Bruton tyrosine kinase (BTK) inhibitors. The first BTK inhibitor approved for clinical use is ibrutinib, which showed excellent efficacy and good tolerability. More recently, the interest is growing for novel more selective BTK inhibitors that may reduce the off-target effects of the drug, thus minimizing side effects and subsequent treatment interruptions or discontinuations. Acalabrutinib is an orally administered irreversible BTK inhibitor, characterized by the lack of inhibition towards other kinases. In this review, we present the most recent data from clinical trials on the clinical efficacy of acalabrutinib and acalabrutinib-based combinations for the treatment of patients with relapsed/refractory and treatment-naïve CLL. We delineate the safety profile of the drug, describe side effects of interest and discuss the clinical management of patients receiving acalabrutinib. Due to its efficacy and the favorable safety profile, acalabrutinib has emerged as a viable therapy option in the current landscape of multiple approved treatments for CLL.