Specific Bruton Tyrosine Kinase Inhibitor Research Articles

Risk of Invasive Fungal Infections in Patients With Chronic Lymphocytic Leukemia Treated With Bruton Tyrosine Kinase Inhibitors: A Case-Control Propensity Score-Matched Analysis.

Prior reports have suggested a possible increase in the frequency of invasive fungal infections (IFIs) with use of a Bruton tyrosine kinase inhibitor (BTKi) for treatment of chronic lymphoid malignancies such as chronic lymphocytic leukemia (CLL), but precise estimates are lacking. We aim to characterize the prevalence of IFIs among patients with CLL, for whom a BTKi is now the first-line recommended therapy. We queried TriNetX, a global research network database, to identify adult patients with CLL using the International Classification of Diseases, Tenth Revision code (C91.1) and laboratory results. We performed a case-control propensity score-matched analysis to determine IFIs events by BTKi use. We adjusted for age, sex, ethnicity, and clinical risk factors associated with an increased risk of IFIs. Among 5358 matched patients with CLL, we found an incidence of 4.6% of IFIs in patients on a BTKi versus 3.5% among patients not on a BTKi at 5 years. Approximately 1% of patients with CLL developed an IFI while on a BTKi within this period. Our adjusted IFI event analysis found an elevated rate of Pneumocystis jirovecii pneumonia (PJP) (0.5% vs 0.3%, P = .02) and invasive candidiasis (3.5% vs 2.7%, P = .012) with the use of a BTKi. The number needed to harm for patients taking a BTKi was 120 and 358 for invasive candidiasis and PJP, respectively. We found an adjusted elevated rate of PJP and invasive candidiasis with BTKi use. The rates are, however, low with a high number needed to harm. Additional studies stratifying other IFIs with specific BTKis are required to identify at-risk patients and preventive, cost-effective interventions.

MAHOGANY: A phase 3 trial of zanubrutinib plus anti-CD20 antibodies vs lenalidomide plus rituximab in patients with relapsed or refractory follicular or marginal zone lymphoma.

TPS7590 Background: Inhibition of Bruton tyrosine kinase (BTK) has emerged as a strategy for treatment of patients (pts) with B-cell malignancies including indolent non-Hodgkin lymphomas. Zanubrutinib is a second-generation, potent, and specific BTK inhibitor and has shown to be more effective and better tolerated than first-generation BTK inhibitors in several diseases including chronic lymphocytic leukemia/small lymphocytic lymphoma and Waldenström macroglobulinemia. Zanubrutinib is approved in >15 countries, including the United States and European Union, for pts with relapsed or refractory (R/R) marginal zone lymphoma (MZL) who received ≥1 anti-CD20–based regimen, based on the single-arm MAGNOLIA trial (Opat et al. Clin Cancer Res 2021). In R/R follicular lymphoma (FL), ROSEWOOD, a phase 2 randomized study of zanubrutinib plus obinutuzumab (ZO) vs obinutuzumab, met its primary endpoint of increased overall response rate (ORR) at primary analysis (Zinzani et al. J Clin Oncol 2022). In this trial, ZO in pts with R/R FL demonstrated deep and durable responses with a favorable safety profile. Methods: MAHOGANY (BGB-3111-308, NCT05100862) is a phase 3 randomized, open-label trial that compares efficacy and safety of a combination of zanubrutinib plus anti-CD20 monoclonal antibody vs lenalidomide plus rituximab in 2 independent cohorts, for pts with either R/R FL or MZL. Key eligibility criteria include histologically confirmed FL (grades 1-3A) or MZL, previously treated with ≥1 anti-CD20–based regimen, relapsed after or refractory to the most recent systemic therapy, in need of treatment, no prior BTK inhibitor exposure, and no prior resistance to a lenalidomide-based regimen. In the FL cohort, pts will be randomized 1:1 to ZO (N = 300) and lenalidomide plus rituximab (N = 300). Randomization is stratified by age (≥60 years vs < 60 years), number of prior lines of therapy (1-2 vs > 2) and rituximab-refractory status (yes vs no). The primary endpoint is progression-free survival (PFS) assessed by an independent review committee (IRC), according to Lugano 2014 criteria. Key secondary endpoints are ORR by IRC assessment and overall survival. In the MZL cohort, pts will be randomized 1:1 to zanubrutinib plus rituximab (N = 75) and lenalidomide plus rituximab (N = 75). Randomization is stratified by age (≥60 years vs < 60 years) and number of prior lines of therapy (1-2 vs > 2). The primary endpoint is PFS assessed by IRC according to Lugano 2014 criteria. The key secondary endpoint is ORR by IRC assessment. Zanubrutinib is given at 160 mg twice daily or 320 mg once daily according to investigator, until progression or unacceptable toxicity. Obinutuzumab or rituximab are given for up to 8 infusions. Lenalidomide is given according to approved label for up to 12 cycles. Recruitment is ongoing. Clinical trial information: NCT05100862 .

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: Inhibition of Bruton tyrosine kinase (BTK) has emerged as a strategy for treatment of patients (pts) with B-cell malignancies including indolent non-Hodgkin lymphomas. Zanubrutinib is a second-generation, potent, and specific BTK inhibitor and has shown to be more effective and better tolerated than first-generation BTK inhibitors in several diseases including chronic lymphocytic leukemia/small lymphocytic lymphoma and Waldenström macroglobulinemia. Zanubrutinib is approved in >15 countries, including the United States and European Union, for pts with relapsed/refractory (R/R) marginal zone lymphoma (MZL) who received ≥1 anti-CD20–based regimen, based on the single-arm MAGNOLIA trial (Opat et al. Clin Cancer Res 2021). In R/R follicular lymphoma (FL), ROSEWOOD, a phase 2 randomized study of zanubrutinib plus obinutuzumab versus obinutuzumab, met its primary endpoint of increased overall response rate (ORR) at primary analysis (Zinzani et al. J Clin Oncol 2022). In this trial, zanubrutinib plus obinutuzumab in pts with R/R FL demonstrated deep and durable responses with a favorable safety profile. Methods: MAHOGANY (BGB-3111-308, NCT05100862) is a phase 3 randomized, open-label trial that compares efficacy and safety of a combination of zanubrutinib plus anti-CD20 monoclonal antibody versus lenalidomide plus rituximab in 2 independent cohorts, for pts with either R/R FL or MZL. Key eligibility criteria include histologically confirmed FL (grades 1–3A) or MZL, previously treated with ≥1 anti-CD20-based regimen, relapsed after or refractory to the most recent systemic therapy, in need of treatment, no prior BTK inhibitor exposure, and no prior resistance to a lenalidomide-based regimen. In the FL cohort, pts will be randomized 1:1 to zanubrutinib plus obinutuzumab (N = 300) and lenalidomide plus rituximab (N = 300). Randomization is stratified by age (≥60 vs. <60 years), number of prior lines of therapy (1–2 vs. >2), and rituximab-refractory status (yes vs. no). The primary endpoint is progression-free survival (PFS) assessed by an independent review committee (IRC) according to Lugano 2014 criteria. Key secondary endpoints are ORR by IRC assessment and overall survival. In the MZL cohort, pts will be randomized 1:1 to zanubrutinib plus rituximab (N = 75) and lenalidomide plus rituximab (N = 75). Randomization is stratified by age (≥60 vs. <60 years) and number of prior lines of therapy (1–2 vs. >2). The primary endpoint is PFS assessed by IRC according to Lugano 2014 criteria. The key secondary endpoint is ORR by IRC assessment. Zanubrutinib is given at 160 mg twice daily or 320 mg once daily according to investigator, until progression or unacceptable toxicity. Obinutuzumab or rituximab are given for up to 8 infusions. Lenalidomide is given according to approved label for up to 12 cycles. Recruitment is ongoing. Encore Abstract—previously submitted to ASCO 2023 and EHA 2023 The research was funded by: BeiGene Keywords: aggressive B-cell non-Hodgkin lymphoma, combination therapies Conflicts of interests pertinent to the abstract L. Sehn Consultant or advisory role AbbVie, Seattle Genetics, Janssen, Amgen, Roche/Genentech, Gilead Sciences, Kite, a Gilead Company, Merck, Teva, TG Therapeutics, AstraZeneca, Incyte, Sandoz-Novartis, Genmab, Celgene/BMS, BeiGene Honoraria: Amgen, AbbVie, Gilead Sciences, Janssen-ORtho, Kite, a Gilead Company, Merck, Roche/Genentech, Seattle Genetics, Teva, AstraZeneca, Incyte, Sandoz-Novartis, Genmab, Celgene/BMS, BeiGene Research funding: Roche/Genentech, Teva C. Sarkozy Consultant or advisory role Janssen, GSK, Incyte, BMS Honoraria: AbbVie Research funding: Roche Educational grants: Roche, Incyte Other remuneration: Incyte A. Salar Consultant or advisory role BeiGene, Roche Research funding: Roche, AbbVie Other remuneration: Kite, a Gilead Company, Janssen J. Trotman Consultant or advisory role BeiGene WM Advisory Board 2022 (uncompensated) Research funding: BeiGene, Janssen, Pharmacyclics, Roche, Celgene/BMS, Selectar P. L. Zinzani Consultant or advisory role Celltrion, Gilead Sciences, Janssen-Cilag, BMS, Servier, Sandoz, MSD, Roche, EUSA Pharma, Kyowa Kirin, Takeda, Secura Bio, TG Therapeutics, Novartis, ADC Therapeutics, Incyte, BeiGene, Novartis J. Zhang Employment or leadership position: BeiGene Stock ownership: BeiGene P. Fustier Employment or leadership position: BeiGene Stock ownership: BeiGene R. Delarue Employment or leadership position: Celgene/BMS, BeiGene Stock ownership: Celgene/BMS, BeiGene L. Nastoupil Consultant or advisory role Sirpant, Iterus Bios Honoraria: Gilead Sciences, Novartis, Janssen Oncology, TG Therapeutics, BMS, ADC Therapeutics, Morphosys, Epizyme, Genmab, Takeda, Genentech/Roche, Caribou Biosciences Research funding: Janssen Biotech, Genentech/Roche, Epizyme, Novartis, IgM Biosciences, Gilead Sciences, Allogene Therapeutics, Takeda, BMS/Celgene Educational grants: Genentech/Roche

Establishment and characterization of a new activated B-cell-like DLBCL cell line, TMD12

We report the establishment of a novel activated B-cell-like (ABC) diffuse large B-cell lymphoma (DLBCL) cell line, designated as TMD12, from a patient with highly refractory DLBCL. ABC-DLBCL is a subtype with a relatively unfavorable prognosis that was originally categorized using gene expression profiling according to its cell of origin. TMD12 cells were isolated from the pleural effusion of the patient at relapse and passaged continuously in vitro for >4 years. The cells displayed cluster of differentiation (CD)19, CD20, CD22, CD38, human leukocyte antigen-DR isotype, and κ positivity and CD5, CD10, CD23, and λ negativity, as detected using flow cytometric analysis. The chromosomal karyotypic analysis, including the spectral karyotyping method, confirmed t(1;19)(q21:q13.1), del(6q23), gain of chromosome 18, and other abnormalities. Mutation analyses, including whole-exome sequencing, revealed that TMD12 cells harbored mutations in MYD88 and CD79B, indicating an ABC subtype. TMD12 cells exhibited chronic active B-cell receptor signaling and constitutive activation of the nuclear factor κB pathway, which is typically associated with sensitivity to a specific Bruton tyrosine kinase inhibitor, ibrutinib. Intriguingly, TMD12 cells displayed moderate resistance to ibrutinib and lacked activation of Janus kinase/signal transducers and activators of transcription 3 signaling, another hallmark of this DLBCL subtype. Treatment with an inhibitor against tumor progression locus 2 (TPL2), a multifunctional intracellular kinase that is activated particularly downstream of Toll-like receptors or MYD88 and IκB kinase α/β (IKKα/β), suppressed the proliferation of TMD12 cells, implying the possible involvement of the TPL2-p105 pathway in the tumorigenesis of ABC-DLBCL. Because only a limited number of ABC-DLBCL cell lines are currently available, TMD12 cells might provide a useful tool in the search for novel druggable targets for this intractable lymphoma.

Abstract 1396: Non-competitive inhibition of proteasome by kinase inhibitors

Abstract Inhibitors of Bruton's Tyrosine Kinase (BTK) and inhibitors of the proteasome are currently in use for treatment of hematologic malignancies. While the ubiquitin proteasome system is necessary for protein homeostasis in all mammalian cells, BTK is unique to some B cell malignancies. However, BTK inhibitors and LU-102, a specific inhibitor of the β2 site of the proteasome, have previously been shown to synergize in hematologic malignancies which do not express BTK, at a 100-fold higher concentration than is needed for complete inhibition of BTK, suggesting an off-target effect of these BTK inhibitors. Triple Negative Breast Cancer (TNBC), a cancer with poor prognosis and no current targeted therapy, also does not express BTK. We found that LU-102 and a specific BTK inhibitor, CGI-1764, are de-facto synthetically lethal to TNBC cells, and that effect of other BTK inhibitors varied from similar synergy to no synergy. This data further supports the idea that synergy is due to off-target effects of BTK inhibitors.We have now found that CGI-1764 is a non-competitive, allosteric inhibitor of all catalytic subunits of the proteasome 20S proteolytic core and exerts its effect in a unique, dose-dependent manner. RNA sequencing shows that the Unfolded Protein Response pathway is upregulated in TNBC cells response to treatment with the CGI-1746+LU-102 combination. We also found that accumulation of ubiquitin conjugates is synergistic indicating that the combination treatment has a synergistic effect on the inhibition of proteasome activity. These findings may pave the path to the development of more potent allosteric inhibitors of the proteasome and show that kinase inhibitors should be screened for inhibition of the proteasome as potential off-target effect. Citation Format: Alexei F. Kisselev, Olasubomi Akintola, John Smith. Non-competitive inhibition of proteasome by kinase inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1396.

BGB-3111 in Combination with Obinutuzumab in Patients with Chronic Lymphocytic Leukemia and Follicular Lymphoma

Introduction: Bruton's Tyrosine Kinase (BTK) plays a critical role in B-cell receptor (BCR) signaling, which mediates B-cell proliferation, migration, and adhesion (Rickert, 2013; Aalipour, 2013; Choe, 2016). The BCR pathway is an established therapeutic target in chronic lymphocytic leukemia (CLL), and pathway members are frequently mutated in follicular lymphoma (FL) (Byrd, 2016; Krysiak, 2017). Ibrutinib, the first-generation BTK inhibitor, has activity in FL and CLL in combination with rituximab (Fowler, 2016; Burger, 2014). BGB-3111 is a potent and specific BTK inhibitor, designed to minimize off-target inhibition of TEC and EGFR family kinases. BGB-3111 has minimal inhibitory effects against ITK and does not inhibit ITK-mediated rituximab-induced antibody-dependent cell-mediated cytotoxicity. Here we present updated interim results of an ongoing study of BGB-3111 in combination with obinutuzumab in patients with CLL/small lymphocytic lymphoma (SLL) and FL.Methods: This is an ongoing, open-label, multicenter, phase 1b study of the combination of BGB-3111 and obinutuzumab in patients with B-cell malignancies with indication-specific expansion cohorts. Eligible patients had Eastern Cooperative Oncology Group performance status of 0-2, absolute neutrophil count >1000/μL, platelets >40,000/μL, adequate renal and hepatic function, and no significant cardiovascular disease. Growth factors and transfusions were allowed. Concomitant anticoagulation was also permitted. The primary endpoint of the expansion cohorts was response rate and duration of response using standard International Working Group (IWG) criteria for each disease. A key secondary endpoint was to evaluate the safety of the combination.Results: As of Jun 1, 2017, 45 patients with CLL/SLL (20 pts with treatment-naïve [TN]; 25 patients with relapsed/refractory [R/R]), and 22 patients with R/R FL were enrolled. Demographic and disease characteristics are shown in the Table. Median follow-up time was 8.4 months (range, 2.6-16.0) for patients with CLL/SLL and 7.7 months (range, 0.3-16.3) for patients with FL. BGB-3111 plus obinutuzumab was well tolerated. One fatal adverse event (AE) occurred (squamous cell carcinoma in a CLL patient with prior squamous cell carcinoma). Serious AEs (SAEs) were reported in 12 (27%) CLL/SLL pts and 5 (23%) FL pts; there was only 1 SAE related to treatment (infusion-related reaction) and 1 SAE related to BGB-3111 (pneumonia). The most common (>20%) any-grade AEs for CLL patients were neutropenia (40%), contusion (22%), and thrombocytopenia; for FL patients, they were thrombocytopenia (27%), contusion (23%), fatigue (23%), and upper respiratory tract infection (23%). Grade 3-4 neutropenia was the only AE that occurred in >2 patients (22% for CLL; 14% for FL). There were no AEs of atrial fibrillation. Patients were evaluable for response if they had completed baseline and ≥1 on-treatment response assessments. Objective response rates (complete response [CR] + partial response) were 89%, 92%, and 69% in TN CLL/SLL, R/R CLL/SLL, and R/R FL, respectively, with 5 CRs in TN CLL/SLL, 4 CRs in R/R CLL/SLL, and 5 CRs in FL. Four patients (1 R/R CLL;3 FL) experienced disease progression; no instances of disease transformation occurred.Conclusions: BGB-3111 plus obinutuzumab is well tolerated and highly active in CLL/SLL and FL. Few patients have discontinued, and responses remain durable within the larger patient sample with continued follow-up. [Display omitted] DisclosuresQuach:Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Badoux:Roche: Consultancy. Prince:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Eisai: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Research Funding. Eek:Border Medical Oncology: Employment; Ramsey Private Hospital Albury Wodonga: Membership on an entity's Board of Directors or advisory committees. Huang:BeiGene: Employment. Zhang:BeiGene: Employment. Wang:BeiGene: Employment. Hedrick:BeiGene: Employment. Novotny:BeiGene: Employment. Flinn:Constellation: Research Funding; Curis: Research Funding; Gilead: Research Funding; Portola: Research Funding; Pharmacyclics: Research Funding; Trillium: Research Funding; KITE: Research Funding; Janssen: Research Funding; Calithera: Research Funding; Incyte: Research Funding; Agios: Research Funding; Infinity: Research Funding; Acerta: Research Funding; Celgene: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics LLC: Research Funding; Verastem: Research Funding; AbbVie Company: Research Funding; TG Therapeutics: Research Funding; Takeda: Research Funding; Seattle Genetics: Research Funding; Pfizer: Research Funding; Merck: Research Funding; Novartis: Research Funding; Beigene: Research Funding; Forty Seven: Research Funding.

Safety and Activity of the Highly Specific BTK Inhibitor BGB-3111 in Combination with the PD-1 Inhibitor BGB-A317 in Patients with B-Cell Lymphoid Malignancies

IntroductionBGB-3111 is a potent, highly specific, and irreversible Bruton tyrosine kinase (BTK) inhibitor, with greater selectivity for BTK vs other TEC- and EGFR-family kinases, and demonstrates favorable pharmacokinetic and pharmacodynamics properties (Tam et al. ASH 2016). BGB-A317, a humanized IgG4 variant monoclonal antibody with no Fc gamma receptor binding, targets the programmed cell death-1 (PD-1) receptor and is being developed for the treatment of solid and hematologic malignancies (Friedlander, ASCO, 2017). The combination of PD-1/PD-L1 inhibitors with B-cell receptor pathway inhibitors is being evaluated in different B-cell malignancies with the expectation of greater benefit for patients. Here, we present early safety data from a Phase 1b trial exploring the combination of BGB-3111 and BGB-A317.MethodsThis is an open-label, multicenter, phase 1b study to evaluate safety, tolerability, and preliminary efficacy of BGB-3111 in combination with BGB-A317 in subjects with B-cell malignancies, including Waldenström's macroglobulinemia (WM), aggressive and indolent non-Hodgkin's lymphoma, and transformed chronic lymphocytic leukemia/follicular lymphoma (FL) amongst other B-cell malignancies. The study includes a standard 3+3 dose escalation phase followed by dose expansion. The dose levels are: Cohort 1, BGB-3111 320 mg once a day (QD) combined with BGB-A317 2.0 mg/kg every 3 weeks (Q3W); Cohort 2, BGB-3111 320 mg QD combined with BGB-A317 5.0 mg/kg Q3W; and Cohort 3, BGB-3111 160 mg BID combined with BGB-A317 200 mg (flat dose) Q3W.ResultsAs of 01 June 2017, 25 pts were enrolled in the dose escalation portion of the trial: 15 pts in Cohort 1 and 10 pts in Cohort 2. Key patient characteristics, safety, and efficacy are shown in the Table.Safety: Median follow - up was 2.8 (range, 0.4-10.7) months. There were no dose-limiting toxicities (DLTs) in Cohort 1. Cohort 2 saw hemolysis in 2 pts, both with WM; one qualified as a DLT. These events were not associated with a positive direct antiglobulin test and resolved with immunosuppressive therapy, but resulted in the decision to exclude further enrollment of WM pts in the trial. No further DLTs were observed after exclusion of WM pts.The most frequent adverse events (AEs) of any cause in Cohort 1 were diarrhea (n=4, 26.7%), fatigue (n=4, 26.7%), and pyrexia (n=3, 20%) and in Cohort 2 were contusion (n=3, 30%), anemia, hemolysis, headache, peripheral edema, thrombocytopenia, and upper respiratory tract infection (n=2, 20% each). Frequent AEs ≥ Grade 3 from both Cohorts included anemia (n=32, 12%), and thrombocytopenia and hemolytic transfusion reaction (n=2, 8% each).Serious AEs related to study treatment were seen in 8 patients: hemolysis (n=2), pneumonitis, infusion-related reaction, abscess limb, pneumonia, anemia, ulcerative keratitis, catheter site hemorrhage, autoimmune encephalitis, dyspnea, and eczema (n=1 each). The encephalitis could not be attributed to other causes and resolved with immunosuppressive therapy. No serious hemorrhages or atrial fibrillation have been reported to date.Discontinuation due to AEs occurred in six patients for the following AEs: hemolysis (n=2), nausea, lymph gland infection, ALT increased and GGT increased (same patient), auto-immune encephalitis, and progression-related complications (n=1 each).Efficacy: Efficacy data is very early with limited follow-up and most pts treated at the lowest dose. So far, 30% of pts have responded, including responses in both WM pts as well as complete responses seen in FL and non-GCB DLBCL pts.ConclusionsThe combination of BGB-3111 and BGB-A317 has a manageable toxicity profile in a wide variety of B-cell malignancies. Autoimmune adverse events, consistent with anti-PD-1 therapy, were observed and managed with supportive care. Notably, hemolysis in 2 WM patients suggestlimitations of this combination in indolent lymphoid diseases such as WM, especially given the risk/ benefit profile of single-agent BGB-3111 in indolent settings .Enrollment is now open for Cohort 3, which will be followed by expansion cohorts to further characterize safety and efficacy of the combination. [Display omitted] DisclosuresCull:Amgen Australia: Other: travel expenses Lugano lymphoma conference 2017; Takeda Australia: Other: travel expenses Highlights of ASH march 2017, Brisbane. Opat:Janssen: Consultancy, Honoraria, Speakers Bureau; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Beigene: Research Funding; Mundipharma: Consultancy; Amgen: Research Funding. Trotman:Janssen Cilag: Other: Funding facilitating research paid to third party (BioGrid Australia), Research Funding. Hilger:BeiGene: Employment. Zhang:BeiGene: Employment. Feng:BeiGene: Employment. Ro:BeiGene: Employment. Huang:BeiGene: Employment. Tam:Abbvie: Honoraria, Research Funding; Janssen Cilag: Honoraria, Research Funding; Roche: Honoraria, Research Funding.

BGB-3111, a Highly Specific BTK Inhibitor, Is Well Tolerated and Highly Active in Chinese Patients with Relapsed/Refractory B-Cell Malignancies: Initial Report of a Phase 1 Trial in China

Introduction: BGB-3111 is a potent, specific and irreversible inhibitor of Bruton's tyrosine kinase (BTK). In its first-in-human study in Australia, New Zealand, South Korea, US and Europe, it was demonstrated that BGB-3111 can achieve complete, continuous BTK occupancy in peripheral blood mononuclear cells and lymph nodes, associated with durable clinical responses in patients (pts) with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and Waldenström's macroglobulinemia (WM). Here we report the initial findings of a Phase 1 trial of BGB-3111 in Chinese pts with B-cell malignancies.Patients/ Methods: Chinese pts with relapsed/ refractory B-cell malignancies were enrolled to 1 of 2 dose cohorts of BGB-3111 (320 mg PO QD or 160 mg PO BID). Adverse events (AEs) are reported per CTCAE v4.03, responses per standard criteria according to histology (NHL IWG criteria 2014, CLL IWG criteria 2013, WM IWWM criteria 2013), BTK occupancy determined using an irreversible binding assay in PBMCs.Results: As of 8 June 2017, 21 pts have been enrolled. Median number of prior therapies was 3 (range 1-9). 11 pts received 160 mg PO BID and 10 pts received 320 mg PO QD. The median follow-up time is 8.8 months (range 1.7-11.1 months). All pts were included for safety evaluation and efficacy analyses. Complete BTK occupancy at dosing trough in PBMCs was demonstrated at both dose levels. As of the cut-off date, there was no dose limiting toxicity (DLT). The most frequent grade 3 or above AEs (≥ 10%) were neutropenia (28.6%), thrombocytopenia (14%), leukocytosis (14%), and lymphocytosis (14%). 4 SAEs have been reported, including one event each of toxic epidermal necrolysis (G4), febrile neutropenia (G3), neutropenia (G4), and thrombocytopenia (G4). One MZL pt was discontinued due to G4 toxic epidermal necrolysis and two pts (1 CLL and 1 FL) were discontinued due to disease progression after 169 days (CLL) and 92 days (FL) of treatment. One death (one FL pt) was reported after drug discontinuation due to disease progression. There were no major bleeding and atrial fibrillation reported. Response to treatment by histology is summarized in Table 1 and Figure 1. As of the cut-off date, 18/21 pts remain on study treatment.Conclusions: BGB-3111 is well tolerated and highly active in Chinese pts with B-cell malignancies. The BTK inhibition and anti-tumor activity and safety profile of BGB-311 in Chinese patients are similar to those profiles we have seen in the previously reported data for BGB-3111. Several Phase 2 studies in different indications, including CLL/SLL, MCL, WM, and non-GCB DLBCL, have been initiated in China to further evaluate the efficacy and safety of BGB-3111 in Chinese pts. [Display omitted] DisclosuresXue:BeiGene: Employment. Yang:BeiGene: Employment. Zhang:BeiGene: Employment. Wang:BeiGene: Employment. Huang:BeiGene: Employment. Feng:BeiGene: Employment.

Efficacy and Safety of Zanubrutinib in Patients with Relapsed/Refractory Marginal Zone Lymphoma: Initial Results of the MAGNOLIA (BGB-3111-214) Trial

Efficacy and Safety of Zanubrutinib in Patients with Relapsed/Refractory Marginal Zone Lymphoma: Initial Results of the MAGNOLIA (BGB-3111-214) Trial

Ibrutinib-Mediated Atrial Fibrillation Attributable to Inhibition of C-Terminal Src Kinase.

Ibrutinib is a Bruton tyrosine kinase inhibitor with remarkable efficacy against B-cell cancers. Ibrutinib also increases the risk of atrial fibrillation (AF), which remains poorly understood. We performed electrophysiology studies on mice treated with ibrutinib to assess inducibility of AF. Chemoproteomic analysis of cardiac lysates identified candidate ibrutinib targets, which were further evaluated in genetic mouse models and additional pharmacological experiments. The pharmacovigilance database, VigiBase, was queried to determine whether drug inhibition of an identified candidate kinase was associated with increased reporting of AF. We demonstrate that treatment of mice with ibrutinib for 4 weeks results in inducible AF, left atrial enlargement, myocardial fibrosis, and inflammation. This effect was reproduced in mice lacking Bruton tyrosine kinase, but not in mice treated with 4 weeks of acalabrutinib, a more specific Bruton tyrosine kinase inhibitor, demonstrating that AF is an off-target side effect. Chemoproteomic profiling identified a short list of candidate kinases that was narrowed by additional experimentation leaving CSK (C-terminal Src kinase) as the strongest candidate for ibrutinib-induced AF. Cardiac-specific Csk knockout in mice led to increased AF, left atrial enlargement, fibrosis, and inflammation, phenocopying ibrutinib treatment. Disproportionality analyses in VigiBase confirmed increased reporting of AF associated with kinase inhibitors blocking Csk versus non-Csk inhibitors, with a reporting odds ratio of 8.0 (95% CI, 7.3-8.7; P<0.0001). These data identify Csk inhibition as the mechanism through which ibrutinib leads to AF. Registration: URL: https://ww.clinicaltrials.gov; Unique identifier: NCT03530215.

Anti-CD20 Therapy Reliance on Antibody-Dependent Cellular Phagocytosis Affects Combination Drug Choice

The efficacy of many therapeutic unconjugated monoclonal antibodies (mAbs), including those targeting CD20 in CLL, requires immune cell-mediated cytotoxicity. mAbs have often been optimized for natural killer (NK) cell antibody-dependent cellular cytotoxicity (ADCC) activity. However, in vivo mouse studies have shown that antibody-dependent cellular phagocytosis (ADCP) by macrophages is the major mechanism of clearance of circulating B cells by anti-CD20 mAbs. To directly compare ADCC versus ADCP, we previously used a panel of anti-CD20 mAbs (rituximab, ofatumumab, obinutuzimab, ocaratuzumab) to test cytotoxicity of paired human NK cells and monocyte-derived macrophages (hMDM) against CLL cells in vitro. All mAbs demonstrated ADCP activity at least 10-fold greater than ADCC as measured by CLL cell depletion per effector cell. Moreover, ADCC and ADCP activity levels did not correlate, meaning that ADCC cannot be used as a surrogate measure of ADCP for these mAb. This could explain why mAb optimization for ADCC activity has often failed to translate into more efficacious treatment. Thus, ADCP may be an effective translational measurement of anti-CD20 mAb performance. Because of the clinical interest in combining anti-CD20 mAb with targeted small molecule inhibitors, we began studying the effects of the Bruton tyrosine kinase (BTK) inhibitors on anti-CD20 mAb-mediated ADCP. Our initial studies showed that ibrutinib (IBR), but not acalabrutinib (Acala), significantly decreased anti-CD20 ADCP as measured by a flow cytometry-based assay that measures single timepoint cell collections. These types of assays cannot easily determine the kinetics and individual effector cell activity of ADCP. Thus, to more fully study the BTK inhibitor effects on ADCP, we developed a live cell time-lapse imaging method for measuring ADCP, utilizing recent advances in microscopy, cellular dye labeling, digital imaging, imaging software and computing. Whole-cell labeling of macrophages enabled visualization of internalized CLL cells as regions of dye exclusion or "voids". Because of the vast number of images acquired during live cell time-lapse imaging, we utilized computer software-aided image recognition and enumeration to measure the number of macrophages and voids inside each macrophage. As a measure of phagocytic engulfment, we developed a void index, which provides a relative measure of phagocytic engulfment per macrophage. Measuring ADCP in this manner replicates clinical observation of mAb therapeutic activity. Clinically, intravenous anti-CD20 mAb therapy typically induces a rapid decrease in circulating CLL cells (within hours), followed by a long period (days) of stable to increased levels of circulating cells. Similarly, our live cell time-lapse video assay shows initial rapid ADCP over the first 2 hours followed by a prolonged period of "hypophagia" with little ADCP for the remainder of the assay (imaged every 2 minutes for 8 hours). This "hypophagia" phenomenon may explain the resistance to therapeutic mAb observed clinically. With these new tools for quantitation of ADCP, we compared the effects of serial dilutions of IBR or Acala on ADCP. Overall, as measured by Area Under the Curve (AUC) analysis, IBR decreased phagocytic capacity of anti-CD20 mediated CLL cell ADCP at concentrations of 0.41 μM and above. By contrast, Acala did not begin to decrease AUC measurements until 3.7 μM, and subsequent AUC values were higher in Acala versus IBR-treated ADCP assays up to the highest tested drug concentration (100 μM). Similarly, the initial ADCP kinetics (void index / min over the first hour) reflected a decrease with IBR treatment at 0.41 μM that continued until a nadir was reached at 33 μM. In contrast, Acala did not induce a decrease in this kinetic measurement until 3.7 μM and a nadir was not reached (up to 100 μM). Thus, IBR significantly decreases ADCP by hMDM at concentrations much lower than a more specific BTK inhibitor, Acala. This result suggests that BTK inhibition has little to no effect on ADCP and furthermore suggests that IBR off-target effects decrease ADCP. IBR off-target candidates include other tyrosine kinases in the TEC (tyrosine kinase expressed in hepatocellular carcinoma) family. These data suggest that a a highly selective BTK inhibitor with little effect on ADCP could be a more suitable drug to combine with therapeutic mAb(s). Disclosures Chu: Pfizer: Equity Ownership; Acerta Pharma: Research Funding. VanDerMeid:AstraZeneca: Research Funding. Izumi:Acerta Pharma: Employment, Equity Ownership, Patents &amp; Royalties: Acalabrutinib patents; AstraZeneca: Equity Ownership. Munugalavadla:Acerta Pharma: Employment; AstraZeneca, Gilead Sciences: Equity Ownership. Barr:TG Therapeutics: Consultancy, Research Funding; Celgene: Consultancy; Pharmacyclics LLC, an AbbVie company: Consultancy, Research Funding; Seattle Genetics: Consultancy; Merck: Consultancy; Genentech: Consultancy; Verastem: Consultancy; Gilead: Consultancy; Astra Zeneca: Consultancy, Research Funding; Janssen: Consultancy; AbbVie: Consultancy. Elliott:Astra Zeneca: Research Funding. Zent:Mentrik Biotech: Research Funding; Astra Zeneca: Research Funding.

A Quantitative Systems Pharmacology (QSP) Model to Predict Receptor Occupancy of Bruton's Tyrosine Kinase (BTK) Inhibitors in Peripheral Blood Mononuclear Cells, Bone Marrow and Lymph Nodes of Patients with B-Cell Malignancies

Background: Bruton tyrosine kinase (BTK) is a key component of the B-cell receptor signaling pathway. The BTK inhibitors ibrutinib and acalabrutinib have been approved for the treatment of various B-cell malignancies. Zanubrutinib is a potent and highly specific next-generation BTK inhibitor currently in Phase 3 clinical testing. Achieving complete and sustained target engagement with respect to BTK receptor occupancy is thought to be an important factor for attaining deeper and durable clinical responses with the BTK inhibitors. Testing for BTK occupancy in peripheral blood mononuclear cells (PBMC) can be assessed in clinical studies. However, it is difficult to sample deep target tissues such as bone marrow (BM) and lymph nodes (LN) in patients to assess receptor occupancy. The objectives of this work were (1) to develop a QSP model to describe and predict the BTK receptor occupancy in PBMC, BM and LN after dosing with these BTK inhibitors in patients with B-cell malignancies, (2) to understand the impact of different dosing regimens (once daily (QD) v/s twice daily (BID)) on BTK receptor occupancy. Methods: A mathematical model was developed that describes: (1) pharmacokinetics (PK) of BTK inhibitors; (2) intracellular concentration of BTK inhibitors in PBMC, BM and LN; (3) binding of BTK inhibitors with BTK including competition with ATP and (4) BTK degradation/turnover rate. This QSP model includes ibrutinib with its metabolite PCI-45227, acalabrutinib with its metabolite ACP-5862, and zanubrutinib. Previously developed minimal Physiologically-based Pharmacokinetic (PBPK) models were used to reproduce PK of BTK inhibitors. Intracellular concentrations of BTK inhibitors were described in the model in accordance with PBPK equations for small molecules (Rodgers and Rowland. J Pharm Sci. 2006) and on the basis of their physico-chemical properties. Parameters and interindividual variability in parameter values were taken from previously developed models and estimated using experimental data. Sensitivity analyses using key model parameters such as BTK degradation/turnover rate were performed. The model was validated using available in vitro and clinical data on BTK occupancy. Results: The QSP model accurately described the observed clinical data on PK of BTK inhibitors during treatment with different doses and regimens of ibrutinib, acalabrutinib and zanubrutinib. There was good agreement between model prediction and observed BTK occupancy in PBMC and LN (Figure 1 and Figure 2). Zanubrutinib (160 mg BID) was predicted to result in higher median BTK occupancy with less variability in both PBMC and LN than ibrutinib (420 mg QD, 560 mg QD) and acalabrutinib (100 mg BID). In the absence of clinical BTK occupancy data in BM, the model predicted that steady-state trough BTK occupancy in BM were also predicted to be higher after zanubrutinib 160 mg BID administration, than those after ibrutinib 560 mg or 420 mg QD administration, and after acalabrutinib 100 mg BID administration. These differences are attributed to the PK properties (higher AUC and fraction unbound in plasma), binding properties to BTK (Kd, inactivation rate constant), and higher lipophilicity for zanubrutinib. The model predicted that 160 mg BID of zanubrutinib resulted in higher median trough BTK occupancy than 320 mg QD with less variability which is consistent with the observed clinical data (Figure 3). Conclusions: A QSP model was successfully developed and validated, which predicted higher median BTK occupancy with less variability for zanubrutinib in PBMC, BM and LN than ibrutinib and acalabrutinib. A BID dosing regimen produces higher BTK occupancy than a QD regimen over the dosing interval. Ongoing clinical trials with 160 mg BID zanubrutinib will help to determine if improved BTK occupancy in these peripheral and deep target tissues translate into improvements in clinical outcomes. Disclosures Sahasranaman: BeiGene: Employment, Equity Ownership. Demin:BeiGene USA, Inc.: Consultancy; InSysBio LLC: Employment. Shchelokov:InSysBio LLC: Employment; BeiGene USA, Inc.: Consultancy. Musatova:BeiGene USA, Inc.: Consultancy; InSysBio LLC: Employment. Budha:BeiGene Ltd.: Employment, Equity Ownership. Ou:BeiGene: Employment.

Phase 2 study of zanubrutinib (BGB-3111) in patients with relapsed/refractory marginal zone lymphoma (R/R MZL).

TPS7568 Background: Bruton tyrosine kinase (BTK) plays a critical role in B-cell receptor signaling, mediating B-cell proliferation, migration, adhesion and survival. BTK inhibition has emerged as a strategy for targeting B-cell malignancies, including MZL. In preclinical studies, zanubrutinib was shown to be a potent, irreversible, highly specific BTK inhibitor with excellent oral bio-availability and favorable pharmacokinetic/pharmacodynamic properties. Clinical data to date have shown that complete and sustained 24-hour BTK occupancy is associated with durable responses and suggested that zanubrutinib is generally well tolerated with low rates of serious adverse events. Preliminary results from the MZL cohort enrolled in the open-label, multicenter, phase 1 study demonstrated responses in 7 of 9 patients for an overall response rate (ORR) of 78%. Cumulative safety data also showed that zanubrutinib monotherapy was associated with infrequent incidence of atrial fibrillation and major hemorrhage and infrequent drug discontinuation due to treatment-related adverse events. This study is designed to evaluate the safety and efficacy of zanubrutinib in patients with R/R MZL. Methods: This ongoing global phase 2, single-arm, open-label study is examining zanubrutinib monotherapy in patients with R/R MZL who have received one or more prior lines of systemic therapy. Patients are treated with oral zanubrutinib at 160 mg twice-daily until progressive disease, unacceptable toxicity, or withdrawal of consent. Eligible patients must have histologically confirmed MZL, have received prior anti-CD20 antibody therapy, and have measurable disease. Disease response is assessed per the 2014 Lugano Classification for non-Hodgkin lymphoma. The primary endpoint is ORR determined by independent review committee (IRC). Key secondary endpoints include ORR by investigator assessment, time to and duration of response, time to treatment discontinuation, progression-free survival (all determined by IRC and investigator assessments), and overall survival and safety. Recruitment is ongoing.

Selective BTK inhibition improves bendamustine therapy response and normalizes immune effector functions in chronic lymphocytic leukemia.

The Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has been shown to be highly effective in patients with chronic lymphocytic leukemia (CLL) and is approved for CLL treatment. Unfortunately, resistance and intolerance to ibrutinib has been observed in several studies, opening the door for more specific BTK inhibitors. CC-292 (spebrutinib) is a BTK inhibitor with increased specificity for BTK and less inhibition of other kinases. Our in vitro studies showed that CC-292 potently inhibited B-cell receptor signaling, activation, proliferation and chemotaxis of CLL cells. In in vivo studies using the adoptive transfer TCL1 mouse model of CLL, CC-292 reduced tumor load and normalized tumor-associated expansion of T cells and monocytes, while not affecting T cell function. Importantly, the combination of CC-292 and bendamustine impaired CLL cell proliferation in vivo and enhanced the control of CLL progression. Our results demonstrate that CC-292 is a specific BTK inhibitor with promising performance in combination with bendamustine in CLL. Further clinical trials are warranted to investigate the therapeutic efficacy of this combination regimen.

Twice Daily Dosing with the Highly Specific BTK Inhibitor, Bgb-3111, Achieves Complete and Continuous BTK Occupancy in Lymph Nodes, and Is Associated with Durable Responses in Patients (pts) with Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL)

Twice Daily Dosing with the Highly Specific BTK Inhibitor, Bgb-3111, Achieves Complete and Continuous BTK Occupancy in Lymph Nodes, and Is Associated with Durable Responses in Patients (pts) with Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL)

Acalabrutinib Increases Mitochondrial Priming and Enhances Venetoclax Sensitivity in CLL Cells

IntroductionThe Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has transformed the management of patients with CLL, yet it does not induce substantial apoptosis in vitro. The mechanisms underlying the ability of BTK inhibitors to kill CLL cells are incompletely understood. Our group previously developed BH3 profiling, a functional assay that determines the proximity of a cell to the threshold of apoptosis, a property called "mitochondrial priming". A new variant of this technique, dynamic BH3 profiling (DBP), measures early drug-induced changes in mitochondrial apoptotic signaling before cell death occurs. Using DBP, we previously found that ibrutinib increases mitochondrial BCL-2 dependence in CLL cells, thereby sensitizing cells to the BCL-2 inhibitor venetoclax (formerly ABT199/GDC-0199). However, it remains unclear whether these are on-target effects of ibrutinib on BTK or off-target effects of ibrutinib on its other targets such as ITK or TEC kinase. Here, we examined acalabrutinib, a 2ndgeneration, highly specific BTK inhibitor currently in clinical trials to determine whether selective BTK inhibition increases BCL-2 dependence in CLL cells.MethodsMononuclear cells were isolated from CLL patients and treated ex vivo with acalabrutinib (provided by Acerta) alone or in combination with venetoclax (APEX Bio Technology) in the presence of NKTert stromal cells. BH3 profiling and dynamic BH3 profiling were then performed as previously described by measuring the release of cytochrome c on a BD FACS Fortessa (Montero J. et al. Cell 2015). Cell viability assays and western blot analyses were performed according to standard protocols. The student’s t-test or one-way ANOVA was used to compare drug treatments with p<=0.05 considered significant.ResultsTo validate our prior finding that ibrutinib increased mitochondrial BCL-2 dependence, we first repeated our prior ex vivo ibrutinib experiments in 3 additional patients and found similar results. Next, we performed DBP on 5 peripheral blood samples from previously untreated CLL patients using ex vivo treatment with acalabrutinib, venetoclax or the combination. Consistent with our findings with ibrutinib treatment, acalabrutinb increased BCL-2 dependence, with all patient samples showing >20% increase in priming ("delta priming") in response to BAD BH3 peptide, with no increase in overall priming (<20% in all patients) measured by BIM BH3 peptide (Figure 1A). Moreover, it did not alter BCL-xL or MCL1 dependence measured by their specific peptides HRK or MS1, respectively. In contrast, venetoclax increased the overall level of mitochondrial priming with minimal effects on BCL-2 dependence. When combining these two drugs, both overall priming and BCL-2 dependence increased. The increase in BCL-2 dependence by ibrutinib resulted in enhanced sensitivity to venetoclax (p=0.0005).To assess whether these ex vivo effects could be replicated in vivo, we next performed DBP using CLL patient samples from 5 patients on the acalabrutinib first-in-human phase I clinical trial (NCT02029443). Delta priming was calculated by comparing pre-treatment samples to samples obtained after 4 weeks of acalabrutinib monotherapy. Consistent with our ex vivo data, acalabrutinib therapy selectively increased mitochondrial BCL-2 dependence in vivo (Figure 1B) without altering BCL-XL or MCL-1 dependence, and overall priming decreased slightly. To provide additional insight into the molecular mechanism underlying the mitochondrial priming changes, we did western blot analyses for BCL-2 family proteins, and found that expression of the pro-apoptotic BIM was increased after acalabrutinib therapy.ConclusionsSelective BTK inhibition with acalabrutinib enhances mitochondrial BCL-2 dependence and increases CLL cell sensitivity to the BCL-2 inhibitor venetoclax. Induction of expression of the pro-apoptotic protein BIM provides an initial clue as to a mechanism underlying these effects. These data strongly suggest that the increase in BCL-2 dependence we previously found with ibrutinib is a BTK-specific effect. Our findings provide a strong pre-clinical rationale supporting clinical trials combining BTK and BCL-2 inhibition. More broadly, we also demonstrate that DBP can be utilized on in vivo treated patient samples to rationally construct combination regimens of targeted agents to treat cancer. [Display omitted] DisclosuresBrown:Pfizer: Consultancy; Sun BioPharma: Consultancy; Celgene: Consultancy; Roche/Genentech: Consultancy; Gilead Sciences: Consultancy; Janssen: Consultancy; Infinity: Consultancy; Abbvie: Consultancy. Letai:AbbVie: Consultancy, Research Funding; Astra-Zeneca: Consultancy, Research Funding; Tetralogic: Consultancy, Research Funding. Davids:Gilead: Honoraria; Pharmacyclics: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; TG Therapeutics: Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding; Infinity: Honoraria, Research Funding.

The BTK Inhibitor, Bgb-3111, Is Safe, Tolerable, and Highly Active in Patients with Relapsed/ Refractory B-Cell Malignancies: Initial Report of a Phase 1 First-in-Human Trial

The BTK Inhibitor, Bgb-3111, Is Safe, Tolerable, and Highly Active in Patients with Relapsed/ Refractory B-Cell Malignancies: Initial Report of a Phase 1 First-in-Human Trial

Mechanisms of ibrutinib resistance in chronic lymphocytic leukaemia and non-Hodgkin lymphoma.

Bruton tyrosine kinase (BTK), a mediator of B-cell receptor (BCR) signalling, has been implicated in the pathogenesis of chronic lymphocytic leukaemia (CLL) and other B-cell malignancies. Ibrutinib is an orally bioavailable and highly specific BTK inhibitor that was recently approved for treatment of patients with recurrent CLL and mantle cell lymphoma (MCL). In addition, ibrutinib has shown efficacy in subsets of patients with diffuse large B cell lymphoma (DLBCL) and Waldenstrom macroglobulinaemia (WM). However, despite ibrutinib's activity in multiple B-cell malignancies, cases of primary and secondary resistance have emerged. The overall reported frequency of resistance is low, but follow-up in many trials was short, and we predict that the incidence of observed resistance will increase as clinical use outside clinical trials expands over time. Mutations within BTK have been described and clearly interfere with drug binding; however, there are also emerging alternative mechanisms that bypass BTK entirely and offer new opportunities for other targeted agents. Improved understanding of mechanisms of primary and secondary resistance is essential to developing appropriate therapeutic strategies to both prevent and address resistance. This review provides a comprehensive analysis of ibrutinib resistance in CLL, MCL, DLBCL and WM and considers potential strategies for further study.

Dual targeting of Bruton's tyrosine kinase and Janus kinase 3 with rationally designed inhibitors prevents graft-versus-host disease (GVHD) in a murine allogeneic bone marrow transplantation model.

The purpose of the present study was to evaluate the effectiveness of targeting Bruton's tyrosine kinase (BTK) with a specific BTK inhibitor, alpha-cyano-beta-hydroxy-beta-methyl-N-(2,5-dibromophenyl)-propenamide (LFM-A13), for prevention of acute fatal graft-versus-host disease (GVHD) in a murine model of allogeneic bone marrow transplantation (BMT). Vehicle-treated control C57BL/6 mice receiving bone marrow/splenocyte grafts from allogeneic BALB/c donors developed severe multi-organ acute GVHD and died after a median survival time (MST) of 40 d. LFM-A13 treatment (25 mg/kg/d) significantly prolonged the MST of the BMT recipients to 47 d. The probability of survival at 2 months after BMT was 2 +/- 2% for vehicle-treated control mice and 22 +/- 6% for mice treated with LFM-A13 (P = 0.0008). Notably, the combination regimen of LFM-A13 plus the standard anti-GVHD drug methotrexate (MTX) (10 mg/m(2)/d) was more effective than LFM-A13 alone, while the combination regimen of LFM-A13 plus the novel anti-GVHD drug JANEX-1 (60 mg/kg/d), targeting Janus kinase 3, was more effective than LFM-A13, JANEX-1 or MTX alone. More than 70% of recipients receiving this most effective GVHD prophylaxis (LFM-A13 + JANEX-1) remained alive throughout the 80-d observation period with an MST of >80 d. Taken together, these results indicate that targeting BTK with the chemical inhibitor LFM-A13 may attenuate the severity of GVHD, especially when it is combined with other anti-GVHD drugs, such as MTX and JANEX-1.