Search

Simple Summary Bruton tyrosine kinase (Btk) is expressed in B-lymphocytes, myeloid cells and platelets. Since the launch of the first in class Btk-inhibitor (BTKi) ibrutinib in 2013, the list of indications and further drug candidates has expanded greatly. BTKi are not only used to treat patients with B-cell malignancies and in development against various autoimmune diseases, but they have been also proposed as novel antithrombotic drugs and been tested in patients with severe COVID-19. The number of BTKi approved or in clinical studies is rapidly increasing. Although X-linked agammaglobulinemia (XLA) patients with Btk deficiency do not show impaired hemostasis, bleeding events are frequently observed upon treatment with many but not all BTKi. This review describes twelve BTKi approved or in clinical trials. By focusing on their pharmacological properties, targeted disease, bleeding side effects and actions on platelets it attempts to clarify the mechanisms underlying bleeding. Moreover, specific platelet function tests in blood are described which will help to estimate the probability of bleeding side effects of newly developed BTKi. Abstract Bruton tyrosine kinase (Btk) is expressed in B-lymphocytes, myeloid cells and platelets, and Btk-inhibitors (BTKi) are used to treat patients with B-cell malignancies, developed against autoimmune diseases, have been proposed as novel antithrombotic drugs, and been tested in patients with severe COVID-19. However, mild bleeding is frequent in patients with B-cell malignancies treated with the irreversible BTKi ibrutinib and the recently approved 2nd generation BTKi acalabrutinib, zanubrutinib and tirabrutinib, and also in volunteers receiving in a phase-1 study the novel irreversible BTKi BI-705564. In contrast, no bleeding has been reported in clinical trials of other BTKi. These include the brain-penetrant irreversible tolebrutinib and evobrutinib (against multiple sclerosis), the irreversible branebrutinib, the reversible BMS-986142 and fenebrutinib (targeting rheumatoid arthritis and lupus erythematodes), and the reversible covalent rilzabrutinib (against pemphigus and immune thrombocytopenia). Remibrutinib, a novel highly selective covalent BTKi, is currently in clinical studies of autoimmune dermatological disorders. This review describes twelve BTKi approved or in clinical trials. By focusing on their pharmacological properties, targeted disease, bleeding side effects and actions on platelets it attempts to clarify the mechanisms underlying bleeding. Specific platelet function tests in blood might help to estimate the probability of bleeding of newly developed BTKi.

Inhibiting the activity of Bruton tyrosine kinase (BTK) prevents the activation of the B‐cell receptor (BCR) signaling pathway, which in turn prevents both B‐cell activation and BTK‐mediated activation of downstream survival pathways. Acalabrutinib is an orally available, highly selective, next-generation inhibitor of BTK. Based on the results of two key phase 3 trials (ELEVATE-TN in patients with previously untreated chronic lymphocytic leukemia [CLL] and ASCEND in patients with relapsed or refractory CLL), which demonstrated superior progression-free survival while maintaining favorable tolerability, acalabrutinib was granted US Food and Drug Administration (FDA) approval in 2019 for the treatment of patients with CLL. Acalabrutinib appears to offer similar efficacy but a significantly improved tolerability profile to first-generation agents. Acalabrutinib is a good candidate to combine with other anti-cancer therapies, including B-cell lymphoma 2 inhibitors and monoclonal antibodies, a factor that may help to further improve clinical outcomes in CLL.

Presentation during EHA2021 : E-Poster Presentation - Session title: Aggressive Non-Hodgkin lymphoma - Clinical; BackgroundDespite the marked efficacy of covalent BTK inhibitors (BTKi) in MCL, WM, and MZL, the development of resistance and discontinuation for adverse events can lead to treatment failure. Moreover, pharmacological liabilities of these agents such as low oral bioavailability or short half-life, can lead to suboptimal BTK target coverage and ultimately result in acquired resistance in some patients (pts). To address these limitations, pirtobrutinib (LOXO-305), a highly selective, non-covalent BTKi that inhibits both WT and C481-mutated BTK with equal low nM potency was developed.AimsTo evaluate safety and efficacy of pirtobrutinib in previously treated MCL and other NHLs.MethodsBRUIN is a multicenter phase 1/2 trial (NCT03740529) enrolling pts with advanced B-cell malignancies who have received >2 prior therapies. Oral pirtobrutinib was dose escalated in a standard 3+3 design in 28-day cycles. The primary endpoint was MTD/RP2D identification. Efficacy evaluable pts included all dosed pts who underwent their first response evaluation or discontinued therapy. Safety was assessed in all pts (n=323). Response was assessed according to Lugano Classification or iWWM. ResultsAs of 27 September 2020, 323 pts with B-cell malignancies (170 CLL/SLL, 61 MCL, 26 WM, and 66 other B-cell lymphomas) were treated on 7 dose levels (25-300mg QD). Median age was 69 (range 50-87) years for MCL pts, 68 (42-84) for WM pts, and 68 (27-86) for other NHLs pts. Median number of prior lines of therapy was 3 (range, 1-8) for MCL, 3 (2-11) for WM, and 4 (2-10) for other NHLs. 93% of MCL, 70% of WM and 36% other NHL pts had received a prior BTKi. Pirtobrutinib demonstrated high oral exposures, with doses ≥100mg QD exceeding the BTK IC90 for the entirety of the dosing interval. No DLTs occurred. Consistent with pirtobrutinib’s selectivity, the only treatment emergent adverse events regardless of attribution or grade in >10% of pts (n=323) were fatigue (20%), diarrhea (17%) and contusion (13%). Grade 3 atrial fibrillation/flutter was not observed; 1 pt had grade 3 hemorrhage in the setting of mechanical trauma. Responses were observed at the first dose level of 25mg QD. A RP2D of 200mg QD was selected. At the efficacy cutoff date, 35 (57%) MCL pts, 18 (69%) WM pts and 34 (52%) other NHL pts remained on therapy. Among the 52 efficacy evaluable prior BTKi treated MCL pts, the ORR was 52% with 13 CR, 14 PR and 9 SD. Median follow up was 6 months (range 0.7-18.3+) for MCL. Responses in MCL were observed in 9/14 pts (64%) with prior autologous or allogeneic transplant, and 2 of 2 with prior CAR-T cell therapy. Among the 19 efficacy-evaluable pts with WM, the ORR was 68% (9 PR, 4 MR, 3 SD), and 69% in prior BTKi treated pts. 10 of 13 WM responders were ongoing (follow-up time from initial response: 0.8-9.2 months). For the 55 efficacy-evaluable other NHL pts, best response was as follows: DLBCL - 24% ORR (4 CR, 2 PR, 2 SD, 12 PD, 5 NE), FL - 50% ORR (2 CR, 2 PR, 1 SD, 3 PD), MZL - 22% ORR (2 PR, 7 SD), Richter’s transformation - 75% ORR (6 PR, 1 SD, 1 NE) and Other (2 B-PLL, 3 Low grade transformation) 1 SD, 2 PD, 2 NE.ConclusionPirtobrutinib demonstrated promising efficacy in MCL pts following multiple prior lines of therapy, including a covalent BTKi. Pirtobrutinib also showed efficacy in previously treated other NHLs. Pirtobrutinib was well tolerated and exhibited a wide therapeutic index.

Objectives Bruton's tyrosine kinase (BTK) plays a non‐redundant signaling role downstream of the B‐cell receptor (BCR) in B cells and the receptors for the Fc region of immunoglobulins (FcR) in myeloid cells. Here, we characterise BIIB091, a novel, potent, selective and reversible small‐molecule inhibitor of BTK. Methods BIIB091 was evaluated in vitro and in vivo in preclinical models and in phase 1 clinical trial. Results In vitro, BIIB091 potently inhibited BTK‐dependent proximal signaling and distal functional responses in both B cells and myeloid cells with IC50s ranging from 3 to 106 nm, including antigen presentation to T cells, a key mechanism of action thought to be underlying the efficacy of B cell‐targeted therapeutics in multiple sclerosis. BIIB091 effectively sequestered tyrosine 551 in the kinase pocket by forming long‐lived complexes with BTK with t 1/2 of more than 40 min, thereby preventing its phosphorylation by upstream kinases. As a key differentiating feature of BIIB091, this property explains the very potent whole blood IC50s of 87 and 106 nm observed with stimulated B cells and myeloid cells, respectively. In vivo, BIIB091 blocked B‐cell activation, antibody production and germinal center differentiation. In phase 1 healthy volunteer trial, BIIB091 inhibited naïve and unswitched memory B‐cell activation, with an in vivo IC50 of 55 nm and without significant impact on lymphoid or myeloid cell survival after 14 days of dosing. Conclusion Pharmacodynamic results obtained in preclinical and early clinical settings support the advancement of BIIB091 in phase 2 clinical trials., In this study, we characterise BIIB091, a novel, potent, selective and reversible small‐molecule inhibitor of Bruton's Tyrosine Kinase (BTK). In vitro, BIIB091‐inhibited BTK‐dependent proximal signaling and distal functional responses in both B cells and myeloid cells, including antigen presentation to T cells, a key mechanism of action thought to be underlying the efficacy of B cell‐targeted therapeutics in MS. In vivo, BIIB091 blocked B‐cell activation, antibody production and germinal center differentiation, however in phase 1 healthy volunteer study, BIIB091 inhibited B‐cell receptor‐mediated activation of naïve and unswitched memory B cells.

The understanding of the B cell receptor (BCR) pathway and its contribution to chronic lymphocytic leukemia (CLL) pathogenesis have led to the development of targeted BCR inhibitors which have transformed the treatment paradigm of CLL. Ibrutinib is a first-in-class oral Bruton’s tyrosine kinase (BTK) inhibitor which has demonstrated improvements in both progression free (PFS) and overall survival (OS) in both the treatment naïve and relapsed/refractory setting as compared to traditional chemoimmunotherapy. Despite its clinical efficacy, many patients discontinue treatment due to adverse events, which are thought to be mediated through off-target kinase inhibition. Zanubrutinib is a second-generation non-covalent BTK inhibitor with higher potency, allowing for inhibition of BTK with fewer off target effects. Early phase clinical trials have demonstrated excellent efficacy and a well-tolerated safety profile. Long-term follow-up is needed, but zanubrutinib holds promise to be an effective therapy for CLL with a manageable side effect profile and will be an exciting addition to our treatment paradigm.

Bruton&rsquo, s tyrosine kinase (BTK) is known as a direct regulator of inflammasome, which is an intracellular target to therapeutically modulate innate immunity. Although there is great interest in developing small molecule-based drugs with BTK inhibition, there are only a few drugs available in the market, due to the difficulty of drug discovery and the potential side effects. To select suitable drug compounds to inhibit BTK signaling, molecular drug screening bioassay processes of single ginsenosides integrated with in silico molecular simulation were performed. The experimental results for the ginsenoside compositions (Rb2 and Rb3) exhibited showed that they effectively suppressed the activity of BTK expression in a rational agreement with molecular docking calculations of the compounds against the BTK binding site. They implemented a possible inhibiting effect of BTK signaling through increasing their molecular affinity for targeting BTK, enabling them to be useful in treating BTK-mediated diseases.

Purpose of ReviewOver the last years, targeted anticancer therapy with small molecule inhibitors and antibodies has much replaced chemoimmunotherapy, which has been the gold standard of care for patients with chronic lymphocytic leukemia (CLL). Here we give an overview of novel targeted agents used in therapy of chronic lymphocytic leukemia, as well as efforts to overcome resistance development, focusing on approved drugs since they gained high relevance in clinical practice.Recent FindingsNovel agents moved to the forefront as a treatment strategy of CLL due to their outstanding efficacy, almost irrespectively of the underlying genetic features. Inhibition of Bruton’s tyrosine kinase (BTK), a key molecule in the B cell receptor pathway, achieved dramatic efficacy even in poor-risk and chemo-refractory patients. Further success was accomplished with venetoclax, which specifically inhibits anti-apoptotic BCL2 and induces apoptosis of CLL cells.SummaryInhibition of BTK or BCL2 is very effective and induces prolongation of progression-free and overall survival. Approved combination treatments such as venetoclax or ibrutinib with obinutuzumab show high responses rates and long remission durations. However, evolution and selection of subclones with continuous treatment leads to resistance towards these novel drugs and disease relapse. Hence, comparison of sequential treatment with combinations and discontinuation of therapy are important aspects which need to be investigated.

Colorectal cancer (CRC) is the fourth cause of death from cancer worldwide mainly due to the high incidence of drug-resistance. During a screen for new actionable targets in drug-resistant tumours we recently identified p65BTK–a novel oncogenic isoform of Bruton's tyrosine kinase. Studying three different cohorts of patients here we show that p65BTK expression correlates with histotype and cancer progression. Using drug-resistant TP53-null colon cancer cells as a model we demonstrated that p65BTK silencing or chemical inhibition overcame the 5-fluorouracil resistance of CRC cell lines and patient-derived organoids and significantly reduced the growth of xenografted tumours. Mechanistically, we show that blocking p65BTK in drug-resistant cells abolished a 5-FU-elicited TGFB1 protective response and triggered E2F-dependent apoptosis. Taken together, our data demonstrated that targeting p65BTK restores the apoptotic response to chemotherapy of drug-resistant CRCs and gives a proof-of-concept for suggesting the use of BTK inhibitors in combination with 5-FU as a novel therapeutic approach in CRC patients. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Summary Patients with chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) with deletion 17p [del(17p)] have poor outcomes with chemoimmunotherapy. Ibrutinib is indicated for the treatment of CLL/SLL, including del(17p) CLL/SLL, and allows for treatment without chemotherapy. This integrated analysis was performed to evaluate outcomes in 230 patients with relapsed/refractory del(17p) CLL/SLL from three ibrutinib studies. With a median of 2 prior therapies (range, 1–12), 18% and 79% of evaluable patients had del(11q) or unmutated IGHV, respectively. With a median follow‐up of 28 months, overall response rate was 85% and estimated 30‐month progression‐free and overall survival rates were 57% [95% confidence interval (CI) 50–64] and 69% (95% CI 61–75), respectively. Patients with normal lactate dehydrogenase or no bulky disease had the most favourable survival outcomes. Sustained haematological improvements in haemoglobin, platelet count and absolute neutrophil count occurred in 61%, 67% and 70% of patients with baseline cytopenias, respectively. New onset severe cytopenias and infections decreased in frequency over time. Progression‐free and overall survival with ibrutinib surpass those of other therapies for patients with del(17p) CLL/SLL. These results provide further evidence of the robust clinical activity of ibrutinib in difficult‐to‐treat CLL/SLL populations.

Glioblastoma multiforme represents one of the deadliest brain tumor types, manifested by a high rate of recurrence and poor prognosis. The presence of glioma stem cells (GSCs) can repopulate the tumor posttreatment and resist therapeutics. A better understanding of GSC biology is essential for developing more effective interventions. We established a CD133 promoter-driven dual reporter, expressing green fluorescent protein (GFP) and firefly luciferase (CD133-LG), capable for in vitro and in vivo imaging of CD133+ GSCs. We first demonstrated the reporter enabled in vitro analyses of GSCs. DBTRG-05MG (Denver Brain Tumor Research Group 05) carrying CD133-LG (DBTRG-05MG-CD133-LG) system reported increased GFP/luciferase activities in neurospheres. Additionally, we identified and isolated CD133+/GFP+ cells with increased tumorigenic properties, stemness markers, Notch1, β-catenin, and Bruton’s tyrosine kinase (Btk). Furthermore, prolonged temozolomide (TMZ) treatment enriched GSCs (reflected by increased percentage of CD133+ cells). Subsequently, Btk inhibitor, ibrutinib, suppressed GSC generation and stemness markers. Finally, we demonstrated real-time evaluation of anti-GSC function of ibrutinib in vivo with TMZ-enriched GSCs. Tumorigenesis was noninvasively monitored by bioluminescence imaging and mice that received ibrutinib showed a significantly lower tumor burden, indicating ibrutinib as a potential GSC inhibitor. In conclusion, we established a dual optical imaging system which enables the identification of CD133+ GSCs and screening for anti-GSC drugs.

Background Diffuse large B cell lymphoma (DLBCL) is the most common form of lymphoma. Although durable remissions can be achieved in more than half of these patients, DLBCL remains a significant clinical challenge, with approximately 30% of patients not being cured. BCR-associated kinases (SYK, BTK, and PI3K) inhibitors have exhibited encouraging pre-clinical and clinical effects, as reported by many researchers. Early studies demonstrated that protein kinase C-β (PKCβ) inhibitors alter phosphorylation level the Bruton’s tyrosine kinase (BTK), which leads to enhanced BTK signaling. Here, for the first time, we investigate whether the combination of PKCβ inhibitor enzastaurin and BTK inhibitor ibrutinib has synergistic anti-tumor effects in DLBCL. Methods In vitro cell proliferation was analyzed using Cell Titer-Glo Luminescent Cell Viability Assay. Induction of apoptosis and cell cycle arrest were measured by flow cytometry. Western Blotting analysis was used to detect the essential regulatory enzymes in related signaling pathways. RNA-seq was conducted to evaluate the whole transcriptome changes brought by co-treatment with low doses of enzastaurin and ibrutinib. The synergistic anti-tumor effects of enzastaurin and ibrutinib were also evaluated in vivo. Results Combination of enzastaurin and ibrutinib produced a lasting synergistic effect on the survival and proliferation of DLBCL cells, including reduction of proliferation, promoting apoptosis, inducting G1 phase arrest, preventing cell invasion and migration, and down-regulating activation of downstream signaling. More importantly, whole-transcriptome changes results showed that combination therapy worked synergistically to regulate whole-transcriptome expression compared with enzastaurin and ibrutinib alone. Co-treatment with low doses of enzastaurin and ibrutinib could effectively downregulate BCR, NF-κB, JAK and MAPK related signaling pathway. Furthermore, the mRNA expression analysis further indicated that co-treatment significantly decreased the mRNA levels of NOTCH1. The combination effect in inhibiting proliferation of DLBCL cells probably was realized through suppression of NOTCH1 expression. Finally, the anti-tumor activity of co-treatment also was demonstrated in vivo. Conclusions Combination of enzastaurin and ibrutinib had synergistic anti-tumor effects in DLBCL, independent of molecular subtype. These results provided a sound foundation for an attractive therapeutic treatment, and the simultaneous suppression of BTK and PKCβ might be a new treatment strategy for DLBCL. Electronic supplementary material The online version of this article (10.1186/s13046-019-1076-4) contains supplementary material, which is available to authorized users.

Il tumore al polmone è la principale causa di morte per tumore al mondo sia negli uomini che nelle donne. Il tumore polmonare non a piccole cellule (NSCLC) è il più frequente ed è relativamente insensibile a chemioterapia e radioterapia. Nonostante lo sviluppo di terapie molecolari personalizzate contro specifiche “mutazioni driver” e la combinazione di chemioterapia e terapie a bersaglio molecolare, la mortalità per tumore al polmone rimane molto alta a causa dello sviluppo di resistenza alle diverse terapie. Pertanto, rimane particolarmente urgente ricercare nuove terapie per NSCLC. Recentemente nel nostro laboratorio abbiamo scoperto p65BTK, una nuova isoforma della tirosina chinasi di bruton (BTK), la quale è risultata essere un nuovo oncogene a valle del pathway di RAS. Abbiamo dimostrato che la sua inibizione diminuisce la crescita e la sopravvivenza delle cellule di cancro del colon e ri-sensibilizza cellule tumorali resistenti ai trattamenti. Gli obiettivi di questo progetto sono: studiare il ruolo di p65BTK nel NSCLC e verificare se p65BTK può essere un nuovo target teranostico nel NSCLC. Studiando una coorte di 382 pazienti abbiamo dimostrato che p65BTK è espresso nel 50% dei tumori di pazienti con NSCLC e la sua espressione correla con l'istotipo, l’abitudine al fumo e lo stato mutazionale di EGFR. In particolare, abbiamo trovato una maggiore espressione di p65BTK in pazienti con adenocarcinoma, non fumatori e con EGFR non mutato. Generalmente questi pazienti non sono eleggibili per la terapia con inibitori di EGFR a causa della mancanza di EGFR mutato. Tramite western blot, abbiamo confermato l’over-espressione di p65BTK sia in linee cellulari umane di NSCLC mutate per RAS o per uno dei geni del pathway di RAS, che in cellule primarie derivate da tumori di topi Kras/Trp53 null, suggerendo una correlazione tra l’aumentata espressione di p65BTK e la iper-attivazione del pathway di RAS nel NSCLC. In seguito, abbiamo dimostrato che l'inibizione di p65BTK tramite diversi inibitori di BTK (Ibrutinib, AVL-292, RN486) riduce efficacemente la proliferazione e la clonogenicità di linee di NSCLC con differenti background genetici. Per determinare se p65BTK può essere considerato un nuovo bersaglio terapeutico nel NSCLC, abbiamo trattato linee resistenti di NSCLC con chemioterapia (Cisplatino, Gemcitabina, Pemetrexed) o inibitori di EGFR (Gefitinib, Erlotinib) in singolo, o in combinazione con concentrazioni non tossiche degli inibitori di BTK, valutandone l’effetto sulla vitalità cellulare. Gli inibitori di BTK usati in combinazione con gli inibitori di EGFR o con la chemioterapia sono risultati più efficaci nel ri-sensibilizzare le linee di NSCLC scarsamente responsive ai trattamenti standard e le diverse combinazioni hanno mostrato diversi gradi di sinergia. In conclusione, abbiamo dimostrato che p65BTK è over-espressa nei tumori di pazienti con NSCLC e in linee cellulari umane e murine di NSCLC. Pertanto, i nostri dati indicano p65BTK come un emergente target nel NSCLC e suggeriscono che la combinazione di inibitori di BTK e chemioterapia o terapia a bersaglio molecolare potrebbe rappresentare un nuovo approccio per superare la resistenza alle terapie nel NSCLC. I prossimi passi saranno volti a validare gli effetti dell'inibizione di p65BTK in modelli ex vivo (sferoidi derivati da cellule di NSCLC) e in vivo in modelli murini di NSCLC. Lung cancer is the leading cause of cancer-related death worldwide both in men and women. In particular, Non-Small Cell Lung Cancer (NSCLC) is the most common subtype and is relatively insensitive to chemotherapy and radiation therapy. Despite the development of personalized molecular targeted therapies against specific driver mutations and the combination of chemotherapy with targeted therapy, lung cancer mortality remains very high because of intrinsic and acquired resistance. Thus, new strategies to overcome these limitations are needed. Recently, we discovered a new isoform of the Bruton Tyrosine Kinase (BTK), referred as p65BTK. We characterized p65BTK as a novel oncogene and a pivotal downstream effector of RAS. Moreover, we showed that its inhibition affected growth and survival of colon cancer cells and reverted resistance to chemotherapy. The aims of this project were: study the role of p65BTK in NSCLC cell biology and verify whether p65BTK may be a novel theranostic target in NSCLC. Studying a cohort of 382 patients, we observed that p65BTK was expressed in 50% of NSCLC patients’ tumors and its expression correlated with histotype, smoke habit and EGFR mutational status. In particular, we found p65BTK significantly more expressed in adenocarcinoma than in squamous carcinoma histotype and in non-smoker as compared to smoker patients. Moreover, its expression was significantly higher in non-smoker patients bearing wild type EGFR. Notably, these patients are not eligible for treatments with EGFR inhibitors due to a lack of EGFR mutation. By western blot analysis we confirmed p65BTK overexpression both in vitro, in NSCLC human cell lines with mutations in RAS or in one of the components of the RAS/MAPK pathway, and ex vivo, in tumor-derived primary cells from Kras/Trp53 null mice, suggesting that p65BTK overexpression correlate with a hyper-activated RAS/MAPK pathway also in NSCLC. Then, we showed that p65BTK inhibition by different BTK inhibitors (Ibrutinib, AVL-292, RN486) strongly impaired proliferation and clonogenicity of NSCLC cell lines with different genetic backgrounds. To determine if p65BTK could be a new theranostic target in NSCLC, representative resistant cell lines were treated with chemotherapy (Cisplatin, Gemcitabine, Pemetrexed) or EGFR-targeted therapy (Gefitinib, Erlotinib) alone or in combination with non-toxic concentrations of BTK inhibitors and then their viability was assessed. We found that BTK inhibitors were effective in re-sensitizing NSCLC cells scarcely responsive to the current treatments when used in combination with EGFR-targeted therapy or chemotherapy. However, the different BTK inhibitors’ combinations showed a better or worse synergy depending on which EGFR inhibitor or chemotherapeutic drug they were combined with. Thus, we demonstrate that p65BTK is overexpressed in NSCLC patients’ tumors and in human and murine NSCLC cells. Moreover, our data indicate p65BTK as an emerging actionable target in NSCLC and suggest that the combination of BTK inhibitors with chemotherapy or targeted therapy may represent a novel therapeutic approach to overcome drug resistance in NSCLC. As future perspectives, we will validate the effects of p65BTK inhibition in ex-vivo (spheroids derived from NSCLC cells) models and in in vivo mouse model of NSCLC.

Introduction: Chemoimmunotherapy has improved outcomes in chronic lymphocytic leukemia, yet it is not curative, with very high relapse rates, and is associated with a significant risk of toxicities. Moreover, patients with higher-risk genetic abnormalities continue to experience poorer outcomes and lower survival. Recently, novel targeted therapies have been developed to increase efficacy and reduce toxicity. Areas covered: Ibrutinib is an oral irreversible inhibitor of Bruton’s tyrosine kinase, a mediator of B-cell receptor signaling, which plays a vital role in various B-cell neoplasms. The drug has been approved for the treatment of several hematological malignancies, including chronic lymphocytic leukemia/small lymphocytic lymphoma, where large trials have shown outcomes never seen before even in high-risk patients. The safety profile appeared furthermore favorable, even in elderly and unfit patients. Expert opinion: Therapy with ibrutinib rarely provides MRD-negative complete remission; an indefinite maintenance is therefore needed, with the risk of developing adverse events (AE) or resistance resulting in treatment interruption or discontinuation. Novel, extremely promising, combination strategies, based on the association of ibrutinib with chemoimmunotherapy, anti-CD20 monoclonal antibody or other targeted agents, are currently being investigated, with the goal of achieving greater depth of remission, especially MRD-negativity, and removing the need for indefinite treatment.

Simple Summary Standard treatment for chronic lymphocytic leukemia (CLL) has experienced a dramatic change over the last years. Until recently, CLL was treated using chemotherapy in combination with anti-CD20 antibody-based immunotherapy. Depending on age and clinical condition, patients received more or less intensive chemotherapy and were at risk of side effects commonly associated with chemotherapy. Currently, patients are mostly treated with so-called novel agents, including BTK inhibitors, Bcl-2 inhibitors and PI3K inhibitors, which are generally well tolerated but have a specific side effect profile. CLL is a chronic disease; therefore, most patients will relapse on or after treatment with these drugs and will require multiple lines of therapy. In this review, we present the current treatment options for patients with CLL and discuss the optimal treatment approaches and sequences, taking into account the specific side effects of each novel agent in the context of different clinical settings. Abstract After impressive developments in recent years with the rise of new targeted agents, chemoimmunotherapy (CIT) only plays a minor role in the treatment of patients with chronic lymphocytic leukemia (CLL). Inhibitors of the Bruton tyrosine kinase (BTK), such as ibrutinib or more recently acalabrutinib, are highly effective, even in poor-risk or chemo-refractory patients. Venetoclax, an inhibitor of the anti-apoptotic BCL2 protein and, to a lesser extent, phosphoinositide-3 kinase (PI3K) delta inhibitors, add to the armamentarium of targeted agents for the treatment of CLL. Furthermore, anti-CD20 monoclonal antibodies are used very successfully either alone or in combination with BTK, BCL2 or PI3K inhibitors. Despite these advances, there is still an ongoing pursuit for new therapeutic approaches in the treatment of CLL. An even bigger challenge poses the determination of the optimal combination and sequence of those drugs. Here, we give an overview of current treatment options in CLL, weighing the advantages and disadvantages of each approach in the light of different clinical settings.

Immune thrombocytopenia (ITP) is a rare autoimmune disorder caused by peripheral platelet destruction and inappropriate bone marrow production. The management of ITP is based on the utilization of steroids, intravenous immunoglobulins, rituximab, thrombopoietin receptor agonists (TPO-RAs), immunosuppressants and splenectomy. Recent advances in the understanding of its pathogenesis have opened new fields of therapeutic interventions. The phagocytosis of platelets by splenic macrophages could be inhibited by spleen tyrosine kinase (Syk) or Bruton tyrosine kinase (BTK) inhibitors. The clearance of antiplatelet antibodies could be accelerated by blocking the neonatal Fc receptor (FcRn), while new strategies targeting B cells and/or plasma cells could improve the reduction of pathogenic autoantibodies. The inhibition of the classical complement pathway that participates in platelet destruction also represents a new target. Platelet desialylation has emerged as a new mechanism of platelet destruction in ITP, and the inhibition of neuraminidase could dampen this phenomenon. T cells that support the autoimmune B cell response also represent an interesting target. Beyond the inhibition of the autoimmune response, new TPO-RAs that stimulate platelet production have been developed. The upcoming challenges will be the determination of predictive factors of response to treatments at a patient scale to optimize their management.

Ibrutinib, the first in class of the oral covalent Bruton tyrosine kinase (BTK) inhibitors, has profoundly changed the treatment landscape of chronic lymphocytic leukemia (CLL). The phase III RESONATE and RESONATE-2 trials first demonstrated the superiority of ibrutinib over ofatumumab in the relapsed/refractory setting and over chlorambucil in older patients with de novo disease. The phase III ECOG–ACRIN trial extended these results to young, fit patients, demonstrating a significant survival advantage to ibrutinib plus rituximab over fludarabine, cyclophosphamide, and rituximab. Similarly, the Alliance trial demonstrated the superiority of ibrutinib over bendamustine with rituximab as frontline in elderly patients. Challenges with ibrutinib include toxicity, development of resistance, and need for indefinite therapy. The second generation BTK inhibitor acalabrutinib may cause less off-target toxicity. The ELEVATE TN trial demonstrated the superiority of acalabrutinib with or without obinutuzumab over chlorambucil and obinutuzumab as frontline therapy for elderly or comorbid patients. Promising early results from the phase II CAPTIVATE and CLARITY trials, which combined ibrutinib with venetoclax, suggest a future role for minimal residual disease (MRD) testing to determine treatment duration. The ongoing phase III GAIA/CLL13, ECOG EA9161, Alliance A041702, CLL17, and [ClinicalTrials.gov identifier: NCT03836261] trials will assess various combinations of ibrutinib/acalabrutinib, venetoclax, and anti-CD20 antibodies. These trials will answer key questions in the treatment of CLL: should novel agents in CLL be used in combination or sequentially? What is the best frontline agent? Can treatment be safely stopped with BTK inhibitors? Can undetectable MRD be used to determine treatment duration? In this review, we will discuss these and other aspects of the evolving role of BTK inhibition in CLL.

The critical role of the tissue microenvironment and B-cell receptor (BCR) signaling in chronic lymphocytic leukemia (CLL) pathogenesis, and the clinical success of targeted agents that disrupt BCR signaling are currently changing the CLL landscape. Three new drugs were recently approved for CLL therapy, and other agents are in late development.In this review, we summarize data on promising new targeted drugs for CLL. The heterogeneous mechanisms of actions of these molecules are described, such as the inhibition of BCR signaling, direct targeting of CD20 molecules on the CLL cell surface, and BCL-2 inhibition. We present preclinical and clinical data from phase I to III studies in order to describe efficacy and side effect profile of these new drugs. Data are derived from peer-reviewed articles indexed in PubMed and from abstracts presented at major international meetings.Ibrutinib and idelalisib are challenging the role of chemo-immunotherapy in CLL therapy in the frontline and relapsed disease settings. High-risk CLL patients particularly benefit from these new agents. Venetoclax and obinutuzumab are other effective agents added to our therapeutic armamentarium. Studies to better define the optimal use of these drugs, alone, or rather in combination or sequenced are underway.

7501Background: Bruton tyrosine kinase (BTK) is a clinically validated target in WM. Acalabrutinib is a highly selective, potent, covalent BTK inhibitor that we evaluated in a Phase 2 study of pts ...

TP53-disrupted chronic lymphocytic leukaemia (CLL) patients show a suboptimal long-term response to ibrutinib. We hereby report that ibrutinib-induced in vitro apoptosis and proliferation inhibition were significantly lower in TP53-mutated (TP53-M) CLL cells compared to TP53 wild-type cells. Contrariwise, venetoclax effectively killed TP53-M cells. Gene expression profile analysis of TP53-M cells revealed a downmodulation of B-cell receptor (BCR)-related genes and an upmodulation of genes with anti-apoptotic/pro-survival activity, suggesting that the survival and proliferation of TP53-M cells are less dependent on the BCR pathway. These observations further support the use of drug combinations for the optimal management of TP53-M CLL patients.

Tumour necrosis factor (TNF) is produced by primary human macrophages in response to stimulation by exogenous pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs) via Toll-like receptor (TLR) signalling. However, uncontrolled TNF production can be deleterious and hence it is tightly controlled at multiple stages. We have previously shown that Bruton's tyrosine kinase (Btk) regulates TLR4-induced TNF production via p38 MAP Kinase by stabilising TNF messenger RNA. Using both gene over-expression and siRNA-mediated knockdown we have examined the role of Btk in TLR7/8 mediated TNF production. Our data shows that Btk acts in the TLR7/8 pathway and mediates Ser-536 phosphorylation of p65 RelA and subsequent nuclear entry in primary human macrophages. These data show an important role for Btk in TLR7/8 mediated TNF production and reveal distinct differences for Btk in TLR4 versus TLR7/8 signalling., Highlights • Btk is required for TLR7/8 signalling in primary human macrophages. • R848-induced TNF mRNA is more Btk dependent than LPS-induced TNF mRNA. • Btk transcriptional control of TNF following R848 requires the promoter and 3′UTR. • Btk knockdown reduces p65RelA translocation to the nucleus upon TLR7/8 stimulation.