Ibrutinib: a novel Bruton's tyrosine kinase inhibitor with outstanding responses in patients with chronic lymphocytic leukemia

Ibrutinib Delays ALS Installation and Increases Survival of SOD1G93A Mice by Modulating PI3K/mTOR/Akt Signaling

Amyotrophic lateral sclerosis (ALS) is a fatal multisystem degenerative disorder with minimal available therapeutic. However, some recent studies showed promising results of immunological-based treatment. Here, we aimed to evaluate the efficacy of ibrutinib against ALS-associated abnormalities by targeting inflammation and muscular atrophy. Ibrutinib was administrated orally to SOD1 G93A mice from 6 to 19 weeks for prophylactic administration and 13 to 19 weeks for therapeutic administration. Our results demonstrated that ibrutinib treatment significantly delayed ALS-like symptom onset in the SOD1 G93A mice, as shown by improved survival time and reduced behavioral impairments. Ibrutinib treatment significantly reduced muscular atrophy by increasing muscle/body weight and decreasing muscular necrosis. The ibrutinib treatment also considerably reduced pro-inflammatory cytokine production, IBA-1, and GFAP expression, possibly mediated by mTOR/Akt/Pi3k signaling in the medulla, motor cortex and spinal cord of the ALS mice. In conclusion, our study demonstrated that ibrutinib could delay ALS onset, increase survival time, and reduce ALS progression by targeting inflammation and muscular atrophy via mTOR/Akt/PI3K modulation.

Enhancing the Generation of Eomeshi CD8+ T Cells Augments the Efficacy of OX40- and CTLA-4-Targeted Immunotherapy

CTLA-4 blockade in combination with an agonist OX40-specific monoclonal antibody synergizes to augment antitumor immunity through enhanced T-cell effector function, leading to increased survival in preclinical cancer models. We have shown previously that anti-OX40/anti-CTLA-4 combination therapy synergistically enhances the expression of Eomesodermin (Eomes) in CD8⁺ T cells. Eomes is a critical transcription factor for the differentiation and memory function of CD8⁺ T cells. We hypothesized that Eomes^hiCD8⁺ T cells were necessary for anti-OX40/anti-CTLA-4 immunotherapy efficacy and that further enhancement of this population would improve tumor-free survival. Indeed, CD8⁺ T cell-specific deletion of Eomes abrogated the efficacy of anti-OX40/anti-CTLA-4 therapy. We also found that anti-OX40/anti-CTLA-4-induced Eomes^hiCD8⁺ T cells expressed lower levels of checkpoint receptors (PD1, Tim-3, and Lag-3) and higher levels of effector cytokines (IFNγ and TNFα) than their Eomes^lo counterparts. Eomes expression is negatively regulated in T cells through interleukin-2-inducible T-cell kinase (ITK) signaling. We investigated the impact of modulating ITK signaling with ibrutinib, an FDA-approved tyrosine kinase inhibitor, and found that anti-OX40/anti-CTLA-4/ibrutinib therapy further enhanced CD8⁺ T cell-specific Eomes expression, leading to enhanced tumor regression and improved survival, both of which were associated with increased T-cell effector function across multiple tumor models. Taken together, these data demonstrate the potential of anti-OX40/anti-CTLA-4/ibrutinib as a triple therapy to improve the efficacy of immunotherapy.

MicroRNA-425 inhibits proliferation of chronic lymphocytic leukaemia cells through regulation of the Bruton's tyrosine kinase/phospholipase Cγ2 signalling pathway

The present study aimed to investigate the effects of microRNA (miR)-425 on the proliferation of chronic lymphocytic leukaemia (CLL) cells and the possible underlying mechanisms. The expression of miR-425 was determined in the B lymphocytes of CLL patients and in normal B lymphocytes by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, MEC-1 cells transfected with miR-425 negative control (NC) or miR-425 mimic were examined. The cell proliferation of different groups was evaluated using an MTT assay, and cell cycle distribution was evaluated using flow cytometry analysis. A dual-luciferase reporter assay was used to verify whether Bruton's tyrosine kinase (BTK) was a target of miR-425. Furthermore, the expression levels of BTK, phospholipase Cγ2 (PLCγ2), Ki-67 and proliferating cell nuclear antigen (PCNA) were determined by RT-qPCR and western blotting. The results revealed that the expression of miR-425 was significantly downregulated in B lymphocytes obtained from CLL patients as compared with that in normal B lymphocytes. When cells were transfected with miR-425 mimic, the proliferation of MEC-1 cells was significantly inhibited at 24, 48 and 72 h compared with the proliferation of control cells. Additionally, the ratio of G0/G1 cells was significantly increased and the ratio of G2/M cells was significantly decreased in miR-425-overexpressing cells compared with that in control cells. The luciferase reporter assay revealed that miR-425 binds to the 3'-untranslated region of BTK mRNA. Finally, BTK, PLCγ2, Ki-67 and PCNA expression was significantly inhibited at the mRNA and protein level in cells where miR-425 was upregulated. In conclusion, miR-425 inhibits the proliferation of MEC-1 cells, potentially by inhibiting BTK/PLCγ2 signalling, and Ki-67 and PCNA expression levels. These results provide a deeper insight for understanding the development of CLL and suggest a potential novel target for the treatment of CLL patients.

The HDAC6-selective inhibitor is effective against non-Hodgkin lymphoma and synergizes with ibrutinib in follicular lymphoma

Follicular lymphoma (FL) is the most common indolent B-cell non-Hodgkin lymphoma (NHL) with genetic alterations of BCL-2, KMT2B, and KMT6. FL is refractory to conventional chemotherapy and is still incurable in most patients. Thus, new drugs and/or novel combination treatment strategies are needed to further improve FL patient outcome. We investigated the efficacy of the histone deacetylase 6 (HDAC6) inhibitor A452 combined with a Bruton's tyrosine kinase (BTK) inhibitor ibrutinib on NHL and the underlying mechanisms compared with the current clinically tested HDAC6 inhibitor ACY-1215. We first showed that FL is the most sensitive to HDAC6 inhibitor. We showed that combining A452 with ibrutinib led to the synergistic inhibition of cell growth and decreased viability of FL cells, as well as increased levels of apoptosis. Similar synergistic interactions occur in chronic lymphocytic leukemia (CLL) and germinal center diffuse large B-cell lymphoma cells (DLBCL). Enhanced cell death is associated with AKT and ERK1/2 inactivation and increased DNA damage (induction of γH2A.X and reduction of pChk1/2). In addition, A452 downregulates c-Myc, an effect significantly enhanced by ibruninib. Although ACY-1215 is less potent than A452, it displays synergism with ibrutinib. Overall, our results suggest that A452 is more effective as an anticancer agent than ACY-1215 in FL. These findings suggest that a combination of HDAC6-selective inhibitor and ibrutinib is a potent therapeutic strategy for NHL including FL.

Novel Self-Assembled Ibrutinib-Phospholipid Complex for Potently Peroral Delivery of Poorly Soluble Drugs with pH-Dependent Solubility

As an irreversible small-molecule kinase inhibitor, ibrutinib (IBR) exhibits excellent tumor suppression in various tumor cells. However, IBR is insoluble at neutral pH and can dissolve only at low pH: thus, commercial IBR products present poor bioavailability and weakened in vivo antitumor activity. Therefore, we aimed to develop a stable IBR-phospholipid complex (IBR-PC) using egg phosphatidylglycerol (EPG) as excipients to improve the bioavailability of IBR and further enhance its antitumor effects. IBR-PC was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray powder diffraction (XPRD), and molecular docking and simulation test, which all explained the interactions of two components. Solubility tests demonstrate that the novel formulation can maintain excellent solubility (above 5 mg/mL) at various pH levels. Storage stability tests show that no change in particle size or content of IBR-PC was observed during the experimental period. In vivo pharmacokinetic results demonstrated that the relative bioavailability of IBR-PC was a 9.14-fold improvement relative to that of IBR suspension (IBR-susp). Furthermore, IBR-PC was associated with enhanced cytotoxic activity in vitro and superior tumor growth suppression in vivo compared to that resulting from the free IBR. Thus, the proposed IBR-PC system is a promising drug delivery system that enhances the oral bioavailability of IBR, resulting in its improved in vivo antitumor effect.

Ibrutinib Exacerbates Bleomycin-Induced Pulmonary Fibrosis via Promoting Inflammation

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible lung disease with high mortality rate. The etiology is unknown and treatment choices are limited. Thus, there is great interest to investigate novel agents for IPF therapy. Ibrutinib, BTK, and ITK irreversible inhibitor is a FDA-approved small molecule for the clinical therapy of B cell lymphoma. Its role in pulmonary fibrosis remains unknown. In this study, we investigated the anti-fibrotic activity of ibrutinib. Strikingly, ibrutinib did not inhibit but exacerbated bleomycin-induced pulmonary fibrosis by increased epithelial cell apoptosis, and inflammation in the lung. The upregulated TGF-β and EMT transformation also contributes to enhanced myofibroblast differentiation and ECM deposition. Our findings reveal the detrimental effects of ibrutinib against bleomycin-mediated fibrosis and added to the understanding of IPF pathogenesis.

Management of Chronic Lymphocytic Leukemia in the Elderly

BACKGROUND

Because chronic lymphocytic leukemia (CLL) typically follows an indolent course, many patients do not need to initiate therapy until they reach a relatively advanced age, when frailty and reduced organ function can make some of the standard treatments difficult to tolerate and less effective. However, recent advances in the understanding of CLL biology and the approval of agents in novel treatment classes have offered significant advances in the management of the disease.

METHODS

The author reviewed current treatment goals in CLL management, including issues surrounding complete remission (CR) and minimal residual disease (MRD); the findings of trials of treatments from novel drug classes, primarily kinase inhibitors and monoclonal antibodies; and current strategies for use of standard and novel therapies for treatment of individuals diagnosed with CLL, particularly elderly patients.

RESULTS

Several agents and regimens featuring improved clinical outcomes and tolerability are now available or in advanced development for the management of CLL patients, including the elderly and those with high-risk disease. These include ibrutinib, idelalisib plus rituximab, and obinutuzumab plus chlorambucil.

CONCLUSION

The availability of Bruton's tyrosine kinase inhibitors and phosphatidylinositol 3-kinase inhibitors and other novel therapies will allow elderly CLL patients to receive more efficacious treatment with greater tolerability than available with traditional approaches for management of the disease.

Therapeutic antitumor immunity by checkpoint blockade is enhanced by ibrutinib, an inhibitor of both BTK and ITK

Monoclonal antibodies can block cellular interactions that negatively regulate T-cell immune responses, such as CD80/CTLA-4 and PD-1/PD1-L, amplifying preexisting immunity and thereby evoking antitumor immune responses. Ibrutinib, an approved therapy for B-cell malignancies, is a covalent inhibitor of BTK, a member of the B-cell receptor (BCR) signaling pathway, which is critical to the survival of malignant B cells. Interestingly this drug also inhibits ITK, an essential enzyme in Th2 T cells and by doing so it can shift the balance between Th1 and Th2 T cells and potentially enhance antitumor immune responses. Here we report that the combination of anti-PD-L1 antibody and ibrutinib suppresses tumor growth in mouse models of lymphoma that are intrinsically insensitive to ibrutinib. The combined effect of these two agents was also documented for models of solid tumors, such as triple negative breast cancer and colon cancer. The enhanced therapeutic activity of PD-L1 blockade by ibrutinib was accompanied by enhanced antitumor T-cell immune responses. These preclinical results suggest that the combination of PD1/PD1-L blockade and ibrutinib should be tested in the clinic for the therapy not only of lymphoma but also in other hematologic malignancies and solid tumors that do not even express BTK.

Bruton's tyrosine kinase inhibitors and their clinical potential in the treatment of B-cell malignancies: focus on ibrutinib

Aberrant signaling of the B-cell receptor pathway has been linked to the development and maintenance of B-cell malignancies. Bruton's tyrosine kinase (BTK), a protein early in this pathway, has emerged as a new therapeutic target in a variety of such malignancies. Ibrutinib, the most clinically advanced small molecule inhibitor of BTK, has demonstrated impressive tolerability and activity in a range of B-cell lymphomas which led to its recent approval for relapsed mantle cell lymphoma and chronic lymphocytic leukemia. This review focuses on the preclinical and clinical development of ibrutinib and discusses its therapeutic potential.

MALT1 paracaspase: a unique protease involved in B-cell lymphomagenesis

SUMMARY MALT1 is a key regulator of adaptive immunity. MALT1-dependent signaling events control survival, proliferation and differentiation of lymphocytes in response to T- or B-cell receptor stimulation. MALT1 not only regulates physiological lymphocyte activation, but also controls oncogenic signaling in distinct lymphoid malignancies. The fusion protein API2–MALT1 generated by the chromosomal translocation t(11;18) acts as an oncoprotein in the late stages of mucosa-associated lymphoid tissue lymphoma. Moreover, MALT1 is critical for survival and proliferation of the activated B-cell type of diffuse large B-cell lymphomas, one of the most aggressive entities of malignant lymphomas. On the molecular level, MALT1 serves a dual role by functioning as a signaling adaptor and a protease. Both of these functions are critical for triggering the adaptive immune response and for promoting lymphomagenesis. Recent data emphasize that MALT1 is a promising drug target for the treatment of aggressive lymphomas.

Accelerating safe drug development: an ideal approach to approval

Although enormous progress in therapeutic research has improved the lives of patients with hematologic malignancies, these earlier achievements resulted from strategic combinations of agents with unique mechanisms of action and nonoverlapping toxicities. Continued investment in the modern era of drug discovery and development will focus on targeted therapies. Targeting of specific molecular pathways is expected to achieve effective tumor cell reduction with less overall toxicity. The translational processes involved in moving novel therapeutic strategies from the laboratory toward the clinic require close monitoring. The efforts in both cancer drug discovery and development will require extensive collaboration among basic scientists, clinical investigators, and regulatory scientists. The transition from older methods of therapeutic research will require laboratory support to define eligible patients based upon their pretreatment profile. The principles of preclinical drug development based upon decades of experience in predicting toxicity and designing therapeutic strategies are still needed to insure that safety is a high priority. The opportunities for developing novel targeted combination therapies in uniquely profiled patients will hopefully enable successful breakthroughs. Several concrete examples of exciting new agents are discussed here. Defining the predicted mechanism of resistance to these new targeted agents will enable investigators to subsequently design strategies to circumvent resistance with effective combinations. Drug discovery and development are complex and expensive, so efficiency and cooperation in task completion must be tracked.