Efficacy and Safety of BTKis in Central Nervous System Lymphoma: A Systematic Review and Meta-Analysis

BACKGROUND

This systematic review and meta-analysis aimed to evaluate the efficacy and safety of Bruton tyrosine kinase inhibitors (BTKis) for central nervous system lymphoma (CNSL).

METHODS

A systematic review was carried out to identify relevant studies from the PubMed, Embase, Cochrane Library, Web of Science, WanFang, CNKI, and CBM databases. The studies included patients with CNSL who received BTKis and reported the overall response (OR), complete remission (CR), and partial response (PR). An overall effect analysis was performed using STATA 15.0. A random-effects model was utilized to calculate the pooled rates, and 95% confidence intervals (CI) were determined for all outcomes.

RESULTS

A total of 21 studies involving 368 patients were included in the meta-analysis. For newly diagnosed CNSL, due to the small simple size, we conducted a quantitative description, and the ORR could reach up to 100%. For relapsed/refractory patients, the pooled ORR was 72% (95% CI: 64-80%, I2 = 54.89%, p = 0.00), with a pooled CR and PR of 43% (95% CI: 33-54%, I2 = 65.40%, p = 0.00) and 23% (95% CI: 13-35%, I2 = 78.05%, p = 0.00), respectively. Most adverse events were hematology-related and generally manageable.

CONCLUSION

BTKis showed acceptable efficacy and safety in treating patients with CNSL. However, large and well-designed trials are still required to confirm BTKis as a treatment for CNSL.

Evaluation of Bruton tyrosine kinase inhibitors monotherapy and combination therapy in lymphocytic leukemia

BTKi is an effective treatment in chronic lymphocytic leukemia. However, head-to-head clinical trials between BTKi are rare. To explore evidence-based treatment decisions, we conducted this network meta-analysis. We searched in PubMed, Cochrane Library and Embase and selected articles of BTKi treatment in CLL patients, with English restrictions. Objective response rate (ORR), progression-free survival (PFS) and safety were outcomes. Combination therapy and acalabrutinib monotherapy achieved great ORR (greater than 80%). Combination therapy (AO and IR) also performed terrific PFS (> 80%). Compared with ibrutinib monotherapy, zanubrutinib, acalabrutinib and IR showed no significance in overall survival. Diarrhea, hypertension, cardiac events, neutropenia were common adverse events of BTKi therapy. IR had higher incidence of hypertension (0.38, 95% CI 0.28-0.48), and IU was more likely occurred cardiac events. Zanubrutinib monotherapy had lower incidence of total serious adverse reaction (0.42, 95% confidence interval (95% CI): 0.36-0.47),while ibrutinib monotherapy occurred higher adverse reactions of grade ≥ 3 (0.77, 95% CI 0.72-0.82). Although both BTKi monotherapy and combination therapy showed great efficacy, combination therapy did not display priority. Meanwhile, safety of BTKi combination therapy needs to be fully and comprehensively considered.Registration number: CRD42022378732.

The Role of the Microenvironment and Cell Adhesion Molecules in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy whose progression largely depends on the lymph node and bone marrow microenvironment. Indeed, CLL cells actively proliferate in specific regions of these anatomical compartments, known as proliferation centers, while being quiescent in the blood stream. Hence, CLL cell adhesion and migration into these protective niches are critical for CLL pathophysiology. CLL cells are lodged in their microenvironment through a series of molecular interactions that are mediated by cellular adhesion molecules and their counter receptors. The importance of these adhesion molecules in the clinic is demonstrated by the correlation between the expression levels of some of them, in particular CD49d, and the prognostic likelihood. Furthermore, novel therapeutic agents, such as ibrutinib, impair the functions of these adhesion molecules, leading to an egress of CLL cells from the lymph nodes and bone marrow into the circulation together with an inhibition of homing into these survival niches, thereby preventing disease progression. Several adhesion molecules have been shown to participate in CLL adhesion and migration. Their importance also stems from the observation that they are involved in promoting, directly or indirectly, survival signals that sustain CLL proliferation and limit the efficacy of standard and novel chemotherapeutic drugs, a process known as cell adhesion-mediated drug resistance. In this respect, many studies have elucidated the molecular mechanisms underlying cell adhesion-mediated drug resistance, which have highlighted different signaling pathways that may represent potential therapeutic targets. Here, we review the role of the microenvironment and the adhesion molecules that have been shown to be important in CLL and their impact on transendothelial migration and cell-mediated drug resistance. We also discuss how novel therapeutic compounds modulate the function of this important class of molecules.

Rituximab combined with Bruton tyrosine kinase inhibitor to treat elderly diffuse large B-cell lymphoma patients: Two case reports

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a common aggressive non-Hodgkin's lymphoma (NHL), accounting for 30%-40% of adult NHLs. This report aims to explore the efficacy and safety of rituximab combined with Bruton tyrosine kinase inhibitors (BTKis) in the treatment of elderly patients with DLBCL.

CASE SUMMARY

The clinical data of two elderly patients with DLBCL who received rituximab combined with BTKi in our hospital were retrospectively analyzed, and the literature was reviewed. The patients were treated with chemotherapy using the R-miniCHOP regimen for two courses. Then, they received rituximab in combination with BTKi.

CONCLUSION

The treatment experience in these cases demonstrates the potential efficacy of rituximab combined with BTKi to treat elderly DLBCL patients, thus providing a new treatment strategy.

How I Manage Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL), is a hematologic malignancy characterized by the uncontrolled proliferation of mature B lymphocytes. CLL is the most prevalent leukemia in Western countries. Its presentation can range from asymptomatic with the incidental finding of absolute lymphocytosis on a routine blood test, to symptomatic disease requiring immediate intervention. Prognosis of the disease is defined by the presence or absence of specific mutations such as TP53, chromosomal abnormalities such as del(17p), a type of IGHV mutational status, and elevation of B2M and LDH. Treatment of CLL in the United States and Europe has evolved over the recent years thanks to the development of targeted therapies. The standard of care has shifted from traditional chemoimmunotherapy approaches to targeted therapies including Bruton tyrosine kinase inhibitors (BTKis) and BCL2 inhibitors, administered either as monotherapy or in combination with CD20 monoclonal antibodies. Several clinical trials have also recently evaluated combinations of BTKi and venetoclax and showed the combination to be well tolerated and able to induce deep remissions. Targeted therapies have a good safety profile overall; however, they also have unique toxicities that are important to recognize. Diarrhea, fatigue, arthralgia, infections, cytopenias, bleeding, and cardiovascular toxicities (including atrial fibrillation, ventricular arrhythmias, and hypertension) are the adverse events (AEs) commonly associated with BTKis. Initiation of therapy with venetoclax requires close monitoring because of the risk for tumor lysis syndrome associated with this agent, particularly in patients with a high disease burden. Development of newer target therapies is ongoing and the therapeutic landscape in CLL is expanding rapidly.

Pharmacovigilance analysis of cardiac risks associated with Bruton tyrosine kinase inhibitors

BACKGROUND

Bruton tyrosine kinase inhibitors (BTKIs) can be associated with several cardiac risks.

RESEARCH DESIGN AND METHODS

The study was conducted based on records from a large spontaneous reporting database, the Food and Drug Administration Adverse Event Reporting System, for cardiac events reported for several BTKI agents. Reporting odds ratio and information components based on statistical shrinkage transformation were utilized to measure disproportionality.

RESULTS

The final number of records for BTKI-related cardiac events was 10 320. Death or life-threatening events occurred in 17.63% of all associated cardiac records. Significant reporting was captured between BTKI (total/specific) and cardiac events, with the strongest association for ibrutinib. A total of 47 positive signals were evacuated for ibrutinib, with atrial fibrillation being the most commonly reported one. Concomitantly, cardiac failure, congestive, cardiac disorder, arrhythmia, pericardial effusion, and atrial flutter were also noticed for relatively stronger signal and disproportionality. Atrial fibrillation was over-reported in the three groups (ibrutinib, acalabrutinib, and zanubrutinib), and acalabrutinib had statistically significant lower reporting compared with ibrutinib.

CONCLUSIONS

Receiving ibrutinib, acalabrutinib, or zanubrutinib might increase the chance of cardiac complications, with ibrutinib posing the highest risk. The type of cardiotoxicity involved in ibrutinib was highly variable.

The Management of Relapsed or Refractory Waldenström's Macroglobulinemia

Waldenström's macroglobulinemia (WM) is an immunoglobulin M monoclonal gammopathy produced by a bone marrow lymphoplasmacytic lymphoma, an indolent non-Hodgkin lymphoma in which the cure is still an unmet challenge. Combinations with alkylating agents, purine analogs, and monoclonal antibodies, Bruton tyrosine kinase, and proteasome inhibitors are used for the treatment of relapsed and refractory patients. Moreover, new additional agents can be seen on the horizon as potential effective therapies. No consensus on a preferred treatment in the relapsed setting is available yet.

Efficacy and safety-related factors of BTK inhibitors as a bridge to CAR-T therapy in R/R FL

Although anti-CD19 chimeric antigen receptor (CAR) T cell therapy has achieved satisfactory results in relapsed/refractory (R/R) follicular lymphoma (FL), patients with R/R FL and high-risk disease characteristics, previous hematopoietic stem cell transplantation, bulky disease, and progression of disease within 2 years (POD24) had a low complete response (CR). Twenty-seven patients with R/R FL, later disease stages, higher tumor burden, or higher previous treatment lines who had received Bruton tyrosine kinase (BTK) inhibitors before anti-CD19 CAR T cell therapy, or received BTK inhibitors as combination therapy, were included in this study. The clinical response and adverse events (AEs) in anti-CD19 CAR T cell therapy were observed. All patients with R/R FL who received BTK inhibitors combined with anti-CD19-CAR T cell therapy had later disease stages, higher tumor burden, and higher treatment lines than those who did not receive BTK inhibitor combination therapy. However, no difference in the clinical response was found between the two groups. The clinical response in the POD24 group was lower than that in the non-POD24 group; however, no difference in the clinical response was found between the FL and transformed FL (tFL) groups, between the follicular lymphoma international prognostic index (FLIPI) 1 1-2 and FLIPI 1 3-5 groups, and between the FLIPI 2 1-2 and FLIPI 2 3-5 groups. The mean anti-CD19 CAR T cell peak was higher in the CAR-T group with BTK inhibitor than in the CAR-T group without BTK inhibitor. Meanwhile, a higher proportion of patients in the non-POD24 group, FL group, and PR group achieved CR after 2 months. No difference in cytokine secretion was found between the CAR-T group with and without BTK inhibitors. It was higher in the non-POD24 group, FLIPI 1 3-5 group, and FLIPI 2 3-5 group. No difference in cytokine release syndrome and immune effector cell-associated neurotoxic syndrome grades was found between the CAR-T groups with or without BTK inhibitors and between the other groups. Poor prognostic factors, other than POD24, did not affect the clinical response to BTK inhibitors in combination with anti-CD19 CAR T cell therapy in patients with R/R FL. Therefore, BTK inhibitors combined with anti-CD19 CAR-T therapy may be an effective and safe approach for patients with R/R FL and high-risk factors.Trial registration: The study was registered at http://www.chictr.org.cn/index.aspx as ChiCTR-ONN-16009862 and http://www.chictr.org.cn/index.aspx as ChiCTR1800019622.

Cost-effectiveness of acalabrutinib regimens in treatment-naïve chronic lymphocytic leukemia in the United States

BACKGROUND

Clinical outcomes in chronic lymphocytic leukemia (CLL) have improved with targeted therapy, including Bruton tyrosine kinase inhibitors such as acalabrutinib.

METHODS

A semi-Markov model with 3 health states (progression-free, progressed disease, and death) estimated cost per quality-adjusted life-year (QALY) gained for acalabrutinib ± obinutuzumab vs chlorambucil + obinutuzumab in treatment-naïve CLL (based on ELEVATE-TN). The model used direct costs and resource utilization from the US Medicare perspective and utility values sourced from literature. Sensitivity analyses tested the robustness of the model.

RESULTS

Over a 30-year lifetime horizon, the model base case analysis suggested that acalabrutinib monotherapy had an incremental cost of $206,329 and 2.52 QALYs gained versus chlorambucil + obinutuzumab, resulting in an incremental cost-effectiveness ratio (ICER) of $81,960/QALY. Acalabrutinib + obinutuzumab had an incremental cost of $423,747 and 2.79 QALYs gained (ICER: $152,153/QALY). Probabilistic sensitivity analysis showed the probability of acalabrutinib monotherapy being cost effective as 59% to 73% at a $100,000-to-150,000/QALY willingness-to-pay threshold; the probability of acalabrutinib + obinutuzumab being cost effective ranged from 34% to 51%.

CONCLUSIONS

Although the analysis is limited by uncertainty in postprogression survival outcomes, acalabrutinib monotherapy is likely cost effective vs chlorambucil + obinutuzumab in treatment-naïve CLL in the US Medicare setting.

Novel combination approaches with targeted agents in frontline chronic lymphocytic leukemia

Targeted therapies have revolutionized the frontline treatment landscape for patients with chronic lymphocytic leukemia (CLL) and have largely displaced a reliance on chemoimmunotherapy when treating this disease. Multiple randomized trials have documented the efficacy of oral therapy with the Bruton tyrosine kinase inhibitors ibrutinib and acalabrutinib (and zanubrutinib, pending a supplemental new drug application in CLL), as well as BCL2 inhibition using venetoclax. In this review, the authors highlight novel therapeutic strategies for using these agents in combination, either as doublet therapy or as triplet therapy, with anti-CD20 antibodies. First, the current treatment landscape is outlined, and the data are reviewed for continuous and time-limited therapeutic approaches, which constitute the current standard of care. Then, more recent reports are described from phase 2 and 3 studies exploring different combination strategies of Bruton tyrosine kinase and BCL2 inhibition for treatment-naive patients. In addition, relevant differences are emphasized between patient characteristics (e.g., patient fitness and the presence of high-risk disease features) and study methodology (e.g., dosing schedule, randomization, and assessment of measurable residual disease) across trials. Finally, the authors revisit the currently available data for these approaches in the context of ongoing studies and future planned trials, evaluating their potential impact on the frontline treatment landscape for CLL in the years to come.

Mixed Diffuse and Tumoral Form of Bing-Neel Syndrome Successfully Treated with Ibrutinib

Introduction

Bing-Neel syndrome (BNS) is a rare and heterogenous manifestation of Waldenström macroglobulinemia (WM) involving central nervous system (CNS) infiltration by malignant lymphoplasmacytic cells. Efforts to standardize diagnostic criteria have improved in recent years, as have treatment options including the use of the Bruton tyrosine kinase inhibitor (BTKI) ibrutinib.

Case Presentation

Here, we present the case of a 70-year-old male with a remote history of WM previously treated with bendamustine and rituximab, who presented to medical attention with several months of left-sided weakness, headache, and ataxia. Brain magnetic resonance imaging revealed numerous enhancing masses in the bilateral cerebral hemispheres, inferior medulla, and upper cervical spine. Laboratory studies showed serum IgM lambda monoclonal gammopathy and elevated free serum kappa and lambda light chains, while cerebrospinal fluid flow cytometry revealed CD19+ B cells. Stereotactic brain biopsy of a right frontal brain lesion was consistent with lymphoplasmacytic lymphoma, confirmed by a positive MYD88 L265P mutation. He received ibrutinib 420 mg orally daily, and this resulted in appreciable clinical and radiologic responses, which have persisted over a 31-month period.

Conclusion

The advent of molecularly targeted agents and novel therapies for WM has provided patients and clinicians with additional therapeutic options. The use of BTK inhibitors with their high-level CNS penetrance, in particular, offers a novel way to treat BNS and improve patient overall survival while maintaining a high level of quality of life. We discuss the importance of MYD88 L265P testing in the context of BNS as well as the expanding role of BTKIs in treating this disease.

Bing-Neel Syndrome: Update on the Diagnosis and Treatment

Bing-Neel syndrome (BNS) is a rare syndrome that occurs in patients with Waldenstrom macroglobulinemia and is characterized by lymphoplasmacytic infiltration into the leptomeningeal tissue and/or the central nervous system. It represents an extramedullary manifestation which may translate into various neurological symptoms. Accurate diagnosis of BNS can be established via histologic sampling and cerebrospinal fluid examination with molecular analysis of some genetic markers including immunoglobulin heavy locus rearrangements and MYD88 L265P mutation. The use of Bruton tyrosine kinase inhibitors such as ibrutinib resulted in promising outcomes. In this review, we discuss the pathophysiology, clinical manifestations, diagnostic characteristics, and an overview of the current treatment modalities of BNS.

BTK Inhibitors in Chronic Lymphocytic Leukemia

PURPOSE OF REVIEW

The treatment landscape of chronic lymphocytic leukemia (CLL) has dramatically changed over the last few years with the introduction of novel targeted agents. Physicians are now faced with several equally effective therapy options when treating patients with CLL. Here, we review the role of Bruton tyrosine kinase (BTK) inhibitors in treating patients with treatment-naïve and relapsed or refractory CLL. We review recent approvals of BTK inhibitors as well as reported and ongoing clinical trial data.

RECENT FINDINGS

The approval of ibrutinib rapidly led to a paradigm shift in the management of CLL. Randomized trials have now compared ibrutinib to several chemoimmunotherapy approaches, which were in favor of ibrutinib. Second-generation more selective BTK inhibitors, including acalabrutinib and zanubrutinib, have been developed, and recent data have led to the approval of acalabrutinib in CLL. Ongoing and future studies focus on either combining BTK inhibitors with other novel agents (e.g., venetoclax, obinutuzumab, or ublituximab) or developing next-generation non-covalent reversible BTK inhibitors that may be effective in treating patients with CLL harboring BTK-resistant mutations. The field of CLL continues to evolve rapidly with new and evolving combination treatments and novel BTK agents, which will continue to change the standard of care for CLL.

The Impact of Atrial Fibrillation on hospitalization Outcomes for Patients With Chronic Lymphocytic Leukemia Using the National Inpatient Sample Database

BACKGROUND

The incidence of atrial fibrillation (AF) in patients with chronic lymphocytic leukemia (CLL) has been on the rise. However, the excess burden added by AF to the morbidity and mortality of CLL patients especially in the hospitalized setting is undetermined.

METHODS

The National Inpatient Sample (NIS) database was accessed to gather data of hospitalized CLL patients with AF from 2009 to 2018. Propensity-score matching (PSM) and logistic regression model were performed to control for baseline patient factors to match 7265 CLL patient admissions with AF and 7265 CLL patient admissions without AF. The primary outcome was all-cause mortality (ACM), while the secondary outcomes included acute coronary syndrome (ACS), acute myocardial infarction (AMI), and the need for percutaneous coronary intervention (PCI), acute heart failure (AHF), acute hypoxic respiratory failure (AHRF), cardiac arrest (CA), cardiogenic shock (CS), stroke, and the total cost of hospitalization.

RESULTS

CLL patients with AF had a higher rate of ACM (6.06% vs 4.47%; odds ratio [OR] 1.39, 95% confidence interval [CI] 1.19-1.61; P =< .001). All other secondary outcomes including ACS, AMI, PCI, AHRF, CA, CS, and stroke were observed at a significantly higher rate in the AF group as well. The median total hospital cost was also higher in the AF group ($9097 vs. $7646; P value < .0001) CONCLUSION: CLL patients with AF are at a significantly increased risk of all-cause mortality, cardiac-related mortality, and stroke. For this population, a multidisciplinary approach should be orchestrated for better management and outcomes.

Bruton tyrosine kinase inhibitors as potential therapeutic agents for COVID-19: A review

Coronavirus disease 2019 (COVID-19) is first detected in December 2019 in Wuhan, China which is a new pandemic caused by SARS-COV-2 that has greatly affected the whole world. Bruton tyrosine kinase (BTK) inhibitors are drugs that are used for the management of cancer, and are being repurposed for COVID-19. BTK regulates macrophage and B cell activation, development, survival, and signaling. Inhibition of BTK has revealed an ameliorative effect on lung injury in patients with severe COVID-19. Thus, this review aimed to summarize evidence regarding the role of Bruton tyrosine kinase inhibitors against COVID-19. To include findings from diverse studies, publications related to BTK inhibitors and Covid-19 were searched from the databases such as SCOPUS, Web of Science, Medline, Google Scholar, PubMed, and Elsevier, using English key terms. Both experimental and clinical studies suggest that targeting excessive host inflammation with a BTK inhibitor is a potential therapeutic strategy in the treatment of patients with severe COVID-19. Currently, BTK inhibitors such as ibrutinib and acalabrutinib have shown a protective effect against pulmonary injury in a small series group of COVID-19 infected patients. Small molecule inhibitors like BTK inhibitors, targeting a wide range of pro-inflammatory singling pathways, may a key role in the management of COVID-19.

Acute gout flare of bilateral first metatarsophalangeal joints due to ibrutinib use in chronic lymphocytic leukemia

INTRODUCTION

Bruton tyrosine kinase inhibitors represent important tools in the therapeutic armamentarium against chronic lymphocytic leukemia (CLL) and other B-lymphoproliferative disorders.

CASE REPORT

We describe herein a unique 65-year-old patient who presented with bilateral foot pain four months after starting treatment with ibrutinib for CLL. Of note, the patient had previously been diagnosed with gout, and was taking allopurinol prophylactically at the time of the event. Compliance with allopurinol was in excess of 99%. Yet, he was diagnosed with acute gout flare of bilateral first metatarsophalangeal (MTP) joints.Management & Outcome: Ibrutinib dose was reduced by one third, and the patient's gout flare up was treated with ibuprofen as needed. After symptoms abated, ibrutinib was continued at 2/3rds of the dose, with an excellent CLL control. The patient tolerated this dose without any further adverse effects.Discussion/Conclusions: We have reported a unique side effect of acute bilateral first MTP joint gout flare likely triggered by ibrutinib use for CLL while the patient was taking a xanthine oxidase inhibitor. The mechanism by which ibrutinib caused this phenomenon remains to be elucidated.

Targeted Treatment of Follicular Lymphoma

Follicular lymphoma (FL) is the most common indolent B-cell lymphoma. Advanced stage disease is considered incurable and is characterized by a prolonged relapsing/remitting course. A significant minority have less favorable outcomes, particularly those with transformed or early progressive disease. Recent advances in our understanding of the unique genetic and immune biology of FL have led to increasingly potent and precise novel targeted agents, suggesting that a chemotherapy-future may one day be attainable. The current pipeline of new therapeutics is unprecedented. Particularly exciting is that many agents have non-overlapping modes of action, offering potential new combinatorial options and synergies. This review provides up-to-date clinical and mechanistic data on these new therapeutics. Ongoing dedicated attention to basic, translational and clinical research will provide further clarity as to when and how to best use these agents, to improve efficacy without eliciting unnecessary toxicity.

[Successful treatment with silver nitrate chemical cauterization for paronychia and granulation in a patient with chronic lymphocytic leukemia undergoing ibrutinib therapy]

A 72-year-old man with leukocytosis, anemia, and lymphadenopathy was diagnosed with chronic lymphocytic leukemia (CLL) in August 2017 and was carefully monitored in a "watch-and-wait" manner until it became an "active disease." Ibrutinib (IBR) was initiated orally in July 2018 at a dose of 420 mg/day after disease progression due to chromosome 17p deletion (del 17p). The patient showed partial response after transient lymphocytosis while on IBR treatment. IBR induces paronychia and skin disorder due to the disruption of disulfide bonds between cysteine and inhibition of epidermal growth factor receptor due to the off-target effect. This results in reduced quality of life. In February 2019, paronychia (grade 1) developed in the patient's right foot's first toe; hence, topical gentamicin and taping therapy were performed. However, the symptoms persisted without any improvements. In July 2019, paronychia/granulation (grade 2) was aggravated and successfully treated with silver nitrate chemical cauterization and taping therapy. The patient was continuously treated with 420 mg/day IBR without dose reduction or discontinuation, resulting in successful disease control of CLL with del 17p.

Bruton tyrosine kinase inhibitors for the frontline treatment of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (cll) is the most commonly diagnosed adult leukemia in Canada. Biologic heterogeneity of cll between patients results in variable disease trajectories and responses to therapy. Notably, compared with patients lacking high-risk features, those with such features-such as deletions in chromosome 17p, aberrations in the TP53 gene, or unmutated immunoglobulin heavy chain variable region genes-experience inferior outcomes and responses to standard chemoimmunotherapy. Novel agents that target the B cell receptor signalling pathway, such as Bruton tyrosine kinase (btk) inhibitors, have demonstrated clinical efficacy and safety in patients with treatment-naïve cll, particularly those with high-risk features. However, given the current lack of head-to-head trials comparing btk inhibitors, selection of the optimal btk inhibitor for patients with cll is unclear and requires consideration of multiple factors. In the present review, we focus on the efficacy, safety, and pharmacologic features of the btk inhibitors that are approved or under clinical development, and we discuss the practical considerations for the use of those agents in the Canadian treatment landscape.

The current role of BTK inhibitors in the treatment of Waldenstrom's Macroglobulinemia

INTRODUCTION

Waldenstrom's Macroglobulinemia (WM) is a rare, indolent lymphoplasmacytic lymphoma characterized by heterogeneous clinical and genomic profile. Bruton's tyrosine kinase (BTK) is central to the signaling pathways required for clonal WM cell survival, and BTK inhibitors currently have an imperative role in the treatment of WM.

AREAS COVERED

The central role of BTK in WM will be described, and the rationale behind the development of BTKi. Clinical trial data that led to the approval of ibrutinib (the first-in-class BTKi) will be reviewed. Despite its potency and safe toxicity profile, ibrutinib does not induce deep remissions, and responses are mutational-status dependent. The mechanisms that lead to resistance to this agent are being investigated. Ibrutinib treatment has to be continuous; consequently, patients face the effects of long-term toxicity. In that context, second-generation inhibitors are in clinical development with fewer off-target effects and an efficacy profile, which will be determined based on long-term follow-up data.

EXPERT OPINION

The optimal therapeutic approach for WM patients remains to be established. The question of whether a combinatory (or synergistic) regimen to overcome resistance and allow for a fixed treatment duration will allow for deep and durable response is being addressed in ongoing clinical trials.

Harnessing the Effects of BTKi on T Cells for Effective Immunotherapy against CLL

B-cell receptor (BCR) signaling and tumor–microenvironment crosstalk both drive chronic lymphocytic leukemia (CLL) pathogenesis. Within the microenvironment, tumor cells shape the T-cell compartment, which in turn supports tumor growth and survival. Targeting BCR signaling using Bruton tyrosine kinase inhibitors (BTKi) has become a highly successful treatment modality for CLL. Ibrutinib, the first-in-class BTKi, also inhibits Tec family kinases such as interleukin-2–inducible kinase (ITK), a proximal member of the T-cell receptor signaling cascade. It is increasingly recognized that ibrutinib modulates the T-cell compartment of patients with CLL. Understanding these T-cell changes is important for immunotherapy-based approaches aiming to increase the depth of response and to prevent or treat the emergence of resistant disease. Ibrutinib has been shown to improve T-cell function in CLL, resulting in the expansion of memory T cells, Th1 polarization, reduced expression of inhibitory receptors and improved immune synapse formation between T cells and CLL cells. Investigating the modulation of BTKi on the T-cell antitumoral function, and having a more complete understanding of changes in T cell behavior and function during treatment with BTKi therapy will inform the design of immunotherapy-based combination approaches and increase the efficacy of CLL therapy.

Review of Bruton tyrosine kinase inhibitors for the treatment of relapsed or refractory mantle cell lymphoma

Mantle cell lymphoma (mcl) is a rare subtype of aggressive B-cell non-Hodgkin lymphoma that remains incurable with standard therapy. Patients typically require multiple lines of therapy, and those with relapsed or refractory (r/r) disease have a very poor prognosis. The Bruton tyrosine kinase (btk) inhibitor ibrutinib has proven to be an effective agent for patients with r/r mcl. Although usually well tolerated, ibrutinib can be associated with unique toxicities, requiring discontinuation in some patients. Effective and well-tolerated alternatives to ibrutinib for patients with r/r mcl are therefore needed. Novel btk inhibitors such as acalabrutinib, zanubrutinib, and tirabrutinib are designed to improve on the safety and efficacy of first-generation btk inhibitors such as ibrutinib. Data from single-arm clinical trials suggest that, compared with ibrutinib, second-generation btk inhibitors have comparable efficacy and might have a more favourable toxicity profile. Those newer btk inhibitors might therefore provide a viable treatment option for patients with r/r mcl.

Acalabrutinib for adults with mantle cell lymphoma

INTRODUCTION

Although advances in mantle cell lymphoma (MCL) therapy have improved overall survival (OS), managing relapsed/refractory (R/R) cases remains a great challenge. Bruton tyrosine kinase (BTK) inhibitors have broadened therapeutic options in MCL and became the backbone of second-line strategies. Areas covered: Ibrutinib, the first-in-class BTK inhibitor registered for MCL therapy, is efficient, with clear benefits of its use. However, ibrutinib-related adverse events due to off-target inhibition of other kinases led to the development of more selective molecules with comparable efficacy and better safety profiles. Expert commentary: Acalabrutinib, a new BTK inhibitor, currently being evaluated in numerous clinical studies is approved by FDA in relapsing/refractory MCL. Its role will evolve over the next few years. Efficacy and good tolerability of acalabrutinib gives even greater opportunity for potential upfront use and new therapeutic combinations, including monoclonal antibodies, antibody-drug conjugates, immune checkpoint inhibitors, bcl-2 (B-cell lymphoma-2) or IP3K (phosphoinositide 3-kinase) inhibitors.

New and emerging Bruton tyrosine kinase inhibitors for treating mantle cell lymphoma - where do they fit in?

INTRODUCTION

Despite recent prognostic improvements, mantle cell lymphoma (MCL) remains incurable. Bruton tyrosine kinase (BTK) is a key receptor in B-cell tumorigenesis, and the benefits of the first BTK inhibitor, ibrutinib, are becoming clear in MCL. However, off-target activities, which contribute to ibrutinib-related adverse events, suggest potential for further improvement of this drug class. Areas covered: The authors systematically interrogated ClinicalTrials.gov for trials containing keywords for BTK and MCL. Published literature for new and emerging BTK inhibitors being investigated in MCL was then identified (PubMed and Embase), summarized, and placed in the context of treatment guidelines. Expert commentary: Reduced off-target effects of new and emerging covalent, irreversible BTK inhibitors under investigation in patients with MCL offer the potential of improved safety compared with ibrutinib. Efficacy may also be favorable based on trial data for acalabrutinib, which has just been approved in the USA as second-line therapy for MCL. The role of BTK inhibitors in treating MCL will evolve substantially over the coming years as results from a number of trials become available, particularly in relation to potential upfront use and possible synergy with other targeted therapies such as B-cell lymphoma 2, phosphoinositide 3-kinase and checkpoint inhibitors.

Novel agents in the treatment of chronic lymphocytic leukemia: a review about the future

Half of a century ago, physicians managing chronic lymphocytic leukemia (CLL) recognized some of its presenting features such as lymphocytosis, lymphadenopathy, and splenomegaly. Subsequently, an enhanced understanding of the disease mechanisms involved in CLL led to new, more targeted treatments. There is now a plethora of treatments available for CLL. In this review article we discuss in detail several of the novel agents that are being studied or approved for the treatment of CLL including: phosphatidylinositol 3-kinase inhibitors (idelalisib and IPI-145), Bruton tyrosine kinase inhibitors (ibrutinib), B cell lymphoma 2 inhibitors (ABT-263 and ABT-199), new anti-CD20 monoclonal antibodies (obinutuzumab), cyclin-dependent kinase inhibitors (flavopiridol and dinaciclib), immunomodulators (lenalidomide) and chimeric antigen receptor T-cell therapy.