Acalabrutinib plus Obinutuzumab in Treatment-Naïve and Relapsed/Refractory Chronic Lymphocytic Leukemia

Analysis of ventricular arrhythmias and sudden death from prospective, randomized clinical trials of acalabrutinib

This analysis investigated the incidence of sudden deaths (SDs) and non-fatal and fatal ventricular arrhythmias (VAs) in five acalabrutinib clinical trials. In total, 1299 patients received acalabrutinib (exposure, 4568.4 patient-years). Sixteen (1.2%) patients experienced SD or VA (event rate, 0.350/100 patient-years). Non-fatal VAs occurred in 11 (0.8%) patients, nine (0.7%) of whom had premature ventricular contractions only. SD and fatal VAs occurred in five (0.4%) patients (event rate, 0.109/100 patient-years; median time to event: 46.2 months). SDs and VAs with acalabrutinib occurred at low rates, and there are insufficient data to point to an increased risk of SD or VA with acalabrutinib.

Ibrutinib-based therapy reinvigorates CD8+ T cells compared to chemoimmunotherapy: immune monitoring from the E1912 trial

ABSTRACT

Bruton tyrosine kinase inhibitors (BTKis) that target B-cell receptor signaling have led to a paradigm shift in chronic lymphocytic leukemia (CLL) treatment. BTKis have been shown to reduce abnormally high CLL-associated T-cell counts and the expression of immune checkpoint receptors concomitantly with tumor reduction. However, the impact of BTKi therapy on T-cell function has not been fully characterized. Here, we performed longitudinal immunophenotypic and functional analysis of pretreatment and on-treatment (6 and 12 months) peripheral blood samples from patients in the phase 3 E1912 trial comparing ibrutinib-rituximab with fludarabine, cyclophosphamide, and rituximab (FCR). Intriguingly, we report that despite reduced overall T-cell counts; higher numbers of T cells, including effector CD8+ subsets at baseline and at the 6-month time point, associated with no infections; and favorable progression-free survival in the ibrutinib-rituximab arm. Assays demonstrated enhanced anti-CLL T-cell killing function during ibrutinib-rituximab treatment, including a switch from predominantly CD4+ T-cell:CLL immune synapses at baseline to increased CD8+ lytic synapses on-therapy. Conversely, in the FCR arm, higher T-cell numbers correlated with adverse clinical responses and showed no functional improvement. We further demonstrate the potential of exploiting rejuvenated T-cell cytotoxicity during ibrutinib-rituximab treatment, using the bispecific antibody glofitamab, supporting combination immunotherapy approaches.

Measurable Residual Disease Monitoring in Lymphoma

PURPOSE OF REVIEW

The utility of analyzing circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and disease in the bone marrow as an adjunctive tool in caring for hematologic cancer patients is expanding. This holds true for lymphoma where these biomarkers are being explored as a means of genotyping and quantifying disease. Regarding the latter, they can be used to monitor measurable residual disease (MRD) during and after treatment. This holds potential for aiding clinical decisions amidst treatment, detecting earlier relapse, and improving prognostication. Here, we review the evidence to support these applications in a variety of lymphoma subtypes.

RECENT FINDINGS

Numerous clinical trials across a variety of lymphomas have demonstrated value in MRD monitoring. MRD monitoring is often prognostic for progression free survival (PFS) and even overall survival (OS) at several time points in a disease course, particularly when utilizing serial measurements. With regards to tailoring treatment, there are a growing number of trials examining MRD-adaptive treatment strategies to intensify or de-escalate treatment to individualize care. Lastly, MRD monitoring has been utilized successfully in detecting earlier relapse when compared to more standard methods of clinical surveillance such as radiographic assessment. Although not routinely implemented into clinical practice, MRD monitoring in lymphoma is helping shape the future landscape of this disease by aiding in prognostication, guiding therapy, and detecting earlier relapse. Steps to standardize and further examine this technology prospectively are being taken to bring MRD monitoring to the forefront of the field.

Efficacy and safety of new-generation Bruton tyrosine kinase inhibitors in chronic lymphocytic leukemia/small lymphocytic lymphoma: a systematic review and meta-analysis

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is a type of mature B lymphocyte clonal proliferative tumor with a specific immunophenotype. Bruton tyrosine kinase inhibitors (BTKi) have been approved for the treatment of CLL/SLL. However, the efficacy and safety of new-generation BTKi-based regimens have not been systematically studied. In this systematic review, we evaluated the efficacy and safety of new-generation BTKi-based regimens for the treatment of patients with CLL/SLL. A comprehensive search on PubMed, Embase, Cochrane Library, and ClinicalTrials.gov. up to January 31, 2023, was conducted by us. Studies reporting data on CLL/SLL patients treated with new-generation BTKi were included. We assessed the overall response rate (ORR), complete response (CR) rate, and 24-month OS/PFS rates for efficacy analysis. For safety analysis, we evaluated the incidence of grade ≥ 3 adverse events (AEs). The meta-analysis included twenty studies. The pooled ORR for new-generation BTKi was 92% (95% CI, 89-95%, I2 = 80.68%, P = 0.00), while the pooled CR rate was 10% (95% CI, 6-14%, I2 = 88.11%, P = 0.00). Research has found that the new-generation BTKi-based therapy had higher efficacy under the following treatment conditions: < 65 years old, treatment-naive (TN)-CLL, and BTKi combination therapy. The ORR/CR rates and 24-month OS/PFS rates of BTKi combination therapy were higher than that of BTKi monotherapy. Compared to acalabrutinib monotherapy, zanubrutinib monotherapy demonstrated higher ORR/CR rates and 24-month OS/PFS rates. Common grade ≥ 3 AEs included cytopenia and hypertension. The new-generation BTKi-based therapy has good tolerance and provides incremental benefits for CLL/SLL patients. Despite the superior efficacy of BTKi combination therapy compared to monotherapy, its AEs rates are relatively high. Compared to acalabrutinib, Zanubrutinib may be the preferred monotherapy for CLL. However, randomized-controlled studies are still needed.

Antibody-mediated phagocytosis in cancer immunotherapy

Unconjugated monoclonal antibodies (mAb) have revolutionized the treatment of many types of cancer. Some of these mAbs promote the clearance of malignant cells via direct cytotoxic effects. More recently, antibody-dependent cellular phagocytosis (ADCP) has been appreciated as a major mechanism of action for a number of widely-used mAbs, including anti-CD20 (rituximab, obinutuzumab), anti-HER2 (trazituzumab), and anti-CD38 (daratumumab). However, as a monotherapy these ADCP-inducing mAbs produce insufficient levels of cytotoxicity in vivo and are not curative. As a result, these mAbs are most effectively used in combination therapies. The efficacy of these mAbs is further hampered by the apparent development of drug resistance by many patients. Here we will explore the role of ADCP in cancer immunotherapy and discuss the key factors that could limit the efficacy of ADCP-inducing mAbs in vivo. Finally, we will discuss current insights and approaches being applied to overcome these limitations.

Cardiovascular Toxicities of BTK Inhibitors in Chronic Lymphocytic Leukemia: JACC: CardioOncology State-of-the-Art Review

Over the past decade, the treatment landscape of chronic lymphocytic leukemia (CLL) has dramatically changed, shifting from cytotoxic chemotherapy to targeted therapies. Bruton's tyrosine kinase (BTK) inhibitors have revolutionized the treatment of CLL and are increasingly applied in many other malignancies. However, ibrutinib, the first BTK inhibitor approved, is associated with serious toxicities, including atrial fibrillation in up to 38% of patients, ventricular arrhythmias, and other cardiovascular toxicities. Emerging data suggest several newer BTK inhibitors (eg, acalabrutinib, zanubrutinib) are still associated with cardiotoxic risks. This review examines the current state of evidence, including incidence rates, risk factors, mechanisms, and management strategies of cardiovascular toxicities with BTK inhibitors and other CLL therapies. We specifically focus on atrial fibrillation, ventricular arrhythmias/sudden death, hypertension, heart failure, bleeding, and stroke. We also touch on other emerging BTK therapies (eg, pirtobrutinib). Finally, we highlight key unanswered questions and future directions of research.

Spontaneous Tumor Lysis Syndrome in a Patient With a Known History of Chronic Lymphocytic Leukemia Prior to Cytotoxic Chemotherapy

Tumor lysis syndrome (TLS) is an oncological emergency resulting in an imbalance of electrolytes released upon tumor cell death leading to life-threatening acute renal failure. Typically, TLS is triggered by cytotoxic chemotherapy; however, it can rarely occur spontaneously. Our case report presents a patient with a known malignancy, but not on any cytotoxic chemotherapy, who presents to the emergency department with metabolic derangements suggestive of spontaneous TLS. Our case highlights the importance of considering an uncommon manifestation of TLS despite the absence of cytotoxic chemotherapy. This case is unique as it demonstrates the manifestations of TLS in a patient with a known stable malignancy and discusses the subsequent management.

Next Generation BTK Inhibitors in CLL: Evolving Challenges and New Opportunities

Ibrutinib revolutionized the CLL treatment approach and prognosis demonstrating its efficacy and safety even at extended follow-up. During the last few years, several next-generation inhibitors have been developed to overcome the occurrence of toxicity or resistance in patients on continuous treatment. In a head-to-head comparison of two phase III trials, both acalabrutinib and zanubrutinib demonstrated a lower incidence of adverse events in respect to ibrutinib. Nevertheless, resistance mutations remain a concern with continuous therapy and were demonstrated with both first- and next-generation covalent inhibitors. Reversible inhibitors showed efficacy independently of previous treatment and the presence of BTK mutations. Other strategies are currently under development in CLL, especially for high-risk patients, and include BTK inhibitor combinations with BCl2 inhibitors with or without anti-CD20 monoclonal antibodies. Finally, new mechanisms for BTK inhibition are under investigations in patients progressing with both covalent and non-covalent BTK and BCl2 inhibitors. Here we summarize and discuss results from main experiences on irreversible and reversable BTK inhibitors in CLL.

Immunotherapy combinations for chronic lymphocytic leukemia: advantages and disadvantages

In the last few years, BTK inhibitors, PI3K inhibitors, and venetoclax have been approved for clinical use against chronic lymphocytic leukemia (CLL), both as single agents, and in combination. This article summarizes recent achievements in the treatment of patients with CLL, and pays special attention to novel targeted drugs and monoclonal antibodies (Mabs). A literature search was conducted of the PubMed and Google Scholar databases. Rituximab and obinutuzumab have been combined with chemotherapy, and more recently, with BTK inhibitors, PI3K inhibitors, and venetoclax. These agents have demonstrated high activity in treatment naïve (TN) and relapsed or refractory (RR) CLL. Immunochemotherapy regimens are currently considered in TN younger patients with IGHV-mutated disease and should not be given in patients without IGHV mutation. BTK inhibitors are more commonly used as monotherapy in TN and RR patients. PI3K inhibitors can be combined with CD20 Mabs, but their use in CLL is limited due to safety concerns. Venetoclax is typically combined with anti-CD20 Mabs in CLL. Generally, the optimal sequencing of therapies remains to be established, and the selection of upfront therapy needs to be tailored to the individual patient.

Treatment patterns in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma post covalent Bruton tyrosine kinase inhibitor treatment: a Japanese claims database study

Standard treatment has not been established for patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) after discontinuation of covalent Bruton tyrosine kinase inhibitor (cBTKi) therapy. This retrospective, administrative database (Medical Data Vision) study described the patient characteristics, treatment patterns, and factors associated with receiving post-first-cBTKi treatment in Japanese patients with CLL/SLL. Patients aged ≥18 years with confirmed CLL/SLL diagnosis and treated with anti-neoplastic drugs indicated for CLL/SLL between March 2013 and February 2022 were included. Patient characteristics at baseline (first line), first cBTKi exposure (first-cBTKi), post-first-cBTKi treatment received, and the treatment sequence of CLL drugs received first line through third line, were described. Time-to-event analyses used the Kaplan-Meier method. Multivariable logistic regression analysis was used to explore factors associated with receiving post-first-cBTKi treatment among patients who discontinued first-cBTKi treatment. Among 2,424 eligible patients (median age: 72.0 years, 61.9% male), 450 (18.6%) received cBTKi in any treatment line. Among patients treated with cBTKi, 273 (60.7%) discontinued treatment; 56.0% of them (n = 153/273) received subsequent treatment. Median duration of post-first-cBTKi treatment was 2.2 months (95% confidence interval [CI]: 1.8, 3.5). The most common regimens post-first-cBTKi were cBTKi therapy (47.7%), bendamustine-based therapy (17.0%), and venetoclax-based therapy (13.1%). Patients aged <75 years (odds ratio [OR] [95% CI]: 2.0 [1.2, 3.4]) and those who did not receive blood transfusion during cBTKi treatment (OR [95% CI]: 2.3 [1.3, 4.1]) were more likely to receive post-first-cBTKi treatment. In conclusion, Japanese patients with CLL/SLL received various treatments for short duration after first-cBTKi discontinuation.

Ventricular arrhythmias and sudden death events following acalabrutinib initiation

Acalabrutinib, a next-generation Bruton's tyrosine kinase inhibitor (BTKi), associates with dramatic efficacy against B-cell malignancies. Recently, unexplained ventricular arrhythmias (VAs) with next-generation BTKi-therapy have been reported. Yet, whether acalabrutinib associates with VAs in long-term follow-up is unknown. Leveraging a large-cohort of 290 consecutive B-cell malignancy patients treated with acalabrutinib from 2014 to 2020, we assessed the incidence of VAs. The primary-endpoint was incident VA development (ventricular fibrillation, ventricular tachycardia, and symptomatic premature ventricular contractions). Probability-scores were assessed to determine likelihood of acalabrutinib-association. Incident rates as function of time-on-therapy were calculated. Weighted average observed incidence rates were compared with expected population rates using relative-risks. Absolute excess risk (AER) for acalabrutinib-associated VAs was estimated. Over 1063 person-years of follow-up, there were 8 cases of incident-VAs, including 6 in those without coronary disease (CAD) or heart failure (HF) and 1 sudden-death; median time-to-event 14.9 months. Among those without prior ibrutinib-use, CAD, or HF, the weighted average incidence was 394 per 100 000 person years compared with a reported incidence of 48.1 among similar-aged non-BTKi-treated subjects (relative risk, 8.2; P < .001; AER, 346). Outside of age, no cardiac or electrocardiographic variables associated with VA development. Collectively, these data suggest VAs may be a class-effect of BTKi therapies.

Beyond ibrutinib: novel BTK inhibitors for the treatment of chronic lymphocytic leukemia

PURPOSE OF THE REVIEW

Ibrutinib was the first Bruton tyrosine kinase inhibitor (BTKi) approved for clinical use, contributing to a dramatic change in the treatment landscape of chronic lymphocytic leukemia (CLL). This review provides an overview of next-generation BTKi that have been recently approved or are being investigated for the treatment of CLL, specifically highlighting differences and similarities compared to ibrutinib.

RECENT FINDINGS

Acalabrutinib presented comparable response rates to ibrutinib with lower rates of adverse events and is currently approved for the treatment of CLL. Zanubrutinib displayed excellent response rates with a lower incidence of BTKi-related adverse events, but major rates of neutropenia, and its approval is awaited. With the aim of overcoming drug resistance, noncovalent BTKi have been developed. Of all the explored agents to date, pirtobrutinib has shown promising results with manageable toxicities.

SUMMARY

For the treatment of CLL, several effective therapeutic strategies to target BTK are or will soon be available: these drugs present different safety profiles, thus making it possible to tailor the treatment choice according to patient's characteristics. Importantly, noncovalent BTKi will provide a therapeutic chance also for those relapsed/refractory CLL patients who are BTKi-resistant and are considered an unmet clinical need.

BTK inhibitors in the treatment of hematological malignancies and inflammatory diseases: mechanisms and clinical studies

Bruton's tyrosine kinase (BTK) is an essential component of multiple signaling pathways that regulate B cell and myeloid cell proliferation, survival, and functions, making it a promising therapeutic target for various B cell malignancies and inflammatory diseases. Five small molecule inhibitors have shown remarkable efficacy and have been approved to treat different types of hematological cancers, including ibrutinib, acalabrutinib, zanubrutinib, tirabrutinib, and orelabrutinib. The first-in-class agent, ibrutinib, has created a new era of chemotherapy-free treatment of B cell malignancies. Ibrutinib is so popular and became the fourth top-selling cancer drug worldwide in 2021. To reduce the off-target effects and overcome the acquired resistance of ibrutinib, significant efforts have been made in developing highly selective second- and third-generation BTK inhibitors and various combination approaches. Over the past few years, BTK inhibitors have also been repurposed for the treatment of inflammatory diseases. Promising data have been obtained from preclinical and early-phase clinical studies. In this review, we summarized current progress in applying BTK inhibitors in the treatment of hematological malignancies and inflammatory disorders, highlighting available results from clinical studies.

Bruton tyrosine kinase inhibitors in B-cell lymphoma: beyond the antitumour effect

Targeting B-cell receptor signalling using Bruton tyrosine kinase (BTK) inhibitors (BTKis) has become a highly successful treatment modality for B-cell malignancies, especially for chronic lymphocytic leukaemia. However, long-term administration of BTKis can be complicated by adverse on- and/or off-target effects in particular cell types. BTK is widely expressed in cells of haematopoietic origin, which are pivotal components of the tumour microenvironment. BTKis, thus, show broad immunomodulatory effects on various non-B immune cell subsets by inhibiting specific immune receptors, including T-cell receptor and Toll-like receptors. Furthermore, due to the off-target inhibition of other kinases, such as IL-2-inducible T-cell kinase, epidermal growth factor receptor, and the TEC and SRC family kinases, BTKis have additional distinct effects on T cells, natural killer cells, platelets, cardiomyocytes, and other cell types. Such mechanisms of action might contribute to the exceptionally high clinical efficacy as well as the unique profiles of adverse effects, including infections, bleeding, and atrial fibrillation, observed during BTKi administration. However, the immune defects and related infections caused by BTKis have not received sufficient attention in clinical studies till date. The broad involvement of BTK in immunological pathways provides a rationale to combine BTKis with specific immunotherapies, such as immune checkpoint inhibitor or chimeric antigen receptor-T-cell therapy, for the treatment of relapsed or refractory diseases. This review discusses and summarises the above-mentioned issues as a reference for clinicians and researchers.

The Safety of Bruton's Tyrosine Kinase Inhibitors in B-cell Malignancies: A Systematic Review

B-cell malignancies, most notably lymphomas, make up most of the non-Hodgkin lymphomas in the United States. There is limited randomized data comparing 1^st and 2^nd generation Bruton Tyrosine Kinase inhibitors. Our aim was to compare the safety profiles of 1^st versus 2^nd generation Bruton Tyrosine Kinase inhibitors. A systematic search was performed from database inception to January 13, 2020. Studies with Bruton Tyrosine Kinase inhibitor monotherapy for the treatment of B-cell malignancies in the adult population (> 18 years old) were utilized and the adverse events were extracted. Fifty-five studies that met the inclusion criteria were included in the systematic review with forty-one studies with 1^st generation and fourteen studies with 2^nd generation. The review included both clinical trials and retrospective studies with average time of follow-up of 2 years for the 1^st generation group and 18 months for the 2^nd generation group. We found that the incidence of cardiovascular adverse events was significantly higher in the 1^st generation group (20.8%) as compared to the 2^nd generation group (6.3%). However, there was a higher incidence of hematologic/oncologic and gastrointestinal side effects in the 2^nd generation group compared to the 1^st (62.3% compared to 39.2% and 36.9% compare to 28.9%). The number of Grade 5 cardiovascular events (death) were same in the 1^st generation group compared to the 2^nd generation. Further research is needed to develop highly selective Bruton Tyrosine Kinase inhibitors to avoid unwanted adverse events by minimizing off-targets. This article is protected by copyright. All rights reserved.

Hypertension and incident cardiovascular events after next-generation BTKi therapy initiation

BACKGROUND

Post-market analyses revealed unanticipated links between first-generation Bruton's tyrosine kinase inhibitor (BTKi) therapy, ibrutinib, and profound early hypertension. Yet, whether this is seen with novel selective second (next)-generation BTKi therapy, acalabrutinib, is unknown.

METHODS

Leveraging a large cohort of consecutive B cell cancer patients treated with acalabrutinib from 2014 to 2020, we assessed the incidence and ramifications of new or worsened hypertension [systolic blood pressure (SBP) ≥ 130 mmHg] after acalabrutinib initiation. Secondary endpoints were major cardiovascular events (MACE: arrhythmias, myocardial infarction, stroke, heart failure, cardiac death) and disease progression. Observed incident hypertension rates were compared to Framingham heart-predicted and ibrutinib-related rates. Multivariable regression and survival analysis were used to define factors associated with new/worsened hypertension and MACE, and the relationship between early SBP increase and MACE risk. Further, the effect of standard antihypertensive classes on the prevention of acalabrutinib-related hypertension was assessed.

RESULTS

Overall, from 280 acalabrutinib-treated patients, 48.9% developed new/worsened hypertension over a median of 41 months. The cumulative incidence of new hypertension by 1 year was 53.9%, including 1.7% with high-grade (≥ 3) hypertension. Applying the JNC 8 cutoff BP of ≥ 140/90 mmHg, the observed new hypertension rate was 20.5% at 1 year, > eightfold higher than the Framingham-predicted rate of 2.4% (RR 8.5, P < 0.001), yet 34.1% lower than ibrutinib (12.9 observed-to-expected ratio, P < 0.001). In multivariable regression, prior arrhythmias and Black ancestry were associated with new hypertension (HR 1.63, HR 4.35, P < 0.05). The degree of SBP rise within 1 year of treatment initiation predicted MACE risk (42% HR increase for each + 5 mmHg SBP rise, P < 0.001). No single antihypertensive class prevented worsened acalabrutinib-related hypertension.

CONCLUSIONS

Collectively, these data suggest that hypertension may be a class effect of BTKi therapies and precedes major cardiotoxic events.

Tyrosine kinase inhibitors and tumor lysis syndrome in hematologic malignancies: A systemic review

BACKGROUND

Effective treatments for hematologic malignancies include therapies that target tyrosine kinase (TK) signaling pathways. Tumor lysis syndrome (TLS) is an oncologic emergency that can occur due to rapid turnover following the initiation of treatments for hematologic malignancy. The incidence of TLS is under-reported and it is unclear as to whether TK inhibitors (TKIs) are associated with TLS.

OBJECTIVE

To conduct a systematic review to determine the incidence of TLS with TKIs.

METHODS

A search was performed using EMBASE, MEDLINE, and Web of Science electronic databases, as well as a manual search of the American Society of Hematology and American Society of Clinical Oncology abstract databases. Keywords included: "tumor lysis syndrome," "tyrosine kinase inhibitors," "lymphoma," and "leukemia."

RESULTS

We identified a total of 57 publications that commented on the incidence of TLS with TKIs for hematologic malignancy. Thirty-nine of those publications reported TLS as an adverse event. TLS was described as an adverse event among essentially all the subclasses of TKIs that are used to manage hematologic malignancies.

CONCLUSION

The overall number of articles commenting on TLS as an adverse event is sparse and there needs to be more transparency regarding the incidence of TLS when employing newer targeted therapies. Physicians should consider the risk of TLS on an individual basis and the added risk of TLS when using TKIs to treat hematologic malignancy.

Combining BTK inhibitors with BCL2 inhibitors for treating chronic lymphocytic leukemia and mantle cell lymphoma

The advent of BTK inhibitors has changed the treatment of patients with chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). The first-in-class BTK inhibitor ibrutinib has shown remarkable therapeutic effects and manageable toxicities in multiple clinical trials. The second-generation BTK inhibitors, including acalabrutinib and zanubrutinib, also show remarkable efficacies. However, using BTK inhibitors as monotherapies requires continuous treatment. Resistance to BTK inhibitors and severe side effects unavoidably occur during BTK inhibitor monotherapy, frequently resulting in treatment failure. The addition of the BCL2 inhibitor venetoclax to BTK inhibitor may improve the therapeutic effects and result in deeper responses, providing a potential fixed-duration treatment, especially for patients with CLL. In this review, by focusing on CLL and MCL, we discussed the rationale for the combinational use and summarized the current data on the combinations of BTK inhibitors and venetoclax in patients with CLL and MCL.

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

INTRODUCTION

: The first-in-class Bruton tyrosine kinase (BTK), ibrutinib, demonstrated remarkable activity in chronic lymphocytic leukemia (CLL). However, its toxicity profile renders it potentially inappropriate for use in patients with bleeding or cardiovascular disorders. In response to the high demand for a safer and efficient BTK inhibitor, with improved toxicity profile, acalabrutinib as a second-generation irreversible BTK inhibitor has been approved for the treatment of CLL.

AREAS COVERED

: This review examines the activity of acalabrutinib in treating treatment-naïve and relapsed refractory CLL and its toxicity profile when compared to ibrutinib and other drugs. It will examine the outcomes of the ELEVATE-TN, ASCEND and ELEVATE-RR studies in detail, with a particular focus on the safety and efficacy of acalabrutinib. The strengths and weaknesses of this drug will be highlighted and future directions for research will be identified.

EXPERT OPINION

: In patients with CLL, acalabrutinib demonstrates a superior safety profile than ibrutinib and similar activity. In the first direct comparison of acalabrutinib with ibrutinib in relapsed/refractory CLL, acalabrutinib was found to demonstrate non-inferior progression-free survival, with fewer cardiovascular adverse events.

The Role of Bruton's Kinase Inhibitors in Chronic Lymphocytic Leukemia: Current Status and Future Directions

The use of Bruton's tyrosine kinase (BTK) inhibitors has changed the management and clinical history of patients with chronic lymphocytic leukemia (CLL). BTK is a critical molecule that interconnects B-cell antigen receptor (BCR) signaling. BTKis are classified into two categories: irreversible (covalent) inhibitors and reversible (non-covalent) inhibitors. Ibrutinib was the first irreversible BTK inhibitor approved by the U.S. Food and Drug Administration in 2013 as a breakthrough therapy in CLL patients. Subsequently, several studies have evaluated the efficacy and safety of new agents with reduced toxicity when compared with ibrutinib. Two other irreversible, second-generation BTK inhibitors, acalabrutinib and zanubrutinib, were developed to reduce ibrutinib-mediated adverse effects. Additionally, new reversible BTK inhibitors are currently under development in early-phase studies to improve their activity and to diminish adverse effects. This review summarizes the pharmacology, clinical efficacy, safety, dosing, and drug-drug interactions associated with the treatment of CLL with BTK inhibitors and examines their further implications.

Targeted Treatment of Chronic Lymphocytic Leukemia: Clinical Utility of Acalabrutinib

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

Chronic lymphocytic leukemia: 2022 update on diagnostic and therapeutic procedures

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is one of the most frequent types of leukemia. It typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that interfere with the regulation of proliferation and of apoptosis in clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as typical B-cell markers.

PROGNOSIS AND STAGING

The clinical staging systems provide prognostic information by using the results of physical examination and blood counts. Various biological and genetic markers provide additional prognostic information. Deletions of the short arm of chromosome 17 (del[17p]) and/or mutations of the TP53 gene predict resistance to chemoimmunotherapy and a shorter time to progression with most targeted therapies. The CLL international prognostic index integrates genetic, biological, and clinical variables to identify distinct risk groups of patients with CLL.

THERAPY

Only patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. When treatment is indicated, several therapeutic options exist: a combination of the B-cell lymphoma 2 (BCL2) inhibitor venetoclax with obinutuzumab, monotherapy with inhibitors of Bruton tyrosine kinase (BTK) such as ibrutinib and acalabrutinib, or chemoimmunotherapy. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds 3 years. If the disease relapses earlier, therapy should be changed using an alternative regimen. Patients with a del(17p) or TP53 mutation are usually resistant to chemotherapy and should, therefore, be treated with targeted agents.

FUTURE CHALLENGES

Combinations of targeted agents are now being investigated to create efficient, potentially curative therapies of CLL with fixed duration. One of the most relevant questions currently addressed in clinical trials is the comparison of monotherapies with BTK inhibitors with fixed duration combination therapies. Moreover, the optimal sequencing of targeted therapies remains to be determined. Alternative therapies are needed for patients with BTK and BCL2 inhibitor double-refractory disease.

Clinical Trials of the BTK Inhibitors Ibrutinib and Acalabrutinib in Human Diseases Beyond B Cell Malignancies

The BTK inhibitors ibrutinib and acalabrutinib are FDA-approved drugs for the treatment of B cell malignances. Both drugs have demonstrated clinical efficacy and safety profiles superior to chemoimmunotherapy regimens in patients with chronic lymphocytic leukemia. Mounting preclinical and clinical evidence indicates that both ibrutinib and acalabrutinib are versatile and have direct effects on many immune cell subsets as well as other cell types beyond B cells. The versatility and immunomodulatory effects of both drugs have been exploited to expand their therapeutic potential in a wide variety of human diseases. Over 470 clinical trials are currently registered at ClinicalTrials.gov to test the efficacy of ibrutinib or acalabrutinib not only in almost every type of B cell malignancies, but also in hematological malignancies of myeloid cells and T cells, solid tumors, chronic graft versus host disease (cGHVD), autoimmune diseases, allergy and COVID-19 (http:www.clinicaltrials.gov). In this review, we present brief discussions of the clinical trials and relevant key preclinical evidence of ibrutinib and acalabrutinib as monotherapies or as part of combination therapies for the treatment of human diseases beyond B cell malignancies. Adding to the proven efficacy of ibrutinib for cGVHD, preliminary results of clinical trials have shown promising efficacy of ibrutinib or acalabrutinib for certain T cell malignancies, allergies and severe COVID-19. However, both BTK inhibitors have no or limited efficacy for refractory or recurrent solid tumors. These clinical data together with additional pending results from ongoing trials will provide valuable information to guide the design and improvement of future trials, including optimization of combination regimens and dosing sequences as well as better patient stratification and more efficient delivery strategies. Such information will further advance the precise implementation of BTK inhibitors into the clinical toolbox for the treatment of different human diseases.

Impact of venetoclax monotherapy on the quality of life of patients with relapsed or refractory chronic lymphocytic leukemia: results from the phase 3b VENICE II trial

Venetoclax, a potent B-cell lymphoma-2 (BCL-2) inhibitor, has demonstrated clinical efficacy in chronic lymphocytic leukemia (CLL). VENICE II is an open-label, single-arm, phase 3b study (NCT02980731) evaluating the impact of venetoclax monotherapy (400 mg once daily) for ≤2 years on health-related quality of life (HRQoL) of patients with relapsed/refractory CLL. The primary endpoint was mean change in the global health status (GHS)/quality of life (QoL) subscale of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) from baseline to Week 48. Overall, 210 patients received ≥1 dose of venetoclax; median treatment duration was 67.4 weeks. The primary endpoint was met with mean improvement of +9.3 points (n = 156, 95% confidence interval 6.1-12.5; p=.004) in GHS/QoL. At Week 48, clinically meaningful improvements were observed for role functioning, fatigue, and insomnia domains of EORTC QLQ-C30, suggesting venetoclax monotherapy has a positive impact on HRQoL. No new safety signals were reported.

Illness representations and psychological outcomes in chronic lymphocytic leukaemia

OBJECTIVES

Chronic lymphocytic leukaemia (CLL) is a lifelong cancer with subtle symptoms. Treatment is not curative and often involves repeated relapses and retreatments. Illness perceptions - cognitive and emotional representations of illness stimuli - were studied in CLL patients to: 1) identify illness perception 'profiles' prior to treatment; and 2) test whether profile membership predicts psychological responses 12 months later as treatment continued.

DESIGN

CLL patients (N = 259), randomized to one of four cancer treatment trials testing targeted therapy, were assessed before starting treatment and at 12 months.

METHODS

The Brief Illness Perception Questionnaire (BIPQ) assessed perceived consequences, timeline, personal/treatment control, identity, comprehension, concern, and emotions toward CLL. Psychological outcomes were depressive symptoms (PHQ-9/BDI-II), negative mood (POMS), and cancer stress (IES-R). Latent profile analysis (LPA) determined number of profiles and differential BIPQ items for each profile. Multilevel models tested profiles as predictors of 12-month psychological outcomes.

RESULTS

LPA selected the three-profile model, with profiles revealing Low (n = 150; 57.9%), Moderate (n = 21; 8.1%), and High-impact (n = 88; 34.0%) illness representations. Profiles were defined by differences in consequences, identity, concern, and emotions. Profile membership predicted all psychological outcomes (ps<.038). Low-impact profile patients endorsed minimal psychological symptoms; High-impact profile patients reported substantial symptoms.

CONCLUSIONS

Results of the first CLL illness representation study provide directions for future clinical efforts. By identifying differences among patients' perceptions of CLL consequences, symptom burden, concerns, and emotional responses, an at-risk patient group might receive tailored psychological treatment. Treatments may address negative perceptions, to reduce psychological risk associated with chronic cancer.

Exposure-response analysis of acalabrutinib and its active metabolite, ACP-5862, in patients with B-cell malignancies

AIMS

Examine relationships between the systemic exposure of acalabrutinib, a highly selective, next-generation Bruton tyrosine kinase inhibitor, and its active metabolite (ACP-5862) vs. efficacy and safety responses in patients with B-cell malignancies who received acalabrutinib as monotherapy or in combination with obinutuzumab.

METHODS

For exposure-efficacy analyses, patients with untreated chronic lymphocytic leukaemia were assessed for best overall response, progression-free survival and tumour regression. For exposure-safety analyses, incidences of grade ≥2 adverse events (AEs), grade ≥3 AEs and grade ≥2 events of clinical interest were assessed in patients with B-cell malignancies. Acalabrutinib and ACP-5862 pharmacokinetic (PK) parameter estimates were obtained from population PK modelling. Exposure calculations were based on study dosing regimens. Total active moieties were calculated to account for contributions of ACP-5862 to overall efficacy/safety.

RESULTS

A total of 573 patients were included (exposure-efficacy analyses, n = 274; exposure-safety analyses, n = 573). Most patients (93%) received acalabrutinib 100 mg twice daily. Median total active area under the concentration-time curve (AUC_24h,ss ) and total active maximal concentration at steady-state (C_max,ss ) were similar for patients who received acalabrutinib as monotherapy or in combination with obinutuzumab, and for responders and nonresponders. No relationship was observed between AUC_24h,ss /C_max,ss and progression-free survival or tumour regression. Acalabrutinib AUC_24h,ss and C_max,ss were generally comparable across groups regardless of AE incidence.

CONCLUSION

No clinically meaningful correlations between acalabrutinib PK exposure and efficacy and safety outcomes were observed. These data support the fixed acalabrutinib dose of 100 mg twice daily in the treatment of patients with B-cell malignancies.

Multifaceted Immunomodulatory Effects of the BTK Inhibitors Ibrutinib and Acalabrutinib on Different Immune Cell Subsets - Beyond B Lymphocytes

The clinical success of the two BTK inhibitors, ibrutinib and acalabrutinib, represents a major breakthrough in the treatment of chronic lymphocytic leukemia (CLL) and has also revolutionized the treatment options for other B cell malignancies. Increasing evidence indicates that in addition to their direct effects on B lymphocytes, both BTK inhibitors also directly impact the homeostasis, phenotype and function of many other cell subsets of the immune system, which contribute to their high efficacy as well as adverse effects observed in CLL patients. In this review, we attempt to provide an overview on the overlapping and differential effects of ibrutinib and acalabrutinib on specific receptor signaling pathways in different immune cell subsets other than B cells, including T cells, NK cells, monocytes, macrophages, granulocytes, myeloid-derived suppressor cells, dendritic cells, osteoclasts, mast cells and platelets. The shared and distinct effects of ibrutinib versus acalabrutinib are mediated through BTK-dependent and BTK-independent mechanisms, respectively. Such immunomodulatory effects of the two drugs have fueled myriad explorations of their repurposing opportunities for the treatment of a wide variety of other human diseases involving immune dysregulation.

Assessing the pharmacokinetics of acalabrutinib in the treatment of chronic lymphocytic leukemia

INTRODUCTION

The first-in-class BTK inhibitor ibrutinib has substantially changed the therapeutic landscape of chronic lymphocytic leukemia (CLL). The next-generation BTK inhibitor acalabrutinib is more selective and may have less off-target toxicities as compared to ibrutinib. Acalabrutinib has demonstrated safety and efficacy in CLL and has been approved to treat CLL.

AREAS COVERED

Current clinical trials investigated acalabrutinib monotherapy or acalabrutinib-based combination therapies in relapsed/refractory and treatment-naive CLL. Data on the efficacy and safety of acalabrutinib in clinical trials were summarized in this review. The pharmacokinetic and pharmacodynamic data of acalabrutinib were also discussed.

EXPERT OPINION

Acalabrutinib selectively inhibits BTK by covalent binding and shows rapid absorption and elimination. Acalabrutinib does not inhibit EGFR, TEC, or ITK and shows fewer off-target toxicities. Completed phase 3 trials have demonstrated that acalabrutinib improves the outcomes of patients with relapsed/refractory CLL and patients with treatment-naive CLL. The phase 3 trial that evaluates acalabrutinib versus ibrutinib has met its primary endpoint. Early phase studies suggested the combinations of acalabrutinib with a CD20 antibody and venetoclax led to high rates of undetectable minimal residual disease in the bone marrow in CLL patients and might provide a fixed-duration therapeutic option for patients with CLL.

Survival trends in chronic lymphocytic leukemia across treatment eras: US SEER database analysis (1985-2017)

In this population-based study, we used the SEER database (1985-2015) to examine survival outcomes in chronic lymphocytic leukemia (CLL) patients followed up to the era of advanced treatments including targeted therapies. Data were extracted for patients 15 years or older with a primary diagnosis of CLL. A period analysis was performed to estimate 5- and 10-year relative survival rates for patients diagnosed during different calendar periods from 1985 to 2015. A mixture cure model was used to examine long-term survivors' proportions among patients diagnosed in 1985-2015 and for two cohorts diagnosed in 2000-2003, followed up to 2012 and 2004-2007, and followed up to 2015. Cox proportional hazard modeling was used for the two cohorts to estimate hazard ratios (HRs) of death adjusted for gender and age. The 5-year and 10-year age-adjusted relative survival rate ranged between 73.7 and 89.4% and from 51.6% to "not reached," respectively, for calendar periods of 1985-1989 to 2010-2014. The long-term survivor proportions varied by age and gender from 0 to 59%. The HRs (95%CI) for the 2004-2007 cohort in comparison to the 2000-2003 cohort were 0.58 (0.43-0.78), 0.58 (0.48-0.70), 0.57 (0.49-0.0.67), 0.68 (0.54-0.85), and 0.83 (0.68-1.02) for the age categories of 45-54, 55-64, 65-74, 75-84, and ≥ 85 years, respectively. Overall, relative survival improved significantly for CLL patients diagnosed between 1985 and 2015. These improvements were markedly better following the introduction of targeted therapies.

A phase 1/2 study of the combination of acalabrutinib and vistusertib in patients with relapsed/refractory B-cell malignancies

In a phase 1b study of acalabrutinib (a covalent Bruton tyrosine kinase (BTK) inhibitor) in combination with vistusertib (a dual mTORC1/2 inhibitor) in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), multiple ascending doses of the combination as intermittent or continuous schedules of vistusertib were evaluated. The overall response rate was 12% (3/25). The pharmacodynamic (PD) profile for acalabrutinib showed that BTK occupancy in all patients was >95%. In contrast, PD analysis for vistusertib showed variable inhibition of phosphorylated 4EBP1 (p4EBP1) without modulation of AKT phosphorylation (pAKT). The pharmacokinetic (PK)/PD relationship of vistusertib was direct for TORC1 inhibition (p4EBP1) but did not correlate with TORC2 inhibition (pAKT). Cell-of-origin subtyping or next-generation sequencing did not identify a subset of DLBCL patients with clinical benefit; however, circulating tumor DNA dynamics correlated with radiographic response. These data suggest that vistusertib does not modulate targets sufficiently to add to the clinical activity of acalabrutinib monotherapy. Clinicaltrials.gov identifier: NCT03205046.

Autoimmune Cytopenia in CLL: Prognosis and Management in the Era of Targeted Therapies

ABSTRACT

Chronic lymphocytic leukemia (CLL) is frequently associated with autoimmune hemolytic anemia and immune thrombocytopenia and, less frequently, with pure red cell aplasia and immune neutropenia. The emergence of these complications is related to an intertwined and complex relationship between patient, disease, and treatment characteristics. The prognostic repercussion of autoimmune cytopenia (AIC) in patients with CLL mainly depends on its response to therapy. For patients with AIC and nonactive CLL, treatment is as in primary, uncomplicated AIC, keeping in mind that no response is an indication for CLL therapy. The success of treating active CLL-related AIC widely relies on a flexible strategy that should include initial therapy with corticosteroids and a rapid shift to effective CLL therapy in nonresponding patients. Targeted therapies (e.g., ibrutinib) that have already demonstrated to be effective in CLL-related AIC will likely offer a unique possibility of treating both AIC and CLL as a single target.

The Evolving Landscape of Chronic Lymphocytic Leukemia on Diagnosis, Prognosis and Treatment

The knowledge of chronic lymphocytic leukemia (CLL) has progressively deepened during the last forty years. Research activities and clinical studies have been remarkably fruitful in novel findings elucidating multiple aspects of the pathogenesis of the disease, improving CLL diagnosis, prognosis and treatment. Whereas the diagnostic criteria for CLL have not substantially changed over time, prognostication has experienced an expansion with the identification of new biological and genetic biomarkers. Thanks to next-generation sequencing (NGS), an unprecedented number of gene mutations were identified with potential prognostic and predictive value in the 2010s, although significant work on their validation is still required before they can be used in a routine clinical setting. In terms of treatment, there has been an impressive explosion of new approaches based on targeted therapies for CLL patients during the last decade. In this current chemotherapy-free era, BCR and BCL2 inhibitors have changed the management of CLL patients and clearly improved their prognosis and quality of life. In this review, we provide an overview of these novel advances, as well as point out questions that should be further addressed to continue improving the outcomes of patients.

Matching-adjusted indirect comparisons of safety and efficacy of acalabrutinib versus other targeted therapies in patients with treatment-naïve chronic lymphocytic leukemia

Acalabrutinib is a highly selective, potent, next-generation, covalent Bruton tyrosine kinase inhibitor with minimal off-target activity. Matching-adjusted indirect comparisons (MAICs) were performed to estimate the safety and efficacy of acalabrutinib compared to other targeted therapies for treatment-naïve patients with chronic lymphocytic leukemia (CLL). Individual patient data for acalabrutinib (ELEVATE-TN trial) were matched to aggregate baseline characteristics for comparators. After matching, acalabrutinib (with or without obinutuzumab) showed improved safety outcomes, except for increased risk of neutropenia (p < 0.001) for acalabrutinib plus obinutuzumab versus ibrutinib and increased risk of leukopenia (p < 0.05) for acalabrutinib (with or without obinutuzumab) versus venetoclax plus obinutuzumab. There was no statistically significant difference in progression-free survival between acalabrutinib (with or without obinutuzumab) and any of the comparators. This MAIC demonstrated a favorable safety profile for acalabrutinib-based therapy compared with other targeted therapies in treatment-naïve patients with CLL, without compromising efficacy.

The regulation and function of CD20: an "enigma" of B-cell biology and targeted therapy

The introduction of anti-CD20 monoclonal antibodies such as rituximab, ofatumumab, or obinutuzumab improved the therapy of B-cell malignancies even though the precise physiological role and regulation of CD20 remains unclear. Furthermore, CD20 expression is highly variable between different B-cell malignancies, patients with the same malignancy, and even between intraclonal subpopulations in an individual patient. Several epigenetic (EZH2, HDAC1/2, HDAC1/4, HDAC6, complex Sin3A-HDAC1) and transcription factors (USF, OCT1/2, PU.1, PiP, ELK1, ETS1, SP1, NFκB, FOXO1, CREM, SMAD2/3) regulating CD20 expression (encoded by MS4A1) have been characterized. CD20 is induced in the context of microenvironmental interactions by CXCR4/SDF1 (CXCL12) chemokine signaling and the molecular function of CD20 has been linked to the signaling propensity of B-cell receptor (BCR). CD20 has also been shown to interact with multiple other surface proteins on B cells (such as CD40, MHCII, CD53, CD81, CD82, and CBP). Current efforts to combine anti-CD20 monoclonal antibodies with BCR signaling inhibitors targeting BTK or PI3K (ibrutinib, acalabrutinib, idelalisib, duvelisib) or BH3-mimetics (venetoclax) lead to the necessity to better understand both the mechanisms of regulation and the biological functions of CD20. This is underscored by the observation that CD20 is decreased in response to the "BCR inhibitor" ibrutinib which largely prevents its successful combination with rituximab. Several small molecules (such as histone deacetylase inhibitors, DNA methyl-transferase inhibitors, aurora kinase A/B inhibitors, farnesyltransferase inhibitors, FOXO1 inhibitors, and bryostatin-1) are being tested to upregulate cell-surface CD20 levels and increase the efficacy of anti-CD20 monoclonal antibodies. Herein, we review the current understanding of CD20 function, and the mechanisms of its regulation in normal and malignant B cells, highlighting the therapeutic implications.

Current and future treatment strategies in chronic lymphocytic leukemia

Treatment decisions for patients with chronic lymphocytic leukemia (CLL) are dependent on symptoms and classification into high-, medium-, or low-risk categories. The prognosis for CLL hinges, in part, on the presence or absence of less-favorable genetic aberrations, including del(17p), del(11q), TP53 dysfunction, and IGHV mutations, as these markers are associated with worse treatment response. Promising results from multiple clinical trials show emerging therapies targeting Burton tyrosine kinase, B-cell leukemia/lymphoma 2, and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta result in better outcomes and prolonged progression-free survival for patients both with and without certain high-risk aberrations. Favorable outcomes using these novel oral targeted therapies, either alone or in combination with other treatments such as anti-CD20 antibodies, has led to their use almost entirely supplanting chemoimmunotherapy in the treatment of CLL. In this narrative review, we summarize the current clinical evidence for the use of targeted mono- and combination therapies for CLL, discuss new and next-generation treatment approaches currently in development, and provide insight into areas of unmet need for the treatment of patients with CLL.

From Biomarkers to Models in the Changing Landscape of Chronic Lymphocytic Leukemia: Evolve or Become Extinct

Simple Summary

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. Thus, predicting the outcome of patients with this disease is a topic of special interest. The rapidly changing treatment landscape of CLL has questioned the value of classical biomarkers and prognostic models. Herein we examine the current state-of-the-art of prognostic and predictive biomarkers in the setting of new oral targeted agents with special focus on the most controversial findings over the last years. We also discuss the available information on the role of “old” and “new” prognostic models in the era of oral small molecules.

Abstract

Chronic lymphocytic leukemia (CLL) is an extremely heterogeneous disease. With the advent of oral targeted agents (Tas) the treatment of CLL has undergone a revolution, which has been accompanied by an improvement in patient’s survival and quality of life. This paradigm shift also affects the value of prognostic and predictive biomarkers and prognostic models, most of them inherited from the chemoimmunotherapy era but with a different behavior with Tas. This review discusses: (i) the role of the most relevant prognostic and predictive biomarkers in the setting of Tas; and (ii) the validity of classic and new scoring systems in the context of Tas. In addition, a critical point of view about predictive biomarkers with special emphasis on 11q deletion, novel resistance mutations, TP53 abnormalities, IGHV mutational status, complex karyotype and NOTCH1 mutations is stated. We also go over prognostic models in early stage CLL such as IPS-E. Finally, we provide an overview of the applicability of the CLL-IPI for patients treated with Tas, as well as the emergence of new models, generated with data from patients treated with Tas.

Managing chronic lymphocytic leukemia in 2020: an update on recent clinical advances with a focus on BTK and BCL-2 inhibitors

The therapeutic landscape of chronic lymphocytic leukemia (CLL) underwent a paradigm shift in 2014 with the approval of ibrutinib, which binds covalently to the C481 residue of Bruton's tyrosine kinase (BTK) and irreversibly inhibits it. A number of large, phase 3 trials conducted in both the frontline and the relapsed/refractory settings resulted in the approval of ibrutinib for all CLL. Indeed, the role of chemoimmunotherapy in CLL is fast dwindling. The limitations of ibrutinib, e.g. the development of resistance-conferring C481 BTK mutations and the toxicity issues of atrial fibrillation and bleeding, in particular, have also become apparent with longer-term follow-up. This has spurred the development of second-generation, irreversible inhibitors with greater selectivity for BTK and third-generation, reversible BTK inhibitors to address C481 site mutations. The last 3 years have also witnessed enormous growth in the therapeutic role of the B-cell lymphoma 2 (BCL-2) antagonist venetoclax, initially approved (in 2016) only for patients with relapsed, 17p-deleted CLL. Venetoclax, in combination with CD20 antibodies, is currently approved for both treatment-naïve and relapsed/refractory patients, regardless of genomic subtype. Robust results have also been reported for ibrutinib plus venetoclax, and "triple" combinations of a BTK inhibitor, venetoclax, and obinutuzumab are now being pursued. The major questions facing the field at present are how best to select patients for BTK inhibitor monotherapy versus venetoclax/obinutuzumab upfront, what to do after failure of both BTK inhibitor(s) and venetoclax, and the ideal way to integrate measurable residual disease data into decisions regarding treatment choice, duration, and discontinuation.

EMA Review of Acalabrutinib for the Treatment of Adult Patients with Chronic Lymphocytic Leukemia

On November 5, 2020, a marketing authorization valid through the European Union (EU) was issued for acalabrutinib monotherapy or acalabrutinib in combination with obinutuzumab (AcalaObi) in adult patients with treatment-naïve (TN) chronic lymphocytic leukemia (CLL) and also for acalabrutinib monotherapy in adult patients with relapsed or refractory (RR) CLL. Acalabrutinib inhibits the Bruton tyrosine kinase, which plays a significant role in the proliferation and survival of the disease. Acalabrutinib was evaluated in two phase III multicenter randomized trials. The first trial (ACE-CL-007) randomly allocated acalabrutinib versus AcalaObi versus chlorambucil plus obinutuzumab (ChlObi) to elderly/unfit patients with TN CLL. The progression-free survival (PFS), as assessed by an independent review committee, was superior for both the AcalaObi (hazard ratio [HR], 0.1; 95% confidence interval [CI], 0.06-0.17) and acalabrutinib (HR, 0.2; 95% CI, 0.13-0.3) arms compared with the ChlObi arm. The second trial (ACE-CL-309) randomly allocated acalabrutinib versus rituximab plus idelalisib or bendamustine to adult patients with RR CLL. Also in this trial, the PFS was significantly longer in the acalabrutinib arm (HR, 0.31; 95% CI, 0.20-0.49). Adverse events for patients receiving acalabrutinib varied across trials, but the most frequent were generally headache, diarrhea, neutropenia, nausea, and infections. The scientific review concluded that the benefit-risk ratio of acalabrutinib was positive for both indications. This article summarizes the scientific review of the application leading to regulatory approval in the EU. IMPLICATIONS FOR PRACTICE: Acalabrutinib was approved in the European Union for the treatment of adult patients with chronic lymphocytic leukemia who have not received treatment before and for those who have received therapy but whose disease did not respond or relapsed afterward. Acalabrutinib resulted in a clinically meaningful and significant lengthening of the time from treatment initiation to further disease relapse or patient's death compared with standard therapy. The overall safety profile was considered acceptable, and the benefit-risk ratio was determined to be positive.

The evolving role of Bruton's tyrosine kinase inhibitors in chronic lymphocytic leukemia

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.

Recurrent XPO1 mutations alter pathogenesis of chronic lymphocytic leukemia

BACKGROUND

Exportin 1 (XPO1/CRM1) is a key mediator of nuclear export with relevance to multiple cancers, including chronic lymphocytic leukemia (CLL). Whole exome sequencing has identified hot-spot somatic XPO1 point mutations which we found to disrupt highly conserved biophysical interactions in the NES-binding groove, conferring novel cargo-binding abilities and forcing cellular mis-localization of critical regulators. However, the pathogenic role played by change-in-function XPO1 mutations in CLL is not fully understood.

METHODS

We performed a large, multi-center retrospective analysis of CLL cases (N = 1286) to correlate nonsynonymous mutations in XPO1 (predominantly E571K or E571G; n = 72) with genetic and epigenetic features contributing to the overall outcomes in these patients. We then established a mouse model with over-expression of wildtype (wt) or mutant (E571K or E571G) XPO1 restricted to the B cell compartment (Eµ-XPO1). Eµ-XPO1 mice were then crossed with the Eµ-TCL1 CLL mouse model. Lastly, we determined crystal structures of XPO1 (wt or E571K) bound to several selective inhibitors of nuclear export (SINE) molecules (KPT-185, KPT-330/Selinexor, and KPT-8602/Eltanexor).

RESULTS

We report that nonsynonymous mutations in XPO1 associate with high risk genetic and epigenetic features and accelerated CLL progression. Using the newly-generated Eµ-XPO1 mouse model, we found that constitutive B-cell over-expression of wt or mutant XPO1 could affect development of a CLL-like disease in aged mice. Furthermore, concurrent B-cell expression of XPO1 with E571K or E571G mutations and TCL1 accelerated the rate of leukemogenesis relative to that of Eµ-TCL1 mice. Lastly, crystal structures of E571 or E571K-XPO1 bound to SINEs, including Selinexor, are highly similar, suggesting that the activity of this class of compounds will not be affected by XPO1 mutations at E571 in patients with CLL.

CONCLUSIONS

These findings indicate that mutations in XPO1 at E571 can drive leukemogenesis by priming the pre-neoplastic lymphocytes for acquisition of additional genetic and epigenetic abnormalities that collectively result in neoplastic transformation.

Acalabrutinib: a highly selective, potent Bruton tyrosine kinase inhibitor for the treatment of chronic lymphocytic leukemia

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.