Toxicities and outcomes of 616 ibrutinib-treated patients in the United States: a real-world analysis

Pharmacogenetic associations of GATA4 and KCNQ1 with ibrutinib cardiovascular toxicity

Ibrutinib treatment is often complicated by cardiovascular side effects (CVSEs). The objective of this retrospective pharmacogenetic study is to replicate a previously reported association of 'high-risk' patients, who are homozygous carriers of at least two of GATA4 rs804280 AA, KCNQ1 rs163182 GG, and KCNQ1 rs2237895 AA, with increased risk of hypertension or atrial fibrillation, and explore associations for other pharmacogenes (e.g. CYP3A4 , CYP3A5 , CYP2D6 , and ABCB1 ) with ibrutinib CVSEs. Univariate associations with P  < 0.05 were adjusted for significant pretreatment cardiovascular conditions. In total 57 patients were included in the analysis. In the primary analysis, 'high-risk' patients were not more likely to experience hypertension or atrial fibrillation (70 vs. 41%, chi-square P value = 0.06). In secondary analyses, 'high-risk' patients were more likely to experience any CVSE during treatment (75 vs. 41%, P  = 0.013), develop a cardiac rhythm or function disorder (65 vs. 24%, P  = 0.008), and have a treatment modification due to CVSE (45 vs. 8%, P  = 0.004). Additionally, high-risk homozygous variant genotypes of KCNQ1 rs163182 GG and rs2237895 AA were each associated with an increased likelihood of treatment modifications due to CVSE (40 vs. 11%, P  = 0.021 and 45 vs. 9%, P  = 0.004, respectively) and cardiac rhythm or function disorders (60 vs. 27%, P  = 0.037 and 60 vs. 27%, P  = 0.037). This study found supportive evidence that 'high-risk' genotype was associated with increased ibrutinib CVSEs. Validation of these associations is necessary before prospective trials testing whether personalized ibrutinib treatment approaches improve clinical outcomes.

Ibrutinib for therapy of steroid-refractory chronic graft-versus-host disease: a multicenter real-world analysis

ABSTRACT

To examine the activity of ibrutinib in steroid-refractory chronic graft-versus-host disease (SR-cGVHD) after the US Food and Drug Administration approval, we conducted a multicenter retrospective study. Data were standardly collected (N = 270 from 19 centers). Involved organs included skin (75%), eye (61%), mouth (54%), joint/fascia (47%), gastrointestinal (GI) (26%), lung (27%), liver (19%), genital (7%), and others (4.4%). The National Institutes of Health (NIH) severity was mild in 5.7%, moderate 42%, and severe 53%. Thirty-nine percent had overlap subtype. Karnofsky performance status (KPS) was ≥80% in 72%. The median prednisone was 0.21 mg/kg (0-2.27). Ibrutinib was started at a median of 18.2 months after cGVHD onset and in earlier lines of therapy (second line, 26%; third, 30%; fourth, 21%; fifth, 9.6%; sixth, 10%; seventh or higher, 1.2%). Among evaluable patients, the 6-month NIH overall response rate (ORR; complete response [CR]/partial response [PR]) was 45% (PR 42%; CR 3%). The median duration of response was 15 months (range, 1-46). Liver involvement had association with 6-month ORR (multivariate [MVA] odds ratio, 5.49; 95% confidence interval [CI], 2.3-14.2; P < .001). The best overall response was 56%, with most (86%) achieving by 1 to 3 months. With a median follow-up for survivors of 30.5 months, failure-free survival (FFS) was 59% (53%-65%) at 6 months and 41% (36%-48%) at 12 months. On MVA, increased age (hazard ratio [HR], 1.01; 95% CI, 1.0-1.02; P = .033), higher baseline prednisone (HR, 1.92; 95% CI, 1.09-3.38; P = .032), and lung involvement (HR, 1.58; 95% CI, 1.1-2.28; P = .016) had worse FFS. Ibrutinib discontinuation was most commonly due to progressive cGVHD (44%) or toxicity (42%). These data support that ibrutinib has activity in SR-cGVHD, provide new insight into factors associated with response and FFS, and demonstrate the toxicity profile associated with discontinuation.

Chronic Lymphocytic Leukemia: 2025 Update on the Epidemiology, Pathogenesis, Diagnosis, and Therapy

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the most frequent type of leukemia. It typically occurs in older patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that interfere with the regulation of proliferation and 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

Two clinical staging systems, Rai and Binet, 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 a shorter time to progression with most targeted therapies. The CLL international prognostic index (CLL-IPI) integrates genetic, biological, and clinical variables to identify distinct risk groups of patients with CLL. The CLL-IPI retains its significance in the era of targeted agents, but the overall prognosis of CLL patients with high-risk stages has improved.

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: combinations of the BCL2 inhibitor venetoclax with obinutuzumab, or venetoclax with ibrutinib, or monotherapy with one of the inhibitors of Bruton tyrosine kinase (BTK). At relapse, the initial treatment may be repeated if the treatment-free interval exceeds 3 years. If the leukemia relapses earlier, therapy should be changed using an alternative regimen.

FUTURE CHALLENGES

Combinations of targeted agents now provide efficient therapies with a fixed duration that generate deep and durable remissions. These fixed-duration therapies have gained territory in the management of CLL, as they are cost-effective, avoid the emergence of resistance, and offer treatment free time to the patient. The cure rate of these novel combination regimens is unknown. Moreover, the optimal sequencing of targeted therapies remains to be determined. A medical challenge is to treat patients who are double-refractory to both BTK and BCL2 inhibitors. These patients need to be treated within experimental protocols using novel drugs.

Assessing adverse event burden in chronic lymphocytic leukemia treatment regimens: what's best for patient quality of life?

INTRODUCTION

In recent years, chronic lymphocytic leukemia (CLL) treatment has changed dramatically. Chemoimmunotherapy with fludarabine/cladribine, cyclophosphamide and rituximab have been almost completely replaced by targeted therapies with small molecules such as Bruton's tyrosine kinase inhibitors or B-cell lymphoma 2 (BCL-2) antagonists. However, few studies have assessed the impact of novel therapies on patient quality of life (QoL).

AREAS COVERED

This article reviews the safety profile of new therapeutic options and their impact on the QoL of CLL patients. The MEDLINE database was searched for English language publications from 2010 through June 2024, including the Proceedings of the American Society of Hematology from over the past five years.

EXPERT OPINION

CLL is a clinically-heterogenous disease predominantly affecting elderly patients. The variable clinical course of disease requires personalization and individualized treatment to achieve the optimal survival outcome and acceptable safety profile, especially in the case of poor prognosis. Clinical trials performed in the past decade indicate that novel drugs, used as a single agent or as part of a conventional chemotherapy, offer promise in minimalizing relapse rates, and may allow more effective and safer treatment options by reducing the risk of adverse events, especially cytopenias and infections.

The preclinical discovery and development of zanubrutinib for the treatment of chronic lymphocytic leukemia

INTRODUCTION

The history of treating chronic lymphocytic leukemia (CLL) inflected in 2014 with the Food and Drug Administration's (FDA) approval of ibrutinib, the first-in-class small molecule inhibitor of the Bruton's tyrosine kinase (BTK). Zanubrutinib is a 2nd generation covalent BTK inhibitor developed and manufactured by BeiGene.

AREAS COVERED

In this review, the authors trace the arc of zanubrutinib development from the preclinical phase through the two landmark phase 3 studies in the CLL space, ALPINE and SEQUOIA. The authors cover contemporary management strategies in CLL and highlight the areas of need that zanubrutinib was designed to mitigate.

EXPERT OPINION

Zanubrutinib entered a fray of novel, exciting therapies for CLL. As the second of two 2nd generation covalent BTK inhibitors its path to prominence in CLL management was narrow. Emphasis during development on kinase selectivity and enhanced bioavailability identified a molecule with superior efficacy and tolerability; hierarchical endpoints in trial design allowed for efficient acquisition of comparative data. Zanubrutinib is endorsed by the National Comprehensive Cancer Network as a preferred, category 1 recommended treatment choice for CLL. Future efforts in combination therapies and response-directed treatment breaks will hopefully lead to still further improvements in use.

The challenge of targeting key drivers of CLL and sequencing therapy in an era of experimental therapeutics

Treatment of chronic lymphocytic leukemia (CLL) has been revolutionized with the introduction of small molecule inhibitors targeting both the B-cell receptor (BCR) signaling pathway and B-cell lymphoma-2 (BCL-2) family of proteins. Inhibitors of Bruton's tyrosine kinase (BTK) and the BH3 mimetic venetoclax are bothcurrently used as the standard of care for patients in the frontline and relapsed/refractory setting of CLL. With the clinical success of both these classes of therapies, sequencing of these agents has become a major challenge in treatment of CLL. In this review we will discuss the current data available for both classes of agents in the front-line and relapsed/refractor setting, considerations when giving these agents, and how we can continue to improve the treatment landscape for CLL.

Chimeric Antigen Receptor-T Cells in the Modern Era of Chronic Lymphocytic Leukemia Treatment

Pathway inhibitors targeting Bruton tyrosine kinase (BTK) and B-cell lymphoma-2 (BCL-2) have dramatically changed the treatment landscape for both treatment-naïve and relapsed/refractory chronic lymphocytic leukemia (CLL). However, with increased utilization, a growing number of patients will experience progressive disease on both agents. This subgroup of "double refractory" patients has limited treatment options and poor prognosis. Chimeric antigen receptor (CAR)-T cells have transformed the treatment of relapsed/refractory B-cell malignancies. Although the earliest success of CAR-T cell therapy was in CLL, the clinical application of this modality has lagged until the recent approval of the first CAR-T cell product for CLL. In this review, we describe the current treatment options for upfront and subsequent therapies and the unmet need for novel agents highlighted by the burgeoning role and challenges of CAR-T cell therapy.

Guidelines for the diagnosis and treatment of chronic lymphocytic leukemia and small lymphocytic lymphoma from Chronic Lymphocytic Leukemia Spanish Group (GELLC)

INTRODUCTION

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults in Western countries, with a median age at diagnosis of 72 years. This guide, developed by the Spanish Group for Chronic Lymphocytic Leukemia (GELLC), addresses the most relevant aspects of CLL, with the objectives of facilitating and aiding the diagnostic process, establishing therapeutic recommendations for choosing the best treatment for each type of patient, as well as standardizing the management of CLL and ensuring equity across different hospitals in terms of the use of the various available treatment regimens.

METHODOLOGY

The references obtained were classified according to the level of evidence and following the criteria established by the Agency for Health Research and Quality, and the recommendations were classified according to the criteria of the National Comprehensive Cancer Network (NCCN).

DIAGNOSIS

The diagnosis of CLL requires the presence of 5 × 109/l clonal B lymphocytes with the characteristic phenotype (CD19, CD5, CD20, CD23, and kappa or lambda chain restriction) demonstrated by flow cytometry in peripheral blood and maintained for at least 3 months. The presence of cytopenia caused by a typical bone marrow infiltrate establishes the diagnosis of CLL, regardless of the number of circulating lymphocytes or existing lymph node involvement. CLL and small lymphocytic lymphoma (SLL) are the same disease with different presentations, so they should be treated the same way. Current international guidelines recommend FISH with the 4 probes as a mandatory test in clinical practice to guide the prognosis of patients. They also recommend determining the mutational status of the immunoglobulin heavy chain variable region (IGHV) before the first treatment and detecting TP53 mutations before the first and subsequent relapses.

TREATMENT

Treatment should be initiated in symptomatic patients with criteria for active disease according to iwCLL. The first aspect to highlight is the prioritization of targeted therapies over immunochemotherapy. In first-line treatment, for patients with del(17p) and/or TP53 mutation, the best therapeutic option is a second-generation covalent Bruton's tyrosine kinase inhibitor (BTKi) administered indefinitely, while in cases without del(17p) or TP53 mutation with mutated IGHV, time-limited therapy with a combination including a BCL2 inhibitor (BCL2i) should be considered as the first therapeutic option. For patients with unmutated IGHV, both continuous BTKi and finite therapy with BCL2i are valid options that should be individually evaluated considering potential toxicities, drug interactions, patient preference, and logistical aspects. In very frail patients, supportive treatment should be considered. In relapse/refractory patients, prior treatment, the biological risk of CLL, the duration of response (if prior finite treatment), or the reason for stopping BTKi (if prior continuous treatment) should be considered.

Real-world outcomes following ibrutinib dose reduction in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma

This study used real-world data from three separate United States (US) databases to evaluate dosing patterns and time to next treatment (TTNT) following the first-incident adverse event (AE) in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) treated with first-line ibrutinib with and without dose reduction (DR). Median TTNT or death in patients with and without a DR following an AE in each database was as follows: Optum Clinformatics Data Mart (CDM): 59.5 and 30.6 months; ConcertAI: 27.1 and 18.0 months; and Medicare Fee-for-Service (FFS): 49.8 and 22.0 months, respectively. Median TTNT or death in patients with cardiac AEs, with and without a DR, was: Optum CDM: 44.4 and 22.9 months; ConcertAI: 29.9 and 18.3 months; and Medicare FFS: 49.6 and 14.0 months, respectively. Ibrutinib DR was associated with fewer outpatient visits and lower CLL/SLL-related medical costs. These findings suggest that utilizing ibrutinib DR may effectively manage tolerability without compromising clinical efficacy.

Sustained benefit of zanubrutinib vs ibrutinib in patients with R/R CLL/SLL: final comparative analysis of ALPINE

ABSTRACT

The ALPINE trial established the superiority of zanubrutinib over ibrutinib in patients with relapsed/refractory chronic lymphocytic leukemia and small lymphocytic lymphoma; here, we present data from the final comparative analysis with extended follow-up. Overall, 652 patients received zanubrutinib (n = 327) or ibrutinib (n = 325). At an overall median follow-up of 42.5 months, progression-free survival benefit with zanubrutinib vs ibrutinib was sustained (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.54-0.84), including in patients with del(17p)/TP53 mutation (HR, 0.51; 95% CI, 0.33-0.78) and across multiple sensitivity analyses. Overall response rate remained higher with zanubrutinib compared with ibrutinib (85.6% vs 75.4%); responses deepened over time with complete response/complete response with incomplete bone marrow recovery rates of 11.6% (zanubrutinib) and 7.7% (ibrutinib). Although median overall survival has not been reached in either treatment group, fewer zanubrutinib patients have died than ibrutinib patients (HR, 0.77 [95% CI, 0.55-1.06]). With median exposure time of 41.2 and 37.8 months in zanubrutinib and ibrutinib arms, respectively, the most common nonhematologic adverse events included COVID-19-related infection (46.0% vs 33.3%), diarrhea (18.8% vs 25.6%), upper respiratory tract infection (29.3% vs 19.8%), and hypertension (27.2% vs 25.3%). Cardiac events were lower with zanubrutinib (25.9% vs 35.5%) despite similar rates of hypertension. Incidence of atrial fibrillation/flutter was lower with zanubrutinib vs ibrutinib (7.1% vs 17.0%); no cardiac deaths were reported with zanubrutinib vs 6 cardiac deaths with ibrutinib. This analysis, at 42.5 months median follow-up, demonstrates that zanubrutinib remains more efficacious than ibrutinib with an improved overall safety/tolerability profile. This trial was registered at www.ClinicalTrials.gov as #NCT03734016.

Real-World Treatment Patterns After Discontinuation of Venetoclax or BTKis in the Frontline Setting Among Older Adults With Chronic Lymphocytic Leukemia

PURPOSE

Venetoclax and Bruton's tyrosine kinase inhibitors (BTKis) are key treatment options for patients with chronic lymphocytic leukemia (CLL) in the frontline setting. This study characterized postdiscontinuation treatment patterns and hospitalization of frontline venetoclax and BTKis in a national sample of older adults with CLL.

METHODS

We identified 1,770 Medicare beneficiaries 66 years and older with CLL initiating venetoclax with obinutuzumab (VEN-O, n = 193) or BTKi treatment (n = 1,577) in the frontline setting between June 01, 2019, and June 30, 2020. Discontinuation was defined as a consecutive 90-day gap in treatment at any point over an 18-month follow-up. BTKi patients were expected to receive treatment continuously; VEN-O patients were expected to complete 11 months of treatment (12 cycles × 28 days = 336 days). The rates of subsequent CLL treatment and all-cause/CLL-related hospitalization were assessed.

RESULTS

Over an 18-month follow-up, 102 (52.8%) VEN-O patients discontinued after completing the fixed-duration period; 597 (37.9%) BTKi and 57 (29.5%) VEN-O patients discontinued treatment prematurely. The median time to discontinuation was 11.9 months (VEN-O) and 4.0 months (BTKi patients), respectively. Few patients (n < 11) who discontinued VEN-O initiated another CLL treatment over a median postdiscontinuation follow-up period of 6.1 months. By contrast, 39.0% of discontinuers in the BTKi group had evidence of subsequent CLL treatment over a median 13.8-month postdiscontinuation follow-up period. Post-BTKi regimens included BCL-2 (35.6%), subsequent BTKi (31.8%), chemotherapy (14.6%), anti-CD20 monotherapy (9.9%), and other (8.2%). The rate of postdiscontinuation all-cause and CLL-related hospitalization per 100 patient-months was 2.0 and 1.5 for the VEN-O group and 3.3 and 2.9 for the BTKi group, respectively.

CONCLUSION

In this real-world study, early discontinuation was more common in patients initiating a BTKi in contrast to VEN-O. Patients who initiated a BTKi also had high rates of subsequent treatment and hospitalization.

BCL2i-Based Therapies and Emerging Resistance in Chronic Lymphocytic Leukemia

Overexpression of the anti-apoptotic protein BCL-2 is a key factor in the pathogenesis of chronic lymphocytic leukemia (CLL) and is associated with poor clinical outcomes. Therapeutic activation of apoptosis in cancer cells using the BCL-2 inhibitor (BCL2i) venetoclax has shown remarkable efficacy in clinical trials, both as monotherapy and combination regimens. However, patients with CLL experience a highly variable clinical course, facing significant challenges in advanced stages due to disease relapse and the emergence of resistant clones. Resistance mechanisms include acquired BCL-2 mutations, alteration of pro-apoptotic and anti-apoptotic proteins, metabolic reprogramming, epigenetic changes, and aberrant signaling pathways. To address this complex disease and improve progression-free survival, strategies targeting multiple signaling pathways and mechanisms have been explored. Randomized clinical trials of venetoclax in combination with Bruton tyrosine kinase (BTK) inhibitors or CD20 monoclonal antibodies have significantly outperformed traditional chemoimmunotherapy in both treatment-naïve and relapsed patients, achieving undetectable minimal residual disease (uMRD) and durable remissions. This review explores the intricate balance between BCL-2 family proteins and their role in the intrinsic apoptosis pathway, discusses venetoclax resistance mechanisms, and highlights the evolving role of venetoclax and other BCL2i-based combination therapies in CLL treatment.

Advancements in B-Cell Non-Hodgkin's Lymphoma: From Signaling Pathways to Targeted Therapies

Lymphoma is the sixth most prevalent cancer globally. Non-Hodgkin's lymphomas are the majority group of lymphomas, with B cells accounting for approximately 95% of these lymphomas. A key feature of B-cell lymphoma is the functional perturbations of essential biological pathways caused by genetic aberrations. These lead to atypical gene expression, providing cells with a selective growth advantage. Molecular analysis reveals that each lymphoma subtype has unique molecular mutations, which pose challenges in disease management and treatment. Substantial efforts over the last decade have led to the integration of this information into clinical applications, resulting in crucial insights into clinical diagnosis and targeted therapies. However, with the growing need for more effective medication development, we anticipate a deeper understanding of signaling pathways and their interactions to emerge. This review aims to demonstrate how the BCR, specific signaling pathways like PI3K/AKT/mTOR, NF-kB, and JAK/STAT are diverse in common types of B-cell lymphoma. Furthermore, it offers a detailed examination of each pathway and a synopsis of the approved or in-development targeted therapies. In conclusion, finding the activated signaling pathways is crucial for developing effective treatment plans to improve the prognosis of patients with relapsed or refractory lymphoma. Trial Registration: ClinicalTrials.gov identifier: NCT02180724, NCT02029443, NCT02477696, NCT03836261, NCT02343120, NCT04440059, NCT01882803, NCT01258998, NCT01742988, NCT02055820, NCT02285062, NCT01855750, NCT03422679, NCT01897571.

FoxO1/Rictor axis induces a non-genetic adaptation to Ibrutinib via Akt activation in chronic lymphocytic leukemia

BTK inhibitor therapy induces peripheral blood lymphocytosis in chronic lymphocytic leukemia (CLL) lasting for several months. It remains unclear whether non-genetic adaptation mechanisms exist, allowing CLL cells' survival during BTK inhibitor-induced lymphocytosis and/or playing a role in therapy resistance. We show that in approximately 70 % of CLL cases, ibrutinib treatment in vivo increases Akt activity above pre-therapy levels within several weeks, leading to compensatory CLL cell survival and a more prominent lymphocytosis on therapy. Ibrutinib-induced Akt phosphorylation (pAktS473) is caused by the upregulation of FoxO1 transcription factor, which induces expression of Rictor, an assembly protein for mTORC2 protein complex that directly phosphorylates Akt at serine 473 (S473). Knock-out or inhibition of FoxO1 or Rictor led to a dramatic decrease in Akt phosphorylation and growth disadvantage for malignant B cells in the presence of ibrutinib (or PI3K inhibitor idelalisib) in vitro and in vivo. FoxO1/Rictor/pAktS473 axis represents an early non-genetic adaptation to BCR inhibitor therapy not requiring PI3Kδ or BTK kinase activity. We further demonstrate that FoxO1 can be targeted therapeutically, and its inhibition induces CLL cells' apoptosis alone or in combination with BTK inhibitors (ibrutinib, acalabrutinib, pirtobrutinib) and blocks their proliferation triggered by T-cell factors (CD40L, IL-4, and IL-21).

Outcomes and prognostic factors in 3306 patients with relapsed/refractory chronic lymphocytic leukemia treated with ibrutinib outside of clinical trials: A nationwide study

We performed a cohort study that included all patients with relapsed/refractory chronic lymphocytic leukemia (R/R CLL) who received ibrutinib in the Italian National Health Service. With a median follow-up of 42.2 months (IQR 30.8-54.6 months), the study involved 3306 patients with a median age of 72.1 years, of whom 42.6% had received ≥2 previous lines of treatment. The estimated 24-month probabilities of being on treatment and alive were 57.9% (95% confidence interval [CI]: 59.6-56.2) and 76.6% (95% CI: 75.2-78.1), respectively. The median time to treatment discontinuation (TTD) was 31.3 months (95% CI: 29.5-33.5). Out of 3306 patients, 2015 (60.9%) discontinued treatment, with 993 cases attributed to death or disease progression (30.0% of all cases). Among the 1022 patients who discontinued treatment for reasons other than progression or death, 564 (17.1%) patients did so due to toxicity or medical decision, while 458 patients (13.8%) were lost to follow-up. Multivariable analysis revealed that age, Eastern Cooperative Oncology Group Performance Status, the number of previous lines of therapy, refractoriness to the last treatment, and reduced renal function were associated with shorter TTD and overall survival (OS). The coexistence of 17p- and TP53 mutations had an independent unfavorable impact on TTD and OS. Nonstandard doses were associated with shorter TTD and advanced stage with shorter OS. The median OS postprogression and postdiscontinuation for other reasons were estimated at 12.9 (95% CI: 11.3-16.2) and 22.7 months (95% CI: 20.2-28.3), respectively. This large real-world study shows that ibrutinib is an effective treatment for R/R CLL. Baseline patient characteristics and double-hit TP53 aberrations were associated with inferior prognosis, and discontinuation due to CLL progression portended a poor outcome.

Atrial fibrillation burden and clinical outcomes following BTK inhibitor initiation

Bruton's tyrosine kinase inhibitors (BTKi) have dramatic efficacy against B-cell malignancies, but link with cardiotoxicity, including atrial fibrillation (AF). Burden, severity, and implications of BTKi-related AF are unknown. Leveraging a large-cohort of consecutive B-cell malignancy patients initiated on BTKi from 2009-2020, we identified patients with extended ambulatory rhythm monitoring. The primary outcome was AF burden after BTKi-initiation. Secondary outcomes included ventricular arrhythmia burden and other arrhythmias. Observed incident-AF rates and burden with next-generation BTKi's were compared to ibrutinib. Multivariable regression defined association between rhythm measures and major adverse cardiac events (MACE), and mortality. There were 98 BTKi-treated patients [38.8% next-generation BTKi's, 14.3% prior-AF], with 28,224 h of monitoring. Median duration BTKi-use was 34 months. Over mean duration 12 days monitoring, 72.4% developed arrhythmias (16.3% incident-AF, 31.6% other SVTs, 14.3% ventricular tachycardia). 14.3% had high AF-burden. AF-burden was similar between ibrutinib and next-generation BTKi's. No single antiarrhythmic-therapy prevented BTKi-related AF. However, antiarrhythmic initiation associated with reduction in arrhythmic burden (P = 0.009). In a multivariable model accounting for traditional cardiovascular risk factors, prior-AF associated with increased post-BTKi AF-burden. In follow-up, high AF burden associated with MACE (HR 3.12, P = 0.005) and mortality (HR 2.97, P = 0.007). Among BTKi-treated patients, high AF burden prognosticates future MACE and mortality risk.

Current Approaches and Novel Agents in the Treatment of Chronic Lymphocytic Leukemia

The treatment of CLL has evolved from traditional chemoimmunotherapy (CIT) to an increasing number of targeted and biologic approaches. Randomized trials have demonstrated superiority of covalent bruton tyrosine kinase inhibitors (cBTKis) over CIT, and second-generation compounds such as acalabrutinib and zanubrutinib appear to have a more favorable efficacy/safety profile than ibrutinib. The noncovalent BTKi, pirtobrutinib, has shown impressive activity after failure of the cBTKis and is quite tolerable. The Bcl-2 inhibitor venetoclax plus a CD20, generally obinutuzumab, provides a high level of efficacy as initial treatment or after failure on a cBTKi, with many patients achieving a state of undetectable minimal residual disease. Promising novel approaches include BTK degraders, bispecific antibodies, and chimeric antigen receptor T-cell (CAR-T)-cell therapy. What is clear is that CIT is archaic, and current and future targeted approaches will continue to improve the outcome for patients with chronic lymphocytic leukemia.

BTK inhibitors: moving the needle on the treatment of chronic lymphocytic leukemia

INTRODUCTION

Bruton's tyrosine kinaseinhibitors (BTKis) changed the trajectory of upfront and relapsed/refractory chronic lymphocytic leukemia (CLL) treatment. However, BTKis are plagued by a spectrum of toxicities. Zanubrutinib was developed to circumvent challenges with prolonged tolerability by increasing BTK selectivity and maximizing efficacy through pharmacokinetic/pharmacodynamic optimization. However, with the availability of ibrutinib, acalabrutinib, and zanubrutinib, limited data exists to guide sequencing of BTKi therapy in the relapsed/refractory setting.

AREAS COVERED

We review the first head-to-head trial (ALPINE) of zanubrutinib versus ibrutinib for the treatment of relapsed/refractory CLL and compare zanubrutinib's clinical efficacy and toxicities, including in patients with del(17p) and/or TP53 mutations to ibrutinib and acalabrutinib.

EXPERT OPINION

Zanubrutinibrepresents one of the new standards of care for relapsed/refractory CLL based on superior progression-free survival and response rates over ibrutinib. Whilezanubrutinib is associated with fewer cardiac toxicities, similar rates of neutropenia and hypertension are noted. Ongoing studies are pushing the envelope, utilizing targeted drug combinations and minimal residual disease markers as well as receptor tyrosine kinase-like orphan receptor 1 inhibitors, chimeric antigen receptor T-cells, and novel BTK degraders. However, zanubrutinibrepresents a strong contender in the arsenal of treatment options for relapsed/refractory CLL.

Fixed-duration pirtobrutinib plus venetoclax with or without rituximab in relapsed/refractory CLL: the phase 1b BRUIN trial

ABSTRACT

Pirtobrutinib is a highly selective, noncovalent (reversible) Bruton tyrosine kinase inhibitor (BTKi). Patients with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) were treated with fixed-duration pirtobrutinib plus venetoclax (PV) or pirtobrutinib plus venetoclax and rituximab (PVR) in this phase 1b trial. Prior covalent BTKi therapy was allowed, but not prior treatment with venetoclax. Patients were assigned to receive PV (n = 15) or PVR (n = 10) for 25 cycles. Most patients (68%) had received prior covalent BTKi therapy. At the data cutoff date, the median time on study was 27.0 months for PV and 23.3 months for PVR. Overall response rates were 93.3% (95% confidence interval [CI], 68.1-99.8) for PV and 100% (95% CI, 69.2-100.0) for PVR, with 10 complete responses (PV: 7; PVR: 3). After 12 cycles of treatment, 85.7% (95% CI, 57.2-98.2) of PV and 90.0% (95% CI, 55.5-99.7) of PVR patients achieved undetectable minimal residual disease (<10-4) in peripheral blood. Progression-free survival at 18 months was 92.9% (95% CI, 59.1-99.0) for PV patients and 80.0% (95% CI, 40.9-94.6) for PVR patients. No dose-limiting toxicities were observed during the 5-week assessment period. The most common grade ≥3 adverse events (AEs) for all patients included neutropenia (52%) and anemia (16%). AEs led to dose reduction in 3 patients and discontinuation in 2. In conclusion, fixed-duration PV or PVR was well tolerated and had promising efficacy in patients with R/R CLL, including patients previously treated with a covalent BTKi. This trial was registered at www.clinicaltrials.gov as #NCT03740529.

Cardiovascular events of Bruton's tyrosine kinase inhibitors: A real-world study based on the United States Food and Drug Administration Adverse Event Reporting System database

AIMS

Bruton's tyrosine kinase inhibitors (BTKIs), including first-generation ibrutinib, second-generation acalabrutinib and zanubrutinib, may be involved in the mechanisms of action related to adverse events (AEs) of the cardiovascular system. We aimed to characterize the cardiovascular AEs of BTKIs reported in the US Food and Drug Administration (FDA) Adverse Event Reporting System, and to compare the cardiovascular risks of BTKIs.

METHODS

Across all indications of three FDA-approved BTKIs, primary suspect drugs were extracted over two periods: from January 2013 to December 2022 (after the approval of the first BTKI), and from January 2020 to December 2022 (all three BTKIs on the market). Disproportionality was measured by reporting odds ratios (RORs) and information components. Additional analyses were performed without incorporating patients with underlying cardiovascular disease (CVD).

RESULTS

A total of 10 353 cases included the uses of ibrutinib, acalabrutinib and zanubrutinib. Ibrutinib was significantly associated with 47 cardiovascular AEs. Acalabrutinib was associated with new signals, including cardiac failure (ROR = 1.82 [1.13-2.93]), pulmonary oedema (ROR = 2.15 [1.19-3.88]), ventricular extrasystoles (ROR = 5.18 [2.15-12.44]), heart rate irregular (ROR = 3.05 [1.53-6.11]), angina pectoris (ROR = 3.18 [1.71-5.91]) and cardiotoxicity (ROR = 25.22 [17.14-37.10]). In addition, cardiovascular events had an earlier onset in acalabrutinib users. Zanubrutinib was only associated with atrial fibrillation. Acalabrutinib and zanubrutinib had lower ROR values than ibrutinib. The AE signals were generally consistent between the population receiving and not receiving CVD medications.

CONCLUSIONS

Potential cardiovascular risks identified in this study were not clearly noted on the label of marketed acalabrutinib. Caution should be paid to the cardiovascular risks of BTKIs having been or being developed.

Real-World Treatment Patterns and Outcomes by Line of Therapy and Race in Patients With Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Treated in the United States: Results From the Final Analysis of the Prospective, Observational, informCLL Registry

BACKGROUND

informCLL is the largest US-based prospective, observational registry of patients with chronic lymphocytic leukemia (CLL) initiating FDA-approved treatment in the era of targeted therapy.

PATIENTS AND METHODS

Patients were enrolled between October 2015 and June 2019. Data were collected for baseline characteristics, treatment patterns, outcomes, and safety.

RESULTS

In total, 1459 eligible patients were enrolled (first line, n = 854; relapsed/refractory, n = 605). The most common index treatments were ibrutinib (first line, 45%; relapsed/refractory, 49%) and chemoimmunotherapy (first line, 43%; relapsed/refractory, 20%). With median follow-up of 31.8 and 30.9 months in first-line and relapsed/refractory cohorts, respectively, median time to next treatment (TTNT) in patients who received any index treatment was not reached (NR) and 48.6 months; estimated proportions without next-line therapy at 48 months were 64% and 50%. Median overall survival (OS) was NR for both cohorts; estimated 48-month OS rates were 81% and 64% in first-line and relapsed/refractory cohorts, respectively. In match-adjusted analyses, TTNT was improved with first-line ibrutinib versus chemoimmunotherapy (median NR vs. 56.5 months; hazard ratio, 0.74; 95% CI, 0.56-0.98). Exposure-adjusted rates of AEs leading to discontinuation and serious AEs were lower with ibrutinib versus chemoimmunotherapy. Estimated 36-month OS rates were similar in Black versus White patients who received any index treatment (first line, 87% vs. 83%; relapsed/refractory, 74% vs. 74%) or ibrutinib (first line, 97% vs. 85%; relapsed/refractory, 81% vs. 77%).

CONCLUSION

In this prospective, large, real-world CLL registry, first-line ibrutinib was associated with longer TTNT than chemoimmunotherapy, with sustained benefit up to 4 years of follow-up.

Pharmacological management of chronic lymphocytic leukemia: current and emerging therapies

INTRODUCTION

Chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL), characterized by its monoclonal lymphoproliferative nature, is an indolent but incurable malignancy. The treatment landscape of CLL/SLL has drastically transformed in the last decade since the introduction of targeted therapy and immune-effector T-cell therapy. The paradigm shift from chemoimmunotherapy to targeted and cellular therapies was largely driven by improved efficacy and safety. With the success of targeted therapies, novel agents and combinations are rapidly emerging on the horizon.

AREAS COVERED

In this review, we will summarize clinical evidence supporting current and emerging therapies with emphasis on investigational therapies and novel combinations of commercial agents. Clinical trials were identified via clinicaltrials.gov, and a PubMed literature search was last performed in June 2024.

EXPERT OPINION

With the availability of more effective and better-tolerated treatments for CLL/SLL, the role of early intervention should be further investigated due to its potential to alter disease course, delay progression, and improve overall survival rates. With many highly effective agents and combinations expected to become commercially available, attention to safety profiles and careful selection of patients for each treatment will be critical, with consideration of comorbidities, logistical issues, and financial burden of treatment.

Ibrutinib and venetoclax in combination for chronic lymphocytic leukemia: synergy in practice

The combination of ibrutinib and venetoclax has emerged as a promising therapeutic strategy for patients with chronic lymphocytic leukemia (CLL). Preclinical investigations demonstrated a synergistic antitumor effect through multiple mechanisms, providing a robust foundation for translating this regimen into clinical trials. Beyond the dual inhibition by 2 small molecules, another innovative concept being tested with this combination is the use of measurable residual disease (MRD)-driven treatment vs fixed-duration treatment to meet the escalating demand for oral, convenient, cost-effective, and time-limited therapeutic approaches. The clinical translation of this combination has yielded remarkable outcomes with significant improvements in the progression-free survival and overall survival rates for both treatment-naïve patients and those with relapsed/refractory CLL. Notably, a substantial proportion of patients achieved undetectable MRD. Clinical trial updates following the initial published results have shown consistency and durability of responses over time. In this review, the initial investigator-initiated trial results for ibrutinib and venetoclax are discussed, several multicenter clinical trial designs and outcomes are examined, variables such as chromosome 17p deletion that influence treatment responses are addressed, and the safety of the regimen is discussed. In addition, we reviewed the usage of this combination in other B-cell malignancies and discussed how current knowledge can be used for shaping the future CLL treatment regimens.

Personalized dose selection for the first Waldenström macroglobulinemia patient on the PRECISE CURATE.AI trial

The digital revolution in healthcare, amplified by the COVID-19 pandemic and artificial intelligence (AI) advances, has led to a surge in the development of digital technologies. However, integrating digital health solutions, especially AI-based ones, in rare diseases like Waldenström macroglobulinemia (WM) remains challenging due to limited data, among other factors. CURATE.AI, a clinical decision support system, offers an alternative to big data approaches by calibrating individual treatment profiles based on that individual's data alone. We present a case study from the PRECISE CURATE.AI trial with a WM patient, where, over two years, CURATE.AI provided dynamic Ibrutinib dose recommendations to clinicians (users) aimed at achieving optimal IgM levels. An 80-year-old male with newly diagnosed WM requiring treatment due to anemia was recruited to the trial for CURATE.AI-based dosing of the Bruton tyrosine kinase inhibitor Ibrutinib. The primary and secondary outcome measures were focused on scientific and logistical feasibility. Preliminary results underscore the platform's potential in enhancing user and patient engagement, in addition to clinical efficacy. Based on a two-year-long patient enrollment into the CURATE.AI-augmented treatment, this study showcases how AI-enabled tools can support the management of rare diseases, emphasizing the integration of AI to enhance personalized therapy.

Targeting Bruton's tyrosine kinase (BTK) as a signaling pathway in immune-mediated diseases: from molecular mechanisms to leading treatments

Bruton's tyrosine kinase (BTK), a nonreceptor tyrosine kinase, plays a remarkable role in the transmission and amplification of extracellular signals to intracellular signaling pathways. Various types of cells use the BTK pathway to communicate, including hematopoietic cells particularly B cells and T cells. The BTK pathway plays a role in controlling the proliferation, survival, and functions of B cells as well as other myeloid cells. First, second, and third-generation BTK inhibitors are currently being evaluated for the treatment of immune-mediated diseases in addition to B cell malignancies. In this article, the available evidence on the action mechanisms of BTK inhibitors is reviewed. Then, the most recent data obtained from preclinical studies and ongoing clinical trials for the treatment of autoimmune diseases, such as pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, systemic lupus erythematosus, Sjögren's disease, rheumatoid arthritis, systemic sclerosis, multiple sclerosis, myasthenia gravis, and inflammatory diseases such as psoriasis, chronic spontaneous urticaria, atopic dermatitis, and asthma are discussed. In addition, adverse effects and complications associated with BTK inhibitors as well as factors predisposing patients to BTK inhibitors complications are discussed.

Evaluation of infectious morbidity due to BTK inhibitors in indolent B-cell lymphomas: latest research findings and systematic analysis

INTRODUCTION

Randomized clinical trials (RCTs) have suggested that BTK inhibitors (BTKis) might increase infectious disease (ID) risk. Systematic analysis of this topic as derived from RCTs and clinical practice is needed.

AREAS COVERED

An extensive Medline, Embase, and Cochrane search of peer-reviewed sources reporting on ID morbidity in patients on BTKis was performed (1 January 2014 - 31 December 2023). Contribution of intrinsic immune defects in indolent B-cell lymphomas to this morbidity was carefully considered.

EXPERT OPINION

Patients with indolent B-cell lymphomas display a wide range of innate and adaptive immune defects. In addition, BTKi use is linked with an increased signal of upper respiratory tract infections (URTIs) and pneumonias, mainly grade 1-2. These agents also increase the risk of rare invasive fungal infections (IFIs), mainly due to Cryptococcus and Aspergillus spp. with a peak within several months after the start of therapy. More than half of these IFIs are fatal. Research suggests a similar ID risk across 1st, 2nd and 3rd generations of BTKis, all causing B-cell dysfunction due to BTK inhibition, along with off-target functional neutrophil/macrophage alterations. Expanding the knowledge base on ID morbidity in patients on BTKis would facilitate timely diagnosis and treatment, and improve clinical outcomes.

Early reappearance of intraclonal proliferative subpopulations in ibrutinib-resistant chronic lymphocytic leukemia

The Bruton's tyrosine kinase (BTK) inhibitor ibrutinib represents an effective strategy for treatment of chronic lymphocytic leukemia (CLL), nevertheless about 30% of patients eventually undergo disease progression. Here we investigated by flow cytometry the long-term modulation of the CLL CXCR4dim/CD5bright proliferative fraction (PF), its correlation with therapeutic outcome and emergence of ibrutinib resistance. By longitudinal tracking, the PF, initially suppressed by ibrutinib, reappeared upon early disease progression, without association with lymphocyte count or serum beta-2-microglobulin. Somatic mutations of BTK/PLCG2, detected in 57% of progressing cases, were significantly enriched in PF with a 3-fold greater allele frequency than the non-PF fraction, suggesting a BTK/PLCG2-mutated reservoir resident within the proliferative compartments. PF increase was also present in BTK/PLCG2-unmutated cases at progression, indicating that PF evaluation could represent a marker of CLL progression under ibrutinib. Furthermore, we evidence different transcriptomic profiles of PF at progression in cases with or without BTK/PLCG2 mutations, suggestive of a reactivation of B-cell receptor signaling or the emergence of bypass signaling through MYC and/or Toll-Like-Receptor-9. Clinically, longitudinal monitoring of the CXCR4dim/CD5bright PF by flow cytometry may provide a simple tool helping to intercept CLL progression under ibrutinib therapy.

Efficacy and safety of first- versus second-generation Bruton tyrosine kinase inhibitors in chronic lymphocytic leukemia: a systematic review and meta-analysis

We conducted this first systematic review and meta-analysis to assess the competitive advantage of 2nd-generation Bruton tyrosine kinase inhibitors (BTKi) compared to 1st-generation BTKi in chronic lymphocytic leukemia (CLL). The literature search was conducted from PubMed, Web of Science, Embase databases, and hematology annual conferences. Data of over response rate (ORR), progression-free survival (PFS), and overall survival (OS) were extracted to a pool meta-analysis of efficacy; adverse events (AEs) were also extracted to a pool meta-analysis of safety. Bias risk assessment and meta-analysis were performed by Review Manager 5.3 and STATA 14 software. A total of 3649 patients from 29 cohorts were included. The results showed that the benefits of ORR and 24-month PFS in 2nd-generation BTKi compared to 1st-generation BTKi were not significant in the whole population but only in the relapsed or refractory (R/R) CLL patient subgroup (ORR: 86.4% vs. 76.2%, p = 0.013; 24-month PFS: 76.9% vs. 67.9%, p = 0.004). Any-grade AEs were comparable between 1st- and 2nd-generation BTKi, but grade 3 or higher AEs were significantly less frequent with 2nd-generation BTKi versus 1st-generation BTKi (grade 3 or higher: 53.1% vs. 72.5%; p = 0.002). Headache was more frequent with 2nd-generation BTKi, while diarrhea and atrial fibrillation were more frequent with 1st-generation BTKi. Only for patients with relapsed or refractory CLL did 2nd-generation BTKi have a competitive advantage, while adverse effects still need to be considered. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO, Identifier 42022342488.

Bruton's tyrosine kinase inhibition for the treatment of allergic disorders

IgE signaling through its high-affinity receptor FcεRI is central to the pathogenesis of numerous allergic disorders. Oral inhibitors of Bruton's tyrosine kinase (BTKis), which are currently Food and Drug Administration-approved for treating B cell malignancies, broadly inhibit the FcεRI pathway in human mast cells and basophils, and therefore may be effective allergen-independent therapies for a variety of allergic diseases. The application of these drugs to the allergy space was previously limited by the low kinase selectivity and subsequent toxicities of early-generation compounds. Fortunately, next-generation, highly selective BTKis in clinical development appear to have more favorable risk-benefit profiles, and their likelihood of being Food and Drug Administration-approved for an allergy indication is increasing. Recent clinical trials have indicated the remarkable and rapid efficacy of the second-generation BTKi acalabrutinib in preventing clinical reactivity to peanut ingestion in adults with peanut allergy. In addition, next-generation BTKis including remibrutinib effectively reduce disease activity in patients with antihistamine-refractory chronic spontaneous urticaria. Finally, several BTKis are currently under investigation in early clinical trials for atopic dermatitis and asthma. In this review, we summarize recent data supporting the use of these drugs as novel therapies in food allergy, anaphylaxis, urticaria, and other allergic disorders. We also discuss safety data derived from trials using both short-term and chronic dosing of BTKis.

Dose Optimization of Targeted Therapies for Oncologic Indications

Therapeutic advances in oncology in the 21st century have contributed to significant declines in cancer mortality. Notably, targeted therapies comprised the largest proportion of oncology drugs approved by the United States (US) Food and Drug Administration (FDA) over the past 25 years and have become the standard of care for the treatment of many cancers. However, despite the metamorphosis of the therapeutic landscape, some aspects of cancer drug development have remained essentially unchanged. In particular, the dose-finding methodology originally developed for cytotoxic chemotherapy drugs continues to be implemented, even though this approach no longer represents the most appropriate strategy for modern cancer therapies. In recognition of the need to reconsider assumptions, adapt the dose selection process for newer drugs, and design alternative strategies, the FDA has undertaken several initiatives in recent years to address these concerns. These actions include the launch of Project Optimus in 2021 and the issuance of draft guidance for industry on dose optimization of oncology drugs in 2023. Amid this evolving regulatory environment, the present manuscript reviews case studies for six different targeted cancer therapies, highlighting how dose-finding challenges have been managed to date by oncologists, sponsors, and regulators.

Arrhythmogenic Ventricular Remodeling by Next-Generation Bruton's Tyrosine Kinase Inhibitor Acalabrutinib

Cardiac arrhythmias remain a significant concern with Ibrutinib (IBR), a first-generation Bruton's tyrosine kinase inhibitor (BTKi). Acalabrutinib (ABR), a next-generation BTKi, is associated with reduced atrial arrhythmia events. However, the role of ABR in ventricular arrhythmia (VA) has not been adequately evaluated. Our study aimed to investigate VA vulnerability and ventricular electrophysiology following chronic ABR therapy in male Sprague-Dawley rats utilizing epicardial optical mapping for ventricular voltage and Ca2+ dynamics and VA induction by electrical stimulation in ex-vivo perfused hearts. Ventricular tissues were snap-frozen for protein analysis for sarcoplasmic Ca2+ and metabolic regulatory proteins. The results show that both ABR and IBR treatments increased VA vulnerability, with ABR showing higher VA regularity index (RI). IBR, but not ABR, is associated with the abbreviation of action potential duration (APD) and APD alternans. Both IBR and ABR increased diastolic Ca2+ leak and Ca2+ alternans, reduced conduction velocity (CV), and increased CV dispersion. Decreased SERCA2a expression and AMPK phosphorylation were observed with both treatments. Our results suggest that ABR treatment also increases the risk of VA by inducing proarrhythmic changes in Ca2+ signaling and membrane electrophysiology, as seen with IBR. However, the different impacts of these two BTKi on ventricular electrophysiology may contribute to differences in VA vulnerability and distinct VA characteristics.

Safety of Extended Pirtobrutinib Exposure in Relapsed and/or Refractory B-Cell Malignancies

INTRODUCTION

Pirtobrutinib, a highly selective, noncovalent (reversible) Bruton tyrosine kinase inhibitor, has demonstrated promising efficacy in B-cell malignancies and is associated with low rates of discontinuation and dose reduction. Pirtobrutinib is administered until disease progression or toxicity, necessitating an understanding of the safety profile in patients with extended treatment.

METHODS

Here we report the safety of pirtobrutinib in patients with relapsed/refractory B-cell malignancies with extended (≥12 months) drug exposure from the BRUIN trial. Assessments included median time-to-first-occurrence of adverse events (AEs), dose reductions, and discontinuations due to treatment-emergent AEs (TEAEs) and select AEs of interest (AESIs).

RESULTS

Of 773 patients enrolled, 326 (42%) received treatment for ≥12 months. In the extended exposure cohort, the median time-on-treatment was 19 months. The most common all-cause TEAEs were fatigue (32%) and diarrhea (31%). TEAEs leading to dose reduction occurred in 23 (7%) and discontinuations in 11 (3%) extended exposure patients. One patient had a fatal treatment-related AE (COVID-19 pneumonia). Infections (73.0%) were the most common AESI with a median time-to-first-occurrence of 7.4 months. Majority of TEAEs and AESIs occurred during the first year of therapy.

CONCLUSIONS

Pirtobrutinib therapy continues to demonstrate an excellent safety profile amenable to long-term administration without evidence of new or worsening toxicity signals.

New Means and Challenges in the Targeting of BTK

Bruton's tyrosine kinase (BTK) is central to the survival of malignant and normal B lymphocytes and has been a crucial therapeutic target of several generations of kinase inhibitors and newly developed degraders. These new means for targeting BTK have added additional agents to the armamentarium for battling cancers dependent on B-cell receptor (BCR) signaling, including chronic lymphocytic leukemia and other non-Hodgkin lymphomas. However, the development of acquired resistance mutations to each of these classes of BTK inhibitors has led to new challenges in targeting BTK as well as novel insights into BCR signaling. The first-generation covalent BTK inhibitor ibrutinib is susceptible to mutations affecting the covalent binding site, cysteine 481 (C481). Newer noncovalent BTK inhibitors, such as pirtobrutinib, overcome C481 mutation-mediated resistance but are susceptible to other kinase domain mutations, particularly at residues Threonine 474 and Leucine 528. In addition, these novel BTK inhibitor resistance mutations have been shown biochemically and in patients to cause cross-resistance to some covalent BTK inhibitors. Importantly, newer generation covalent BTK inhibitors zanubrutinib and acalabrutinib are susceptible to the same mutations that confer resistance to noncovalent inhibitors. The BTK L528W mutation is of particular interest as it disrupts the kinase activity of BTK, rendering it kinase dead. This observation suggests that BTK may act independently of its kinase activity as a scaffold. Thus, the timely development of BTK degrading proteolysis targeting drugs has allowed for degradation, rather than just enzymatic inhibition, of BTK in B-cell lymphomas, and early clinical trials to evaluate BTK degraders are underway.

Bruton's tyrosine kinase inhibitor-related cardiotoxicity: The quest for predictive biomarkers and improved risk stratification

Ibrutinib was the first Bruton's tyrosine kinase (BTK) inhibitor approved for the treatment of patients with chronic lymphocytic leukemia (CLL). While producing durable responses and prolonging survival, roughly 20-25% of patients experience dose limiting side effects, mostly consisting of cardiovascular toxicities like severe hypertension and atrial fibrillation. While clinical predictors of BTK inhibitor-related cardiotoxicity have been proposed and may aid in risk stratification, there is no routine risk model used in clinical practice today to identify patients at highest risk. A recent study investigating genetic predictors of ibrutinib-related cardiotoxicity found that single nucleotide polymorphisms in KCNQ1 and GATA4 were significantly associated with cardiotoxic events. If replicated in larger studies, these biomarkers may improve risk stratification in combination with clinical factors. A clinicogenomic risk model may aid in identifying patients at highest risk of developing BTK inhibitor-related cardiotoxicity in which further risk mitigation strategies may be explored.

Outcomes with ibrutinib in patients with chronic lymphocytic leukaemia: Results from the German multicentre REALITY study

OBJECTIVES

To assess treatment adherence, effectiveness and safety outcomes of patients with chronic lymphocytic leukaemia (CLL) receiving ibrutinib in a real-world setting.

METHODS

Patients enrolled in REALITY were ≥18 years with a confirmed diagnosis of CLL and were receiving ibrutinib as a first-line (1L), 2L or ≥3L therapy. Treatment retention, adherence, progression-free survival (PFS), overall survival (OS) and time to next therapy were assessed at 1 and 2 years overall, by typology and by cytogenetic subgroups. PFS and OS were analysed using Kaplan-Meier methods.

RESULTS

Exactly 302 patients were enrolled across 57 sites in Germany, from January 2017 to July 2021. One-year retention rates were 69.9% overall (primary endpoint), 77.9% for 1L patients, and 77.6%/78.8% for high-risk patients with del17p/TP53. At 2 years, PFS/OS rates were 77.8%/90.7% overall (1L, 82.7%/90.4%), and were consistent across cytogenetic subgroups. PFS rates were higher for 1L versus ≥3L patients. Patients with the low-acceptance/low-control typology at baseline were less likely to retain treatment at 1 year versus the high-acceptance/high-control typology. No new safety signals were observed.

CONCLUSIONS

The REALITY study provides further evidence of the effectiveness and safety of ibrutinib in patients with CLL in a real-world setting, particularly in earlier treatment lines.

Evaluating zanubrutinib for the treatment of adults with chronic lymphocytic leukemia or small lymphocytic lymphoma

INTRODUCTION

This review evaluates zanubrutinib as a treatment option for adults with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Zanubrutinib, a covalent BTK (Bruton's tyrosine kinase) inhibitor, was recently approved by the US FDA based in part on head-to-head data demonstrating improved efficacy and safety compared to ibrutinib.

AREAS COVERED

The review discusses the efficacy, safety, and comparative advantages of zanubrutinib, highlighting its safety profile compared to other BTK inhibitors. It also addresses the unmet needs of current therapies in CLL/SLL and provides an overview of competitor compounds and ongoing research in BTK inhibition.

EXPERT OPINION

Zanubrutinib, the first BTK inhibitor to demonstrate superior efficacy and safety compared to another BTK inhibitor in CLL, is likely to be widely adopted due to its high-quality data and ease of use. Looking ahead, pirtobrutinib, a novel non-covalent BTK inhibitor, has shown promise in heavily pretreated CLL patients, including those unresponsive to covalent inhibitors, with ongoing phase 3 trials comparing it against ibrutinib. The field is also exploring time-limited therapies like the combination of ibrutinib and venetoclax, with ongoing trials evaluating different combinations to optimize efficacy and minimize toxicity, indicating a promising future for combination therapies in CLL treatment.

Treatment Sequencing in Chronic Lymphocytic Leukemia in 2024: Where We Are and Where We Are Headed

As treatments with BTK inhibitors and BCL2 inhibitors have replaced the use of chemoimmunotherapy in CLL in both first-line and relapsed patients, it becomes critical to rationalize their use and exploit the full potential of each drug. Despite their proven, robust, and manifest efficacy, BTKis and BCL2is fail to provide long-term disease control in some categories of patients, and to date this is an unmet clinical need that is critical to recognize and address. Ongoing clinical trials are evaluating new treatment algorithms and new molecules to progressively thin this population. In this review for each category of patients we explicate the different possible patterns of treatment sequencing based on currently available evidence, starting from the frontline to currently ongoing trials, in order to optimize therapies as much as possible.

BTK inhibitors in CLL: second-generation drugs and beyond

ABSTRACT

BTK inhibitors (BTKis) are established standards of care in multiple B-cell malignancies including chronic lymphocytic leukemia, mantle cell lymphoma, and Waldenstrom macroglobulinemia. The first-generation BTKi ibrutinib demonstrated superiority over standard chemoimmunotherapy regimens in multiple randomized trials but is limited by cardiovascular side effects such as atrial fibrillation and hypertension. Second-generation BTKis have improved selectivity and demonstrate reduced rates of cardiovascular complications in 3 head-to-head ibrutinib studies. The emergence of BTK C481S mutation has led to the development of noncovalent, "reversible" BTKis, such as pirtobrutinib, which are agnostic to the C481S mutation. However, these inhibitors are associated with resistant mutations outside the C481 hot spot. These variant non-C481 mutations are of great clinical interest because some are shared among pirtobrutinib, zanubrutinib, and acalabrutinib, with potential implications for cross resistance and treatment sequencing. Finally, BTK protein degraders with in vitro activity against C481 and non-C481 mutations are currently in clinical development. Here, we review the evolution of therapeutic BTK-targeting and discuss future directions for clinical research.

Matching-Adjusted Indirect Comparison of Brexucabtagene Autoleucel (ZUMA-2) and Pirtobrutinib (BRUIN) in Patients with Relapsed/Refractory Mantle Cell Lymphoma Previously Treated with a Covalent Bruton Tyrosine Kinase Inhibitor

INTRODUCTION

Patients with relapsed/refractory (R/R) mantle cell lymphoma (MCL) often require multiple lines of treatment and have a poor prognosis, particularly after failing covalent Bruton tyrosine kinase inhibitor (cBTKi) therapy. Newer treatments such as brexucabtagene autoleucel (brexu-cel, chimeric antigen receptor T cell therapy) and pirtobrutinib (non-covalent BTKi) show promise in improving outcomes.

METHODS

Without direct comparative evidence, an unanchored matching-adjusted indirect comparison was conducted to estimate the relative treatment effects of brexu-cel and pirtobrutinib for post-cBTKi R/R MCL. Using logistic propensity score models, individual patient-level data from ZUMA-2 brexu-cel-infused population (N = 68) were weighted to match pre-specified clinically relevant prognostic factors based on study-level data from the BRUIN cBTKi pre-treated cohort (N = 90). The base-case model incorporated the five most pertinent factors reported in ≥ 50% of both trial populations: morphology, MCL International Prognostic Index, number of prior lines of therapy, disease stage, and prior autologous stem cell transplant. A sensitivity analysis additionally incorporated TP53 mutation and Ki-67 proliferation. Relative treatment effects were expressed as odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

In the base-case model, brexu-cel was associated with higher rates of objective response (OR 10.39 [95% CI 2.81-38.46]) and complete response (OR 10.11 [95% CI 4.26-24.00]), and improved progression-free survival (HR 0.44 [95% CI 0.25-0.75]), compared to pirtobrutinib. Overall survival and duration of response favored brexu-cel over pirtobrutinib but the differences crossed the bounds for statistical significance. Findings were consistent across the adjusted and unadjusted analyses.

CONCLUSIONS

Findings suggest that brexu-cel may offer clinically and statistically significant benefits regarding objective response, complete response, and progression-free survival compared to pirtobrutinib among patients with R/R MCL after prior cBTKi therapy. Given the short follow-up and high degree of censoring in BRUIN, an analysis incorporating updated BRUIN data may provide more definitive overall survival results.

Reversible Covalent Inhibition─Desired Covalent Adduct Formation by Mass Action

Covalent inhibition has seen a resurgence in the last several years. Although long-plagued by concerns of off-target effects due to nonspecific reactions leading to covalent adducts, there has been success in developing covalent inhibitors, especially within the field of anticancer therapy. Covalent inhibitors can have an advantage over noncovalent inhibitors since the formation of a covalent adduct may serve as an additional mode of selectivity due to the intrinsic reactivity of the target protein that is absent in many other proteins. Unfortunately, many covalent inhibitors form irreversible adducts with off-target proteins, which can lead to considerable side-effects. By designing the inhibitor to form reversible covalent adducts, one can leverage competing on/off kinetics in complex formation by taking advantage of the law of mass action. Although covalent adducts do form with off-target proteins, the reversible nature of inhibition prevents accumulation of the off-target adduct, thus limiting side-effects. In this perspective, we outline important characteristics of reversible covalent inhibitors, including examples and a guide for inhibitor development.

Cost Effectiveness of Zanubrutinib Versus Ibrutinib in Relapsed or Refractory Chronic Lymphocytic Leukemia

BACKGROUND

While the efficacy and safety of zanubrutinib have been established in relapsed or refractory chronic lymphocytic leukemia, the evidence on cost effectiveness is still lacking.

OBJECTIVE

We aimed to evaluate the cost effectiveness of zanubrutinib versus ibrutinib in relapsed or refractory chronic lymphocytic leukemia from the commercial payer perspective in the USA.

METHODS

A partitioned survival model was developed based on survival curves from the phase III ALPINE trial. We reconstructed patient-level data for each curve and conducted a parametric estimation to incorporate long-term clinical outcomes and treatment costs into the model. Medical costs and utilities were obtained from public data and previous cost-effectiveness studies. A discount rate of 3.0% per annum was applied and costs were adjusted to 2023 US dollars. The incremental cost-effectiveness ratio was calculated by dividing the incremental costs of zanubrutinib over ibrutinib by the incremental life-years or quality-adjusted life-years. Deterministic and probabilistic sensitivity analyses were performed to examine the robustness of the results.

RESULTS

Over a 10-year analysis period, the incremental cost-effectiveness ratio of zanubrutinib versus ibrutinib was $91,260 per life-year gained and $120,634 per quality-adjusted life-year gained, making it cost effective within a threshold of $150,000 per quality-adjusted life-year gained. The incremental cost-effectiveness ratio was most sensitive to drug acquisition costs and progression-free survival distributions, and the probability of zanubrutinib being cost effective was approximately 52.8%, with a 30.0% likelihood of dominance.

CONCLUSIONS

Zanubrutinib is likely to be cost effective versus ibrutinib in relapsed or refractory chronic lymphocytic leukemia in the USA, but the high threshold should be noted. Our findings may provide a basis for pricing strategy and reimbursement decisions for zanubrutinib.

Ultra-deep mutational landscape in chronic lymphocytic leukemia uncovers dynamics of resistance to targeted therapies

BTK inhibitors, Bcl-2 inhibitors, and other targeted therapies have significantly improved the outcomes of patients with chronic lymphocytic leukemia (CLL). With increased survivorship, monitoring disease and deciphering potential mechanisms of resistance to these agents are critical for devising effective treatment strategies. We used duplex sequencing, a technology that enables detection of mutations at ultra-low allelic frequencies, to identify mutations in five genes associated with drug resistance in CLL and followed their evolution in two patients who received multiple targeted therapies and ultimately developed disease progression on pirtobrutinib. In both patients we detected variants that expanded and reached significant cancer cell fractions (CCF). In patient R001, multiple known resistance mutations in both BTK and PLCG2 appeared following progression on zanubrutinib (BTK p.L528W, p.C481S; PLCG2 S707F, L845F, R665W, and D993H). In contrast, patient R002 developed multiple BTK mutations following acalabrutinib treatment, including known resistance mutations p.C481R, p.T474I and p.C481S. We found that pirtobrutinib was able to suppress, but not completely eradicate, BTK p.C481S mutations in both patients, but other resistance mutations such as mutations in PLCG2 and new BTK mutations increased while the patients were receiving pirtobrutinib. For example, BTK p.L528W in patient R001 increased in frequency more than 1,000-fold (from a CCF of 0.02% to 35%), and the CCF in p.T474I in patient R002 increased from 0.03% to 4.2% (more than 100-fold). Our data illuminate the evolutionary dynamics of resistant clones over the patients' disease course and under selective pressure from different targeted treatments.

Posaconazole-ibrutinib interaction cannot be avoided by staggered dosing: How to optimize ibrutinib dose during posaconazole treatment

AIMS

Ibrutinib is used in the treatment of certain B-cell malignancies. Due to its CYP3A4-mediated metabolism and highly variable pharmacokinetics, it is prone to potentially harmful drug-drug interactions.

METHODS

In a randomized, placebo-controlled, three-phase crossover study, we examined the effect of the CYP3A4-inhibiting antifungal posaconazole on ibrutinib pharmacokinetics. Eleven healthy participants ingested repeated doses of 300 mg of posaconazole either in the morning or in the evening, or placebo. A single dose of ibrutinib (30, 70 or 140 mg, respectively) was administered at 9 AM, 1 or 12 h after the preceding posaconazole/placebo dose.

RESULTS

On average, morning posaconazole increased the dose-adjusted geometric mean area under the plasma concentration-time curve from zero to infinity (AUC0-∞ ) and peak plasma concentration (Cmax ) of ibrutinib 9.5-fold (90% confidence interval [CI] 6.3-14.3, P < 0.001) and 8.5-fold (90% CI 5.7-12.8, P < 0.001), respectively, while evening posaconazole increased those 10.3-fold (90% CI 6.7-16.0, P < 0.001) and 8.2-fold (90% CI 5.2-13.2, P < 0.001), respectively. Posaconazole had no significant effect on the half-life of ibrutinib, but substantially reduced the metabolite PCI-45227 to ibrutinib AUC0-∞ ratio. There were no significant differences in ibrutinib pharmacokinetics between morning and evening posaconazole phases.

CONCLUSIONS

Posaconazole increases ibrutinib exposure substantially, by about 10-fold. This interaction cannot be avoided by dosing the drugs 12 h apart. In general, a 70-mg daily dose of ibrutinib should not be exceeded during posaconazole treatment to avoid potentially toxic systemic ibrutinib concentrations.

Recent advances in genomics and therapeutics in mantle cell lymphoma

Over the past decades, significant strides have been made in understanding the pathobiology, prognosis, and treatment options for mantle cell lymphoma (MCL). The heterogeneity observed in MCL's biology, genomics, and clinical manifestations, including indolent and aggressive forms, is intricately linked to factors such as the mutational status of the variable region of the immunoglobulin heavy chain gene, epigenetic profiling, and Sox11 expression. Several intriguing subtypes of MCL, such as Cyclin D1-negative MCL, in situ mantle cell neoplasm, CCND1/IGH FISH-negative MCL, and the impact of karyotypic complexity on prognosis, have been explored. Notably, recent immunochemotherapy regimens have yielded long-lasting remissions in select patients. The therapeutic landscape for MCL is continuously evolving, with a shift towards nonchemotherapeutic agents like ibrutinib, acalabrutinib, and venetoclax. The introduction of BTK inhibitors has brought about a transformative change in MCL treatment. Nevertheless, the challenge of resistance to BTK inhibitors persists, prompting ongoing efforts to discover strategies for overcoming this resistance. These strategies encompass non-covalent BTK inhibitors, immunomodulatory agents, BCL2 inhibitors, and CAR-T cell therapy, either as standalone treatments or in combination regimens. Furthermore, developing novel drugs holds promise for further improving the survival of patients with relapsed or refractory MCL. In this comprehensive review, we methodically encapsulate MCL's clinical and pathological attributes and the factors influencing prognosis. We also undertake an in-depth examination of stratified treatment alternatives. We investigate conceivable resistance mechanisms in MCL from a genetic standpoint and offer precise insights into various therapeutic approaches for relapsed or refractory MCL.

Real-world analysis of adverse event rates after initiation of ibrutinib among Medicare beneficiaries with chronic lymphocytic leukemia

BACKGROUND

The first-generation BTK inhibitor ibrutinib is a standard-of-care therapy in the treatment of chronic lymphocytic leukemia (CLL) despite potential side effects that often lead to discontinuation.

METHODS

This study used 2013-2019 claims data to describe the incidence rate of adverse events (AEs) among elderly Medicare beneficiaries newly initiating ibrutinib for CLL.

RESULTS

The final sample contained 11,870 Medicare beneficiaries with CLL (mean age 77.2) newly initiating ibrutinib, of whom 65.2% discontinued over mean follow-up of 2.3 years. The overall incidence rate of AEs was 62.5 per 1000 patient-months for all discontinuers and 32.9 per 1000 patient-months for non-discontinuers. Discontinuers had a higher incidence rate of AEs per 1000 patient-months compared with non-discontinuers for all AEs examined, including infection (22.8 vs. 14.5), atrial fibrillation (15.1 vs. 7.0), anemia (21.9 vs. 14.5), and arthralgia/myalgia (19.5 vs. 13.6).

CONCLUSION

In this first real-world study of a national sample of elderly US patients treated with ibrutinib, we found a clear unmet need for improved management of ibrutinib-related AEs and/or new treatments to improve real-world outcomes in patients with CLL.

A phase 2 study of ibrutinib maintenance following first-line high-dose methotrexate-based chemotherapy for elderly patients with primary central nervous system lymphoma

BACKGROUND

Elderly patients account for nearly 70% of all primary central nervous system lymphoma (PCNSL) cases. They cannot tolerate aggressive treatment and have poor prognosis with a median overall survival (OS) of less than 2 years and progression-free survival (PFS) of 6-16 months. Ibrutinib penetrates the blood-brain barrier and has shown activity in PCNSL.

METHODS

This prospective study investigated whether ibrutinib maintenance is feasible, and whether it can benefit elderly PCNSL patients in terms of expected 2-year PFS. It is an open label, phase 2 study in newly diagnosed PCNSL patients 60-85 years old who responded to first-line high-dose methotrexate (HDMTX)-based treatment with partial or complete response. Ibrutinib maintenance (560 mg/d) was continued until disease progression or intolerable toxicity.

RESULTS

Twenty patients were enrolled, with a median age of 72 years (range, 61-80). Median time on ibrutinib maintenance was 12.5 (range, 2-46) months. Twelve patients stopped treatment: five due to central nervous system relapse and seven due to adverse events that were mainly grade 2. Five patients died (25%) all due to relapse. The 1- and 2-year PFS are 90% and 72.6%, respectively, and the 2-year OS is 89%.

CONCLUSIONS

The study reached its primary end points and also showed that ibrutinib maintenance is tolerated reasonably well by the elderly. Therefore, this study supports the concept that ibrutinib maintenance should be further evaluated as an optional consolidation measure in the elderly.

Dual-targeted regimens for the frontline treatment of CLL

The treatment landscape of chronic lymphocytic leukemia (CLL) has evolved considerably over the past decade due to the development of effective novel agents with varying mechanisms of action, including Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 (BCL2) inhibitors. Extrapolating upon the success of anti-CD20-directed chemoimmunotherapy, a dual-targeted approach has been explored in treatment-naive patients with CLL. Anti-CD20 monoclonal antibody combinations with BTK inhibitors as well as BCL2 inhibitors have demonstrated superiority over traditional cytotoxic chemoimmunotherapy regimens such as fludarabine, cyclophosphamide, and rituximab; bendamustine-rituximab; and obinutuzumab-chlorambucil. Impressive clinical benefit is seen in both younger and older patients, those with comorbidities, and, most importantly, those with poor prognostic features. Given this success, combinations of BTK inhibitors and venetoclax have been explored in clinical trials. These dual-targeted regimens provide remarkable efficacy while allowing for an all-oral approach and fixed duration of treatment. Current investigations under way are evaluating the utility of a triplet approach with the addition of obinutuzumab in comparison to a doublet approach.