Fixed-Duration Ibrutinib-Venetoclax in Patients with Chronic Lymphocytic Leukemia and Comorbidities

SOHO State of the Art Updates and Next Questions | Impact of Biologic Markers on Outcomes With Novel Therapy in Chronic Lymphocytic Leukaemia

Treatment of CLL has changed remarkably in the last decade and novel agents are the standard therapy in various jurisdictions. However, the biology of CLL still plays an important part in the treatment choice and disease outcomes. In this post chemo-immunotherapy era for CLL, number of biological factors have lost their clinical significance and most patients will benefit from continuous or time-limited therapy. However, TP53 and IGHV mutation status still retains clinical significance in determining outcomes with various therapeutic approaches. New emerging biological markers including drug-specific mutations are adding to the complexity of decision making in relapsed CLL. End of treatment minimal residual disease analysis (MRD) adds prognostic information to the outcomes with time-limited therapy. MRD-guided duration of treatment may improve further outcomes, but longer clinical follow-up is needed before this approach is incorporated in clinical guidelines. The review gives an update on the impact of biological markers on outcomes with novel agents.

Perspectives on Current Challenges and Emerging Approaches for Lymphoma Management From the First Bridging the Gaps in Leukemia, Lymphoma, and Multiple Myeloma Conference

Recent years have brought a much-needed paradigm shift to the management and treatment of mature B-cell lymphomas. Pathophysiologic and clinical heterogeneity within the various subtypes have historically contributed to treatment challenges and differences in outcomes. Novel genomic tools and therapeutic modalities give promise for improved patient outcomes, but are also making treatment planning increasingly complex. To bridge the gaps between therapeutic advancements and clinical practice, an assembly of multidisciplinary hematologic oncology faculty convened to deliberate on the prevailing challenges, knowledge gaps, and controversies in B-cell lymphoma and chronic lymphocytic leukemia management. Many controversies and questions were identified regarding treatment selection, sequencing, and high-risk subtypes. There is a need for head-to-head trials in this therapeutic area to help answer some of these questions. The insights explored and the gaps in knowledge identified by this panel will inform a follow-up conference in 2025 that will employ the modified Delphi method to develop and publish formal consensus recommendations that can provide actionable guidance to practicing clinicians.

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 5 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.

Ibrutinib lead-in followed by venetoclax plus ibrutinib for relapsed/refractory chronic lymphocytic leukemia: the SAKK 34/17 trial

ABSTRACT

The combination of ibrutinib plus venetoclax (IV) in chronic lymphocytic leukemia (CLL) treatment leverages their complementary mechanisms of action. Studies investigating IV typically begin with a short initial course of ibrutinib, followed by venetoclax introduction for a limited duration, typically 12 months. The Swiss Group for Clinical Cancer Research (SAKK) 34/17 study is a single-arm, multicenter, phase 2 trial evaluating the effectiveness of a modified IV schedule in patients with relapsed/refractory (R/R) CLL. No prior exposure to BTK or BCL2 inhibitors was allowed. The lead-in phase with ibrutinib was extended to 6 months to reduce the tumor burden and related tumor lysis syndrome (TLS) risk. Additionally, the treatment phase with IV is prolonged to a minimum of 24 months to enhance the undetectable minimal residual disease (uMRD; 10-4) rate. The primary end point was the rate of complete response or complete response with incomplete bone marrow recovery (CR/CRi) with uMRD in both bone marrow (BM) and peripheral blood (PB). Secondary end points included assessing the proportion of patients transitioning to a low-risk category for TLS after receiving ibrutinib lead-in. Of the 30 enrolled patients with R/R CLL, 40.0% achieved uMRD CR/CRi by intention-to-treat analysis, and 53.3% showed uMRD in the BM and PB. After the lead-in period with ibrutinib, 57.1% of patients achieved a low risk of TLS. At cycle 31, the progression-free survival rate was 89.9%. These results contribute to the increasing body of evidence supporting the idea that a longer IV duration is beneficial for enhancing therapeutic effectiveness. This trial was registered at www.clinicaltrials.gov as #NCT03708003.

The Impact of Minimal Residual Disease Measurement in the Management of Chronic Lymphocytic Leukemia

Background: The treatment of chronic lymphocytic leukemia (CLL) has advanced considerably in recent years. Bruton's tyrosine kinase inhibitors (BTKis) and B-cell lymphoma 2 inhibitors (BCL2is) such as venetoclax have largely supplanted chemoimmunotherapy for both frontline and relapsed CLL. With the introduction of additional innovative agents and regimens, the clinical role of measurable residual disease (MRD) has become complicated. Methods: In this article, we will review the existing literature on MRD and its utility in the management of CLL. We will review the definitions of MRD, review MRD detection methods, and discuss the use of MRD in the current CLL treatment landscape. In doing so, we will clarify the present and conceivable future roles of MRD for the treatment of CLL. Conclusions: MRD is a powerful tool to assess response to CLL therapies, and can be prognostic with certain treatment regimens, such as fixed-duration venetoclax-based treatment. While we do not recommend MRD testing in routine clinical practice, we believe it has an important role in assessing treatment response and will be utilized routinely in the future. Further studies to incorporate MRD into treatment strategies for CLL are ongoing and will help to inform how we utilize it in clinical practice.

Prognostic factors in chronic lymphocytic leukaemia - the old, the new and the future

Prognostic assessment in chronic lymphocytic leukemia (CLL) is essential for delivery of timely, personalized therapy. TP53 status, karyotype, IGHV mutational status, minimal residual disease (MRD), gene mutations and markers of cell proliferation were important prognostic tools in the era of chemo-immunotherapy (CIT). With BCL2 inhibitors (BCL2i), outcome is still impacted by IGHV status, TP53 status, complex karyotype, and achievement of undetectable MRD. On the other hand, BTK inhibitors (BTKi) are agnostic to IGHV status, rarely cause MRD negative remissions and are less clearly impacted by TP53 status. Although based on less mature data, outcomes with BCL2i/BTKi combinations are likely influenced by TP53 and IGHV status. Responses to non-covalent BTKI (ncBTKI) are impacted by the mechanism of resistance to previous covalent BTKi. Finally, responses to chimeric antigen receptor T cell therapy (CAR-T) appear independent of TP53 status, but dependent on overall T- cell fitness.

Efficacy and Safety of First-line Targeted Therapies in Physically Fit Patients With Chronic Lymphocytic Leukemia: A Systematic Review and Network Meta-analysis

PURPOSE

Targeted therapies are promising treatment options for fit patients with untreated chronic lymphocytic leukemia (CLL). However, there is a lack of data on their relative efficacy and safety. The aim of this systematic review was to assess the relative efficacy and safety of first-line targeted therapies (including venetoclax [VEN], obinutuzumab [OBI], ibrutinib [IBR], and other options) for physically fit patients with untreated CLL.

METHODS

A systematic literature review of major medical databases (MEDLINE, Embase, and Cochrane Central Register of Controlled Trials) and additional data sources was conducted to identify randomized controlled trials providing data of interest. Progression-free survival (PFS) and undetectable minimal residual disease (MRD(-)) in peripheral blood (PB) were analyzed, along with other end points. A Bayesian network meta-analysis was used for data analysis. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, and its protocol was registered in the International Prospective Register of Systematic Reviews (CRD42023393903).

FINDINGS

The network meta-analysis results reported no significant differences between targeted therapies for PFS. However, IBR + VEN and VEN + OBI + IBR reported the highest probability of being the most effective options based on surface under the cumulative ranking curve values. For MRD(-)PB, VEN + OBI + IBR reported a significant advantage over other therapies, with surface under the cumulative ranking curve values confirming it as the most effective option in this term.

IMPLICATIONS

Targeted therapies may offer a promising treatment option for fit patients with previously untreated CLL. Among the therapies assessed, IBR + rituximab and VEN + OBI + IBR emerge as the most effective therapeutic options for prolonging PFS, while VEN + OBI + IBR and VEN + OBI reported favorable outcomes in achieving MRD(-)PB. However, further research is needed to validate these findings.

Ibrutinib and Venetoclax in Relapsed and Refractory Follicular Lymphoma

BACKGROUND

Bruton tyrosine kinase (BTK) inhibitors are approved in several B-cell malignancies, including the recent authorization of zanubrutinib for relapsed or refractory follicular lymphoma (FL).

METHODS

Based on preclinical studies demonstrating synergy with ibrutinib and the B-cell lymphoma (BCL)-2 inhibitor, venetoclax, in FL cell lines, we conducted a multicenter phase Ib/II study evaluating this combination in relapsed or refractory FL.

RESULTS

The recommended phase 2 dose was ibrutinib 560 mg and venetoclax 600 mg. There was no evidence of clinical tumor lysis syndrome, despite the omission of a venetoclax ramp up. At a median duration of therapy of 6 months, the most common adverse events were low grade diarrhea (83%), infection (75%), and rash (58%). Amongst the 24 patients enrolled, the overall and complete response (CR) rates were 63% and 21%. At a median follow up of 6.9 months, the median progression-free survival was 8.2 months, and the median duration of CR (n = 5) was 38 months.

CONCLUSION

The combination of a BTK and BCL2 inhibitor is efficacious in relapsed/refractory FL and represents a unique dual-targeted approach warranting further investigation.

Chronic lymphocytic leukemia: what clinical progress have we seen in the last five years?

INTRODUCTION

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults. Although treatment has shifted from immunochemotherapy to novel targeted drugs over the last 10 years, novel therapies remain under investigation, particularly in relapsed and refractory patients.

AREAS COVERED

This review describes the use of approved targeted drugs and novel therapies in treatment-naïve and relapsed or refractory CLL. Particular attention is paid to the management of double-refractory patients, and the discovery of novel drugs in the last five years.

EXPERT OPINION

Targeted drugs are effective and well-tolerated in the treatment of CLL. In the last five years, several novel agents have been investigated in preclinical studies and clinical trials, including combinations of approved drugs, novel BTK and BCL2 inhibitors, BTK degraders, bispecific antibodies and CAR-T cells. It is anticipated that some should be approved in the near future.

Underrepresentation of Small Lymphocytic Lymphoma in Clinical Trials for Chronic Lymphocytic Leukemia

BACKGROUND

Although chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are the same biologic disease entity and warrant identical treatment approaches, patients with SLL have frequently been excluded from clinical trials in CLL.

METHODS

This study assessed the representation of patients with SLL among Phase II or III clinical trials cited in the 2024 National Comprehensive Cancer Network (NCCN) treatment guidelines.

RESULTS

Patients with SLL were explicitly eligible for only 21 (38%) of the 56 clinical trials for CLL, comprising 222 (6%) of the 3440 enrolled patients. Notably, 380 patients with SLL were enrolled in 16 separate non-CLL clinical trials alongside patients with indolent B-cell lymphomas such as follicular lymphoma. In CLL trials, patients with SLL were included in a greater proportion of studies evaluating BTK inhibitors (67%) or BTK/BCL2 inhibitor combinations (67%) compared to BCL2 inhibitors (0%) or chemoimmunotherapy (0%).

CONCLUSIONS

Although recent and upcoming trials show a promising trend toward the inclusion of patients with SLL, further advocacy is needed to raise awareness of the biological similarities between CLL and SLL and to promote the representation of patients with SLL in CLL/SLL clinical research.

Pharmacological profiling in CLL patients during pirtobrutinib therapy and disease progression

Pirtobrutinib is a reversible Bruton's tyrosine kinase (BTK) inhibitor that has shown efficacy for patients with chronic lymphocytic leukemia (CLL) in BRUIN trial. These patients were previously treated with covalent BTK inhibitor (cBTKi) and either discontinued cBTKi or had disease progression during therapy. As a result, some patients had wild-type BTK while others had mutant BTK (mostly C481 site where cBTKi binds). All patients received pirtobrutinib monotherapy. Twenty-six patients with CLL from BRUIN were treated at MD Anderson and twenty-three were followed up for at least two years. We compared baseline features between patients who had progressive-disease versus those who remained on therapy during the first 24 cycles of pirtobrutinib therapy. We performed pharmacological profiling of peripheral blood mononuclear cells taken from patients at pretreatment, during pirtobrutinib therapy, and at progression. Relapsed/refractory CLL to prior cBTKi, baseline BTK mutations, unmutated IGHV, bulky lymph nodes, XPO1 mutation and complex karyotype were more prevalent attributes in the pirtobrutinib progressive-disease subgroup. Interestingly, among patients who had progressive-disease, only three patients had baseline wild-type BTK, while eleven had mutant BTK (mostly C481). As reported before, we also observed that C481S mutant clone was decreased during therapy while T474 mutant either developed or increased. We did pharmacological profiling in samples taken during pirtobrutinib therapy when disease is responsive and primary cells are sensitive to pirtobrutinib. We also analyzed sensitivity of CLL cells to other targeted and clinically available agents when patient had PD on pirtobrutinib and needed a new treatment regimen. Ex vivo pharmacologic profiling suggested that during pirtobrutinib therapy, peripheral blood mononuclear cells (CLL cells) became resensitized to ibrutinib and other targeted agents. Combination therapy, including ibrutinib and venetoclax, was effective regardless of genomic background and even after relapse from pirtobrutinib monotherapy.

Double Strike in Chronic Lymphocytic Leukemia-The Combination of BTK and BCL2 Inhibitors in Actual and Future Clinical Practice

In the recent 2024 ESMO guidelines, the combination of venetoclax and ibrutinib was listed as one of the first-line treatment options for CLL patients. These drugs were first-in-class medicines that revolutionized CLL management, extending patients' overall survival even in cases refractory to immunochemotherapy. However, since the approval of both compounds, more and more Bruton Tyrosine Kinase inhibitors (BTKis) and B-cell lymphoma 2 inhibitors (BCL2is) have been discovered. Their efficacy and safety are the reasons for their use in monotherapy among both treatment-naïve and relapsed patients with CLL. Currently, several ongoing clinical trials are investigating the rationale for the combination of BCL2is and BTKis. In this review, we discuss the recent advancements in the field of co-therapy with BTKis and BCL2is.

MRD-guided zanubrutinib, venetoclax, and obinutuzumab in relapsed CLL: primary end point analysis from the CLL2-BZAG trial

ABSTRACT

The phase 2 CLL2-BZAG trial tested a measurable residual disease (MRD)-guided combination treatment of zanubrutinib, venetoclax, and obinutuzumab after an optional bendamustine debulking in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). In total, 42 patients were enrolled and 2 patients with ≤2 induction cycles were excluded from the analysis population per protocol. Patients had a median of 1 prior therapy (range, 1-5); 18 patients (45%) had already received a Bruton tyrosine kinase (BTK) inhibitor (BTKi); 7 patients (17.5%) venetoclax; and, of these, 5 (12.5%) had received both. Fifteen patients (37.5%) had a TP53 mutation/deletion, and 31 (77.5%) had unmutated immunoglobulin heavy chain variable region gene. With a median observation time of 21.5 months (range, 8.0-35.3) the most common adverse events were COVID-19 (n = 26 patients), diarrhea (n = 15), infusion-related reactions (n = 15), thrombocytopenia (n = 14), nausea (n = 12), fatigue (n = 12), and neutropenia (n = 12). Two patients had fatal adverse events (COVID-19, and fungal pneumonia secondary to COVID-19). After 6 months of the triple combination, all patients responded, and 21 (52.5%; 95% confidence interval, 36.1-68.5) showed undetectable MRD (uMRD) in the peripheral blood. In many patients, remissions deepened over time, with a best uMRD rate of 85%. The estimated progression-free and overall survival rates at 18 months were 96% and 96.8%, respectively. No patient has yet required a subsequent treatment. In summary, the MRD-guided triple combination of zanubrutinib, venetoclax, and obinutuzumab induced deep remissions in a relapsed CLL population enriched for patients previously treated with a BTKi/venetoclax. This trial was registered at www.clinicaltrials.gov as #NCT04515238.

Consensus recommendations from the 2024 Lymphoma Research Foundation workshop on treatment selection and sequencing in CLL or SLL

ABSTRACT

Over the past decade, treatment recommendations for patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) have shifted from traditional chemoimmunotherapy to targeted therapies. Multiple new therapies are commercially available, and, in many cases, a lack of randomized clinical trial data makes selection of the optimal treatment for each patient challenging. Additionally, many patients continue to receive chemoimmunotherapy in the United States, suggesting a gap between guidelines and real-world practice. The Lymphoma Research Foundation convened a workshop comprising a panel of CLL/SLL experts in the United States to develop consensus recommendations for selection and sequencing of therapies for patients with CLL/SLL in the United States. Herein, the recommendations are compiled for use as a practical clinical guide for treating providers caring for patients with CLL/SLL, which complement existing guidelines by providing a nuanced discussion relating how our panel of CLL/SLL experts in the United States care for patients in a real-world environment.

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.

Upfront fixed-duration treatment strategies for chronic lymphocytic leukemia in Arab populations: a position statement from the Gulf region

The treatment landscape for chronic lymphocytic leukemia (CLL) has expanded dramatically over the last decade, with a wide range of effective treatments now available. Clinical management of CLL varies widely depending on patient profile, meaning the optimal treatment in Arab patients, who tend to be young and often present with comorbidities, including diabetes and obesity, requires specific considerations. In the absence of regional guidelines, a group of experts from across the Gulf region and one international expert from Germany convened to discuss and agree upon a position statement for venetoclax-based fixed-duration treatment strategies for Arab patients with CLL. Our position is that ibrutinib-venetoclax should be the first choice as first-line therapy for all fit CLL patients in the region, regardless of age. The advantages of an all-oral, fixed-duration treatment are discussed in the context of a young Arab patient population, including excellent patient and physician convenience, limited accumulative risk of toxicities, uncomplicated logistics, and low burden of healthcare administration costs. Finally, we discuss the management of key safety considerations in Arab populations including ethnic neutropenia, risk of cardiotoxic events, considerations during intermittent fasting, and avoiding adverse drug-drug interactions, e.g., with anti-tuberculosis or anti-obesity medications.

Evidence-based investigation of the efficacy and safety of venetoclax-containing regimens versus chemoimmunotherapy in chronic lymphocytic leukemia

Randomized controlled trials (RCTs) comparing the treatment outcomes and adverse events of venetoclax-containing regimens with chemoimmunotherapy in chronic lymphocytic leukemia (CLL) are scarce, and the available data are heterogeneous. We carried out a meta-analysis and systematic review to explore the efficacy and safety of these novel venetoclax combination therapies in CLL patients. Five RCTs (11 articles) involving 2481 CLL patients were included. Through a detailed pooled odds ratio analysis, it was revealed that, in terms of 1-year to 5-year progression-free survival (PFS) and overall survival (OS), venetoclax combination therapy demonstrated an obvious superiority over chemoimmunotherapy. In patients with unmutated immunoglobulin heavy chain variable region gene (IGHV), the 1-year to 5-year PFS was notably better with venetoclax combination therapy. In those with mutated IGHV, the 1-year to 4-year PFS was also improved with the use of venetoclax-containing regimens, although the 5-year PFS was comparable between the two treatment regimens. In patients with del(17p) and/or TP53 mutations, the 2-year, 3-year, and 4-year PFS were significantly superior with venetoclax-containing regimens. There were no significant differences between venetoclax-containing regimens and chemoimmunotherapy in all grade 3 or 4 adverse events, neutropenia, thrombocytopenia, infections, pneumonia, sepsis, infusion-related reactions, or tumor lysis syndrome. Venetoclax-containing regimens were associated with a decreased risk of anemia, leukopenia, febrile neutropenia, and pyrexia, but an increased risk of diarrhea and hypertension. Our results demonstrate the superiority of venetoclax-containing regimens in CLL patients, particularly in those with unmutated IGHV and del(17p) and/or TP53 mutations.

Fixed-Duration Acalabrutinib Combinations in Untreated Chronic Lymphocytic Leukemia

BACKGROUND

Whether fixed-duration acalabrutinib-venetoclax (with or without obinutuzumab) would result in better progression-free survival than chemoimmunotherapy in patients with untreated chronic lymphocytic leukemia (CLL) is unknown.

METHODS

In this phase 3, open-label trial, we included patients 18 years of age or older who had an Eastern Cooperative Oncology Group performance-status score of 0 to 2 (range, 0 to 5, with higher numbers indicating greater disability) and who did not have a 17p deletion or TP53 mutation. Patients were randomly assigned, in a 1:1:1 ratio, to receive acalabrutinib-venetoclax (acalabrutinib, cycles 1 to 14; venetoclax, cycles 3 to 14), acalabrutinib-venetoclax-obinutuzumab (as above, plus obinutuzumab, cycles 2 to 7), or chemoimmunotherapy with the investigator's choice of fludarabine-cyclophosphamide-rituximab or bendamustine-rituximab (cycles 1 to 6). The primary end point was progression-free survival (acalabrutinib-venetoclax vs. chemoimmunotherapy) in the intention-to-treat population, assessed by blinded independent central review.

RESULTS

A total of 867 patients underwent randomization: 291 were assigned to receive acalabrutinib-venetoclax, 286 acalabrutinib-venetoclax-obinutuzumab, and 290 chemoimmunotherapy (of whom 143 received fludarabine-cyclophosphamide-rituximab and 147 bendamustine-rituximab). The median age of the patients was 61 years (range, 26 to 86), 64.5% were men, and 58.6% had unmutated IGHV. Estimated 36-month progression-free survival at a median follow-up of 40.8 months was 76.5% with acalabrutinib-venetoclax, 83.1% with acalabrutinib-venetoclax-obinutuzumab, and 66.5% with chemoimmunotherapy (hazard ratio for disease progression or death with acalabrutinib-venetoclax vs. chemoimmunotherapy, 0.65 [95% confidence interval {CI}, 0.49 to 0.87], P = 0.004; for the comparison of acalabrutinib-venetoclax-obinutuzumab with chemoimmunotherapy, P<0.001). Estimated 36-month overall survival was 94.1% with acalabrutinib-venetoclax, 87.7% with acalabrutinib-venetoclax-obinutuzumab, and 85.9% with chemoimmunotherapy. Neutropenia, the most common adverse event of clinical interest of grade 3 or higher, was reported in 32.3%, 46.1%, and 43.2% in the three groups, respectively; death from coronavirus disease 2019 was reported in 10, 25, and 21 patients in the three groups.

CONCLUSIONS

Acalabrutinib-venetoclax with or without obinutuzumab significantly prolonged progression-free survival as compared with chemoimmunotherapy in fit patients with previously untreated CLL. (Funded by AstraZeneca; AMPLIFY ClinicalTrials.gov number, NCT03836261.).

Resistance mechanisms and approach to chronic lymphocytic leukemia after BTK inhibitor therapy

Bruton tyrosine kinase (BTK), an essential component of the B-cell receptor (BCR) signaling pathway, is a validated target in chronic lymphocytic leukemia. Ibrutinib, acalabrutinib, and zanubrutinib are covalent BTK inhibitors (cBTKi) that bind to residue C481, leading to sustained target inhibition. A significant proportion of patients develop resistance to continuous cBTKi therapy, predominantly via mutations in BTK and its immediate downstream effector, PLCG2. The noncovalent BTKi pirtobrutinib does not require binding to C481 and can restore BTK inhibition after progression on a cBTKi. However, non-C481 BTK mutations conferring resistance to pirtobrutinib have been identified. Furthermore, the scaffolding function of BTK, activation of bypass signaling pathways, and the tumor microenvironment may contribute to BTKi resistance. Targeting BTK for degradation is an emerging strategy that appears effective against multiple BTK mutations, and inhibitors of downstream BCR signaling proteins are under development. This review addresses BTKi resistance mechanisms and therapeutic approaches after cBTKi failure.

BTK Is the Target That Keeps on Giving: A Review of BTK-Degrader Drug Development, Clinical Data, and Future Directions in CLL

Effective available treatment options for patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) who relapse after becoming refractory to both a covalent Bruton Tyrosine Kinase inhibitor (cBTKi) and a B cell leukemia/lymphoma 2 inhibitor (BCL2i) remain limited, and prognosis is very poor. Emerging areas of drug development include cellular therapies such as chimeric antigen receptor T-cell therapy and bispecific antibodies. However, cost, accessibility, toxicity, and the need for either prolonged or repeated hospitalization prevent universal application of these therapies. Given this area of unmet clinical need, we present this review article on Bruton Tyrosine Kinase (BTK) degraders in patients with CLL/SLL. We focus on their development as a drug class, the up-to-date clinical data available, as well as future directions. BTK protein degraders are a novel drug class with an alternate mechanism of action (MOA), compared to cBTKis and non-covalent BTKis (ncBTKis), causing ubiquitination of BTK, thereby leading to its degradation through the proteasome. Encouraging pre-clinical data show that this MOA allows BTK protein degraders to overcome common BTK mutations. We focus on four agents which are under investigation in B-cell malignancies in early clinical trials: BGB-16673, NX-2127, NX-5948, and AC676. Preliminary data suggest a comparable safety and toxicity profile between agents across this drug class with many patients on phase 1 trials deriving durable clinical benefit. Optimal sequencing of BTK degraders in the therapeutic landscape of CLL/SLL treatment is yet to be established. Further trials investigating these agents in combination with other targeted CLL agents may help to further understand their applicability. An effective, tolerable oral class of drugs would be invaluable in the treatment of patients with multiply relapsed CLL/SLL.

SOHO State of the Art Updates and Next Questions | Covalent Bruton's Tyrosine Kinase Inhibitors in Chronic Lymphocytic Leukemia

Inhibitors of Bruton's tyrosine kinase (BTK) are among the most widely used therapies for chronic lymphocytic leukemia (CLL) and established a new expectation for efficacy and safety in the treatment of this disease. Currently there are 3 covalent inhibitors of BTK approved for the treatment of CLL: ibrutinib, acalabrutinib, and zanubrutinib. The first-in-class covalent BTK inhibitor is ibrutinib, which as monotherapy has excellent efficacy in the front-line setting with a 7-year progression free survival (PFS) of 59%. Ibrutinib-based therapies have also demonstrated superiority over standard chemoimmunotherapy in the front-line and the relapsed/refractory setting. Acalabrutinib is a second-generation BTK inhibitor that has higher selectivity to BTK. Acalabrutinib has efficacy in both frontline and relapsed CLL and is associated with a decreased incidence of atrial fibrillation and hypertension when compared to ibrutinib. Like acalabrutinib, zanubrutinib was designed to be more selective for BTK than ibrutinib and to maximize BTK inhibition in tissues. Zanubrutinib has demonstrated clinical efficacy in first line and relapsed/refractory setting. These agents are indicated as monotherapy, with dosing until disease progression or intolerable toxicity, and are mainly differentiated by safety profile, although efficacy differences may exist as well. Combination with CD20 monoclonal antibodies and/or BCL2 inhibitors are alternative options for use. Here we will review efficacy and safety considerations with these agents.

Comparing the efficacy and safety of first-line treatments for chronic lymphocytic leukemia: a network meta-analysis

BACKGROUND

The chronic lymphocytic leukemia treatment strategies have transitioned from chemotherapy and chemoimmunotherapy to chemotherapy-free regimens. Frequentist network meta-analysis allows for direct and indirect comparisons between different treatments.

METHODS

Randomized controlled trials assessing first-line treatments were included. Outcomes were progression-free survival (PFS), overall survival, undetectable minimal residual disease, objective response rate, and adverse events. Studies with comparable characteristics also underwent subgroup analysis, stratifying by age, comorbidities, IGHV status, and cytogenetic abnormalities.

RESULTS

A total of 30 eligible trials involved 12 818 patients, and 30 treatments were included. Acalabrutinib demonstrated a PFS advantage over ibrutinib and obinutuzumab-venetoclax in patients aged older than 65 years or with unmutated IGHV. In younger patients with comorbidities, acalabrutinib-obinutuzumab had superior PFS compared with ibrutinib-obinutuzumab, ibrutinib-venetoclax, and obinutuzumab-venetoclax. For older patients with comorbidities, acalabrutinib and acalabrutinib-obinutuzumab outperformed obinutuzumab-venetoclax without statistically difference between them. Minimal residual disease-guided ibrutinib-venetoclax surpassed obinutuzumab-venetoclax in patients without comorbidities. Ibrutinib-obinutuzumab exhibited extended PFS benefits compared with obinutuzumab-venetoclax in patients with mutated IGHV or with del(17p) and/or TP53 mutations. Ibrutinib-venetoclax and ibrutinib-obinutuzumab had lower neutropenia rates than obinutuzumab-venetoclax. Ibrutinib-venetoclax had fewer infections than acalabrutinib and acalabrutinib-obinutuzumab. Acalabrutinib-obinutuzumab caused less diarrhea than ibrutinib-venetoclax but more headaches than ibrutinib-obinutuzumab and obinutuzumab-venetoclax. Obinutuzumab-venetoclax had lower hypertension rates than ibrutinib-obinutuzumab. Ibrutinib-venetoclax had fewer arthralgia than acalabrutinib-obinutuzumab. For any grade secondary primary neoplasms, ibrutinib-venetoclax and obinutuzumab-venetoclax was less than acalabrutinib-obinutuzumab.

CONCLUSION

Tailored chemotherapy-free regimens can be selected based on age, comorbidities, IGHV status, and cytogenetic abnormalities to optimize treatment outcomes while considering different adverse events spectra.

Measurable residual disease-driven treatment in first-line chronic lymphocytic leukaemia

The therapeutic paradigm for patients suffering from chronic lymphocytic leukaemia continues to rapidly evolve. Fixed duration therapies continue to develop using novel-novel non-chemotherapeutic combinations. B-cell lymphoma 2 (BCL2) inhibitors in combination with either anti-CD20 antibody or Bruton tyrosine kinase inhibitors are able to achieve deep responses. Levels of attained 'negative' measurable residual disease (MRD, also known as minimal residual disease) have been shown to predict survival outcomes in a number of settings, including following immunochemotherapy and BCL2-combinations. This review will outline the current data supporting fixed duration treatment approaches, the use of MRD in clinical practice, alongside the challenges and possibilities for MRD utility in the future.

Holding the therapy in CLLp53: mechanisms to achieve durable responses

Chronic lymphocytic leukemia (CLL) is a common leukemia, mainly affecting the elderly. Originating in the bone marrow, CLL involves the accumulation of B lymphocytes and progresses slowly, though 50-60% of patients will require therapy. At diagnosis, the presence of p53 protein aberrations, such as 17p deletion and TP53 mutation, arises in approximately one out of 10 patients. Even in the era of targeted therapies, these aberrations remain the most important prognostic factors. Current guidelines favor continuous BTK inhibitor therapy in patients with CLLp53, though adverse events and drug resistance may lead to discontinuation. Herein, we discuss the effects of B-cell receptor and BCL-2 inhibition, as well as the role of the immune system, in two elderly CLLp53 patients with prolonged responses to different therapies.

Venetoclax dose escalation rapidly activates a BAFF/BCL-2 survival axis in chronic lymphocytic leukemia

ABSTRACT

Venetoclax, a first-in-class BH3 mimetic drug that targets B-cell lymphoma-2 (BCL-2), has improved the outcomes of patients with chronic lymphocytic leukemia (CLL). Early measurements of the depth of the venetoclax treatment response, assessed by minimal residual disease, are strong predictors of long-term clinical outcomes. However, there are limited data on the early changes induced by venetoclax treatment that might inform strategies to improve responses. To address this gap, we conducted longitudinal mass cytometric profiling of blood cells from patients with CLL during the first 5 weeks of venetoclax monotherapy. At baseline, we resolved CLL heterogeneity at the single-cell level to define multiple subpopulations in all patients based on proliferative, metabolic, and cell survival proteins. Venetoclax induced a significant reduction in all CLL subpopulations and caused rapid upregulation of the prosurvival BCL-2, BCL-extra large, and mantle cell lymphoma-1 proteins in surviving cells, which had reduced sensitivity to the drug. In mouse models, the venetoclax-induced elevation of survival proteins in B cells and CLL-like cells that persisted was recapitulated, and genetic models demonstrated that extensive apoptosis and access to the B-cell cytokine, B-cell activating factor (BAFF), were essential. Accordingly, in patients with CLL who were treated with venetoclax or the anti-CD20 antibody obinutuzumab there was marked elevation in BAFF and an increase in prosurvival proteins in leukemic cells that persisted. Overall, these data highlight the rapid adaptation of CLL cells to targeted therapies through homeostatic factors and support cotargeting of cytokine signals to achieve deeper and more durable long-term responses.

The evolving frontline management of CLL: are triplets better than doublets? How will we find out?

Frontline therapy for chronic lymphocytic leukemia (CLL) has substantially advanced in the previous decade. While monotherapy with a Bruton's tyrosine kinase (BTK) inhibitor is an excellent option for many patients, combination therapies are of high clinical interest as they can induce deep responses and durable remissions, and in many cases allow discontinuation of therapy. There are several doublet therapies that are currently in clinical use. These include combinations of BTK inhibitors (ibrutinib, acalabrutinib, zanubrutinib) or BCL2 inhibitors (venetoclax) with anti-CD20 monoclonal antibodies, and combinations of BTK and BCL2 inhibitors. While BTK inhibitors with anti-CD20 monoclonal antibodies still typically require indefinite therapy, combinations involving the BCL2 inhibitor venetoclax have allowed for successful therapy discontinuation. Triplets, which combine all 3 of these paradigms, are of interest especially for patients with higher-risk disease. While triplets have been mainly studied in single-arm trials with excellent outcomes, comparative data to doublets are limited. In this article, we outline the doublet and triplet regimens that have been evaluated in CLL as well as the data from trials comparing doublets and triplets.

Risk-stratification in frontline CLL therapy: standard of care

The treatment of chronic lymphocytic leukemia (CLL) has been transformed over the past decade based on a better understanding of disease biology, especially regarding molecular genetic drivers and relevant signaling pathways. Agents focusing on B-cell receptor (in particular Bruton tyrosine kinase [BTK]) and apoptosis (BCL2) targets have replaced chemoimmunotherapy (CIT) as the treatment standard. BTK and BCL2 inhibitor-based therapy has consistently shown prolonged progression-free survival and in some instances even increased overall survival against CIT in frontline phase 3 trials. This improvement is particularly pronounced in high-risk CLL subgroups defined by unmutated IGHV, deletion 17p (17p-), and/or the mutation of TP53, making CIT in these subgroups essentially obsolete. Despite remarkable advances, these markers also retain a differential prognostic and predictive impact in the context of targeted therapies, mandating risk-stratification in frontline management. Furthermore, BTK- and BCL2-targeting agents differ in their adverse event profiles, requiring adjustment of treatment choice based on patient characteristics such as coexisting conditions, comedications, and delivery-of-care aspects.

Consensus guidelines for the management of treatment-naïve chronic lymphocytic leukaemia in Singapore (2024)

Introduction

Chronic lymphocytic leukaemia (CLL) has a heterogeneous disease course and a variable preva-lence across populations. Appropriate management for achieving optimal outcomes requires consideration of multiple factors, including disease-related factors like genomic alterations, patient characteristics and fitness, availability and access to treatments, and logistics/cost. This review aims to provide comprehen-sive and pragmatic recommendations for the management of treatment-naïve (TN) CLL that are relevant to Singapore's clinical context.

Method

Clinical consensus statements were developed by an expert panel of haematologists from Singapore through a 2-round modified Delphi process. Statements were drafted using recent evidence-based guidelines and published literature. Panel members reviewed draft statements, provided anonymised feedback and proposed modifications where relevant. A physical meeting was held to facilitate discussion, voting and endorsement of the final consensus statements.

Results

The final consensus included 15 statements covering major TN CLL patient subsets. The recommendations highlight the importance of molecular testing for key biomarkers, where available/accessible, to guide initial therapy. Due to the superior efficacy of targeted agents (Bruton's tyrosine kinase inhibitors [BTKis] and B-cell lymphoma 2 inhibitors [BCL2is]) these are favoured over standard chemotherapy or chemotherapy-immunotherapy, especially for patients with del(17p) or TP53 mutation, and less fit patients.

Conclusion

These consensus statements provide practical recommendations for the current manage-ment of TN CLL patients in Singapore and similar healthcare systems based on up-to-date evidence. Regular updates to treatment guidelines are important to ensure responsiveness to emerging evidence and evolving clinical practices and to improve patient outcomes and quality of life.

Navigating the changing landscape of BTK-targeted therapies for B cell lymphomas and chronic lymphocytic leukaemia

The B cell receptor (BCR) signalling pathway has an integral role in the pathogenesis of many B cell malignancies, including chronic lymphocytic leukaemia, mantle cell lymphoma, diffuse large B cell lymphoma and Waldenström macroglobulinaemia. Bruton tyrosine kinase (BTK) is a key node mediating signal transduction downstream of the BCR. The advent of BTK inhibitors has revolutionized the treatment landscape of B cell malignancies, with these agents often replacing highly intensive and toxic chemoimmunotherapy regimens as the standard of care. In this Review, we discuss the pivotal trials that have led to the approval of various covalent BTK inhibitors, the current treatment indications for these agents and mechanisms of resistance. In addition, we discuss novel BTK-targeted therapies, including covalent, as well as non-covalent, BTK inhibitors, BTK degraders and combination doublet and triplet regimens, to provide insights on the best current treatment paradigms in the frontline setting and at disease relapse.

Molecular Composition and Kinetics of B Cells During Ibrutinib Treatment in Patients with Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of B cells due to constitutive B-cell receptor (BCR) signaling, leading to apoptosis resistance and increased proliferation. This study evaluates the effects of the Bruton Tyrosine Kinase (BTK) inhibitor ibrutinib on the molecular composition, clonality, and kinetics of B cells during treatment in CLL patients. Employing a multi-omics approach of up to 3.2 years of follow-up, we analyzed data from 24 CLL patients, specifically focusing on nine patients treated with ibrutinib monotherapy. In this study, clonal stability was observed within the ibrutinib-treated group following an effective initial clinical response, where clonotype frequencies of residual CLL cells remained high and stable, ranging from 74.9% at 1.5 years to 87.7% at approximately 3 years. In contrast, patients treated with the B-cell lymphoma 2 (BCL2) inhibitor venetoclax exhibited substantial reductions in clonal frequencies, approaching molecular eradication. Deep whole-exome sequencing revealed minimal genomic progression in the ibrutinib group, maintaining somatic drivers and variant allele frequencies (VAF) above 0.2 throughout treatment. At the single-cell level, the NF-κB pathway inhibition and apoptotic signals were detected or even augmented during treatment in ibrutinib-treated patients. These findings may corroborate the role of ibrutinib in stabilizing the genomic landscape of CLL cells, preventing significant genomic evolution despite maintaining a high clonal burden within the residual B-cell compartment.

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.

BCL-2 and BTK inhibitors for chronic lymphocytic leukemia: current treatments and overcoming resistance

INTRODUCTION

In the last decade, BTK inhibitors and the BCL-2 inhibitor venetoclax have replaced immunochemotherapy in the treatment of CLL.

AREAS COVERED

This review describes the use of BTK inhibitors and BCL2 inhibitors in the treatment of naive and relapsed or refractory CLL, with particular attention to the mechanisms of resistance. It also addresses the management of double-refractory patients, and the discovery of novel drugs. The corpus of papers was obtained by a search of the PubMed and Google Scholar databases for articles in English.

EXPERT OPINION

Covalent BTK inhibitors and venetoclax are commonly recommended for previously-untreated and relapsed/refractory CLL. However, resistance to both drug classes can develop over time. As such, double-refractory patients are difficult to manage and novel approaches are urgently needed.

Recent Advances in the Molecular Biology of Chronic Lymphocytic Leukemia: How to Define Prognosis and Guide Treatment

Chronic Lymphocytic Leukemia (CLL) is the most frequent type of leukemia in Western countries. In recent years, there have been important advances in the knowledge of molecular alterations that underlie the disease's pathogenesis. Very heterogeneous prognostic subgroups have been identified by the mutational status of immunoglobulin heavy variable genes (IGVH), FISH analysis and molecular evaluation of TP53 mutations. Next-generation sequencing (NGS) technologies have provided a deeper characterization of the genomic and epigenomic landscape of CLL. New therapeutic targets have led to a progressive reduction of traditional chemoimmunotherapy in favor of specific biological agents. Furthermore, in the latest clinical trials, the minimal residual disease (MRD) has emerged as a potent marker of outcome and a guide to treatment duration. This review focuses on recent insights into the understanding of CLL biology. We also consider the translation of these findings into the development of risk-adapted and targeted therapeutic approaches.

Utilizing risk factors to guide treatment decisions in chronic lymphocytic leukemia

INTRODUCTION

In the era of chemo-immunotherapy, high-risk factors unequivocally predicted inferior outcomes for patients with CLL. The widespread adoption of BTK inhibitors has challenged the practical implications of such testing, as many patients have improved outcomes despite the presence of high-risk features. The impact of adverse prognostic factors, such as unmutated IGHV, on survival has been ameliorated by continuous treatment with BTK inhibitors, but not by finite-duration therapy with venetoclax-based combinations. Furthermore, TP53 abnormalities continue to be associated with worse outcomes in the era of novel agents. New treatment modalities, such as pirtobrutinib, lisocabtagene maraleucel, and ongoing studies combining BTK inhibitors with venetoclax, raise new questions on the significance of prognostic factors of survival for patients with CLL.

AREAS COVERED

Herein, we summarized the available literature on patients with CLL harboring high-risk biomarkers, with a focus on data from key clinical trials.

EXPERT OPINION

Testing for prognostic biomarkers will remain relevant to identify patients who may have increased benefit from novel therapeutic strategies, such as combination therapies and novel agents. Patients with high-risk disease should be encouraged to participate in clinical trials.

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.

The Economic Impact of Treatment Sequencing in Chronic Lymphocytic Leukemia in Canada Using Venetoclax plus Obinutuzumab

BACKGROUND

Bruton tyrosine kinase inhibitors (BTKis) represent an advancement in chronic lymphocytic leukemia; however, these agents are administered continuously until disease progression or unacceptable toxicity, raising concerns about their affordability. Venetoclax in combination with obinutuzumab (VO) is a fixed-duration (12-month) treatment, approved in Canada in 2020. This study estimated the total cumulative cost of different treatment sequences and evaluated the economic impact of introducing treatment sequences with/without VO, from a Canadian health care system perspective.

METHODS

A 10-year partitioned survival model was developed, considering key clinical parameters and direct medical costs. Results were stratified by TP53 aberration.

RESULTS

Treatment sequences starting with first-line (1L) VO resulted in lower 10-year cumulative costs compared to sequences starting with BTKis administered until disease progression, across both TP53 aberration subgroups. With a maximum of three lines of treatment over a 10-year period, cumulative costs were largely determined by the first two lines of treatment. When comparing sequences with the same 1L treatment, sequences with BTKis in second-line incurred greater costs compared to fixed-duration regimens.

CONCLUSIONS

Overall, the economic impact of treating all patients with VO led to 10-year cumulative savings of CAD 169,341 and CAD 293,731 per patient, without and with TP53 aberration, respectively. These savings are mainly due to reductions in treatment costs associated with fixed treatment duration.

Safety profile of first-line targeted therapies in elderly and/or comorbid chronic lymphocytic leukaemia patients (unfit subpopulation). A systematic review and network meta-analysis

This systematic literature review (CRD42023393903) and a Bayesian network meta-analysis (NMA) aimed to assess the relative safety profile of first-line targeted therapies (acalabrutinib, ibrutinib, obinutuzumab, ofatumumab, pirtobrutinib, ublituximab, umbralisib, venetoclax, zanubrutinib) in chronic lymphocytic leukaemia (CLL) patients with advanced age and/or comorbidities. The NMA revealed that zanubrutinib was the safest treatment option in terms of the overall safety profile (e.g., serious adverse events [AEs] grade 1-5), followed by venetoclax-obinutuzumab, which showed an advantage in terms of AEs grade 1-5. The use of Bruton's tyrosine kinase inhibitor (BTKi) monotherapy was more favourable in terms of the risk of haematological AEs, but chemoimmunotherapy showed advantages in terms of cardiovascular, gastrointestinal, and infectious AEs. The risk of secondary cancers was similar between treatments. In conclusion, targeted therapies are associated with variable and clinically relevant AEs. The therapies appear to be safer when used as monotherapy rather than in combination with immunological agents in naïve CLL patients with advanced age and/or comorbidities.

Understanding the interplay between chronic lymphocytic leukemia and type 2 diabetes

INTRODUCTION

Comorbidities play an important role in the management of chronic lymphocytic leukemia (CLL) and may influence survival and treatment outcomes. Considering the aging general population and increasing incidence of type 2 diabetes (T2D), a comprehensive understanding of the interplay between CLL and T2D is essential for optimizing care and outcomes.

AREAS COVERED

We present current knowledge on co-existing CLL and T2D including prevalence, shared etiology and risk factors and how the conditions and treatment hereof may influence the outcome of one another. A literature search was performed using PubMed with the cutoff date on 1 February 2024.

EXPERT OPINION

The increased mortality observed in persons with CLL who have co-existing T2D is partially ascribed to infections, prompting physicians managing individuals with both conditions to consider closer monitoring during instances of infection and individualized prophylaxis. People with CLL and T2D should be managed for CLL in accordance with the international working group on CLL criteria, and we recommend that physicians exercise particular care not to delay treatment for these individuals. Multidisciplinary approaches with involvement of several specialties may be required for optimal supportive care of co-occurring T2D and CLL.

Severe infections in patients with chronic lymphocytic leukemia included in trials investigating BTK and BCL2 inhibitors

Bruton tyrosine kinase inhibitors (BTKi) and the BCL-2 inhibitor venetoclax have significantly improved the prognosis of patients with chronic lymphocytic leukemia (CLL). However, the incidence of severe infections in patients receiving these agents needs to be better understood. Our review aimed to provide an overview of grade ≥3 infections in patients with CLL who received BTKi and venetoclax-based therapy in prospective trials. Infection rates were influenced by the age of patients and the duration of follow-up. For treatment-naive (TN) patients receiving BTKi, infection rates ranged between 11.4 % and 27.4 % and were close to 30 % in relapsed/refractory (R/R) patients. TN and R/R patients receiving fixed-duration venetoclax-based treatments showed variable rates, with maximum values around 20 %. Opportunistic and fatal infections were uncommon. In conclusion, infections remain a concern in patients with CLL receiving targeted agents. A better definition of factors increasing infection vulnerability could help identify those patients who require infection prophylaxis.

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.

Chronic lymphocytic leukaemia

The last decade has seen remarkable progress in our understanding of disease biology of chronic lymphocytic leukaemia (CLL) and the development of novel targeted therapies. Randomised clinical trials have reported improved progression-free survival and overall survival with targeted therapies compared with chemoimmunotherapy, and thereby the role of chemoimmunotherapy in todays' era for treatment of CLL is limited. Bruton tyrosine kinase (BTK) inhibitors, BCL2 inhibitors, and CD20 monoclonal antibodies have been established as appropriate therapy options for patients with CLL, both as the first-line treatment and in the treatment of relapsed or refractory CLL. Several ongoing phase 3 trials are exploring different combinations of targeted therapies, and the results of these trials might change the treatment framework in first-line treatment of CLL. Non-covalent BTK inhibitors, chimeric antigen receptor T-cell therapy, and other therapeutic strategies are being investigated in relapsed CLL. Some of the therapies used in relapsed CLL, such as non-covalent BTK inhibitors, are now being pursued in earlier lines of therapy, including first-line treatment of CLL.

Targeting the tumor microenvironment for treating double-refractory chronic lymphocytic leukemia

ABSTRACT

The introduction of BTK inhibitors and BCL2 antagonists to the treatment of chronic lymphocytic leukemia (CLL) has revolutionized therapy and improved patient outcomes. These agents have replaced chemoimmunotherapy as standard of care. Despite this progress, a new group of patients is currently emerging, which has become refractory or intolerant to both classes of agents, creating an unmet medical need. Here, we propose that the targeted modulation of the tumor microenvironment provides new therapeutic options for this group of double-refractory patients. Furthermore, we outline a sequential strategy for tumor microenvironment-directed combination therapies in CLL that can be tested in clinical protocols.

BTK inhibitors: past, present, and future

Bruton's tyrosine kinase (BTK) inhibitors have revolutionized the treatment landscape for B cell lymphomas such as chronic lymphocytic leukemia (CLL). The first-in-class BTK inhibitor ibrutinib has recently been succeeded by covalent BTK inhibitors that are safer but still face challenges of resistance mutations. The noncovalent BTK inhibitor pirtobrutinib was recently approved for relapsed and refractory CLL, and whether noncovalent BTK inhibitors will supplant covalent BTK inhibitors as upfront treatment options either alone or in combination will be determined. Meanwhile, newer BTK inhibitors and BTK degraders are vying for their place in the potential future landscape of B cell cancers as well as autoimmune diseases. This review will cover the latest progress in BTK inhibitor development and where the field is moving in light of these recent discoveries.

Acalabrutinib, venetoclax, and obinutuzumab in relapsed/refractory CLL: final efficacy and ctDNA analysis of the CLL2-BAAG trial

ABSTRACT

The phase 2 CLL2-BAAG trial tested the measurable residual disease (MRD)-guided triple combination of acalabrutinib, venetoclax, and obinutuzumab after optional bendamustine debulking in 45 patients with relapsed/refractory chronic lymphocytic leukemia (CLL). MRD was measured by flow cytometry (FCM; undetectable MRD <10-4) in peripheral blood (PB) and circulating tumor DNA (ctDNA) using digital droplet polymerase chain reaction of variable-diversity-joining (VDJ) rearrangements and CLL-related mutations in plasma. The median number of previous treatments was 1 (range, 1-4); 18 patients (40%) had received a Bruton tyrosine kinase inhibitor (BTKi) and/or venetoclax before inclusion, 14 of 44 (31.8%) had TP53 aberrations, and 34 (75.6%) had unmutated immunoglobulin heavy-chain variable region genes. With a median observation time of 36.3 months and all patients off-treatment for a median of 21.9 months, uMRD <10-4 in PB was achieved in 42 of the 45 patients (93.3%) at any time point, including 17 of 18 (94.4%) previously exposed to venetoclax/BTKi and 13 of 14 (92.9%) with TP53 aberrations. The estimated 3-year progression-free and overall survival rates were 85.0% and 93.8%, respectively. Overall, 585 paired FCM/ctDNA samples were analyzed and 18 MRD recurrences (5 with and 13 without clinical progression) occurred after the end of treatment. Twelve samples were first detected by ctDNA, 3 by FCM, and 3 synchronously. In conclusion, time-limited MRD-guided acalabrutinib, venetoclax, and obinutuzumab achieved deep remissions in almost all patients with relapsed/refractory CLL. The addition of ctDNA-based analyses to FCM MRD assessment seems to improve early detection of relapses. This trial was registered at www.clinicaltrials.gov as #NCT03787264.

Realizing precision medicine in chronic lymphocytic leukemia: Remaining challenges and potential opportunities

Patients with chronic lymphocytic leukemia (CLL) exhibit diverse clinical outcomes. An expanding array of genetic tests is now employed to facilitate the identification of patients with high-risk disease and inform treatment decisions. These tests encompass molecular cytogenetic analysis, focusing on recurrent chromosomal alterations, particularly del(17p). Additionally, sequencing is utilized to identify TP53 mutations and to determine the somatic hypermutation status of the immunoglobulin heavy variable gene. Concurrently, a swift advancement of targeted treatment has led to the implementation of novel strategies for patients with CLL, including kinase and BCL2 inhibitors. This review explores both current and emerging diagnostic tests aimed at identifying high-risk patients who should benefit from targeted therapies. We outline existing treatment paradigms, emphasizing the importance of matching the right treatment to the right patient beyond genetic stratification, considering the crucial balance between safety and efficacy. We also take into consideration the practical and logistical issues when choosing a management strategy for each individual patient. Furthermore, we delve into the mechanisms underlying therapy resistance and stress the relevance of monitoring measurable residual disease to guide treatment decisions. Finally, we underscore the necessity of aggregating real-world data, adopting a global perspective, and ensuring patient engagement. Taken together, we argue that precision medicine is not the mere application of precision diagnostics and accessibility of precision therapies in CLL but encompasses various aspects of the patient journey (e.g., lifestyle exposures and comorbidities) and their preferences toward achieving true personalized medicine for patients with CLL.