ASCEND: Phase III, Randomized Trial of Acalabrutinib Versus Idelalisib Plus Rituximab or Bendamustine Plus Rituximab in Relapsed or Refractory Chronic Lymphocytic Leukemia

Efficacy of venetoclax plus rituximab for relapsed CLL: 5-year follow-up of continuous or limited- duration therapy

We report long-term follow-up of the phase 1b study of venetoclax and rituximab (VenR) in patients with relapsed chronic lymphocytic leukemia (CLL), including outcomes with continuous or limited-duration therapy. Patients received venetoclax daily (200-600 mg) and rituximab over 6 months and then received venetoclax monotherapy. Patients achieving complete response (CR), CR with incomplete marrow recovery (CRi), or undetectable minimal residual disease (uMRD) assessed by flow cytometry (<10-4 cutoff) were allowed, but not required, to discontinue therapy, while remaining in the study and could be retreated with VenR upon progression. Median follow-up for all patients (N = 49) was 5.3 years. Five-year rates (95% CI) for overall survival, progression-free survival, and duration of response were 86% (72-94), 56% (40-70), and 58% (40-73), respectively. Of the 33 deep responders (CR/CRi or uMRD), 14 remained on venetoclax monotherapy (continuous therapy), and 19 stopped venetoclax therapy (limited-duration therapy) after a median of 1.4 years. Five-year estimates of ongoing response were similar between continuous (71%; 95% CI, 39-88) or limited-duration therapy (79% [49-93]). Six of 19 patients in the latter group had subsequent disease progression, all >2 years off venetoclax (range, 2.1-6.4). Four patients were retreated with VenR, with partial responses observed in the 3 evaluable to date. VenR induced deep responses that were highly durable with either continuous or limited-duration therapy. Retreatment with VenR induced responses in patients with CLL progression after discontinuing therapy. Continuous exposure to venetoclax in deep responders does not appear to provide incremental benefit.

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

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

How I treat and prevent venous thrombotic complications in patients with lymphoma

Venous thromboembolism (VTE) is a common complication occurring in 5-10% of patients with lymphoma. As the complexity of lymphoma management has increased with novel therapies, so too has the treatment of VTE. Therapeutic options for the treatment of cancer-associated VTE have expanded from only warfarin and low-molecular-weight heparins (LMWHs) to include the direct oral anticoagulants (DOACs) apixaban, edoxaban and rivaroxaban. There have been no head-to-head trials comparing different DOACs in this setting and randomized trials comparing a DOAC with LMWH dalteparin differ in trial design and results. Drug-drug interactions, drug-specific side effects and patient selection are important considerations when prescribing anticoagulant therapy. In all patients, the relative risks of thrombosis and bleeding, the availability of the anticoagulant, and the life expectancy of the patient are vital elements in selecting the most appropriate anticoagulant (which can vary over time) for the individual patient. We describe the intricacies and challenges of treating thrombotic complications in patients with lymphoma with an emphasis on evidence and guideline-based care.

Cell therapy of chronic lymphocytic leukaemia: Transplants and chimeric antigen receptor (CAR)-T cells

There is substantial progress in the therapy of chronic lymphocytic leukaemia (CLL), much of it the result of new drug development. As such the definition of high-risk CLL is changing. Nevertheless, few persons with CLL are cured with current therapy. Two types of cell therapies of CLL are currently being evaluated or re-evaluated in the context of these advances: haematopoietic cell transplants and chimeric antigen receptor (CAR)-T-cells. We discuss the potential role of these cell therapies in the context of the evolving therapy topography of CLL including how these therapies work and who, if anyone, is an appropriate candidate for cell therapy.

Phase II study of acalabrutinib in ibrutinib-intolerant patients with relapsed/refractory chronic lymphocytic leukemia

B-cell receptor signaling inhibition by targeting Bruton tyrosine kinase (BTK) is effective in treating chronic lymphocytic leukemia. The BTK inhibitor ibrutinib may be intolerable for some patients. Acalabrutinib is a more selective BTK inhibitor that may be better tolerated by patients who are intolerant to ibrutinib. A phase II study of acalabrutinib was conducted in patients with relapsed/refractory chronic lymphocytic leukemia who were ibrutinib-intolerant and had continued disease activity. Intolerance was defined as having discontinued ibrutinib due to persistent grade 3/4 adverse events or persistent/recurrent grade 2 adverse events despite dose modification/interruption. Patients received oral acalabrutinib 100 mg twice daily until disease progression or intolerance. Sixty patients were treated. The overall response rate to acalabrutinib was 73% and three patients (5%) achieved complete remission. At a median follow-up of 35 months, the median progression-free and overall survival were not reached; 24-month estimates were 72% and 81%, respectively. The most frequent adverse events with acalabrutinib were diarrhea (53%), headache (42%), contusion (40%), dizziness (33%), upper respiratory tract infection (33%), and cough (30%). The most common reasons for acalabrutinib discontinuation were progressive disease (23%) and adverse events (17%). Most patients with baseline samples (49/52; 94%) and all with on-treatment samples (3/3; 100%) had no detectable BTK and/or PLCG2 mutations. Acalabrutinib is effective and tolerable in most patients with relapsed/refractory chronic lymphocytic leukemia who are intolerant of ibrutinib. Acalabrutinib may be useful for patients who may benefit from BTK inhibitor therapy but are ibrutinib intolerant. ClinicalTrials.gov identifier: NCT02717611.

The Chronic Lymphocytic Leukemia Comorbidity Index (CLL-CI): A Three-Factor Comorbidity Model

PURPOSE

Comorbid medical conditions define a subset of patients with chronic lymphocytic leukemia (CLL) with poor outcomes. However, which comorbidities are most predictive remains understudied.

EXPERIMENTAL DESIGN

We conducted a retrospective analysis from 10 academic centers to ascertain the relative importance of comorbidities assessed by the cumulative illness rating scale (CIRS). The influence of specific comorbidities on event-free survival (EFS) was assessed in this derivation dataset using random survival forests to construct a CLL-specific comorbidity index (CLL-CI). Cox models were then fit to this dataset and to a single-center, independent validation dataset.

RESULTS

The derivation and validation sets comprised 570 patients (59% receiving Bruton tyrosine kinase inhibitor, BTKi) and 167 patients (50% receiving BTKi), respectively. Of the 14 CIRS organ systems, three had a strong and stable influence on EFS: any vascular, moderate/severe endocrine, moderate/severe upper gastrointestinal comorbidity. These were combined to create the CLL-CI score, which was categorized into 3 risk groups. In the derivation dataset, the median EFS values were 58, 33, and 20 months in the low, intermediate, and high-risk groups, correspondingly. Two-year overall survival (OS) rates were 96%, 91%, and 82%. In the validation dataset, median EFS values were 81, 40, and 23 months (two-year OS rates 97%/92%/88%), correspondingly. Adjusting for prognostic factors, CLL-CI was significantly associated with EFS in patients treated with either chemo-immunotherapy or with BTKi in each of our 2 datasets.

CONCLUSIONS

The CLL-CI is a simplified, CLL-specific comorbidity index that can be easily applied in clinical practice and correlates with survival in CLL.

Tafasitamab combined with idelalisib or venetoclax in patients with CLL previously treated with a BTK inhibitor

Patients with relapsed/refractory chronic lymphocytic leukemia (R/R CLL) whose treatment failed with a Bruton's tyrosine kinase inhibitor have poor outcomes. We investigated tafasitamab plus idelalisib (cohort A) or venetoclax (cohort B) in this patient population in a phase II study (NCT02639910). In total, 24 patients were enrolled (cohort A: n = 11, median time on study, 7.4 months; cohort B: n = 13, median time on study, 15.6 months). The most common treatment-emergent adverse event (TEAE) in cohort A was anemia (63.6%) and in cohort B was infusion-related reaction (53.8%). The most common severe TEAE was neutropenia (cohort A: 45.5%; cohort B: 46.2%). The best overall response rate was 90.9% (cohort A) and 76.9% (cohort B). Undetectable minimal residual disease in peripheral blood was achieved in 2/8 patients (cohort A) and 6/7 patients (cohort B). Overall, these results suggest that anti-CD19 antibody-based combinations may be important in the treatment of patients with CLL.

The future of antibody therapy in chronic lymphocytic leukemia

INTRODUCTION

Outcomes in chronic lymphocytic leukemia (CLL) have been dramatically improved with the addition of anti-CD20 antibodies to chemotherapy, defining a new standard of care for many years. More recently, therapies targeting fundamental signaling and anti-apoptotic pathways within the CLL cell have demonstrated dramatic clinical responses, including in patients with high-risk prognostic markers, thus emerging as preferred therapy for many patients. While the addition of anti-CD20 antibodies to traditional chemotherapy resulted in significant improvements in outcomes, the role of monoclonal antibodies in the era of targeted agents remains an active area of investigation. Furthermore, since the advent of next-generation anti-CD20 antibodies, the role of specific anti-CD20 antibodies remains an open question.

AREAS COVERED

In this review, we highlight the important role that anti-CD20 antibody therapy has had in the field of CLL, both when used with chemotherapy and in combination with targeted therapy, as well as the current studies that are further exploring this treatment paradigm in the modern era.

EXPERT OPINION

While anti-CD20 antibodies have played a pivotal role in the treatment of CLL, additional studies will be required to determine the optimal application of these therapies in combination with targeted therapy.

Bruton's tyrosine kinase Inhibitors and Cardiotoxicity: More Than Just Atrial Fibrillation

Purpose of Review

The purpose of this review is to summarize the epidemiology, mechanisms, and management of cardiovascular complications of Bruton’s Tyrosine Kinase inhibitors (BTKIs).

Recent Findings

Ibrutinib increases the risk of atrial fibrillation, bleeding, and hypertension compared with non-BTKI therapies. The evidence to support an association between ibrutinib and other cardiovascular complications including ventricular tachyarrhythmias or cardiomyopathy is limited. Ibrutinib metabolism can be inhibited by some medications used to treat cardiovascular complications. The cardiovascular effects of more selective BTKIs, such as acalabrutinib, remain to be determined.

Summary

Future research should address the mechanisms underlying the cardiovascular complications of BTKIs and how best to manage them. The risks and benefits of more selective BTKIs as compared with ibrutinib require further evaluation.

Acalabrutinib in management of chronic lymphocytic leukemia: An Indian perspective

The treatment landscape of chronic lymphocytic leukemia (CLL) has witnessed immense changes in the past decade. Several newer target therapies and their combinations with anti‐CD 20 therapies have got approval for management of CLL in the treatment‐naïve and relapsed/refractory setting. Also, the availability of newer diagnostic techniques has helped differentiate the disease into high‐ and low‐risk CLL which acts not just as a prognostic marker but also helps decide the best drug management that can be administered to the patients. Targeted therapy has largely overtaken chemoimmunotherapy in the management of CLL, except for a small subset of the population (young and fit with IGHV mutation). However, with targeted therapy, there is also an issue of previously uncommon treatment‐emergent adverse events, the duration of therapy, and financial toxicity. The aim of this review article is to gather results from all landmark CLL trials and discuss the feasibility of incorporating Acalabrutinib in the CLL landscape from an Indian perspective.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Resistance to Bruton's Tyrosine Kinase Inhibitors: The Achilles Heel of Their Success Story in Lymphoid Malignancies

Bruton's tyrosine kinase inhibitors (BTKi) have significantly changed the treatment landscape for patients with B-cell malignancies including chronic lymphocytic leukemia (CLL), Waldenstrom's macroglobulinemia (WM), mantle cell lymphoma (MCL), and marginal zone lymphoma (MZL). Unfortunately, patients with BTKi resistant disease have shortened survival. Clinical and molecular risk factors, such as number of prior therapies and presence of TP53 mutations, can be used to predict patients at the highest risk of developing BTKi resistance. Many mechanisms of BTKi resistance have been reported with mutations in BTK and phospholipase C g 2 supported with the most data. The introduction of venetoclax has lengthened the survival of patients with BTKi resistant disease. Ongoing clinical trials with promising treatment modalities such as next-generation BTKi and chimeric antigen receptor T-cell therapy have reported promising efficacy in patients with BTKi resistant disease. Continued research focusing on resistance mechanisms and methods of how to circumvent resistance is needed to further prolong the survival of patients with BTKi resistant B-cell malignancies.

Treating CLL with Bruton Tyrosine Kinase Inhibitors: The Role of the Outpatient Oncology Nurse

OBJECTIVES

To summarize the role of Bruton tyrosine kinase (BTK) inhibitors in the management of chronic lymphocytic leukemia with a focus on the nursing role in relation to patients with chronic lymphocytic leukemia being treated with BTK inhibitors.

DATA SOURCES

These include published articles (PubMed) and national and international guideline documents.

CONCLUSION

BTK inhibitors have revolutionized the therapy of chronic lymphocytic leukemia and have become the most frequently used therapy today. Despite the many advantages of BTK inhibitors, adverse events remain a leading cause of treatment discontinuation, particularly for the first-in-class BTK inhibitor. Second-generation BTK inhibitors appear to have a better tolerability profile but still require adverse event management given their prolonged duration of therapy. Awareness and management of side effects by the oncology care team is essential for ensuring both compliance and safety with ongoing treatment.

IMPLICATIONS FOR NURSING PRACTICE

Chronic lymphocytic leukemia is a chronic illness with a long-life expectancy. For the patients who require therapy, BTK inhibitor therapy is a frequently applied treatment with impressive efficacy. BTK inhibitors are continued indefinitely until disease progression or significant toxicity; therefore, the overall principles of careful assessment for side effects, diligent management for these, and individualized patient support provided by oncology nurses is vital in this patient population.

Integrating New Therapies for Chronic Lymphocytic Leukemia

ABSTRACT

Over the last 2 decades, treatment of chronic lymphocytic leukemia (CLL) therapy has drastically changed, resulting in greatly improved survival and treatment tolerance with current targeted therapies. First, the transition from chemotherapy (alkylating agents, nucleoside analogs) to chemoimmunotherapy with the addition of anti-CD20 antibodies resulted in deeper and more complete remissions, with an improvement in progression-free and overall survival. Over the last few years, chemoimmunotherapy has gradually been replaced by new targeted agents, based on further improvement in survival, especially in patients with high-risk CLL, and fewer adverse effects, that is, a lack of myelosuppression and lack of DNA damage and associated risk of secondary acute myeloid leukemia/myelodysplastic syndrome. The most active targeted treatments for CLL patients are the kinase inhibitors, which inhibit signaling of surface receptors, especially the B-cell antigen receptor, and the BCL-2 antagonist venetoclax. Among the kinase inhibitors, Bruton tyrosine kinase inhibitors are highly effective and generally well-tolerated and induce durable responses in the vast majority of patients. PI3 kinase inhibitors are alternatives for patients with intolerance to Bruton tyrosine kinase inhibitors. This review discusses the rationale for the transition from chemotherapy-based treatment to the novel agents, the activity, adverse effects, sequencing, and combinations of the novel agents and provides an outlook into future CLL therapy for the next decade.

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

ABSTRACT

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

Challenges with Approved Targeted Therapies against Recurrent Mutations in CLL: A Place for New Actionable Targets

Chronic lymphocytic leukemia (CLL) is characterized by a high degree of genetic variability and interpatient heterogeneity. In the last decade, novel alterations have been described. Some of them impact on the prognosis and evolution of patients. The approval of BTK inhibitors, PI3K inhibitors and Bcl-2 inhibitors has drastically changed the treatment of patients with CLL. The effect of these new targeted therapies has been widely analyzed in TP53-mutated cases, but few data exist about the response of patients carrying other recurrent mutations. In this review, we describe the biological pathways recurrently altered in CLL that might have an impact on the response to these new therapies together with the possibility to use new actionable targets to optimize treatment responses.

Targeting Bruton's Tyrosine Kinase in CLL

Targeting the B-cell receptor signaling pathway through BTK inhibition proved to be effective for the treatment of chronic lymphocytic leukemia (CLL) and other B-cell lymphomas. Covalent BTK inhibitors (BTKis) led to an unprecedented improvement in outcome in CLL, in particular for high-risk subgroups with TP53 aberration and unmutated immunoglobulin heavy-chain variable-region gene (IGHV). Ibrutinib and acalabrutinib are approved by the US Food and Drug Administration for the treatment of CLL and other B-cell lymphomas, and zanubrutinib, for patients with mantle cell lymphoma. Distinct target selectivity of individual BTKis confer differences in target-mediated as well as off-target adverse effects. Disease progression on covalent BTKis, driven by histologic transformation or selective expansion of BTK and PLCG2 mutated CLL clones, remains a major challenge in the field. Fixed duration combination regimens and reversible BTKis with non-covalent binding chemistry hold promise for the prevention and treatment of BTKi-resistant disease.

Chemoimmunotherapy in the First-Line Treatment of Chronic Lymphocytic Leukaemia: Dead Yet, or Alive and Kicking?

The paradigm of first-line treatment of chronic lymphocytic leukaemia (CLL) is currently undergoing a radical change. On the basis of several randomised phase III trials showing prolongation of progression-free survival, chemoimmunotherapy is being replaced by treatment based on novel, orally available targeted inhibitors such as Bruton tyrosine kinase inhibitors ibrutinib and acalabrutinib or bcl-2 inhibitor venetoclax. However, the use of these agents may be associated with other disadvantages. First, with the exception of one trial in younger/fit patients, no studies have so far demonstrated benefit regarding the ultimate endpoint of overall survival. Second, oral inhibitors are extremely expensive and thus currently unavailable due to the absence of reimbursement in some countries. Third, treatment with ibrutinib and acalabrutinib necessitates long-term administration until progression; this may be associated with accumulation of late side effects, problems with patient compliance, and selection of resistant clones. Therefore, the identification of a subset of patients who could benefit from chemoimmunotherapy would be ideal. Current data suggest that patients with the mutated variable region of the immunoglobulin heavy chain (IGHV) achieve fairly durable remissions, especially when treated with fludarabine, cyclophosphamide, and rituximab (FCR) regimen. This review discusses current options for treatment-naïve patients with CLL.

Acalabrutinib in treatment-naive chronic lymphocytic leukemia

Acalabrutinib has demonstrated significant efficacy and safety in relapsed chronic lymphocytic leukemia (CLL). Efficacy and safety of acalabrutinib monotherapy were evaluated in a treatment-naive CLL cohort of a single-arm phase 1/2 trial (ACE-CL-001). Adults were eligible for enrollment if chemotherapy was declined or deemed inappropriate due to comorbidities (N = 99). Patients had a median age of 64 years and 47% had Rai stage III/IV disease. Acalabrutinib was administered orally 200 mg once daily, or 100 mg twice daily until progression or intolerance. A total of 99 patients were treated; 57 (62%) had unmutated immunoglobulin heavy-chain variable gene, and 12 (18%) had TP53 aberrations. After median follow-up of 53 months, 85 patients remain on treatment; 14 discontinued treatment, mostly because of adverse events (AEs) (n = 6) or disease progression (n = 3). Overall response rate was 97% (90% partial response; 7% complete response), with similar outcomes among all prognostic subgroups. Because of improved trough BTK occupancy with twice-daily dosing, all patients were transitioned to 100 mg twice daily. Median duration of response (DOR) was not reached; 48-month DOR rate was 97% (95% confidence interval, 90-99). Serious AEs were reported in 38 patients (38%). AEs required discontinuation in 6 patients (6%) because of second primary cancers (n = 4) and infection (n = 2). Grade ≥3 events of special interest included infection (15%), hypertension (11%), bleeding events (3%), and atrial fibrillation (2%). Durable efficacy and long-term safety of acalabrutinib in this trial support its use in clinical management of symptomatic, untreated patients with CLL.

A retrospective observational study to evaluate the clinical outcomes and routine management of patients with chronic lymphocytic leukaemia treated with idelalisib and rituximab in the UK and Ireland (RETRO-idel)

Idelalisib (IDL) is an oral first‐in‐class phosphatidylinositol 3‐kinase delta (PI3Kδ) inhibitor approved for chronic lymphocytic leukaemia (CLL) alongside rituximab (R) since 2014. However, little data exist on routine practice. The RETRO‐idel was a protocol‐led, retrospective study of 110 patients [n = 27 front‐line (1L)] who received IDL‐R. The primary end‐point was clinical overall response rate (ORR). The median (range) follow‐up of the whole cohort was 30·2 (0·1–51·9) months. The median (range) age was 72 (48–89) years. Tumour protein p53‐disruption was common [100% 1L, 32·5% relapsed/refractory (R/R)]. The best ORR (intention‐to‐treat) was 88·2% (1L 96·3%, R/R 85·5%). Overall, the median event‐free survival (mEFS) was 20·3 months and time‐to‐next treatment was 29·2 months. The mEFS for 1L patients was 18·7 months and R/R patients was 21·7 months. The 3‐year overall survival was 56·1% (95% confidence interval 45·7–65·3). IDL was discontinued in 87·3% (n = 96). More patients discontinued due to adverse events in the front‐line setting (1L 63·0% vs. R/R 44·6%) and due to progressive disease in R/R patients (20·5% vs. 3·7% in 1L). Lower respiratory tract infection/pneumonia were reported in 34·5% (Grade ≥3, 19·1%), diarrhoea in 30·9% (Grade ≥3, 6·4%), and colitis in 9·1% (Grade ≥3, 5·5%). Overall, these data describe clear efficacy for IDL‐R in routine practice. No new safety signals were identified, although careful management of known toxicities is required.

Will New Drugs Replace Transplants for Chronic Lymphocytic Leukaemia?

Transplants have been used to treat chronic lymphocytic leukemia (CLL) for more than 35 years. Use has been restricted to <1 percent of highly selected persons typically failing concurrent conventional therapies. As therapies of CLL have evolved, so have indications for transplantation and transplant techniques. The data that we review indicate that transplants can result in long-term leukemia-free survival in some persons but are associated with substantial transplant-related morbidity and mortality. We discuss the mechanisms underlying the anti-leukemia effects of transplants including drugs, ionizing radiations, immune-mediated mechanisms and/or a combination. We discuss prognostic and predicative covariates for transplant outcomes. Importantly, we consider whether there is presently a role of transplants in CLL and who, if anyone, is an appropriate candidate in the context of new drugs.

Bruton Tyrosine Kinase Inhibitors in Chronic Lymphocytic Leukemia: Beyond Ibrutinib

Bruton tyrosine kinase inhibitors have indisputably transformed the treatment landscape of chronic lymphocytic leukemia, but require continuous therapy to maintain response. This places emphasis on their unique toxicity profile and potential loss of efficacy owing to resistance. Data from single-arm clinical studies are suggestive of comparable efficacy and favorable toxicity profiles of next-generation Bruton tyrosine kinase inhibitors. This is supported by the ASPEN study in Waldenstrom's macroglobulinemia, which convincingly demonstrated that zanubrutinib has a better toxicity profile than ibrutinib. Novel, reversible Bruton tyrosine kinase inhibitors are showing the potential to improve long-term efficacy by overcoming common mechanisms of resistance.

Treatment of Chronic Lymphocytic Leukemia After Discontinuation of Bruton's Tyrosine Kinase Inhibitors

The Bruton's tyrosine kinase inhibitors (BTKis) ibrutinib and acalabrutinib have led to durable responses for patients with both treatment-naïve and relapsed/refractory chronic lymphocytic leukemia (CLL). Many patients, however, ultimately discontinue BTKis due to toxicity or progressive CLL. This article reviews the two most common reasons for ibrutinib and acalabrutinib discontinuation, including adverse events as well as CLL progression. The data for specific CLL-directed therapies following BTKi discontinuation, including venetoclax, phosphatidylinositol 3-kinase inhibitors, cellular therapies, and ongoing clinical trials, are reviewed. An evidence-based sequencing algorithm for treatment of CLL following BTKi discontinuation is proposed.

The Evolving Use of Phosphatidylinositol 3-Kinase Inhibitors for the Treatment of Chronic Lymphocytic Leukemia

B cells express 4 phosphatidylinositol 3-kinase (PI3K) isoforms and have a dependence on p110δ for survival. The design of isoform-selective inhibitors is possible, and pharmacologic inhibition of p110δ is toxic to neoplastic chronic lymphocytic leukemia (CLL) cells for both cell-intrinsic and cell-extrinsic reasons. Idelalisib is a first-in-class p110δ inhibitor that exhibits efficacy for the treatment of relapsed CLL irrespective of adverse prognostic features. Duvelisib is a p110γ/δ inhibitor with a similar efficacy and safety profile to idelalisib. Recent data indicate that umbralisib, a p110δ/CK-1ε dual inhibitor, is safe and effective when administered to patients with CLL.

First-Line Therapy for Chronic Lymphocytic Leukemia: Bruton Tyrosine Kinase or BCL2 or Both?

Novel therapies largely have replaced chemoimmunotherapy as optimal first-line treatment of chronic lymphocytic leukemia (CLL). Approved novel therapies for CLL in the first-line setting include Bruton tyrosine kinase inhibitors, ibrutinib and acalabrutinib, and the BCL2 inhibitor venetoclax. Each of these novel agents has its own unique attributes and they have not been compared head to head in randomized trials. This review summarizes the pivotal trials that led to the approval of novel agents and compares the features of each agent to guide treatment decisions in treatment-naïve CLL. Ongoing studies investigating combinations of novel agents in the first-line setting also are discussed.

Frontline Treatment for Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL): Targeted Therapy vs. Chemoimmunotherapy

PURPOSE OF REVIEW

The treatment options for chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) have expanded significantly in the last few years, including the use of new classes of oral small molecular inhibitors targeting the B cell receptor signaling pathway or the apoptosis machinery. Targeted therapy with or without immunotherapy has quickly emerged as a new standard for frontline treatment of CLL/SLL, though the previous standard chemoimmunotherapy (CIT) remains a treatment option. In this review, we present data from key clinical trials to evaluate the benefits and risks associated with different frontline treatment approaches.

RECENT FINDINGS

We reviewed recently published and presented clinical trials on frontline CLL/SLL treatment, with particular focus on the comparison of CIT vs. targeted therapies, including inhibitors of Bruton's tyrosine kinase (BTK) or of the anti-apoptotic protein Bcl-2. Various BTK inhibitors as continuous treatment with or without anti-CD20 monoclonal antibodies have compared favorably to the conventional CITs in previously untreated CLL/SLL patients of various ages and comorbidities. Fixed duration treatment with the Bcl-2 inhibitor venetoclax combined with anti-CD20 monoclonal antibodies also showed superiority in clinical outcomes compared to CIT. Subgroup analysis interestingly showed that IgHV-mutated CLL/SLL might still derive similar benefits from CIT. Ongoing clinical trials are investigating combined targeted therapies of venetoclax plus a BTK inhibitor to try to further improve the efficacy while limiting the duration of treatment. Targeted therapies are becoming the new standard of care for frontline treatment of CLL/SLL although conventional CIT remains an option group of fit patients with low risk features. Novel strategies are being studied using targeted therapy combinations to optimize the depth of response in a time-limited fashion.

Phase 2 study of the safety and efficacy of umbralisib in patients with CLL who are intolerant to BTK or PI3Kδ inhibitor therapy

Intolerance is the most common reason for kinase inhibitor (KI) discontinuation in chronic lymphocytic leukemia (CLL). Umbralisib, a novel highly selective phosphatidylinositol 3-kinase δ (PI3Kδ)/CK1ε inhibitor, is active and well tolerated in CLL patients. In this phase 2 trial (NCT02742090), umbralisib was initiated at 800 mg/d in CLL patients requiring therapy, who were intolerant to prior BTK inhibitor (BTKi) or PI3K inhibitor (PI3Ki) therapy, until progression or toxicity. Primary end point was progression-free survival (PFS). Secondary end points included time to treatment failure and safety. DNA was genotyped for CYP3A4, CYP3A5, and CYP2D6 polymorphisms. Fifty-one patients were enrolled (44 BTKi intolerant and 7 PI3Kδi intolerant); median age was 70 years (range, 48-96), with a median of 2 prior lines of therapy (range, 1-7), 24% had del17p and/or TP53 mutation, and 65% had unmutated IGHV. Most common adverse events (AEs) leading to prior KI discontinuation were rash (27%), arthralgia (18%), and atrial fibrillation (16%). Median PFS was 23.5 months (95% CI, 13.1-not estimable), with 58% of patients on umbralisib for a longer duration than prior KI. Most common (≥5%) grade ≥3 AEs on umbralisib (all causality) were neutropenia (18%), leukocytosis (14%), thrombocytopenia (12%), pneumonia (12%), and diarrhea (8%). Six patients (12%) discontinued umbralisib because of an AE. Eight patients (16%) had dose reductions and were successfully rechallenged. These are the first prospective data to confirm that switching from a BTKi or alternate PI3Ki to umbralisib in this BTKi- and PI3Ki-intolerant CLL population can result in durable well-tolerated responses.

Current Treatment Options in CLL

After impressive developments in recent years with the rise of new targeted agents, chemoimmunotherapy (CIT) only plays a minor role in the treatment of patients with chronic lymphocytic leukemia (CLL). Inhibitors of the Bruton tyrosine kinase (BTK), such as ibrutinib or more recently acalabrutinib, are highly effective, even in poor-risk or chemo-refractory patients. Venetoclax, an inhibitor of the anti-apoptotic BCL2 protein and, to a lesser extent, phosphoinositide-3 kinase (PI3K) delta inhibitors, add to the armamentarium of targeted agents for the treatment of CLL. Furthermore, anti-CD20 monoclonal antibodies are used very successfully either alone or in combination with BTK, BCL2 or PI3K inhibitors. Despite these advances, there is still an ongoing pursuit for new therapeutic approaches in the treatment of CLL. An even bigger challenge poses the determination of the optimal combination and sequence of those drugs. Here, we give an overview of current treatment options in CLL, weighing the advantages and disadvantages of each approach in the light of different clinical settings.

Acalabrutinib: A Selective Bruton Tyrosine Kinase Inhibitor for the Treatment of B-Cell Malignancies

Bruton tyrosine kinase (BTK) is a validated target for treatment of B-cell malignancies, and oral inhibitors of BTK have emerged as a standard of care for these diseases. Acalabrutinib is a second generation, highly selective, potent, covalent BTK inhibitor that exhibits minimal off-target activity in in vitro assays, providing the potential to improve tolerability over the first-in-class BTK inhibitor, ibrutinib. Acalabrutinib was approved for the treatment of relapsed/refractory mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) in the US in 2017 and 2019, respectively. Acalabrutinib is also undergoing trials for other B-cell malignancies, both as monotherapy and in combinations. In this review, we discuss results from clinical trials evaluating the efficacy and safety of acalabrutinib in patients with CLL, MCL, and Waldenstrom's macroglobulinemia. Recent phase 3 data showed that acalabrutinib improved progression-free survival (PFS) compared with rituximab plus idelalisib or rituximab plus bendamustine in patients with relapsed/refractory CLL, and acalabrutinib with or without obinutuzumab improved PFS compared with chlorambucil plus obinutuzumab in patients with treatment-naïve CLL. Overall, acalabrutinib had a tolerable safety profile, with most adverse events being grade 1/2 severity (most commonly headache and diarrhea) and a low rate of discontinuation due to adverse events.

Allogeneic stem cell transplantation for chronic lymphocytic leukemia in the era of novel agents

Although novel agents (NAs) have improved outcomes for patients with chronic lymphocytic leukemia (CLL), a subset will progress through all available NAs. Understanding outcomes for potentially curative modalities including allogeneic hematopoietic stem cell transplantation (alloHCT) following NA therapy is critical while devising treatment sequences aimed at long-term disease control. In this multicenter, retrospective cohort study, we examined 65 patients with CLL who underwent alloHCT following exposure to ≥1 NA, including baseline disease and transplant characteristics, treatment preceding alloHCT, transplant outcomes, treatment following alloHCT, and survival outcomes. Univariable and multivariable analyses evaluated associations between pre-alloHCT factors and progression-free survival (PFS). Twenty-four-month PFS, overall survival (OS), nonrelapse mortality, and relapse incidence were 63%, 81%, 13%, and 27% among patients transplanted for CLL. Day +100 cumulative incidence of grade III-IV acute graft-vs-host disease (GVHD) was 24%; moderate-severe GVHD developed in 27%. Poor-risk disease characteristics, prior NA exposure, complete vs partial remission, and transplant characteristics were not independently associated with PFS. Hematopoietic cell transplantation-specific comorbidity index independently predicts PFS. PFS and OS were not impacted by having received NAs vs both NAs and chemoimmunotherapy, 1 vs ≥2 NAs, or ibrutinib vs venetoclax as the line of therapy immediately pre-alloHCT. AlloHCT remains a viable long-term disease control strategy that overcomes adverse CLL characteristics. Prior NAs do not appear to impact the safety of alloHCT, and survival outcomes are similar regardless of number of NAs received, prior chemoimmunotherapy exposure, or NA immediately preceding alloHCT. Decisions about proceeding to alloHCT should consider comorbidities and anticipated response to remaining therapeutic options.

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

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

Safety and antitumor activity of acalabrutinib for relapsed/refractory B-cell malignancies: A Japanese phase I study

This multicenter, open-label, phase I study assessed the safety and antitumor activity of acalabrutinib in Japanese patients with relapsed/refractory (r/r) B-cell malignancies. Parts 1 (dose confirmation) and 2 (dose expansion) of this three-part study are reported. Treatment was a single dose of 100 mg acalabrutinib (day 1), followed by a washout period and then twice daily 100 mg acalabrutinib in part 1, or twice daily 100 mg acalabrutinib in part 2. Patients from parts 1 and 2 with r/r chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), and r/r mantle cell lymphoma (MCL) were assessed as r/r CLL/SLL and r/r MCL cohorts, respectively. Twenty-five patients received treatment (part 1, n = 6). Median age was 71.0 years. Nine (one patient from part 1) and 13 (two patients from part 1) patients were included in the r/r CLL/SLL and r/r MCL cohorts, respectively. Treatment-related adverse events (AEs) occurred in 88% of patients (grade ≥3, 36%); the most common were headache (28%) and purpura (24%), both grade 1/2. No AEs resulted in treatment discontinuation or death. Median duration of treatment was 31, 20, and 7 months for part 1, r/r CLL/SLL cohort, and r/r MCL cohort, respectively. Overall response rate (ORR) was 89% and 62% for the r/r CLL/SLL and r/r MCL cohorts, respectively. The median progression-free survival (PFS) was not reached for the r/r CLL/SLL cohort and was 7 months for the r/r MCL cohort. Acalabrutinib (100 mg twice daily) was generally safe and well-tolerated in adult Japanese patients with B-cell malignancies.

Assessment of the effects of Syk and BTK inhibitors on GPVI-mediated platelet signaling and function

Spleen tyrosine kinase (Syk) and Bruton's tyrosine kinase (BTK) play critical roles in platelet physiology, facilitating intracellular immunoreceptor tyrosine-based activation motif (ITAM)-mediated signaling downstream of platelet glycoprotein VI (GPVI) and GPIIb/IIIa receptors. Small molecule tyrosine kinase inhibitors (TKIs) targeting Syk and BTK have been developed as antineoplastic and anti-inflammatory therapeutics and have also gained interest as antiplatelet agents. Here, we investigate the effects of 12 different Syk and BTK inhibitors on GPVI-mediated platelet signaling and function. These inhibitors include four Syk inhibitors, Bay 61-3606, R406 (fostamatinib), entospletinib, TAK-659; four irreversible BTK inhibitors, ibrutinib, acalabrutinib, ONO-4059 (tirabrutinib), AVL-292 (spebrutinib); and four reversible BTK inhibitors, CG-806, BMS-935177, BMS-986195, and fenebrutinib. In vitro, TKIs targeting Syk or BTK reduced platelet adhesion to collagen, dense granule secretion, and alpha granule secretion in response to the GPVI agonist cross-linked collagen-related peptide (CRP-XL). Similarly, these TKIs reduced the percentage of activated integrin αIIbβ3 on the platelet surface in response to CRP-XL, as determined by PAC-1 binding. Although all TKIs tested inhibited phospholipase C γ2 (PLCγ2) phosphorylation following GPVI-mediated activation, other downstream signaling events proximal to phosphoinositide 3-kinase (PI3K) and PKC were differentially affected. In addition, reversible BTK inhibitors had less pronounced effects on GPIIb/IIIa-mediated platelet spreading on fibrinogen and differentially altered the organization of PI3K around microtubules during platelets spreading on fibrinogen. Select TKIs also inhibited platelet aggregate formation on collagen under physiological flow conditions. Together, our results suggest that TKIs targeting Syk or BTK inhibit central platelet functional responses but may differentially affect protein activities and organization in critical systems downstream of Syk and BTK in platelets.

Pooled analysis of safety data from clinical trials evaluating acalabrutinib monotherapy in mature B-cell malignancies

Bruton tyrosine kinase (BTK) inhibition is an effective therapy for many B-cell malignancies. Acalabrutinib is a next-generation, potent, highly selective, covalent BTK inhibitor. To characterize acalabrutinib tolerability, we pooled safety data from 1040 patients with mature B-cell malignancies treated with acalabrutinib monotherapy in nine clinical studies (treatment-naïve: n = 366 [35%], relapsed/refractory: n = 674 [65%]; median [range] age: 67 [32-90] years; median [range] prior treatments: 1 [0-13]; median [range] duration of exposure: 24.6 [0.0-58.5] months). The most common adverse events (AEs) were headache (38%), diarrhea (37%), upper respiratory tract infection (22%), contusion (22%), nausea (22%), fatigue (21%), and cough (21%). Serious AEs (SAEs) occurred in 39% of patients; pneumonia (6%) was the only SAE that occurred in ≥2%. Deaths due to AEs occurred in 52 patients (5%); pneumonia (n = 8) was the only fatal AE to occur in ≥3 patients. AEs led to treatment discontinuation in 9%. Rates for the AEs of interest (all grades) included infections (67%), hemorrhages (46%), neutropenia (16%), anemia (14%), second primary malignancies (12%), thrombocytopenia (9%), hypertension (8%), and atrial fibrillation (4%). This pooled analysis confirmed acalabrutinib's tolerability and identified no newly emerging late toxicities, supporting acalabrutinib as a long-term treatment for patients with mature B-cell malignancies.

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

Simple Summary

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

Abstract

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

Comparison Between Venetoclax-based and Bruton Tyrosine Kinase Inhibitor-based Therapy as Upfront Treatment of Chronic Lymphocytic Leukemia (CLL): A Systematic Review and Network Meta-analysis

BACKGROUND

Available targeted agents (TAs) for the upfront therapy of chronic lymphocytic leukemia (ie, ibrutinib, acalabrutinib, venetoclax) have rarely been compared in head-to-head clinical trials. In search of data for evidence-based treatment decisions, a systematic literature review and network meta-analysis was performed.

MATERIALS AND METHODS

The screening process adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines (PRISMA).

RESULTS

Only 3 trials were suitable for the base-case network analysis (ILLUMINATE, ELEVATE-TN, and CLL14). Regarding progression-free survival (PFS), fixed-effect analyses comparing ibrutinib-obinutuzumab (IO) with venetoclax-obinutuzumab (VO) (relative risk [RR], 1.52; 95% confidence interval [CI], 0.82-2.81), acalabrutinib (A) with IO (RR, 0.87; 95% CI, 0.47-1.61), and A with VO (RR, 0.57; 95% CI, 0.32-1.01) revealed that the upper limit of the 95% CI for RR did exceed the 1.0 value. This indicates a lack of significant difference in PFS for IO, VO, and A. In contrast, acalabrutinib plus obinutuzumab (AO) improved PFS in comparison with IO (RR, 0.43; 95% CI, 0.22-0.87) and VO (RR, 0.29; 95% CI, 0.15-0.56). No differences in the frequency of adverse events was observed across different TAs. Also, the analysis of PFS in relationship with high-risk genetic features (ie, TP53 aberrations, IGHV unmutated, 11q deletion) showed similar results for different TAs. However, patients with unmutated IGHV status fared better with AO than with VO in terms of PFS.

CONCLUSIONS

This systematic review and network meta-analysis indicated that upfront AO prolongs PFS in comparison with IO and VO, whereas no differences are observed between IO, VO, and single-agent A. Hopefully, ongoing studies will further delineate the position of different TAs in chronic lymphocytic leukemia therapy based on effectiveness, availability, safety, cost, and treatment objectives.

Real Life Use of Bendamustine in Elderly Patients with Lymphoid Neoplasia

BACKGROUND

Bendamustine is a cytotoxic alkylating drug with a broad range of indications as a single agent or in combination therapy in lymphoid neoplasia patients. However, its tolerability in elderly patients is still debated.

METHODS

An observational, retrospective study was carried out; patients with chronic lymphocytic leukemia (CLL) or lymphoma, aged ≥ 65 years old, treated with bendamustine-based regimens in first or subsequent lines between 2010 and 2020 were considered eligible.

RESULTS

Overall, 179 patients aged ≥ 65 years were enrolled, 53% between 71 and 79 years old. Cumulative Illness Rating Scale (CIRS) comorbidity score was ≥6 in 54% patients. Overall survival (OS) at 12 months was 95% (95% confidence interval [CI]: 90-97%); after a median follow up of 50 months, median OS was 84 months. The overall response rate was 87%, with 56% complete responses; the median time to progression (TTP) was 61 months. The baseline factors affecting OS by multivariable analysis were sex, histological diagnosis, renal function, and planned bendamustine dose, while only type of lymphoma and bendamustine dose impacted on TTP. Main adverse events were neutropenia (grade ≥ 3: 43%) and infections (any grade: 36%), with 17% of patients requiring hospital admission.

CONCLUSIONS

The responses to bendamustine, as well as survival, are relevant even in advanced age patients, with a manageable incidence of acute toxicity.

Incorporating Novel Targeted and Immunotherapeutic Agents in Treatment of B-Cell Lymphomas

The introduction of novel targeted agents and immunotherapeutic modalities into the treatment of B-cell lymphomas has drastically shifted the treatment landscape. In diffuse large B-cell lymphoma, recent approvals of CAR T-cell therapy, the antibody-drug conjugate polatuzumab, and the anti-CD19 monoclonal antibody tafasitamab have provided efficacious options for patients with relapsed and refractory disease. These immunotherapies attempt to harness power from the patient's own immune system to eradicate lymphoma. In chronic lymphocytic leukemia, oral targeted kinase inhibitors such as ibrutinib and acalabrutinib (Bruton tyrosine kinase inhibitors) and venetoclax (BCL2 inhibitor) are now favored over chemoimmunotherapy for upfront treatment because of improved progression-free survival across all subgroups (including high-risk subgroups such as unmutated immunoglobulin variable heavy chain and chromosome 17p deletion). In indolent lymphomas, several PI3K inhibitors are approved for treatment of relapsed disease. However, uptake of these agents has been limited because of toxicity concerns. Combination of lenalidomide and rituximab has been a safe and effective immune modality for patients with refractory indolent lymphomas; it is currently being used as a backbone to bring other targeted agents such as tazemetostat (EZH2 inhibitor) into earlier lines of treatment. In this article, we will review novel commercially available agents in the treatment of relapsed/refractory diffuse large B-cell lymphoma, treatment-naïve chronic lymphocytic leukemia, and relapsed/refractory indolent lymphomas. We will evaluate clinical trials that led to their approval and will provide an outlook into the future novel agents currently under investigation in B-cell malignancies.

PI3K Inhibitors in Cancer: Clinical Implications and Adverse Effects

The phospatidylinositol-3 kinase (PI3K) pathway is a crucial intracellular signaling pathway which is mutated or amplified in a wide variety of cancers including breast, gastric, ovarian, colorectal, prostate, glioblastoma and endometrial cancers. PI3K signaling plays an important role in cancer cell survival, angiogenesis and metastasis, making it a promising therapeutic target. There are several ongoing and completed clinical trials involving PI3K inhibitors (pan, isoform-specific and dual PI3K/mTOR) with the goal to find efficient PI3K inhibitors that could overcome resistance to current therapies. This review focuses on the current landscape of various PI3K inhibitors either as monotherapy or in combination therapies and the treatment outcomes involved in various phases of clinical trials in different cancer types. There is a discussion of the drug-related toxicities, challenges associated with these PI3K inhibitors and the adverse events leading to treatment failure. In addition, novel PI3K drugs that have potential to be translated in the clinic are highlighted.

Efficacy of idelalisib and rituximab in relapsed/refractory chronic lymphocytic leukemia treated outside of clinical trials. A report of the Gimema Working Group

Because the efficacy of new drugs reported in trials may not translate into similar results when used in the real‐life, we analyzed the efficacy of idelalisib and rituximab (IR) in 149 patients with relapsed/refractory chronic lymphocytic leukemia treated at 34 GIMEMA centers. Median progression‐free survival (PFS) and overall survival were 22.9 and 44.5 months, respectively; performance status (PS) ≥2 and ≥3 previous lines of therapy were associated with shorter PFS and overall survival (OS). 48% of patients were on treatment at 12 months; the experience of the centers (≥5 treated patients) and PS 0–1 were associated with a significantly longer treatment duration (p = 0.015 and p = 0.002, respectively). TP53 disruption had no prognostic significance. The overall response rate to subsequent treatment was 49.2%, with median OS of 15.5 months and not reached in patients who discontinued, respectively, for progression and for toxicity (p < 0.01). Treatment breaks ≥14 days were recorded in 96% of patients and adverse events mirrored those reported in trials. In conclusion, this real‐life analysis showed that IR treatment duration was longer at experienced centers, that the ECOG PS and ≥3 lines of previous therapy are strong prognostic factor and that the overall outcome with this regimen was superimposable to that reported in a randomized trial.

Oral PI3K-δ,γ Inhibitor for the Management of People with Chronic Lymphocytic Leukemia and Small Lymphocytic Lymphoma: A Narrative Review on Duvelisib

The development of highly effective targeted therapies has led to a new treatment paradigm in patients with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL). Despite these advances, many patients will eventually require alternative treatment strategies due to the emergence of tolerability issues or resistance to these novel agents. Duvelisib is a first-in-class, potent oral agent with dual inhibitor activity against the δ and γ isoforms of phosphoinositide 3-kinase (PI3Kδ and PI3Kγ), which are specific to the hematopoietic system. Dysregulation of the PI3K/PTEN/AKT/mTOR pathway has been implicated in cancer cell growth, survival and metabolism and has been the subject of cancer drug development in recent years. Duvelisib demonstrated activity in CLL/SLL in early trials, leading to further evaluation in the Phase 3 DUO trial that compared duvelisib against ofatumumab in patients with relapsed/refractory CLL/SLL. This trial led to the Food and Drug Administration (FDA) approval for the treatment of adult patients with CLL/SLL after at least two prior lines of therapy. The major reason for therapy discontinuation is the development of serious adverse events, which include severe infections and diarrhea/colitis, precluding its widespread use. Ongoing clinical trials are evaluating duvelisib in combination strategies and with alternate dosing schedules in patients with CLL/SLL. With close monitoring, duvelisib can be a promising drug for the treatment of patients with relapsed or refractory CLL/SLL. This review summarizes the relevant clinical data from recent clinical advances in CLL and aims to interpret the duvelisib trials while exploring strategies to improve its use and adverse event management in the era of novel targeted agents.

Heat Shock Proteins in Lymphoma Immunotherapy

Immunotherapy harnessing the host immune system for tumor destruction revolutionized oncology research and advanced treatment strategies for lymphoma patients. Lymphoma is a heterogeneous group of cancer, where the central roles in pathogenesis play immune evasion and dysregulation of multiple signaling pathways. Immunotherapy-based approaches such as engineered T cells (CAR T), immune checkpoint modulators and NK cell-based therapies are now in the frontline of lymphoma research. Even though emerging immunotherapies showed promising results in treating lymphoma patients, low efficacy and on-target/off-tumor toxicity are of a major concern. To address that issue it is suggested to look into the emerging role of heat shock proteins. Heat shock proteins (HSPs) showed to be highly expressed in lymphoma cells. HSPs are known for their abilities to modulate immune responses and inhibit apoptosis, which made their successful entry into cancer clinical trials. Here, we explore the role of HSPs in Hodgkin and Non-Hodgkin lymphoma and their involvement in CAR T therapy, checkpoint blockade and NK cell- based therapies. Understanding the role of HSPs in lymphoma pathogenesis and the ways how HSPs may enhance anti-tumor responses, may help in the development of more effective, specific and safe immunotherapy.

Novel Agents in Chronic Lymphocytic Leukemia: New Combination Therapies and Strategies to Overcome Resistance

Simple Summary

Nowadays, many patients with chronic lymphocytic leukemia (CLL) are treated with so-called novel agents, including BTK inhibitors, Bcl-2 inhibitors and PI3K inhibitors. As CLL is a chronic disease, most patients will relapse on or after treatment with these drugs and various mechanisms behind this resistance to novel agents have been described. In this review, we present the current evidence on resistance to novel agents, discuss approaches to prevent its development and provide guidance on the treatment of patients who have already acquired resistance.

Abstract

The approval of Bruton’s tyrosine kinase (BTK) inhibitors such as ibrutinib and acalabrutinib and the Bcl-2 inhibitor venetoclax have revolutionized the treatment of chronic lymphocytic leukemia (CLL). While these novel agents alone or in combination induce long lasting and deep remissions in most patients with CLL, their use may be associated with the development of clinical resistance. In this review, we elucidate the genetic basis of acquired resistance to BTK and Bcl-2 inhibition and present evidence on resistance mechanisms that are not linked to single genomic alterations affecting these target proteins. Strategies to prevent resistance to novel agents are discussed in this review with a special focus on new combination therapies.

Lessons, Challenges and Future Therapeutic Opportunities for PI3K Inhibition in CLL

Simple Summary

The phosphoinositide 3-kinase (PI3K) is a family of kinases that play a key role in the biology of chronic lymphocytic leukemia (CLL). Inhibitors of PI3K demonstrated efficacy in the treatment of CLL, associated with significant adverse events that limited the clinical use of this drugs. In this review, we underlined the relevance of PI3K inhibitors in CLL, we collected recent data about the use of these molecules in clinical practice and in clinical trial discussing strategies for the management of adverse events, which could help to improve the use of these therapies in the treatment of CLL.

Abstract

Chronic lymphocytic leukemia (CLL) shows constitutive phosphatidylinositol 3-kinase (PI3K) activation resulting from aberrant regulation of the B-cell receptor (BCR) signaling. PI3K inhibitors have been evaluated in CLL therapy, bringing a new treatment opportunity for patients with this disease. Despite the proven therapeutic efficacy, the use of approved PI3K inhibitors is limited by severe immune-mediated toxicities and given the availability of other more tolerable agents. This article reviews the relevance of PI3K signaling and pharmacologic inhibition in CLL. Data on efficacy and toxicity of PI3K inhibitors are also presented, as well as strategies for overcoming barriers for their clinical use in CLL treatment.

Content validity and psychometric evaluation of the Functional Assessment of Chronic Illness Therapy-Fatigue scale in patients with chronic lymphocytic leukemia

PURPOSE

Fatigue is a prominent symptom in individuals with chronic lymphocytic leukemia (CLL). This work evaluates the content validity and psychometric properties of the Functional Assessment of Chronic Illness Therapy-Fatigue scale (FACIT-Fatigue) in patients with CLL to determine if it is fit for purpose in CLL research.

METHODS

The FACIT-Fatigue yields a 13-item total score from a five-item symptom subscale and an eight-item impact subscale. To evaluate content validity, cognitive debriefing interviews were conducted with 40 patients with CLL in the first-line or relapsed or refractory setting. Psychometric properties, including structural validity, internal consistency, construct and known-groups validity, were investigated using data from a phase 3 trial in relapsed or refractory CLL (NCT02970318).

RESULTS

Interviewed patients considered the FACIT-Fatigue items relevant to their CLL experience, understood the terminology and agreed with response options. Confirmatory factor analysis confirmed the presence of symptom and impact subscales, but also supported unidimensionality of the FACIT-Fatigue. The FACIT-Fatigue total, symptom and impact subscales demonstrated good internal consistency (Cronbach's coefficient α > 0.85 and McDonald's omega ω > 0.90), and strong correlations with relevant EORTC QLQ-C30 scales (all Spearman's r ≥ 0.5). Known-groups validity was shown by significant differences between groups defined by baseline performance status, hemoglobin level and constitutional symptoms (all p < .0001). Cluster analysis supported FACIT-Fatigue score thresholds of 30 and 34 to define a severe fatigue population.

CONCLUSIONS

Content validity and psychometric evaluation in patients with CLL demonstrated that the FACIT-Fatigue has good psychometric properties and is fit for purpose in CLL.

Comparative Analysis of BTK Inhibitors and Mechanisms Underlying Adverse Effects

The cytoplasmic protein-tyrosine kinase BTK plays an essential role for differentiation and survival of B-lineage cells and, hence, represents a suitable drug target. The number of BTK inhibitors (BTKis) in the clinic has increased considerably and currently amounts to at least 22. First-in-class was ibrutinib, an irreversible binder forming a covalent bond to a cysteine in the catalytic region of the kinase, for which we have identified 228 active trials listed at ClinicalTrials.gov. Next-generation inhibitors, acalabrutinib and zanubrutinib, are approved both in the United States and in Europe, and zanubrutinib also in China, while tirabrutinib is currently only registered in Japan. In most cases, these compounds have been used for the treatment of B-lymphocyte tumors. However, an increasing number of trials instead addresses autoimmunity and inflammation in multiple sclerosis, rheumatoid arthritis, pemphigus and systemic lupus erythematosus with the use of either irreversibly binding inhibitors, e.g., evobrutinib and tolebrutinib, or reversibly binding inhibitors, like fenebrutinib. Adverse effects (AEs) have predominantly implicated inhibition of other kinases with a BTKi-binding cysteine in their catalytic domain. Analysis of the reported AEs suggests that ibrutinib-associated atrial fibrillation is caused by binding to ERBB2/HER2 and ERBB4/HER4. However, the binding pattern of BTKis to various additional kinases does not correlate with the common assumption that skin manifestations and diarrhoeas are off-target effects related to EGF receptor inhibition. Moreover, dermatological toxicities, diarrhoea, bleedings and invasive fungal infections often develop early after BTKi treatment initiation and subsequently subside. Conversely, cardiovascular AEs, like hypertension and various forms of heart disease, often persist.

Zanubrutinib (BGB-3111), a Second-Generation Selective Covalent Inhibitor of Bruton's Tyrosine Kinase and Its Utility in Treating Chronic Lymphocytic Leukemia

The understanding of the B cell receptor (BCR) pathway and its contribution to chronic lymphocytic leukemia (CLL) pathogenesis have led to the development of targeted BCR inhibitors which have transformed the treatment paradigm of CLL. Ibrutinib is a first-in-class oral Bruton’s tyrosine kinase (BTK) inhibitor which has demonstrated improvements in both progression free (PFS) and overall survival (OS) in both the treatment naïve and relapsed/refractory setting as compared to traditional chemoimmunotherapy. Despite its clinical efficacy, many patients discontinue treatment due to adverse events, which are thought to be mediated through off-target kinase inhibition. Zanubrutinib is a second-generation non-covalent BTK inhibitor with higher potency, allowing for inhibition of BTK with fewer off target effects. Early phase clinical trials have demonstrated excellent efficacy and a well-tolerated safety profile. Long-term follow-up is needed, but zanubrutinib holds promise to be an effective therapy for CLL with a manageable side effect profile and will be an exciting addition to our treatment paradigm.

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

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