Addition of rituximab to fludarabine and cyclophosphamide in patients with chronic lymphocytic leukaemia: a randomised, open-label, phase 3 trial

Should Undetectable Minimal Residual Disease Be the Goal of Chronic Lymphocytic Leukemia Therapy?

With the advent of highly effective novel therapies for chronic lymphocytic leukemia, conventional response assessment is not able to sensitively capture depth of response. To achieve a more precise assessment of response, minimal residual disease has been introduced to more accurately classify and quantify treatment outcomes. It is now considered a strong predictor of outcome in chronic lymphocytic leukemia, although its interpretation depends on the therapeutic context. This review discusses available methods of minimal residual disease measurement. It summarizes minimal residual disease data from pivotal clinical trials and discusses potential implications for future studies and minimal residual disease-based clinical strategies.

Zanubrutinib (BGB-3111) plus obinutuzumab in patients with chronic lymphocytic leukemia and follicular lymphoma

Zanubrutinib (BGB-3111) is a next-generation Bruton tyrosine kinase inhibitor designed to be more selective with fewer off-target effects. We conducted a phase 1 study to assess the safety of its combination with obinutuzumab and evaluate early efficacy in 81 patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) or relapsed/refractory (R/R) follicular lymphoma (FL). In this phase 1b study, zanubrutinib was tolerable at 160 mg twice daily or 320 mg once daily combined with IV obinutuzumab in patients with CLL/SLL (n = 45) and FL (n = 36). Common adverse events (AEs) included upper respiratory tract infection (51%; n = 23), neutropenia (44%; n = 20), contusion (33%; n = 15), cough, diarrhea, or fatigue (27%; n = 12 each), and pyrexia (22%; n = 10) in CLL/SLL patients and upper respiratory tract infection (39%; n = 14), contusion (28%; n = 10), fatigue (25%; n = 9), and cough (22%; n = 8) in FL patients. Neutropenia was the most common grade 3/4 AE (CLL/SLL, 31% [n = 14]; FL, 14% [n = 5]). Five patients required temporary dose reductions, and 5 discontinued the study drug because of AEs. Overall response rate (ORR) was 100% (n = 20) in treatment-naïve CLL patients and 92% (n = 23) in R/R CLL patients. ORR in 36 R/R FL patients was 72% (n = 26), with 14 complete and 12 partial responses. Median follow-up was 29 months (range, 8-37) for CLL patients and 20 months (range, 2-37) for FL patients. Zanubrutinib and obinutuzumab combination therapy was generally well tolerated. This trial was registered at www.clinicaltrials.gov as #NCT02569476.

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.

Discovery of Candidate DNA Methylation Cancer Driver Genes

Epigenetic alterations, such as promoter hypermethylation, may drive cancer through tumor suppressor gene inactivation. However, we have limited ability to differentiate driver DNA methylation (DNAme) changes from passenger events. We developed DNAme driver inference-MethSig-accounting for the varying stochastic hypermethylation rate across the genome and between samples. We applied MethSig to bisulfite sequencing data of chronic lymphocytic leukemia (CLL), multiple myeloma, ductal carcinoma in situ, glioblastoma, and to methylation array data across 18 tumor types in TCGA. MethSig resulted in well-calibrated quantile-quantile plots and reproducible inference of likely DNAme drivers with increased sensitivity/specificity compared with benchmarked methods. CRISPR/Cas9 knockout of selected candidate CLL DNAme drivers provided a fitness advantage with and without therapeutic intervention. Notably, DNAme driver risk score was closely associated with adverse outcome in independent CLL cohorts. Collectively, MethSig represents a novel inference framework for DNAme driver discovery to chart the role of aberrant DNAme in cancer. SIGNIFICANCE: MethSig provides a novel statistical framework for the analysis of DNA methylation changes in cancer, to specifically identify candidate DNA methylation driver genes of cancer progression and relapse, empowering the discovery of epigenetic mechanisms that enhance cancer cell fitness.This article is highlighted in the In This Issue feature, p. 2113.

Ibrutinib combinations in CLL therapy: scientific rationale and clinical results

Ibrutinib has revolutionized the treatment of chronic lymphocytic leukemia (CLL). This drug irreversibly inhibits Bruton tyrosine kinase (BTK) by covalently binding to the C481 residue in the BTK kinase domain. BTK is a pivotal protein for B cell receptor signaling and tissue homing of CLL cells. Preclinical investigations have established the importance of the B cell receptor pathway in the maintenance and survival of normal and malignant B cells, underscoring the importance of targeting this axis for CLL. Clinical trials demonstrated overall and progression-free survival benefit with ibrutinib in multiple CLL subgroups, including patients with relapsed or refractory disease, patients with 17p deletion, elderly patients, and treatment-naïve patients. Consequently, ibrutinib was approved by the US Food and Drug Administration for newly diagnosed and relapsed disease. Ibrutinib has transformed the treatment of CLL; however, several limitations have been identified, including low complete remission rates, development of resistance, and uncommon substantial toxicities. Further, ibrutinib must be used until disease progression, which imposes a financial burden on patients and society. These limitations were the impetus for the development of ibrutinib combinations. Four strategies have been tested in recent years: combinations of ibrutinib with immunotherapy, chemoimmunotherapy, cell therapy, and other targeted therapy. Here, we review the scientific rationale for and clinical outcome of each strategy. Among these strategies, ibrutinib with targeted agent venetoclax results in high complete response rates and, importantly, high rates of undetectable minimal residual disease. Although we concentrate here on ibrutinib, similar combinations are expected or ongoing with acalabrutinib, tirabrutinib, and zanubrutinib, second-generation BTK inhibitors. Future investigations will focus on the feasibility of discontinuing ibrutinib combinations after a defined time; the therapeutic benefit of adding a third agent to ibrutinib-containing combinations; and profiling of resistant clones that develop after combination treatment. A new standard of care for CLL is expected to emerge from these investigations.

Fludarabine-Cyclophosphamide-Rituximab Treatment in Chronic Lymphocytic Leukemia, Focusing on Long Term Cytopenias Before and After the Era of Targeted Therapies

The widespread application of fludarabine, cyclophosphamide, and rituximab combination is limited due to its toxicity, particularly the prolonged cytopenias. The study aimed to compare the prolonged cytopenias depending on fitness and report real-life data on dose reduction measures and efficacy. According to our database, 120 and 14 patients were treated with FCR between 2011 and 2015 and between 2016 and 2019. Out of the first cohort, 34 patients were treated in subsequent lines. The complete and partial remission rate after first-line treatment was 79%, 16% in the first cohort and 86%, 14% in the second cohort, respectively; and 47%, 35% after non first-line treatment. Based on today's standards, only 37.5% of the patients were fit for FCR. The frequency of persistent cytopenia was 14%, and it was significantly associated with fitness (χ ² (1) = 6.001, p = 0.014 for all patients). The small number of FCR treated patients after 2016 shows how the availability of targeted therapies, mostly ibrutinib, in later lines changed the first-line choice. Recently, it is recommended first-line for fit patients with mutated IGHV and no TP53 aberrations. With this narrow indication, a decrease in the frequency of persistent cytopenias is predicted.

Blood cancer health disparities in the United States Hispanic population

Cancer is a challenging, multifaceted disease that involves a combination of biological and nonbiological factors. Aside from COVID-19, cancer is the second leading cause of death in the United States and the first among Hispanic Americans. The Hispanic population is the largest minority group in the United States, which is rapidly growing in size. Unfortunately, U.S. Hispanics and other minority groups experience many different health disparities, resulting in poor survival outcomes and a reduced quality of life. Factors such as genomic mutations, lower socioeconomic status, lack of education, reduced access to health care, comorbidities, and environmental factors all contribute to these health-care inequalities. In the context of blood cancer health disparities, Hispanic patients are often diagnosed at a younger age and have worse outcomes compared with non-Hispanic individuals. In this commentary, we highlight the existing knowledge about cancer health disparities in the Hispanic population, with a focus on chronic and acute leukemia. In our experience at the U.S./Mexican border, analysis of several different blood cancers demonstrated that younger Hispanic patients with acute lymphoid or myeloid leukemia have higher incidence rates and worse prognoses. A combined approach, involving improved health-care access and better knowledge of the underlying factors, will allow for more timely diagnoses and the development of intervention strategies aimed at reducing or eliminating the disparities.

Stimuli-responsive nanoparticles based on poly acrylic derivatives for tumor therapy

Serve side effects caused by discriminate damage of chemotherapeutic drugs to normal cell and cancer cells remain a main obstacle in clinic. Hence, continuous efforts have been made to find ways to effectively enhance drug delivery and reduce side effects. Recent decades have witnessed impressive progresses in fighting against cancer, with improved understanding of tumor microenvironment and rapid development in nanoscale drug delivery system (DDS). Nanocarriers based on biocompatible materials provide possibilities to improve antitumor efficiency and minimize off-target effects. Among all kinds of biocompatible materials applied in DDS, polymeric acrylic derivatives such as poly(acrylamide), poly(acrylic acid), poly(N-isopropylacrylamide) present inherent biocompatibility and stimuli-responsivity, and relatively easy to be functionalized. Furthermore, nanocarrier based on polymeric acrylic derivatives have demonstrated high drug encapsulation, improved uptake efficiency, prolonged circulation time and satisfactory therapeutic outcome in tumor. In this review, we aim to discuss recent progress in design and development of stimulus-responsive poly acrylic polymer based nanocarriers for tumor targeting drug delivery.

Of Lymph Nodes and CLL Cells: Deciphering the Role of CCR7 in the Pathogenesis of CLL and Understanding Its Potential as Therapeutic Target

The lymph node (LN) is an essential tissue for achieving effective immune responses but it is also critical in the pathogenesis of chronic lymphocytic leukemia (CLL). Within the multitude of signaling pathways aberrantly regulated in CLL the homeostatic axis composed by the chemokine receptor CCR7 and its ligands is the main driver for directing immune cells to home into the LN. In this literature review, we address the roles of CCR7 in the pathophysiology of CLL, and how this chemokine receptor is of critical importance to develop more rational and effective therapies for this malignancy.

A phase II Japanese trial of fludarabine, cyclophosphamide and rituximab for previously untreated chronic lymphocytic leukemia

Objective

Fludarabine, cyclophosphamide and rituximab (FCR) is the standard regimen for fit patients with untreated CD20-positive chronic lymphocytic leukemia (CLL). However, this combination is unavailable in Japan because rituximab is not approved for CLL. We investigated the efficacy and safety of FCR in this single-arm, multicenter study designed as a bridging study to the CLL8 study by the German CLL Study Group.

Methods

The study enrolled previously untreated patients with CLL of Binet stage B or C with active disease. Patients with a Cumulative Illness Rating Scale score of ≤6 and creatinine clearance of ≥70 ml/min were eligible. Patients received 6 cycles of FCR every 28 days and were followed for up to 1 year.

Results

Seven patients were enrolled. The best overall response rate according to the 1996 NCI-WG Guidelines, the primary endpoint of the study, was 71.4% (95% confidence interval, 29.0–96.3%), with one patient achieving complete response. No deaths or progression occurred during follow-up. The main adverse event was hematotoxicity. CD4-positive T-cell count decreased in all patients; most patients showed no reduction in serum immunoglobulin G.

Conclusion

Although the number of patients was limited, FCR appears to be effective with manageable toxicity for treatment-naïve fit Japanese patients with CD20-positive CLL.

Clinical trial number

JapicCTI-132285.

Macrophage hypophagia as a mechanism of innate immune exhaustion in mAb-induced cell clearance

Macrophage antibody (Ab)-dependent cellular phagocytosis (ADCP) is a major cytotoxic mechanism for both therapeutic unconjugated monoclonal Abs (mAbs) such as rituximab and Ab-induced hemolytic anemia and immune thrombocytopenia. Here, we studied the mechanisms controlling the rate and capacity of macrophages to carry out ADCP in settings of high target/effector cell ratios, such as those seen in patients with circulating tumor burden in leukemic phase disease. Using quantitative live-cell imaging of primary human and mouse macrophages, we found that, upon initial challenge with mAb-opsonized lymphocytes, macrophages underwent a brief burst (<1 hour) of rapid phagocytosis, which was then invariably followed by a sharp reduction in phagocytic activity that could persist for days. This previously unknown refractory period of ADCP, or hypophagia, was observed in all macrophage, mAb, and target cell conditions tested in vitro and was also seen in vivo in Kupffer cells from mice induced to undergo successive rounds of αCD20 mAb-dependent clearance of circulating B cells. Importantly, hypophagia had no effect on Ab-independent phagocytosis and did not alter macrophage viability. In mechanistic studies, we found that the rapid loss of activating Fc receptors from the surface and their subsequent proteolytic degradation were the primary mechanisms responsible for the loss of ADCP activity in hypophagia. These data suggest hypophagia is a critical limiting step in macrophage-mediated clearance of cells via ADCP, and understanding such limitations to innate immune system cytotoxic capacity will aid in the development of mAb regimens that could optimize ADCP and improve patient outcome.

The future of laboratory testing in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is a malignant lymphoproliferative disorder characterised by the accumulation of dysfunctional B-lymphocytes in the blood and lymphoid tissues. It is a clonally complex disease with a high degree of both intra-tumoural and inter-patient heterogeneity. This variability leads to a wide range of clinical outcomes and highlights the critical need for accurate prognostic tests in CLL. With the advent of a range of new targeted agents for CLL in recent years, there is also a clinical need for improved predictive tests to therapy. This review of laboratory testing in CLL focuses on emerging technologies for prognostication including single nucleotide polymorphism microarray for karyotypic analysis, targeted next generation sequencing analysis of the immunoglobulin heavy chain variable region gene as well as genes recurrently mutated in the disease such as TP53, and detection of minimal residual disease.

Risk-adapted, ofatumumab-based chemoimmunotherapy and consolidation in treatment-naïve chronic lymphocytic leukemia: a phase 2 study

High-risk cytogenetics and minimal residual disease (MRD) after chemoimmunotherapy (CIT) predict unfavorable outcome in chronic lymphocytic leukemia (CLL). This phase 2 study investigated risk-adapted CIT in treatment-naïve CLL (NCT01145209). Patients with high-risk cytogenetics received induction with fludarabine, cyclophosphamide, and ofatumumab. Those without high-risk cytogenetics received fludarabine and ofatumumab. After induction, MRD positive (MRD+) patients received 4 doses of ofatumumab consolidation. MRD negative (MRD-) patients had no intervention. Of 28 evaluable for response, all responded to induction and 10 (36%) achieved MRD-. Two-year progression-free survival (PFS) was 71.4% (CI₉₅, 56.5-90.3%). There was no significant difference in median PFS between the high-risk and the standard-risk groups. Ofatumumab consolidation didn't convert MRD + to MRD-. In the MRD + group, we saw selective loss of CD20 antigens during therapy. In conclusion, risk-adapted CIT is feasible in treatment-naïve CLL. Ofatumumab consolidation didn't improve depth of response in MRD + patients. Loss of targetable CD20 likely reduces efficacy of consolidation therapy.

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.

Immune Dysfunction in Patients with Chronic Lymphocytic Leukemia and Challenges during COVID-19 Pandemic

The novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) has been first described in December 2019 in Wuhan, China, and has led to a worldwide pandemic ever since. Initial clinical data imply that cancer patients are particularly at risk for a severe course of SARS-CoV-2. In patients with chronic lymphocytic leukemia (CLL), infections are a main contributor to morbidity and mortality driven by an impaired immune system. Treatment initiation is likely to induce immune modulation that further increases the risk for severe infections. This article aims to give an overview on pathogenesis and risk of infectious complications in patients with CLL. In this context, we discuss current data of SARS-CoV-2 infections in patients with CLL and how the pandemic impacts their management.

Low-dose fludarabine and cyclophosphamide combined with rituximab in the first-line treatment of elderly/comorbid patients with chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL): long-term results of project Q-lite by the Czech CLL Study Group

Therapeutic options used to be very limited for treatment-naïve elderly/comorbid patients with chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) before the introduction of chemo-immunotherapy. Because dose-reduced fludarabine-based regimens yielded promising results, the Czech CLL Study Group initiated a prospective observational study to assess safety and efficacy of low-dose fludarabine and cyclophosphamide combined with rituximab (FCR) in elderly/comorbid patients. Between March 2009 and July 2012, we enrolled 107 patients considered ineligible for full-dose FCR (median age, 70 years; median Cumulative Illness Rating Scale score, 5; median creatinine clearance, 69 ml/min). Notably, 77% patients had unfavourable biological prognosis [unmutated immunoglobulin heavy-chain variable-region gene (IGHV), 74%; deletion 17p, 9%). Fludarabine was reduced to 12 mg/m² intravenously (iv) or 20 mg/m² orally on days 1-3 and cyclophosphamide to 150 mg/m² iv/orally on days 1-3. Grade 3-4 neutropenia occurred in 56% of the patients, but there were serious infections in only 15%. The median progression-free survival was 29 months, but was markedly longer in patients with mutated IGHV (median 53 months), especially in absence of del 11q or 17p (median 74 months). Low-dose FCR is a well-tolerated and effective first-line regimen for selected elderly/comorbid patients with CLL/SLL with favourable biology. The study was registered at clinicaltrials.gov (NCT02156726).

Safety and efficacy of obinutuzumab alone or with chemotherapy in previously untreated or relapsed/refractory chronic lymphocytic leukaemia patients: Final analysis of the Phase IIIb GREEN study

The manageable toxicity profile of obinutuzumab (GA101; G) alone or with chemotherapy in first-line (1L; fit and non-fit) and relapsed/refractory (R/R) patients with chronic lymphocytic leukaemia (CLL) was established in the primary analysis of the Phase IIIb GREEN trial (Clinicaltrials.gov: NCT01905943). The final analysis (cut-off, 31 January 2019) is reported here. Patients received G (1000 mg) alone (G-mono; fit and non-fit patients) or with chemotherapy [fludarabine and cyclophosphamide (FC; fit patients); chlorambucil (non-fit patients); bendamustine (any patient)]. Study endpoints were safety (primary) and efficacy (secondary). Subgroup analyses were performed on prognostic biomarkers in 1L CLL. Overall, 630 patients received 1L and 341 received R/R CLL treatment. At the final analysis, no new safety signals were observed [Grade ≥ 3 adverse events (AEs): 1L 82·7%, R/R 84·5%; serious AEs: 1L 58·1%, R/R 62·5%]. Neutropenia (1L 50·5%, R/R 53·4%) and thrombocytopenia (1L 14·6%, R/R 19·1%) were the most common Grade 3-5 AEs. G-mono-, G-bendamustine and G-FC-treated patients with unmutated immunoglobulin heavy chain trended towards shorter progression-free survival. Achievement of minimal residual disease negativity was greatest in 1L patients treated with G-FC. In this final analysis of the GREEN trial, the safety profile of G was consistent with current risk management strategies. Biomarker analyses supported efficacy in the specific subgroups.

Impact of age and treatment institution type on outcomes of patients treated for chronic lymphocytic leukemia in British Columbia, Canada

Older age has been shown to adversely impact overall survival (OS) in chronic lymphocytic leukemia (CLL) however, prior population-based studies did not analyze the impact of cytogenetic abnormalities or were prior to the availability of ibrutinib.

OBJECTIVES

i) We sought to compare outcomes of patients based on their age at treatment to examine if older age has an impact on OS in patients who were treated during the period when fludarabine-rituximab was the standard upfront therapy and when ibrutinib was first introduced and ii) compare outcomes based on whether the patient received primary treatment at an academic or community-based centre.

METHODS

The BC Provincial CLL Database, a population-based databasewas used to include patients who have received treatment in British Columbia (BC), Canada between 2004 and 2016.

RESULTS

A total of 1122 patients were included (<70 years at treatment, n = 589) with median age at diagnosis 66 years. Younger patients had higher Rai stage (55% vs. 44% stage I-II, p < 0.001), higher lymphocyte count at diagnosis (13 × 10⁹/L vs. 10 × 10⁹/L, p = 0.004), greater proportion with B-symptoms at diagnosis (15% vs 10%, p = 0.004), shorter time from diagnosis to treatment (13.9 months vs. 21.4 months, p = 0.001), higher proportion treated at an academic centre (79% vs. 69%, p < 0.001) and more were treated with fludarabine-rituximab or FCR (69% vs. 42%, p < 0.001) compared to older patients. Older patients had both a significantly (p < 0.001) shorter OS from treatment start (4.7 years) and disease specific survival (8.1 years) than younger patients (median OS and DSS not reached). Of interest, there was no difference in OS between patients treated at an academic centre or community centre (p = 0.087). First-line treatment with chemoimmunotherapy improved OS (HR 0.465, 95% CI: 0.381-.567).

CONCLUSIONS

Older age but not treatment-institution type adversely impacts overall survival and CLL survival in treated patients in BC.

Therapeutic Options for Patients with TP53 Deficient Chronic Lymphocytic Leukemia: Narrative Review

Chronic lymphocytic leukemia (CLL), which is the most common type of leukemia in western countries in adults, is characterized by heterogeneity in clinical course, prognosis and response to the treatment. Although, in recent years a number of factors with probable prognostic value in CLL have been identified (eg NOTCH1, SF3B1 and BIRC-3 mutations, or evaluation of microRNA expression), TP53 aberrations are still the most important single factors of poor prognosis. It was found that approximately 30% of all TP53 defects are mutations lacking 17p13 deletion, whereas sole 17p13 deletion with the absence of TP53 mutation consists of 10% of all TP53 defects. The detection of del(17)(p13) and/or TP53 mutation is not a criterion itself for starting antileukemic therapy, but it is associated with an aggressive course of the disease and poor response to the standard chemoimmunotherapy. Treatment of patients with CLL harbouring TP53-deficiency requires drugs that promote cell death independently of TP53. Novel and smarter therapies revolutionize the treatment of del(17p) and/or aberrant TP53 CLL, but development of alternative therapeutic approaches still remains an issue of critical importance.

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

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

Bendamustine, followed by ofatumumab and ibrutinib in chronic lymphocytic leukemia (CLL2-BIO): primary endpoint analysis of a multicenter, open-label phase-II trial

The introduction of targeted agents has revolutionized the treatment of chronic lymphocytic leukemia but only few patients achieve a complete remission and minimal residual disease negativity with ibrutinib monotherapy. This multicenter, investigator-initiated, phase II study is evaluating sequential treatment with two cycles of bendamustine debulking for patients with a higher tumor load, followed by ofatumumab and ibrutinib induction and maintenance treatment. An all-comer population, irrespective of prior treatment, physical fitness and genetic factors, was included. The primary endpoint was the investigator-assessed overall response rate at the end of induction treatment. Of 66 patients enrolled, one patient with early treatment discontinuation was excluded from the efficacy analysis as predefined by the protocol. Thirty-nine patients (60%) were treatment-naïve and 26 patients (40%) had relapsed/refractory chronic lymphocytic leukemia, 21 patients (32%) had a del(17p) and/or TP53 mutation and 45 patients (69%) had unmutated IGHV status. At the end of the induction, 60 of 65 patients (92%) responded and nine (14%) achieved minimal residual disease negativity (<10^-4) in peripheral blood. No unexpected or cumulative toxicities occurred. The most common grade 3 or 4 adverse events, according to the Common Toxicity Criteria, were neutropenia, anemia, infusion-related reactions, and diarrhea. This sequential treatment of bendamustine debulking, followed by ofatumumab and ibrutinib was well tolerated without unexpected safety signals and showed a good efficacy with an overall response rate of 92%. Ongoing maintenance treatment aims at deeper responses with minimal residual disease negativity. However, ibrutinib should still be used as a single agent outside clinical trials. Clinicaltrials.gov number: NCT02689141.

Chronic Lymphocytic Leukemia

Patients with chronic lymphocytic leukemia can be divided into three categories: those who are minimally affected by the problem, often never requiring therapy; those that initially follow an indolent course but subsequently progress and require therapy; and those that from the point of diagnosis exhibit an aggressive disease necessitating treatment. Likewise, such patients pass through three phases: development of the disease, diagnosis, and need for therapy. Finally, the leukemic clones of all patients appear to require continuous input from the exterior, most often through membrane receptors, to allow them to survive and grow. This review is presented according to the temporal course that the disease follows, focusing on those external influences from the tissue microenvironment (TME) that support the time lines as well as those internal influences that are inherited or develop as genetic and epigenetic changes occurring over the time line. Regarding the former, special emphasis is placed on the input provided via the B-cell receptor for antigen and the C-X-C-motif chemokine receptor-4 and the therapeutic agents that block these inputs. Regarding the latter, prominence is laid upon inherited susceptibility genes and the genetic and epigenetic abnormalities that lead to the developmental and progression of the disease.

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

Ibrutinib, the first in class of the oral covalent Bruton tyrosine kinase (BTK) inhibitors, has profoundly changed the treatment landscape of chronic lymphocytic leukemia (CLL). The phase III RESONATE and RESONATE-2 trials first demonstrated the superiority of ibrutinib over ofatumumab in the relapsed/refractory setting and over chlorambucil in older patients with de novo disease. The phase III ECOG–ACRIN trial extended these results to young, fit patients, demonstrating a significant survival advantage to ibrutinib plus rituximab over fludarabine, cyclophosphamide, and rituximab. Similarly, the Alliance trial demonstrated the superiority of ibrutinib over bendamustine with rituximab as frontline in elderly patients. Challenges with ibrutinib include toxicity, development of resistance, and need for indefinite therapy. The second generation BTK inhibitor acalabrutinib may cause less off-target toxicity. The ELEVATE TN trial demonstrated the superiority of acalabrutinib with or without obinutuzumab over chlorambucil and obinutuzumab as frontline therapy for elderly or comorbid patients. Promising early results from the phase II CAPTIVATE and CLARITY trials, which combined ibrutinib with venetoclax, suggest a future role for minimal residual disease (MRD) testing to determine treatment duration. The ongoing phase III GAIA/CLL13, ECOG EA9161, Alliance A041702, CLL17, and [ClinicalTrials.gov identifier: NCT03836261] trials will assess various combinations of ibrutinib/acalabrutinib, venetoclax, and anti-CD20 antibodies. These trials will answer key questions in the treatment of CLL: should novel agents in CLL be used in combination or sequentially? What is the best frontline agent? Can treatment be safely stopped with BTK inhibitors? Can undetectable MRD be used to determine treatment duration? In this review, we will discuss these and other aspects of the evolving role of BTK inhibition in CLL.

Chimeric antigen receptor T-cell therapy for the treatment of lymphoid malignancies: is there an excess risk for infection?

Therapy with genetically engineered chimeric antigen receptor (CAR) T cells targeting the CD19 antigen is promising for a number of refractory or relapsed B-cell malignancies. Information on the infectious complications of this immunotherapeutic strategy is scarce and difficult to interpret, as many factors influence infection incidence and outcomes. CAR T-cell therapy is usually given to patients with haematological cancers who have been heavily pretreated and are severely immunosuppressed. Moreover, the risk of infection is increased by the administration of lymphodepleting chemotherapy before CAR T-cell infusion, and by the development of complications such as cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome, which are managed with anti-interleukin-6 antibodies, or corticosteroids, or both. On-target, off-tumour toxicities, such as B-cell aplasia, hypogammaglobulinaemia, and persistent or biphasic cytopenia, are common. In this Review, we evaluate the reported infectious complications of CAR T-cell therapy and associated risk factors and offer perspectives on its infection risk.

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

Inhibiting the activity of Bruton tyrosine kinase (BTK) prevents the activation of the B-cell receptor (BCR) signaling pathway, which in turn prevents both B-cell activation and BTK-mediated activation of downstream survival pathways. Acalabrutinib is an orally available, highly selective, next-generation inhibitor of BTK. Based on the results of two key phase 3 trials (ELEVATE-TN in patients with previously untreated chronic lymphocytic leukemia [CLL] and ASCEND in patients with relapsed or refractory CLL), which demonstrated superior progression-free survival while maintaining favorable tolerability, acalabrutinib was granted US Food and Drug Administration (FDA) approval in 2019 for the treatment of patients with CLL. Acalabrutinib appears to offer similar efficacy but a significantly improved tolerability profile to first-generation agents. Acalabrutinib is a good candidate to combine with other anti-cancer therapies, including B-cell lymphoma 2 inhibitors and monoclonal antibodies, a factor that may help to further improve clinical outcomes in CLL.

Impact of Oral Targeted Therapy on the Economic Burden of Chronic Lymphocytic Leukemia in Canada

Background: Continuous oral targeted therapy (OTT) for chronic lymphocytic leukemia (CLL) represents an effective therapy but also a major economic burden on the healthcare system. This study aimed to estimate future direct costs, along with the prevalence, of CLL in the era of continuous OTT in Canada. Methods: The economic burden of OTT was modelled and compared to chemoimmunotherapy (CIT), for CLL treatment. The burden was assessed/projected from 2011 to 2025. For the OTT scenario, CIT was considered the standard of care before 2015, while OTT was considered standard of care for patients with either unmutated immunoglobulin heavy-chain variable (IGHV) or del(17p)/TP53 mutations starting in 2015 and, from 2020 onwards, for all first-line treatments except for patients with mutated IGHV. A Markov model was developed including four health states: watchful-waiting, first-line treatment, relapse and death. Costs of therapy, follow-up/monitoring and adverse events were included. Key clinical parameters were extracted from pivotal clinical trials. Results: As incidence rates and rate of survival are increasing, the prevalence of CLL in Canada is projected to increase 1.8-fold, from 8301 patients in 2011 to 14,654 by 2025. Correspondingly, the total annual costs of CLL management are predicted to increase 15.7-fold, from $60.8 million to $957.5 million during that same period. Conclusions: Although OTT enhances survival for patients with CLL, it is nonetheless associated with an important economic burden due to the projected vast increase in costs from 2011 to 2025. Changes in clinical strategies, such as implementation of a fixed OTT treatment duration, could help alleviate financial burden.

Incorporating molecular biomarkers into the continuum of care in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a mature B-cell malignancy characterized by marked heterogeneity. Discoveries in disease biology over the past two decades have helped explain clinical variability and heralded the arrival of the targeted therapy era. In this article, we review improvements in risk stratification which have coincided with this progress, including individual biomarkers and their incorporation into prognostic models. Amidst an ever-expanding list of biomarkers, we seek to bring focus to the essential tests to improve patient care and counseling at particular times in the disease course, beginning with prognosis at diagnosis. The majority of patients do not require treatment at the time of diagnosis, making time-to-first-treatment a key initial prognostic concern. Prognostic and predictive biomarkers are then considered at subsequent major junctures, including at the time of treatment initiation, while on therapy, and at the time of relapse on novel agents.

A platform trial in practice: adding a new experimental research arm to the ongoing confirmatory FLAIR trial in chronic lymphocytic leukaemia

BACKGROUND

The FLAIR trial in chronic lymphocytic leukaemia has a randomised, controlled, open-label, confirmatory, platform design. FLAIR was successfully amended to include an emerging promising experimental therapy to expedite its assessment, greatly reducing the time to reach the primary outcome compared to running a separate trial and without compromising the validity of the research or the ability to recruit to the trial and report the outcomes. The methodological and practical issues are presented, describing how they were addressed to ensure the amendment was a success.

METHODS

FLAIR was designed as a two-arm trial requiring 754 patients. In stage 2, two new arms were added: a new experimental arm and a second control arm to protect the trial in case of a change in practice. In stage 3, the original experimental arm was closed as its planned recruitment target was reached. In total, 1516 participants will be randomised to the trial.

RESULTS

The changes to the protocol and randomisation to add and stop arms were made seamlessly without pausing recruitment. The statistical considerations to ensure the results for the original and new hypotheses are unbiased were approved following peer review by oversight committees, Cancer Research UK, ethical and regulatory committees and pharmaceutical partners. These included the use of concurrent comparators in case of any stage effect, appropriate control of the type I error rate and consideration of analysis methods across trial stages. The operational aspects of successfully implementing the amendments are described, including gaining approvals and additional funding, data management requirements and implementation at centres.

CONCLUSIONS

FLAIR is an exemplar of how an emerging experimental therapy can be assessed within an existing trial structure without compromising the conduct, reporting or validity of the trial. This strategy offered considerable resource savings and allowed the new experimental therapy to be assessed within a confirmatory trial in the UK years earlier than would have otherwise been possible. Despite the clear efficiencies, treatment arms are rarely added to ongoing trials in practice. This paper demonstrates how this strategy is acceptable, feasible and beneficial to patients and the wider research community.

TRIAL REGISTRATION

ISRCTN Registry ISRCTN01844152 . Registered on August 08, 2014.

Concurrent BK polyomavirus, adenovirus and cytomegalovirus infections in a patient treated for chronic lymphocytic leukaemia

A 58-year-old woman with chronic lymphocytic leukaemia (CLL) presented with 2 weeks of fever and haematuria following chemo-immunotherapy. CT scan showed thickening of her left urethra and bladder, suggesting pyleo-ureteritis with cystitis. The patient was initially treated for suspected bacterial urinary tract infection although repeated blood and urine cultures remained negative. She then received multiple transfusions for chemotherapy-induced pancytopenia while her urinary symptoms did not improve. Due to her immunocompromised status, she was tested for viral infection, which revealed, BK polyomavirus, adenovirus and cytomegalovirus in serum and urine. Cidofovir was initially administered to treat these infections while ganciclovir was used with filgrastim due to neutropenia. The patient subsequently improved. This case represents a diagnostic and therapeutic challenge due to the multiple concurrent viral infections causing haematuria as well as the combined post-chemo-immunotherapy and antiviral myelotoxicity in a CLL patient.

Genomic Instability and Clonal Evolution in Chronic Lymphocytic Leukemia: Clinical Relevance

Genomic instability and clonal heterogeneity can influence cancer progression, response to therapy, and relapse. Chronic lymphocytic leukemia (CLL) harbors a variety of clones and subclones that will evolve differently according to intrinsic (microenvironment) and extrinsic (therapy) pressures. Different patterns of clonal evolution have been described, providing insights into the CLL leukemic cell, dynamics, selection, and treatment refractoriness. With the help of genomic technologies allowing a granular resolution of CLL clones, novel synergic therapeutic strategies can be tested with the aim of reaching a genomic-epigenomic ultrapersonalized, tailored approach. These efforts should consider the presence of targetable alterations, continuous cancer reshaping conferring disease refractoriness, and intratumoral clonal equilibrium to possibly avoid clonal selection.

Is There a Role for Chemotherapy in the Era of Targeted Therapies?

PURPOSE OF REVIEW

The treatment landscape of chronic lymphocytic leukemia has been rapidly evolving over the past few years. The prior standard of care, chemoimmunotherapy, is being replaced by targeted agents, and the utility of chemotherapy has come under question. In this review, we examine recent data comparing chemoimmunotherapy to targeted agents, how these data impact clinical management, and whether there are potential future roles for cytotoxic chemotherapy.

RECENT FINDINGS

Clinical trials have shown improved clinical outcomes with targeted agents compared to traditional chemoimmunotherapy. Based on these data, the current treatment paradigm primarily favors targeted agents over chemoimmunotherapy, with a few exceptions. However, targeted agents have notable limitations, and thus, there may be a future role of cytotoxic chemotherapy when administered in combination with targeted agents. Although targeted agents have nearly replaced chemoimmunotherapy in the treatment of chronic lymphocytic leukemia, novel combinations utilizing chemotherapy are being developed that may lead to better outcomes.

Predictive significance of selected gene mutations in relapsed and refractory chronic lymphocytic leukemia patients treated with ibrutinib

BACKGROUND

Ibrutinib, an inhibitor of the Bruton's kinase (BTK), is characterized by high efficacy in the therapy of patients with relapsed and refractory chronic lymphocytic leukemia (RR-CLL).

AIMS

To analyze the potential significance of the mutational status of selected 30 genes on the disease outcome in 45 patients with RR-CLL using custom-made gene panel and sequencing on Illumina MiSeq FGx platform.

RESULTS

The highest rate of mutations was observed in TP53 (n = 18; 40.0%), NOTCH1 (n = 13; 28.8%), SF3B1 (n = 11; 24.4%), ATM (n = 7; 15.6%), MED12 (n = 6, 13.3%), CHD2 (n = 5; 11.1%), XPO1 (n = 5; 11.1%), NFKBIE (n = 5; 11.1%), BIRC3 (n = 4; 8.9%), SPEN (n = 4; 8.9%), POT1 (n = 4; 8.9%), EGR2 (n = 3; 6.7%), and RPS15 (n = 3; 6.7%). With a median observation time of 45.9 months, the median progression-free survival (PFS) and overall survival (OS) were not reached. The 36-month estimated rate of PFS and OS were 64% and 68.2%, respectively. The overall response rate was noted in 23 patients (51.1%), while twenty (44.4%) patients achieved stability. Progression was noted in 2 (4.5%) cases. Analyzed molecular factors had no impact on PFS and OS.

CONCLUSION

Despite accumulation of several poor prognostic factors in our real-life cohort of heavily pretreated patients with CLL, ibrutinib treatment showed long-term clinical benefit.

Treatment algorithm for Japanese patients with chronic lymphocytic leukemia in the era of novel targeted therapies

Treatment for patients with chronic lymphocytic leukemia (CLL) is becoming more individualized due to the recent introduction of novel molecularly targeted therapies into the therapeutic armamentarium. Genomic and molecular risk factors in CLL patients determine the individual risk for disease progression and response to therapy, and can impact survival. In this review article, we discuss current treatment strategies for CLL patients in Japan, where the novel targeted agents, the BTK inhibitor ibrutinib and BCL2 antagonist venetoclax, now are available and increasingly used in clinical practice. We also discuss the importance of CLL risk factors for making therapy decisions, focusing on immunoglobulin variable region heavy chain (IGHV) mutation status, 11q deletion, and 17p deletion. Treatment approaches for CLL have rapidly changed in the past few years because of these new targeted agents. They are highly effective, well tolerated, and have been demonstrated in a series of large randomized clinical trials to improve survival when compared with conventional chemotherapy-based treatment. Therefore, for most patients, especially high-risk CLL patients, BTK inhibitor and BCL2 antagonist therapies are preferred over chemo-immunotherapy. Currently ongoing studies seek to determine the best sequence for these new agents and whether a combination therapy approach is beneficial. With these developments, a new era of chemotherapy-free treatment for CLL patients is expected.

Pathogenesis of chronic lymphocytic leukemia and the development of novel therapeutic strategies

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries and is characterized by the clonal expansion of mature CD5+ B cells. There have been substantial advances in the field of CLL research in the last decade, including the identification of recurrent mutations, and clarification of clonal architectures, signaling molecules, and the multistep leukemogenic process, providing a comprehensive understanding of CLL pathogenesis. Furthermore, the development of therapeutic approaches, especially that of molecular target therapies against CLL, has markedly improved the standard of care for CLL. This review focuses on the recent insights made in CLL leukemogenesis and the development of novel therapeutic strategies.

Comparison of acalabrutinib plus obinutuzumab, ibrutinib plus obinutuzumab and venetoclax plus obinutuzumab for untreated CLL: a network meta-analysis

The optimal chemotherapy-free regimens for treatment-naive CLL still remains undefined. We searched relevant published reports. Three trials with 1017 subjects were identified. In the network meta-analysis, acalabrutinib plus obinutuzumab (Aca + Obi) improved PFS than ibrutinib plus obinutuzumab (Ibu + Obi) (HR:0.43, p = .02) and venetoclax plus obinutuzumab (Ven + Obi) (HR:0.30, p < .001) as IRC assessment. Sensitivity analysis of investigator assessment also showed improved PFS with Aca + Obi than Ibu + Obi (HR:0.46, p = .04) and Ven + Obi (HR:0.34, p = .002). Among these first-line treatments (Aca + Obi, Ibu + Obi, Ven + Obi and chlorambucil plus obinutuzumab (Chl + Obi)), Aca + Obi regimen had the highest probability of 99.1% (IRC assessment) or 98.0% (investigator assessment) to reach the longest PFS. The survival advantage with Aca + Obi was not statistically significant, compared to Ibu + Obi (HR:0.51, p = .21) and Ven + Obi (HR:0.38, p = .07). No significant difference was found in AEs analysis. Our data indicated that Aca + Obi seemed to prolong the PFS than Ibu + Obi and Ven + Obi. Considering our limits, prospective clinical trials directly comparing these regimens are warranted.

Complement Activation in the Treatment of B-Cell Malignancies

Unconjugated monoclonal antibodies (mAb) have revolutionized the treatment of B-cell malignancies. These targeted drugs can activate innate immune cytotoxicity for therapeutic benefit. mAb activation of the complement cascade results in complement-dependent cytotoxicity (CDC) and complement receptor-mediated antibody-dependent cellular phagocytosis (cADCP). Clinical and laboratory studies have showed that CDC is therapeutically important. In contrast, the biological role and clinical effects of cADCP are less well understood. This review summarizes the available data on the role of complement activation in the treatment of mature B-cell malignancies and proposes future research directions that could be useful in optimizing the efficacy of this important class of drugs.

Prognostic Role of Lymphocyte/Monocyte Ratio in Chronic Lymphocytic Leukemia

Background

Chronic lymphocytic leukemia (CLL) is a B-lymphoproliferative disease with varying clinical characteristics, which occurs mostly in older ages. In studies from literature, we see that different parameters are examined to determine the prognosis of CLL. The main purpose of our study is to determine the relationship of lymphocyte/monocyte ratio (LMR) value in CLL, which has been previously shown to be a prognostic factor in various solid organ tumors and some hematological malignancies.

Methods

A total of 173 patients who were followed up between 2005 and 2019 were retrospectively analyzed. The diagnostic age, gender, laboratory, absolute lymphocyte and monocyte count, LMR and overall survival (OS), treatment and responses, recurrence, cytogenetic subtype and mortality rates were examined.

Results

The median LMR was 26.7 and it was considered as cut-off value of 26. A positive correlation was found between LMR and Rai Stage. LMR was significantly higher in patients who have an indication for treatment or who died.

Conclusions

In our study, in CLL, LMR has been shown to be over 26 in advanced stages, in relapse or with indication of a treatment. With the increase of LMR, it was found that survival and disease-free gap decreased.

Bioengineering of nano metal-organic frameworks for cancer immunotherapy

Immunotherapy techniques, such as immune checkpoint inhibitors, chimeric antigen receptor (CAR) T cell therapies and cancer vaccines, have been burgeoning with great success, particularly for specific cancer types. However, side effects with fatal risks, dysfunction in tumor microenvironment and low immune response rates remain the bottlenecks in immunotherapy. Nano metal-organic frameworks (nMOFs), with an accurate structure and a narrow size distribution, are emerging as a solution to these problems. In addition to their function of temporospatial delivery, a large library of their compositions, together with flexibility in chemical interaction and inherent immune efficacy, offers opportunities for various designs of nMOFs for immunotherapy. In this review, we overview state-of-the-art research on nMOFs-based immunotherapies as well as their combination with other therapies. We demonstrate that nMOFs are predominantly customized for vaccine delivery or tumor-microenvironment modulation. Finally, a prospect of nMOFs in cancer immunotherapy will be discussed.

Venetoclax: a real game changer in treatment of chronic lymphocytic leukemia

Venetoclax – a novel, orally bioavailable inhibitor of B-cell lymphoma-2 – has demonstrated substantial clinical activity in the treatment of chronic lymphocytic leukemia. Alone or in combination with other targeted agents, venetoclax results in high rate of durable responses and undetectable measurable residual disease. The peculiarity of venetoclax is that it allows for fixed durations of therapy of 12 months in the frontline and 24 months in the relapsed/refractory setting, with a favorable impact on compliance and pharmacoeconomics. This approach implies a change of therapeutic paradigm in chronic lymphocytic leukemia from continuous to time-fixed therapy. Nowadays, it remains challenging to identify patients suitable for the optimal approach. Clinical trials addressing the issue of continuous versus time-limited therapy are ongoing.

Skipping a step: what happened to the design of randomized clinical trials in chronic lymphocytic leukaemia?

Clinical research of chronic lymphocytic leukaemia (CLL) has been advancing at an unprecedented pace. Several randomized studies in the current era of oral targeted agents seem to have skipped one step and proceeded directly to combinations with antibodies, omitting the testing of novel-agent monotherapy. Thus, the ibrutinib + rituximab combination was used as the experimental arm in a major trial for untreated fit patients while two other trials subsequently showed that addition of rituximab to ibrutinib does not produce any meaningful benefit. Similarly, two large trials omitted venetoclax monotherapy and proceeded directly to venetoclax + rituximab or obinutuzumab versus chemoimmunotherapy. While such trials are undoubtedly cheaper, quicker and easier to manage, they leave the CLL community with uncertainty regarding the real role of the monoclonal antibody components. Thus, we are left with regimens which are undoubtedly effective, but might actually be unnecessarily toxic and expensive. The solution to this problem is simple: future randomized trials should be carefully designed in a 'step by step' fashion which would provide the CLL community with simple yet robust answers regarding efficacy of novel regimens so that these can be introduced to practice following the best principles of evidence-based medicine.

Immune Dysfunctions and Immune-Based Therapeutic Interventions in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy characterized by a wide range of tumor-induced alterations, which affect both the innate and adaptive arms of the immune response, and accumulate during disease progression. In recent years, the development of targeted therapies, such as the B-cell receptor signaling inhibitors and the Bcl-2 protein inhibitor venetoclax, has dramatically changed the treatment landscape of CLL. Despite their remarkable anti-tumor activity, targeted agents have some limitations, which include the development of drug resistance mechanisms and the inferior efficacy observed in high-risk patients. Therefore, additional treatments are necessary to obtain deeper responses and overcome drug resistance. Allogeneic hematopoietic stem cell transplantation (HSCT), which exploits immune-mediated graft-versus-leukemia effect to eradicate tumor cells, currently represents the only potentially curative therapeutic option for CLL patients. However, due to its potential toxicities, HSCT can be offered only to a restricted number of younger and fit patients. The growing understanding of the complex interplay between tumor cells and the immune system, which is responsible for immune escape mechanisms and tumor progression, has paved the way for the development of novel immune-based strategies. Despite promising preclinical observations, results from pilot clinical studies exploring the safety and efficacy of novel immune-based therapies have been sometimes suboptimal in terms of long-term tumor control. Therefore, further advances to improve their efficacy are needed. In this context, possible approaches include an earlier timing of immunotherapy within the treatment sequencing, as well as the possibility to improve the efficacy of immunotherapeutic agents by administering them in combination with other anti-tumor drugs. In this review, we will provide a comprehensive overview of main immune defects affecting patients with CLL, also describing the complex networks leading to immune evasion and tumor progression. From the therapeutic standpoint, we will go through the evolution of immune-based therapeutic approaches over time, including i) agents with broad immunomodulatory effects, such as immunomodulatory drugs, ii) currently approved and next-generation monoclonal antibodies, and iii) immunotherapeutic strategies aiming at activating or administering immune effector cells specifically targeting leukemic cells (e.g. bi-or tri-specific antibodies, tumor vaccines, chimeric antigen receptor T cells, and checkpoint inhibitors).

Current Perspectives on Therapy for Chronic Lymphocytic Leukemia

Therapy for chronic lymphocytic leukemia has improved dramatically over the past decade with the introduction of new targeted therapies and a paradigm shift toward targeted therapies for the majority of patients. Better understanding of prognostic factors has helped tailor therapy for individual patients, and work continues to identify optimal therapy for each patient. When therapy is required, most patients will be treated with targeted therapies, either the Bruton tyrosine kinase (BTK) inhibitors ibrutinib or acalabrutinib or the BCL-2 inhibitor venetoclax in combination with obinutuzumab. Without head-to-head comparisons showing differential efficacy among these options, considerations regarding safety, patient preference, and ability to sequence therapy currently influence treatment decisions. Also, clinical trials investigating combinations of these therapies have the potential to further change the standard of care. In this review, we cover the currently available options for the frontline treatment of chronic lymphocytic leukemia (CLL) and discuss safety considerations and toxicity management with each agent as well as novel combination strategies currently under investigation.

Anti-CD20 treatment for B-cell malignancies: current status and future directions

INTRODUCTION

The introduction of anti-CD20 monoclonal antibody therapy with rituximab in the 1990s greatly improved outcomes for patients with B-cell malignancies. Disease resistance or relapse after successful initial therapy and declining efficacy of subsequent rounds of treatment were the basis for the development of alternative anti-CD20-based antibody therapies.

AREAS COVERED

The novel anti-CD20 antibodies of atumumab, ublituximab, and obinutuzumab were developed to be differentiated via structural and mechanistic features over rituximab. We provide an overview of preclinical and clinical data, and demonstrate ways in which the pharmacodynamic properties of these novel agents translate into clinical benefit for patients.

EXPERT OPINION

Of the novel anti-CD20 antibodies, only obinutuzumab has shown consistently improved efficacy over rituximab in randomized pivotal trials in indolent non-Hodgkin lymphoma and chronic lymphocytic leukemia. The Phase 3 GALLIUM trial demonstrated significant improvements in progression-free survival with obinutuzumab-based immunochemotherapy over rituximab-based immunochemotherapy. Novel combinations of obinutuzumab, including with chemotherapy-free options are being explored, such as with the newly approved combinations of obinutuzumab with venetoclax, ibrutinib, or acalabrutinib. The biggest unmet need remains in the treatment of diffuse large B-cell lymphoma; emerging options in this field include the use of CAR-T cells and T-cell bispecific antibodies.

Acalabrutinib monotherapy in patients with relapsed/refractory chronic lymphocytic leukemia: updated phase 2 results

Therapeutic targeting of Bruton tyrosine kinase (BTK) has dramatically improved survival outcomes for patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Acalabrutinib is an oral, highly selective BTK inhibitor that allows for twice-daily dosing due to its selectivity. In this phase 1b/2 study, 134 patients with relapsed/refractory CLL or SLL (median age, 66 years [range, 42-85 years]; median prior therapies, 2 [range, 1-13]) received acalabrutinib 100 mg twice daily for a median of 41 months (range, 0.2-58 months). Median trough BTK occupancy at steady state was 97%. Most adverse events (AEs) were mild or moderate, and were most commonly diarrhea (52%) and headache (51%). Grade ≥3 AEs (occurring in ≥5% of patients) were neutropenia (14%), pneumonia (11%), hypertension (7%), anemia (7%), and diarrhea (5%). Atrial fibrillation and major bleeding AEs (all grades) occurred in 7% and 5% of patients, respectively. Most patients (56%) remain on treatment; the primary reasons for discontinuation were progressive disease (21%) and AEs (11%). The overall response rate, including partial response with lymphocytosis, with acalabrutinib was 94%; responses were similar regardless of genomic features (presence of del(11)(q22.3), del(17)(p13.1), complex karyotype, or immunoglobulin variable region heavy chain mutation status). Median duration of response and progression-free survival (PFS) have not been reached; the estimated 45-month PFS was 62% (95% confidence interval, 51% to 71%). BTK mutation was detected in 6 of 9 patients (67%) at relapse. This updated and expanded study confirms the efficacy, durability of response, and long-term safety of acalabrutinib, justifying its further investigation in previously untreated and treated patients with CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02029443.