Treatment of Chronic Lymphocytic Leukemia

The road to chemotherapy-free treatment in chronic lymphocytic leukaemia

PURPOSE OF REVIEW

The treatment landscape of chronic lymphocytic leukaemia (CLL) has tremendously evolved in the last decades, from chemo to chemoimmunotherapy (CIT) and, eventually, to pathway inhibitors that target critical pathways for leukaemic cells survival. Also, treatment goals are moving towards achieving undetectable minimal residual disease with little toxicity.

RECENT FINDINGS

We performed a thorough review of the history of treatment approvals by both the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This review especially focuses on therapies that are currently approved by both agencies. The indications and particular characteristics of each drug are examined.

SUMMARY

Currently available treatment approaches for CLL offer the opportunity to individualize therapy for every single patient with CLL. Inhibitors of B-cell receptor (BCR) signalling pathways and antiapoptotic proteins are nowadays the treatment of choice for most CLL patients, but CIT can be an option for younger and fit patients with low-risk disease [mutated IGHV, no del(11q) or del(17p)/TP53 mutations].

Targeting of HSP70/HSF1 Axis Abrogates In Vitro Ibrutinib-Resistance in Chronic Lymphocytic Leukemia

Simple Summary

The use of ibrutinib has changed the management and clinical history of patients with multiple-treated chronic lymphocytic leukemia (CLL). Nevertheless, an increasing number of patients develop resistance to treatment, with mechanisms still to be fully clarified. Since HSP70 plays a pivotal role in mediating the survival and the progression of CLL, we herein addressed the role of HSP70 and its regulator HSF1 in the development of ibrutinib-mediated resistance. We found an increase in both proteins when the treatment was failing, and thus the disease was progressing. This suggests the involvement of HSP70 in mechanisms of drug resistance. Moreover, we demonstrated that the use, at different levels, of HSP70/HSF1 axis inhibitors could represent a novel rational therapeutic approach to overcome ibrutinib resistance in those patients who relapsed after this type of treatment.

Abstract

The Btk inhibitor ibrutinib has significantly changed the management of chronic lymphocytic leukemia (CLL) patients. Despite its clinical efficacy, relapses occur, and outcomes after ibrutinib failure are poor. Although BTK and PLCγ2 mutations have been found to be associated with ibrutinib resistance in a fair percentage of CLL patients, no information on resistance mechanisms is available in patients lacking these mutations. The heat shock protein of 70 kDa (HSP70) and its transcription factor heat shock factor 1 (HSF1) play a role in mediating the survival and progression of CLL, as well as taking part in drug resistance in various cancers. We demonstrated that resveratrol and related phenols were able to induce apoptosis in vitro in leukemic cells from CLL untreated patients by acting on the HSP70/HSF1 axis. The same was achieved in cells recovered from 13 CLL patients failing in vivo ibrutinib treatment. HSP70 and HSF1 levels decreased following in vitro treatment, correlating to apoptosis induction. We suggest an involvement of HSP70/HSF1 axis in controlling resistance to ibrutinib in CLL cells, since their inhibition is effective in inducing in vitro apoptosis in cells from ibrutinib refractory patients. The targeting of HSP70/HSF1 axis could represent a novel rational therapeutic strategy for CLL, also for relapsing patients.

A perspective on prognostic models in chronic lymphocytic leukemia in the era of targeted agents

Despite the increase in the number of prognostic models currently available for evaluating patients with chronic lymphocytic leukemia (CLL), their current application and utilization in clinical practice in the era of targeted agents is unclear. A critical reappraisal of recently developed prognostic models is presented in this review. The underlying CLL's genetic instability and changes in the host's health and comorbidities can all contribute to the acquisition of additional risk factors for adverse outcomes during the course of the disease. Therefore, available risk models solely based on pretreatment variables only partially predict patients' clinical outcome. A dynamic prognostic model that takes into account changes in the risk profile over time could indeed be useful in routine clinical practice. The next generation of risk assessment models should incorporate post-treatment and response biomarkers such as minimal residual disease. Finally, recent advances in the field of machine learning present novel opportunities to generate models capable of providing an individualized estimation of clinical outcomes in CLL. However, in the era of improved prognostic models, it is important to remember that these indices should supplement but not replace clinical expertise and medical decision-making.

PI3K inhibitors are finally coming of age

Overactive phosphoinositide 3-kinase (PI3K) in cancer and immune dysregulation has spurred extensive efforts to develop therapeutic PI3K inhibitors. Although progress has been hampered by issues such as poor drug tolerance and drug resistance, several PI3K inhibitors have now received regulatory approval - the PI3Kα isoform-selective inhibitor alpelisib for the treatment of breast cancer and inhibitors mainly aimed at the leukocyte-enriched PI3Kδ in B cell malignancies. In addition to targeting cancer cell-intrinsic PI3K activity, emerging evidence highlights the potential of PI3K inhibitors in cancer immunotherapy. This Review summarizes key discoveries that aid the clinical translation of PI3Kα and PI3Kδ inhibitors, highlighting lessons learnt and future opportunities.

Immunomolecular evaluation of dihydroartemisinin effects on apoptosis in chronic lymphocytic leukemia cell lines

INTRODUCTION

Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin, has recently shown to induce apoptosis in many types of cancer cells. In this study, we aimed to determine the effects of DHA on apoptosis in human chronic lymphocytic leukemia (CLL) cell lines.

METHODS

The cells were treated separately and combined by DHA and Fludurabine (FLU) during 24, 48 and 72 hours. The cell viabilities determined by XTT method. Following separate and combined treatment of IC50 concentrations of DHA and FLU to the cells during 24 hours, the cells were analyzed by flow cytometry to determine the effects on apopotis staining with AnnexinV FITC and PI. mRNA and protein expression levels of TCTP, Mcl-1, Bcl-2, Bax and Caspase-3 were analyzed to find out the molecular mechanisms of apoptosis by using quantitative real-time PCR and flow cytometric methods.

RESULTS

Treatment with DHA alone or in combination with FLU induced apoptosis in a dose dependent manner in CLL cells. DHA alone was more effective than FLU alone or combined treatment with DHA and FLU. Our results suggest that Bcl-2 protein family member Bax was active in the apoptotic response of CLL cells after DHA treatment. Moreover, the apoptotic response induced by DHA was independent from the p53 mutation status of the CLL cells.

CONCLUSION

DHA might be a potential anti-cancer therapeutic for CLL.

Deubiquitinases in hematological malignancies

Deubiquitinases (DUBs) are enzymes that control the stability, interactions or localization of most cellular proteins by removing their ubiquitin modification. In recent years, some DUBs, such as USP7, USP9X and USP10, have been identified as promising therapeutic targets in hematological malignancies. Importantly, some potent inhibitors targeting the oncogenic DUBs have been developed, showing promising inhibitory efficacy in preclinical models, and some have even undergone clinical trials. Different DUBs perform distinct function in diverse hematological malignancies, such as oncogenic, tumor suppressor or context-dependent effects. Therefore, exploring the biological roles of DUBs and their downstream effectors will provide new insights and therapeutic targets for the occurrence and development of hematological malignancies. We summarize the DUBs involved in different categories of hematological malignancies including leukemia, multiple myeloma and lymphoma. We also present the recent development of DUB inhibitors and their applications in hematological malignancies. Together, we demonstrate DUBs as potential therapeutic drug targets in hematological malignancies.

Perspectives on Precision Medicine in Chronic Lymphocytic Leukemia: Targeting Recurrent Mutations-NOTCH1, SF3B1, MYD88, BIRC3

Chronic lymphocytic leukemia (CLL) is highly heterogeneous, with extremely variable clinical course. The clinical heterogeneity of CLL reflects differences in the biology of the disease, including chromosomal alterations, specific immunophenotypic patterns and serum markers. The application of next-generation sequencing techniques has demonstrated the high genetic and epigenetic heterogeneity in CLL. The novel mutations could be pharmacologically targeted for individualized approach in some of the CLL patients. Potential neurogenic locus notch homolog protein 1 (NOTCH1) signalling targeting mechanisms in CLL include secretase inhibitors and specific antibodies to block NOTCH ligand/receptor interactions. In vitro studies characterizing the effect of the splicing inhibitors resulted in increased apoptosis of CLL cells regardless of splicing factor 3B subunit 1 (SF3B1) status. Several therapeutic strategies have been also proposed to directly or indirectly inhibit the toll-like receptor/myeloid differentiation primary response gene 88 (TLR/MyD88) pathway. Another potential approach is targeting nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and inhibition of this prosurvival pathway. Newly discovered mutations and their signalling pathways play key roles in the course of the disease. This opens new opportunities in the management and treatment of CLL.

Genetics of Chronic Lymphocytic Leukemia

ABSTRACT

During the past 10 years, relevant advances have been made in the understanding of the pathogenesis of chronic lymphocytic leukemia via the integrated analysis of its genome and related epigenome, and transcriptome. These analyses also had an impact on our understanding of the initiation, as well as of the evolution of chronic lymphocytic leukemia, including resistance to chemotherapy and sensitivity and resistance to novel targeted therapies. This chapter will review the current state of the art in this field, with emphasis on the genetic heterogeneity of the disease and the biological pathways that are altered by the genetic lesions.

Immunomodulatory Drugs for the Treatment of B Cell Malignancies

Accumulating evidence suggests that the tumor microenvironment (TME) is involved in disease progression and drug resistance in B cell malignancies, by supporting tumor growth and facilitating the ability of malignant cells to avoid immune recognition. Immunomodulatory drugs (IMiDs) such as lenalidomide have some direct anti-tumor activity, but critically also target various cellular compartments of the TME including T cells, NK cells, and stromal cells, which interfere with pro-tumor signaling while activating anti-tumor immune responses. Lenalidomide has delivered favorable clinical outcomes as a single-agent, and in combination therapy leads to durable responses in chronic lymphocytic leukemia (CLL) and several non-Hodgkin lymphomas (NHLs) including follicular lymphoma (FL), diffuse large B cell lymphoma (DLBCL), and mantle cell lymphoma (MCL). Recently, avadomide, a next generation cereblon E3 ligase modulator (CELMoD), has shown potent anti-tumor and TME immunomodulatory effects, as well as promising clinical efficacy in DLBCL. This review describes how the pleiotropic effects of IMiDs and CELMoDs could make them excellent candidates for combination therapy in the immuno-oncology era-a concept supported by preclinical data, as well as the recent approval of lenalidomide in combination with rituximab for the treatment of relapsed/refractory (R/R) FL.

Lymphocyte doubling time in chronic lymphocytic leukemia modern era: a real-life study in 848 unselected patients

The prognostic significance of lymphocyte doubling time (LDT) in chronic lymphocytic leukemia (CLL) was identified when the biology of the disease was poorly understood and therapy was not effective. We assessed the clinical and biological significance of LDT in 848 CLL patients in a real-life setting and the context of new biomarkers and effective therapy. A short LDT (≤12 months) was enriched for adverse biomarkers. Patients with a rapid LDT did need therapy shortly after diagnosis (median 23 months vs. not reached; p < 0.001) and had a poorer overall survival (median 95 months vs. not reached p < 0.001). LDT, IGHV mutational status, Beta-2 microglobulin, and Rai clinical stage were independent predictors for time to first treatment in the whole series and in Binet stage A patients. No correlation was observed between LDT and response to chemoimmunotherapy. However, a short LDT along with age ≥65 years, high-risk FISH (del(17p), del(11q)), unmutated IGHV, increased Beta-2 microglobulin, and TP53 mutations predicted short survival. Moreover, the prognostic significance of LDT was independent of the CLL-IPI and the Barcelona/Brno prognostic model. LDT remains an important outcome marker in the modern CLL era and should be incorporated into the clinical assessment and stratification of CLL patients.

Ibrutinib Plus Venetoclax for First-line Treatment of Chronic Lymphocytic Leukemia: A Nonrandomized Phase 2 Trial

Importance

Oral targeted therapies have advanced the treatment of chronic lymphocytic leukemia (CLL). These therapies include Bruton tyrosine kinase inhibitors, used as monotherapy, and the Bcl-2 inhibitor venetoclax, typically combined with the CD20 monoclonal antibody. Preclinical studies have shown synergy between Bruton tyrosine kinase inhibitors and the Bcl-2 inhibitor venetoclax.

Objective

To examine the rate of complete remission, complete remission with incomplete count recovery, and bone marrow-undetectable measurable residual disease (U-MRD) after treatment with the combination of ibrutinib and venetoclax.

Design, Setting, and Participants

A single-center, phase 2 nonrandomized trial enrolled patients from August 17, 2016, to June 5, 2018. Participants included previously untreated patients with CLL who met International Workshop on CLL 2008 criteria for treatment indication. Patients were required to have at least 1 of the following features: del(17p), TP53-mutated CLL, del(11q), unmutated immunoglobulin heavy-chain variable gene, or age 65 years or older.

Interventions

Therapy consisted of ibrutinib, 420 mg/d, monotherapy for 3 cycles, thereafter combined with venetoclax (standard weekly dose ramp-up to 400 mg/d) for a total of 24 cycles of combination treatment. Responses were assessed at serial points according to International Workshop on CLL 2008 criteria. Measurable residual disease (MRD) was assessed by multicolor flow cytometry with a sensitivity of 10-4.

Main Outcomes and Measures

Outcomes included complete remission, complete remission with incomplete count recovery, and bone marrow U-MRD rate.

Results

Eighty patients (57 [71%] men) were treated; median age was 65 years (range, 26-83 years). The median follow-up for all 80 patients was 38.5 months (range, 5.6-51.1 months). Five patients discontinued the study during the ibrutinib monotherapy phase; the remaining 75 patients received combination therapy. On an intent-to-treat analysis of combined treatment, 45 (56%) patients achieved bone marrow U-MRD remission at 12 cycles and 53 (66%) patients achieved bone marrow U-MRD remission at 24 cycles. Overall, 60 (75%) patients achieved bone marrow U-MRD remission as their best response. Responses were seen across all high-risk subgroups, independent of the immunoglobulin heavy-chain variable gene mutation status, fluorescence in situ hybridization category, or TP53 mutation. The 3-year progression-free survival was 93%, and 3-year overall survival was 96%. No patient had CLL progression; 2 patients developed Richter transformation.

Conclusions and Relevance

The findings of this study suggest that combination therapy with ibrutinib and venetoclax might be beneficial for previously untreated patients with CLL. Remissions appeared to be durable during a follow-up of more than 3 years, with activity seen across high-risk disease subgroups, including those with del(17p)/TP53-mutated CLL.

Trial Registration

ClinicalTrials.gov Identifier: NCT02756897.

Evaluation and associated risk factors for neutropenia with venetoclax and obinutuzumab in the treatment of chronic lymphocytic leukemia

Background

The time‐limited combination of venetoclax and obinutuzumab (VenG) was established by the German CLL Study Group in the CLL14 trial for the upfront management of newly diagnosed chronic lymphocytic leukemia (CLL), showing a superior progression free survival benefit. The incidence of grade 3–4 neutropenia was reported in the range of 52.8%–57.7%. However, patients who develop neutropenia with this combination have yet to be formally characterized in the literature as it has impact on the clinical practice setting.

Aim

To determine the incidence of grade 3 and 4 neutropenia and identify risk factors for neutropenia among CLL patients treated with the VenG regimen.

Methods

We conducted a retrospective, single‐center study of all adult patients with a diagnosis of CLL treated with VenG at the University of Colorado Hospital. Demographic information, laboratory data, clinical data, and medication prescriptions were collected from the patients' electronic medical record.

Results

A total of 14 patients (73%) developed neutropenia during the course of therapy. The mean time to neutropenia from the start of treatment was 42 days (range 1–131). Our cohort harbored more high risk disease features and more comorbidities (CIRS score of 12). Four patients (28.6%) in the neutropenic group developed infectious complications during therapy and 6 (31%) patients were unable to be dose escalated to the final FDA approved dose of 400 mg.

Conclusion

Our study cohort had higher incidence of grade 3 and 4 neutropenia occurring in 73% of patients. This could be attributed to a higher rate of comorbidities, high risk features, concomitant interacting medications, and prior chemotherapy. Further studies are warranted to determine if growth factor support is efficacious to achieve dose escalation with this therapy.

A Rare Side Effect of Ibrutinib: Tumor Lysis Syndrome

Chronic lymphocytic leukemia (CLL) is a progressive disease with an indolent course, and tumor lysis syndrome (TLS) is rarely seen in CLL. Ibrutinib is a novel bruton kinase (BTK) inhibitor increasingly used in CLL treatment. Ibrutinib has significant side effects such as atrial fibrillation, bleeding, diarrhea, and infections. However, TLS is reported rarely with ibrutinib treatment. This report focuses on a 69-year-old female patient diagnosed with relapsed CLL who developed grade 4 TLS after ibrutinib monotherapy. The patient developed TLS on the third day of ibrutinib treatment necessitating discontinuation of the treatment and initiation of hemodialysis and supportive care. Ibrutinib treatment was re-initiated at a daily dose of 140 mg therapy after an interval of seven days, and then any additional side effect was not seen. Tumor lysis syndrome secondary to ibrutinib has been reported in an increasing number of cases. There is currently no information on managing adverse effects of TLS attributed to ibrutinib. Consequently, ibrutinib treatment of this patient was not terminated, and restarted after a short interval. It must not be forgotten that TLS secondary to ibrutinib treatment may be rarely seen, and can be life-threatening. Treatment with ibrutinib should be initiated in consideration of this side effect, and the development of complication of TLS may not necessitate discontinuation of ibrutinib treatment.

Management of Chronic Lymphocytic Leukemia in Less-Resourced Countries

ABSTRACT

Despite the practice-changing advances achieved in the prognostic stratification and treatment of chronic lymphocytic leukemia (CLL), a large fraction of the world population resides in countries where access to many of these advances remains unavailable or subject to severe constraints. Although some of these countries display incidence rates of CLL that are lower than those of developed Western countries, a large number of patients are expected to be diagnosed with CLL in these regions every year. In this article, we review issues regarding management of CLL in some less-resourced countries, with a focus on the evidence basis for epidemiological and clinical information on this disease, the availability of diagnostic and therapeutic resources, and participation in clinical trials. Going forward, challenges that still need to be addressed include the development of unified countrywide registries, guidelines for management applicable to each country, wider availability of prognostic tools, access to new drugs, and policies that ensure these drugs are affordable to all patients worldwide.

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.

Comparative Efficacy of First-Line Treatments of Chronic Lymphocytic Leukemia: Network Meta-Analyses of Survival Curves

BACKGROUND

Multiple treatment options in first-line chronic lymphocytic leukemia (CLL) pose a challenge in identifying the best treatment. We performed novel network meta-analyses (NMA; 8 trials, 11 treatments) on the Kaplan-Meier curves to compare treatments for fludarabine-ineligible patients on progression-free survival (PFS), time-to-next-treatment (TTNT) and overall survival (OS).

METHODS

Using the Guyot method of enhanced secondary analysis of digitized survival data and applying the fixed lognormal distribution model, we extracted the survival proportions and hazard ratios (HR) over 60 months of follow-up, including PFS comparisons by unmutated/mutated IGHV and del 17p.

RESULTS

Acalabrutinib-plus-obinutuzumab was associated with higher 5-year PFS proportions than ibrutinib (HR = 0.42, 95% CrI = 0.25-0.63) but not acalabrutinib, ibrutinib-plus-obinutuzumab, ibrutinib-plus-rituximab or venetoclax-plus-obinutuzumab. In patients with un-mutated (but not with mutated) IGHV higher PFS proportions and favorable HRs were observed for acalabrutinib, acalabrutinib-plus-obinutuzumab, and ibrutinib-plus-obinutuzumab relative to ibrutinib; and targeted therapies were superior over chemoimmunotherapies in patients with del 17p. Targeted therapies containing ibrutinib or acalabrutinib regimens were associated with superior TTNT over venetoclax-plus-obinutuzumab and all chemoimmunotherapies. OS NMA generally found no difference between therapies except for some chemoimmunotherapies.

CONCLUSIONS

Overall, only acalabrutinib-plus-obinutuzumab was associated with superior 5-year PFS gains over ibrutinib, which in turn was similar or superior in PFS benefit over other targeted therapies. Acalabrutinib and ibrutinib with obinutuzumab and acalabrutinib monotherapy were associated with greater 5-year TTNT benefits. Despite marked 5-year OS for many regimens, a differential 5-year OS benefit could not be ascertained.

BCL-2 Inhibition as Treatment for Chronic Lymphocytic Leukemia

OPINION STATEMENT

At the end of the 1990s, with the advent of imatinib for chronic myeloid leukemia and rituximab for B cell lymphoproliferative diseases with CD20 expression, there was a great conceptual evolution in the treatment of onco-hematological diseases. Researchers from around the world and the pharmaceutical industry began to focus their efforts on the so-called target therapy used alone or associated with classic chemotherapeutic drugs. In chronic lymphocytic leukemia, the development of second-generation anti-CD20 antibodies, biosimilars, PI3K (phosphatidylinositol 3-kinases) inhibitors, BTK (Bruton's tyrosine kinase) inhibitors, and anti-bcl 2 drugs represented mainly by venetoclax brought new, broader, and more effective opportunities in the treatment of this disease. This breakthrough occurred mainly regarding patients with alteration in 17p or mutation of the p53 gene for whom selecting the new drugs that act on B cell signaling (BTK and PI3K inhibitors) in the first line is mandatory. In fit patients with immunoglobulin heavy chain mutation, it is still acceptable to use the chemotherapy regimen with fludarabine, cyclophosphamide, and rituximab (FCR) and, in those who do not fit or are not IgVH-mutated, bendamustine-rituximab regimen. However, the first-line use of ibrutinib or venetoclax associated with immunotherapy within the concepts of infinite (ibrutinib) or finite (venetoclax) treatment has been increasingly used. In the second line, venetoclax, ibrutinib, and idelalisib have become the preferred treatments. I believe that a process of instruction and decision shared with patients considering the risks-benefits-cost and access to treatments should guide the choices within these concepts. Another fundamental aspect to discuss is the objective of the treatment for chronic lymphocytic leukemia (CLL) for a specific patient: the increase progression-free survival and overall survival and/or the achievement of minimal residual disease. CLL is the most common leukemia in adults with a median age at diagnosis of 72 years. The clinical course is heterogeneous, and outcomes are influenced by individual clinical presentation and disease biology. Molecular and genomic factors, including fluorescence in situ hybridization (FISH) testing, karyotype, and immunoglobulin heavy chain variable region gene (IGHV) mutational status, are important to treatment decisions and to predict the clinical course. However, despite disease biology, the presence of active disease is the most important criteria to initiate treatment. In the past decade, target therapies that inhibit B cell receptor signaling pathways and, more recently, BCL2 antagonists have emerged as a new treatment paradigm: chemo-free with fixed duration therapy. Bruton's tyrosine kinase inhibitors (BTK) are a class of oral medications approved for frontline and relapsed disease, effective for achieving lasting response and disease control with a good safety profile. BTK inhibitors are an attractive option for high-risk patients who are not candidates for an intensive regimen. However, it is a continuous therapy, and drug resistance or severe adverse events could lead to treatment suspension. BCL2 antagonists are an attractive alternative to BTK inhibitors. Anti-apoptotic BCL2 is associated with tumor genesis and chemotherapy resistance. The BCl2, an anti-apoptotic protein located in the mitochondrial membrane, is a major contributor to the pathogenesis of lymphoid malignancies and is overexpressed in CLL cells promoting clonal cell survival. Venetoclax is a potent and selective member of the BH3 mimetic drugs and a physiologic antagonist of BCL2. Venetoclax has demonstrated quick and durable responses in naïve and relapsed or refractory CLL (r/r CLL) patients, including high-risk patients. Furthermore, it has shown deeper responses, achieving a higher incidence of negative minimal residual disease (MRD) with a fixed duration therapy. In the past decade, there was a remarkable progress in CLL treatment. However, neither of the new target therapies is considered curative or free of toxicity. This article will focus on the treatment approach of CLL patients with BCl2 antagonists. Treatment strategy (combined versus monotherapy; continuous versus limited duration therapy), toxicity profile, and future directions will be exposed in this review.

The global, regional, and national burden of cancer among adolescents and young adults in 204 countries and territories, 1990-2019: a population-based study

BACKGROUND

Accurate appraisal of burden of adolescents and young adults (AYAs) cancers is crucial to informing resource allocation and policy making. We report on the latest estimates of burden of AYA cancers in 204 countries and territories between 1990 and 2019 in association with socio-demographic index (SDI).

PATIENTS AND METHODS

Estimates from the Global Burden of Disease study 2019 were used to analyse incidence, mortality, and disability-adjusted life years (DALYs) due to AYA cancers at global, regional, and national levels by sex. Association between AYA cancer burden and SDI were investigated. Burdens of AYA cancers were contextualized in comparison with childhood and older adult cancers. All estimates are reported as counts and age-standardized rates per 100,000 person-years.

RESULTS

In 2019, there were 1.2 million incident cases, 0.4 million deaths, and 23.5 million DALYs due to AYA cancers globally. The highest age-standardized incidence rate occurred in Western Europe (75.3 [Females] and 67.4 [Males] per 100,000 person-years). Age-standardized death (23.2 [Females] and 13.9 [Males] per 100,000 person-years) and DALY (1328.3 [Females] and 1059.2 [Males] per 100,000 person-years) rates were highest in Oceania. Increasing SDI was associated with a higher age-standardized incidence rate. An inverted U-shaped association was identified between SDI and death and DALY rates. AYA cancers collectively is the second leading cause of non-communicable diseases-related deaths globally in 2019. DALYs of AYA cancers ranked the second globally and the first in low and low-middle SDI locations when compared with that of childhood and older adult cancers.

CONCLUSION

The global burden of AYA cancers is substantial and disproportionally affect populations in limited-resource settings. Capacity building for AYA cancers is essential in promoting equity and population health worldwide.

Immune Therapy for Chronic Lymphocytic Leukemia: Allogeneic Transplant, Chimeric Antigen Receptor T-cell Therapy, and Beyond

Despite significant improvement in clinical outcomes of chronic lymphocytic leukemia (CLL), patients who experience failure of Bruton tyrosine kinase inhibitors or venetoclax benefit from immune therapy approaches. Allogeneic transplant is a potentially curative treatment of CLL but is associated with risk of morbidity and mortality. Although still experimental, chimeric antigen receptor T-cell therapy provides durable remissions in patients with deep molecular responses. This review summarizes the relevant literature and discusses an approach to treatment sequencing and timing of referral for immune therapy. Novel immunotherapy approaches are being investigated and potentially can be utilized in sequence or combination with targeted agents.

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.

SIRT3 overexpression and epigenetic silencing of catalase regulate ROS accumulation in CLL cells activating AXL signaling axis

Mitochondrial metabolism is the key source for abundant ROS in chronic lymphocytic leukemia (CLL) cells. Here, we detected significantly lower superoxide anion (O₂⁻) levels with increased accumulation of hydrogen peroxide (H₂O₂) in CLL cells vs. normal B-cells. Further analysis indicated that mitochondrial superoxide dismutase (SOD)2, which converts O₂⁻ into H₂O₂ remained deacetylated in CLL cells due to SIRT3 overexpression resulting its constitutive activation. In addition, catalase expression was also reduced in CLL cells suggesting impairment of H₂O₂-conversion into water and O₂ which may cause H₂O₂-accumulation. Importantly, we identified two CpG-islands in the catalase promoter and discovered that while the distal CpG-island (−3619 to −3765) remained methylated in both normal B-cells and CLL cells, variable degrees of methylation were discernible in the proximal CpG-island (−174 to −332) only in CLL cells. Finally, treatment of CLL cells with a demethylating agent increased catalase mRNA levels. Functionally, ROS accumulation in CLL cells activated the AXL survival axis while upregulated SIRT3, suggesting that CLL cells rapidly remove highly reactive O₂⁻ to avoid its cytotoxic effect but maintain increased H₂O₂-level to promote cell survival. Therefore, abrogation of aberrantly activated cell survival pathways using antioxidants can be an effective intervention in CLL therapy in combination with conventional agents.

Current and emerging investigational venetoclax-based therapies in chronic lymphocytic leukemia

Introduction: Venetoclax has emerged as a breakthrough treatment which has revolutionized the therapeutic paradigm of chronic lymphocytic leukemia (CLL). This is primarily attributed to the efficacy of venetoclax as a time-limited, chemo-free, therapy in a field dominated by targeted agents given on a continuous schedule. Furthermore, compelling clinical data support the use of venetoclax in combination with other targeted agents in the hope of preventing drug resistance due to the emergence of acquired mutations.Areas covered: This paper provides an overview of clinical results of newly approved or investigational venetoclax-based therapies for CLL. In view of current and potential roles in CLL care, the strengths and disadvantages of venetoclax-combinations are discussed. The MEDLINE database, ClinicalTrials.gov and conference proceedings were all reviewed to select the relevant literature.Expert opinion: While the advent of venetoclax-based combinations has significantly expanded the therapeutic options for patients with CLL, further research with longer follow-up is required to address remaining open questions such as (I) the role of venetoclax as fixed duration therapy(II) timing and threshold of minimal residual disease (MRD) assessment for therapy discontinuation, (III) the efficacy of novel triplet combinations with venetoclax as backbone therapy, (IV) indications for the re-initiation of therapy with venetoclax.

AID in Chronic Lymphocytic Leukemia: Induction and Action During Disease Progression

The enzyme activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) of immunoglobulin (Ig) genes, critical actions for an effective adaptive immune response. However, in addition to the benefits generated by its physiological roles, AID is an etiological factor for the development of human and murine leukemias and lymphomas. This review highlights the pathological role of AID and the consequences of its actions on the development, progression, and therapeutic refractoriness of chronic lymphocytic leukemia (CLL) as a model disease for mature lymphoid malignancies. First, we summarize pertinent aspects of the expression and function of AID in normal B lymphocytes. Then, we assess putative causes for AID expression in leukemic cells emphasizing the role of an activated microenvironment. Thirdly, we discuss the role of AID in lymphomagenesis, in light of recent data obtained by NGS analyses on the genomic landscape of leukemia and lymphomas, concentrating on the frequency of AID signatures in these cancers and correlating previously described tumor-gene drivers with the presence of AID off-target mutations. Finally, we discuss how these changes could affect tumor suppressor and proto-oncogene targets and how they could be associated with disease progression. Collectively, we hope that these sections will help to better understand the complex paradox between the physiological role of AID in adaptive immunity and its potential causative activity in B-cell malignancies.

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.

Clinical and molecular characteristics and treatment patterns of adolescent and young adult patients with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) rarely presents in adolescent and young adult (AYA) patients (patients aged 15-39 years). Disease characteristics and outcomes of AYA patients with CLL are not well understood, particularly in the era of novel oral targeted therapies. We analysed outcomes of 227 AYA patients with CLL diagnosed in the last two decades and evaluated at our institution. Median time to first treatment (TTFT) was 2·2 years, and five- and 10-year overall survival (OS) were 90% and 78%, respectively. Pre-treatment elevated beta 2-microglobulin, advanced Rai stage, del(11q) or del(17p) by FISH, unmutated IGHV and CD38 positivity were associated with both shorter TTFT and OS. Within the subgroup of patients who received oral targeted therapy at any time, del(11q) or del(17p) and complex karyotype were associated with shorter OS. First-line treatment choice was significantly associated with time to second treatment (P < 0·001). Patients harbouring del(11q) or del(17p) experienced shorter time to Richter transformation and were more likely to undergo an allogeneic stem cell transplant. There was a significant association between age and both OS and time to Richter transformation. Our study is the first analysis of AYA patients with CLL with a large number of patients treated with oral targeted therapies.

Clinical Outcomes in Patients with Multi-Hit TP53 Chronic Lymphocytic Leukemia Treated with Ibrutinib

PURPOSE

TP53 aberration (TP53 mutation and/or 17p deletion) is the most important predictive marker in chronic lymphocytic leukemia (CLL). Although each TP53 aberration is considered an equal prognosticator, the prognostic value of carrying isolated (single-hit) or multiple (multi-hit) TP53 aberrations remains unclear, particularly in the context of targeted agents.

PATIENTS AND METHODS

We performed deep sequencing of TP53 using baseline samples collected from 51 TP53 aberrant patients treated with ibrutinib in a phase II study (NCT01500733).

RESULTS

We identified TP53 mutations in 43 patients (84%) and del(17p) in 47 (92%); 9 and 42 patients carried single-hit and multi-hit TP53, respectively. The multi-hit TP53 subgroup was enriched with younger patients who had prior treatments and unmutated immunoglobulin heavy-chain variable region gene status. We observed significantly shorter overall survival, progression-free survival (PFS), and time-to-progression (TTP) in patients with multi-hit TP53 compared with those with single-hit TP53. Clinical outcomes were similar in patient subgroups stratified by 2 or >2 TP53 aberrations. In multivariable analyses, multi-hit TP53 CLL was independently associated with inferior PFS and TTP. In sensitivity analyses, excluding mutations below 1% VAF demonstrated similar outcome. Results were validated in an independent population-based cohort of 112 patients with CLL treated with ibrutinib.

CONCLUSIONS

In this study, single-hit TP53 defines a distinct subgroup of patients with an excellent long-term response to single-agent ibrutinib, whereas multi-hit TP53 is independently associated with shorter PFS. These results warrant further investigations on prognostication and management of multi-hit TP53 CLL.See related commentary by Bomben et al., p. 4462.

The Impact of Chlorambucil and Valproic Acid on Cell Viability, Apoptosis and Expression of p21, HDM2, BCL2 and MCL1 Genes in Chronic Lymphocytic Leukemia

Malignant cells in chronic lymphocytic leukemia (CLL) show resistance to apoptosis, as well as to chemotherapy, which are related to deletions or mutations of TP53, high expression of MCL1 and BCL2 genes and other abnormalities. Thus, the main goal of the present study was to assess the impact of chlorambucil (CLB) combined with valproic acid (VPA), a known antiepileptic drug and histone deacetylation inhibitor, on apoptosis of the cells isolated from 17 patients with CLL. After incubation with CLB (17.5 µM) and VPA (0.5 mM), percentage of apoptosis, as well as expression of two TP53 target genes (p21 and HDM2) and two genes from Bcl-2 family (BCL2 and MCL1), were tested. As a result, an increased percentage of apoptosis was observed for CLL cells treated with CLB and VPA, and with CLB alone. Under the treatment with the drug combination, the expression of p21 gene was visibly higher than under the treatment with CLB alone. At the same time, the cultures under CLB treatment showed visibly higher expression of BCL2 than the cultures with VPA alone. Thus, the present study strongly suggests further investigations on the CLB and VPA combination in CLL treatment.

T-cell dysfunction in chronic lymphocytic leukemia from an epigenetic perspective

Cellular immunotherapeutic approaches such as chimeric antigen receptor (CAR) T-cell therapy in chronic lymphocytic leukemia (CLL) thus far have not met the high expectations. Therefore it is essential to better understand the molecular mechanisms of CLLinduced T-cell dysfunction. Even though a significant number of studies are available on T-cell function and dysfunction in CLL patients, none examine dysfunction at the epigenomic level. In non-malignant T-cell research, epigenomics is widely employed to define the differentiation pathway into T-cell exhaustion. Additionally, metabolic restrictions in the tumor microenvironment that cause T-cell dysfunction are often mediated by epigenetic changes. With this review paper we argue that understanding the epigenetic (dys)regulation in T cells of CLL patients should be leveled to the knowledge we currently have of the neoplastic B cells themselves. This will permit a complete understanding of how these immune cell interactions regulate T- and B-cell function. Here we relate the cellular and phenotypic characteristics of CLL-induced T-cell dysfunction to epigenetic studies of T-cell regulation emerging from chronic viral infection and tumor models. This paper proposes a framework for future studies into the epigenetic regulation of CLL-induced Tcell dysfunction, knowledge that will help to guide improvements in the utility of autologous T-cell based therapies in CLL.

Chronic Lymphocytic Leukemia in Neurofibromatosis Type 1 Patients: Case Report and Literature Review of a Rare Occurrence

Neurofibromatosis type 1 (NF1) is an autosomal dominant genodermatosis that may also occur as the result of a spontaneous mutation. The diagnosis can be established by the presence of two of the seven National Institutes of Health (NIH) diagnostic criteria; several dermatologic manifestations are NIH criteria used to establish the diagnosis: axillary and inguinal freckling, café-au-lait macules, and neurofibromas. Mucosal evaluation of the eyes may detect a fourth criteria: pigmented iris hamartomas (Lisch nodules). The remaining NIH criteria include optic path glioma, distinctive osseus lesions, and a positive family history of the condition. A breast cancer 2 (BRCA2) positive woman with NF1 and chronic lymphocytic leukemia is described. Patients with NF1 have an increased lifetime risk to develop breast cancer, gastrointestinal stromal tumor, malignant glioma, malignant peripheral nerve sheath tumor, and rhabdomyosarcoma. Chronic lymphocytic leukemia occurring in NF1 patients is rare; including my female patient reported in this paper, chronic lymphocytic leukemia has only been reported in three individuals with NF1--two women and one man. The man and the other woman presented with advanced chronic lymphocytic leukemia and treatment with antineoplastic therapy at diagnosis; the man achieved clinical remission and the woman passed away from complications associated with therapy-refractory progression of her leukemia. My female patient required treatment 41 months after diagnosis and had a good clinical response; she has been without significant disease progression for 34 months. Similar to NF1, breast cancer 1 (BRCA1) and BRCA2 mutations are associated with an increased lifetime risk of developing cancer--particularly breast and ovarian carcinoma. An increased risk of chronic lymphocytic leukemia has also been demonstrated in patients with mutations of either BRCA1 or BRCA2. Also, albeit uncommon, either BRCA1 or BRCA2 mutation has been detected in women with NF1 who develop breast cancer. In conclusion, the development of chronic lymphocytic leukemia in NF1 patients may be coincidental and not associated with the underlying genodermatosis; however, the occurrence of chronic lymphocytic leukemia in my patient with NF1, in part, may be related to her BRCA2 positivity.

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.

Properties of FDA-approved small molecule phosphatidylinositol 3-kinase inhibitors prescribed for the treatment of malignancies

The discovery of the phosphatidylinositol 3-kinase (PI 3-kinase) pathway was a major advance in understanding eukaryotic signal transduction. The high frequency of PI 3-kinase pathway mutations in many cancers stimulated the development of drugs targeting these oncogenic mutants. The PI 3-kinases are divided into three classes and Class I PI 3-kinases, which catalyze the phosphorylation of phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2) to generate phosphatidylinositol-3,4,5-trisphosphate (PIP3), are the main subject of this review. The class I PI 3-kinases are made up of p110α, p110β, p110δ, and p110γ catalytic subunits. These catalytic subunits are constitutively bound to regulatory subunits (p85α, p85β, p55γ, p101, and p87 proteins). The p85/p55 regulatory subunits heterodimerize with p110α or p110δ thereby forming complexes that are regulated chiefly by receptor protein-tyrosine kinases. The p101 and p87 subunits heterodimerize with p110γ to form complexes that are regulated mainly by G protein-coupled receptors (GPCRs). Complexes containing the p110β subunit are activated by receptor protein-tyrosine kinases as well as GPCRs. Following the generation of PIP3, the AKT and mTOR protein-serine/threonine kinases are activated leading to cell growth, proliferation, and survival. Like protein kinases, the PI 3-kinase domains consist of a bilobed structure connected by a hinge-linker segment. ATP and most PI 3-kinase and protein kinase inhibitors form hydrogen bonds with hinge residues. The small and large lobes of PI 3-kinases and protein kinases have a very similar three-dimensional structure called the protein kinase fold. Both PI 3-kinases and eukaryotic protein kinases possess an activation segment that begins with a DFG triad (Asp-Phe-Gly); the activation segment of protein kinases usually ends with an APE (Ala-Pro-Glu) signature while that of PI 3-kinases ends with a PFxLT (Pro-Phe-Xxx-Leu-Thr) signature. Dormant PI 3-kinases have a collapsed activation loop and active PI 3-kinases have an extended activation loop. The distance between the α-carbon atom of the DFG-D residue at the beginning of the activation loop and that of the PFxLT-F residue at the end of the activation loop in dormant PI 3-kinases is about 13 Å; this distance in active PI 3-kinases is about 18 Å. The protein kinase catalytic loop has an HRD (His-Arg-Asp) signature while that of the PI 3-kinases reverses the order with a DRH triad. Alpelisib is an orally effective FDA-approved PI 3-kinase-α inhibitor used for the treatment of breast cancer. Copanlisib, duvelisib, idelalisib, and umbralisib are PI 3-kinase-δ inhibitors that are approved for the third-line treatment of follicular lymphomas and other hematological disorders. Copanlisib is also a potent inhibitor of PI 3-kinase-α. Of the five approved drugs, all are orally bioavailable except copanlisib. Idelalisib interacts with the active conformation of PI 3-kinase-δ and is classified as a type I inhibitor. Alpelisib and copanlisib interact with inactive PI 3-kinase-α and PI 3-kinase-γ, respectively, and are classified as a type I½ antagonists. Except for umbralisib with a molecular weight of 571.5, all five drugs conform to the Lipinski rule of five for oral effectiveness. Copanlisib, however, must be given intravenously. Alpelisib and copanlisib inhibit PI 3-kinase-α, which is involved in insulin signaling, and both drugs promote insulin-resistance and produce hyperglycemia. The five FDA-approved PI 3-kinase inhibitors produce significant on-target toxicities, more so than many approved protein kinase antagonists. The development of PI 3-kinase inhibitors with fewer toxicities is an important long-term therapeutic goal.

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

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.

The multi-kinase inhibitor TG02 induces apoptosis and blocks B-cell receptor signaling in chronic lymphocytic leukemia through dual mechanisms of action

The constitutive activation of B-cell receptor (BCR) signaling, together with the overexpression of the Bcl-2 family anti-apoptotic proteins, represents two hallmarks of chronic lymphocytic leukemia (CLL) that drive leukemia cell proliferation and sustain their survival. TG02 is a small molecule multi-kinase inhibitor that simultaneously targets both of these facets of CLL pathogenesis. First, its inhibition of cyclin-dependent kinase 9 blocked the activation of RNA polymerase II and transcription. This led to the depletion of Mcl-1 and rapid induction of apoptosis in the primary CLL cells. This mechanism of apoptosis was independent of CLL prognostic factors or prior treatment history, but dependent on the expression of BAX and BAK. Second, TG02, which inhibits the members of the BCR signaling pathway such as Lck and Fyn, blocked BCR-crosslinking-induced activation of NF-κB and Akt, indicating abrogation of BCR signaling. Finally, the combination of TG02 and ibrutinib demonstrated moderate synergy, suggesting a future combination of TG02 with ibrutinib, or use in patients that are refractory to the BCR antagonists. Thus, the dual inhibitory activity on both the CLL survival pathway and BCR signaling identifies TG02 as a unique compound for clinical development in CLL and possibly other B cell malignancies.

Hypercalcaemia, renal failure, anaemia and osteolytic lesions (CRAB) in chronic lymphocytic leukaemia mimicking multiple myeloma

Classical CRAB features (hypercalcaemia, renal failure, anaemia, osteolytic lesions) have been traditionally defined in patients with plasma cell dyscrasia. But these can be rare and uncommon presentations of other chronic lymphoproliferative disorders (CLPD). The pathophysiological basis of CRAB features in other CLPD need to be explored further for better outcomes and therapeutic interventions. These can present a diagnostic dilemma and requires extensive workup to rule out coexisting malignancy and myeloma. Here, we report an unusual case of B CLPD in a middle-aged male who presented with classical CRAB features along with a brief literature review. After detailed investigations, he was diagnosed as chronic lymphocytic leukaemia, without any second malignancy and responded well to ibrutinib-based therapy.

Venetoclax as a therapeutic option for the treatment of chronic lymphocytic leukemia: the evidence so far

INTRODUCTION

Venetoclax, an oral, BCL-2 inhibitor, is approved by the FDA for treatment of CLL in all lines of therapy. Data from landmark studies, including the CLL14 and MURANO trials, demonstrated marked improvement in clinical outcomes compared to chemoimmunotherapy when venetoclax was used in combination with CD20 monoclonal antibodies for fixed treatment duration.

AREAS COVERED

This article reviews the mechanism of action of venetoclax and discusses how curtailing the BCL signaling pathway undermines CLL pathophysiology. The authors also give their clinical experience with the drug, with emphasis on assessing and managing the risk of venetoclax-associated tumor lysis syndrome (TLS).

EXPERT OPINION

Venetoclax has positioned itself as one of the primary treatment options for CLL, given the consistent efficacy and deep remissions it has elicited across multiple settings of the disease with a time-limited schedule. Accurate TLS risk evaluation and stringent adherence to the dose-escalation protocols will help optimize patient outcomes. Finally, we expect that current and future studies will (1) ascertain the ideal treatment duration using the minimal residual disease state as a guide and (2) help us understand the optimal role of venetoclax in combination or in sequence with other novel targeted therapies in the treatment of CLL.

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.

The role of m6A modification in the biological functions and diseases

N⁶-methyladenosine (m6A) is the most prevalent, abundant and conserved internal cotranscriptional modification in eukaryotic RNAs, especially within higher eukaryotic cells. m6A modification is modified by the m6A methyltransferases, or writers, such as METTL3/14/16, RBM15/15B, ZC3H3, VIRMA, CBLL1, WTAP, and KIAA1429, and, removed by the demethylases, or erasers, including FTO and ALKBH5. It is recognized by m6A-binding proteins YTHDF1/2/3, YTHDC1/2 IGF2BP1/2/3 and HNRNPA2B1, also known as "readers". Recent studies have shown that m6A RNA modification plays essential role in both physiological and pathological conditions, especially in the initiation and progression of different types of human cancers. In this review, we discuss how m6A RNA methylation influences both the physiological and pathological progressions of hematopoietic, central nervous and reproductive systems. We will mainly focus on recent progress in identifying the biological functions and the underlying molecular mechanisms of m6A RNA methylation, its regulators and downstream target genes, during cancer progression in above systems. We propose that m6A RNA methylation process offer potential targets for cancer therapy in the future.

The contribution of CD200 to the diagnostic accuracy of Matutes score in the diagnosis of chronic lymphocytic leukemia in limited resources laboratories

Flow cytometry immunophenotyping has an essential role in distinguishing chronic lymphocytic leukemia from other B-chronic lymphoproliferative disorders. Recently, CD200 is considered as a relatively consistent marker in chronic lymphocytic leukemia. We retrospectively assessed CD200 expression in 252 patients with B chronic lymphoproliferative disorders with four-color flow cytometry. CD200 expression estimation included the proportion of positive cells (≥30%) and the mean fluorescence intensity ratio. Additionally, we have incorporated CD200 into Matutes score, also replaced FMC7 and CD79b in an attempt to improve the score discriminative power. Of 252 patients enrolled, 199(79%) patients were classified as chronic lymphocytic leukemia and 53 (21%) as other B-chronic lymphoproliferative disorders. All chronic lymphocytic leukemia cases and 20 of 53 (37.7%) of other B-chronic lymphoproliferative disorders demonstrated high CD200 expression (≥30%). Further, CD200 (≥30%) revealed a higher accuracy in comparison to other markers in Matutes score (range: 51%–92.5%). Also, CD200 addition to the Matutes score has correctly recognized all 199 chronic lymphocytic leukemia cases including 10 atypical chronic lymphocytic leukemia cases. As for non-CLL cases, 20 of 53 attained a higher score, yet keeping the original diagnosis. Moreover, CD200 enhanced the diagnostic accuracy of Matutes score to 100%, and when included in a simplified 4-markers score, showed an accuracy of 99.8% compared to 99.4% of Matutes score. In conclusion, CD200 is an accurate diagnostic marker for chronic lymphocytic leukemia, and can refine the modified Matutes score accuracy when added with other markers.

ER Stress and Unfolded Protein Response in Leukemia: Friend, Foe, or Both?

The unfolded protein response (UPR) is an evolutionarily conserved adaptive signaling pathway triggered by a stress of the endoplasmic reticulum (ER) lumen compartment, which is initiated by the accumulation of unfolded proteins. This response, mediated by three sensors-Inositol Requiring Enzyme 1 (IRE1), Activating Transcription Factor 6 (ATF6), and Protein Kinase RNA-Like Endoplasmic Reticulum Kinase (PERK)—allows restoring protein homeostasis and maintaining cell survival. UPR represents a major cytoprotective signaling network for cancer cells, which frequently experience disturbed proteostasis owing to their rapid proliferation in an usually unfavorable microenvironment. Increased basal UPR also participates in the resistance of tumor cells against chemotherapy. UPR activation also occurs during hematopoiesis, and growing evidence supports the critical cytoprotective role played by ER stress in the emergence and proliferation of leukemic cells. In case of severe or prolonged stress, pro-survival UPR may however evolve into a cell death program called terminal UPR. Interestingly, a large number of studies have revealed that the induction of proapoptotic UPR can also strongly contribute to the sensitization of leukemic cells to chemotherapy. Here, we review the current knowledge on the consequences of the deregulation of UPR signaling in leukemias and their implications for the treatment of these diseases.

Comorbidities at Diagnosis, Survival, and Cause of Death in Patients with Chronic Lymphocytic Leukemia: A Population-Based Study

This study aimed to examine the prevalence of comorbidities in patients diagnosed with chronic lymphocytic leukemia (CLL), and to assess its influence on survival and cause-specific mortality at a population-based level. Incident CLL cases diagnosed in the Girona province (Spain) during 2008–2016 were extracted from the Girona Cancer Registry. Rai stage and presence of comorbidities at diagnosis, further categorized using the Charlson comorbidity index (CCI), were obtained from clinical records. Observed (OS) and relative survival (RS) were estimated and Cox’s proportional hazard models were used to explore the impact of comorbidity on mortality. Among the 400 cases included in the study, 380 (99.5%) presented at least one comorbidity at CLL diagnosis, with diabetes without end organ damage (21%) being the most common disease. 5-year OS and RS were 68.8 (95% CI: 64.4–73.6) and 99.5 (95% CI 3.13–106.0), respectively, which decreased markedly with increasing CCI, particularly in patients with CCI ≥ 3. Multivariate analysis identified no statistically significant association between the CCI and overall CLL-related or CLL-unrelated mortality. In conclusion, a high CCI score negatively influenced the OS and RS of CLL patients, yet its effect on mortality was statistically non-significant when also considering age and the Rai stage.

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.

Heterogeneity of TP53 Mutations and P53 Protein Residual Function in Cancer: Does It Matter?

The human TP53 locus, located on the short arm of chromosome 17, encodes a tumour suppressor protein which functions as a tetrameric transcription factor capable of regulating the expression of a plethora of target genes involved in cell cycle arrest, apoptosis, DNA repair, autophagy, and metabolism regulation. TP53 is the most commonly mutated gene in human cancer cells and TP53 germ-line mutations are responsible for the cancer-prone Li-Fraumeni syndrome. When mutated, the TP53 gene generally presents missense mutations, which can be distributed throughout the coding sequence, although they are found most frequently in the central DNA binding domain of the protein. TP53 mutations represent an important prognostic and predictive marker in cancer. The presence of a TP53 mutation does not necessarily imply a complete P53 inactivation; in fact, mutant P53 proteins are classified based on the effects on P53 protein function. Different models have been used to explore these never-ending facets of TP53 mutations, generating abundant experimental data on their functional impact. Here, we briefly review the studies analysing the consequences of TP53 mutations on P53 protein function and their possible implications for clinical outcome. The focus shall be on Chronic Lymphocytic Leukemia (CLL), which also has generated considerable discussion on the role of TP53 mutations for therapy decisions.