A novel anti-CD19 monoclonal antibody (GBR 401) with high killing activity against B cell malignancies

High-Throughput and Format-Agnostic Mispairing Assay for Multispecific Antibodies Using Intact Mass Spectrometry

Multispecific antibodies have gained significant importance in a broad indication space due to their ability to engage multiple epitopes simultaneously and to thereby overcome therapeutic barriers. With growing therapeutic potential, however, the molecular complexity increases, thus intensifying the demand for innovative protein engineering and analytical strategies. A major challenge for multispecific antibodies is the correct assembly of light and heavy chains. Engineering strategies exist to stabilize the correct pairing, but typically individual engineering campaigns are required to arrive at the anticipated format. Mass spectrometry has proven to be a versatile tool to identify mispaired species. However, due to manual data analysis procedures, mass spectrometry is limited to lower throughputs. To keep pace with increasing sample numbers, we developed a high-throughput-capable mispairing workflow based on intact mass spectrometry with automated data analysis, peak detection, and relative quantification using Genedata Expressionist. This workflow is capable of detecting mispaired species of ∼1000 multispecific antibodies in three weeks and thus is applicable to complex screening campaigns. As a proof of concept, the assay was applied to engineering a trispecific antibody. Strikingly, the new setup has not only proved successful in mispairing analysis but has also revealed its potential to automatically annotate other product-related impurities. Furthermore, we could confirm the assay to be format-agnostic, as shown by analyzing several different multispecific formats in one run. With these comprehensive capabilities, the new automated intact mass workflow can be applied as a universal tool to detect and annotate peaks in a format-agnostic approach and in high-throughput, thus enabling complex discovery campaigns.

Chicken-derived CD20 antibodies with potent B-cell depletion activity

We report four novel anti-human CD20 (hCD20) monoclonal antibodies (mAbs) discovered from a phylogenetically distant species-chickens. The chicken-human chimaeric antibodies exhibit at least 10-fold enhanced antibody-dependent cellular cytotoxicity (ADCC) and 4-8-fold stronger complement-dependent cytotoxicity (CDC) relative to the clinically used mouse-human chimaeric anti-hCD20 antibody rituximab (RTX). Thus, to our knowledge these mAbs are the first to significantly outperform RTX in both Fc-mediated mechanisms of action. The antibodies show 20-100-fold superior depletion of B cells in whole blood from healthy humans relative to RTX and retain efficacy in vivo. One of the mAbs, AC1, can bind mouse CD20, indicating specificity for a novel hCD20 epitope inaccessible to current (mouse-derived) anti-hCD20 mAbs. A humanized version of one antibody, hAC11-10, was created by complementarity-determining region (CDR) grafting into a human variable region framework and this molecule retained the ADCC, in vitro human whole-blood B-cell depletion, and in vivo lymphoma cell depletion activities of the parent. These mAbs represent promising monotherapy candidates for improving upon current less-than-ideal clinical outcomes in lymphoid malignancies and provide an arsenal of biologically relevant molecules for the development of next-generation CD20-mediated immunotherapies including bispecific T-cell engagers (BiTE), antibody-drug conjugates (ADC) and chimaeric antigen receptor-engineered T (CAR-T) cells.

Development and functional characterization of novel fully human anti-CD19 chimeric antigen receptors for T-cell therapy

Impressive outcomes have been achieved by chimeric antigen receptor (CAR)-T cell therapy using murine-derived single-chain variable fragment (scFv) FMC63 specific for CD19 in patients with B cell malignancies. However, evidence suggests that human anti-mouse immune responses might be responsible for poor persistence and dysfunction of CAR-T cells, leading to poor outcomes or early tumor recurrence. Substituting a fully human scFv for murine-derived scFv may address this clinically relevant concern. In this study, we discovered two human anti-CD19 scFv candidates through an optimized protein/cell alternative panning strategy and evaluated their function in CAR-T cells and CD19/CD3 bispecific antibody formats. The two clones exhibited excellent cytotoxicity in CAR-T cells and bispecific antibodies in vitro compared with the benchmarks FMC63 CAR-T cells and blinatumomab. Furthermore, Clone 78-BBz CAR-T cells exhibited similar in vivo antitumor activity to FMC63-BBz CAR-T cells. Our results indicate that Clone 78-BBz CAR has excellent efficacy and safety profile and is a good candidate for clinical development.

FUT8 Alpha-(1,6)-Fucosyltransferase in Cancer

Aberrant glycosylation is a universal feature of cancer cells that can impact all steps in tumour progression from malignant transformation to metastasis and immune evasion. One key change in tumour glycosylation is altered core fucosylation. Core fucosylation is driven by fucosyltransferase 8 (FUT8), which catalyses the addition of α1,6-fucose to the innermost GlcNAc residue of N-glycans. FUT8 is frequently upregulated in cancer, and plays a critical role in immune evasion, antibody-dependent cellular cytotoxicity (ADCC), and the regulation of TGF-β, EGF, α3β1 integrin and E-Cadherin. Here, we summarise the role of FUT8 in various cancers (including lung, liver, colorectal, ovarian, prostate, breast, melanoma, thyroid, and pancreatic), discuss the potential mechanisms involved, and outline opportunities to exploit FUT8 as a critical factor in cancer therapeutics in the future.

Reactive oxygen/nitrogen species contribute substantially to the antileukemia effect of APO866, a NAD lowering agent

APO866 is a small molecule drug that specifically inhibits nicotinamide phosphoribosyltransferase (NAMPT), a key enzyme involved in nicotinamide adenine dinucleotide (NAD) biosynthesis from the natural precursor nicotinamide. Although, the antitumor activity of APO866 on various types of cancer models has been reported, information regarding mechanisms by which APO866 exerts its cytotoxic effects is not well defined. Here we show that APO866 induces a strong, time-dependent increase in highly reactive ROS, nitric oxide, cytosolic/mitochondrial superoxide anions and hydrogen peroxide. We provide evidence that APO866-mediated ROS production is modulated by PARP1 and triggers cell death through mitochondria depolarization and ATP loss. Genetic or pharmacologic inhibition of PARP1 prevented hydrogen peroxide accumulation, caspase activation, mitochondria depolarization, ATP loss and abrogates APO866-induced cell death, suggesting that the integrity of PARP1 status is required for cell death. Conversely, PARP1 activating drugs enhanced the anti-leukemia activity of APO866 Collectively, our studies show that APO866 induces ROS/RNS productions, which mediate its anti-leukemia effect. These results support testing new combinatorial strategies to enhance the antitumor activities of APO866.

The "less-is-more" in therapeutic antibodies: Afucosylated anti-cancer antibodies with enhanced antibody-dependent cellular cytotoxicity

Therapeutic monoclonal antibodies are the fastest growing class of biological therapeutics for the treatment of various cancers and inflammatory disorders. In cancer immunotherapy, some IgG1 antibodies rely on the Fc-mediated immune effector function, antibody-dependent cellular cytotoxicity (ADCC), as the major mode of action to deplete tumor cells. It is well-known that this effector function is modulated by the N-linked glycosylation in the Fc region of the antibody. In particular, absence of core fucose on the Fc N-glycan has been shown to increase IgG1 Fc binding affinity to the FcγRIIIa present on immune effector cells such as natural killer cells and lead to enhanced ADCC activity. As such, various strategies have focused on producing afucosylated antibodies to improve therapeutic efficacy. This review discusses the relevance of antibody core fucosylation to ADCC, different strategies to produce afucosylated antibodies, and an update of afucosylated antibody drugs currently undergoing clinical trials as well as those that have been approved.

Co-engaging CD47 and CD19 with a bispecific antibody abrogates B-cell receptor/CD19 association leading to impaired B-cell proliferation

CD19 is a B cell-specific receptor that regulates the threshold of B cell receptor (BCR)-mediated cell proliferation. A CD47xCD19 bispecific antibody (biAb) was generated to target and deplete B cells via multiple antibody-mediated mechanisms. Interestingly, the biAb, constructed of a CD19 binding arm and a CD47 binding arm, inhibited BCR-mediated B-cell proliferation with an effect even more potent than a CD19 monoclonal antibody (mAb). The inhibitory effect of the biAb was not attributable to CD47 binding because a monovalent or bivalent anti-CD47 mAb had no effect on B cell proliferation. Fluorescence resonance energy transfer analysis demonstrated that co-engaging CD19 and CD47 prevented CD19 clustering and its migration to BCR clusters, while only engaging CD19 (with a mAb) showed no impact on either CD19 clustering or migration. The lack of association between CD19 and the BCR resulted in decreased phosphorylation of CD19 upon BCR activation. Furthermore, the biAb differentially modulated BCR-induced gene expression compared to a CD19 mAb. Taken together, this unexpected role of CD47xCD19 co-ligation in inhibiting B cell proliferation illuminates a novel approach in which two B cell surface molecules can be tethered, to one another in order, which may provide a therapeutic benefit in settings of autoimmunity and B cell malignancies.

Cancer Immunotherapy in Diffuse Large B-Cell Lymphoma

Remarkable progress has been made in the field of cancer immunotherapy in the past few years. Immunotherapy has become a standard treatment option for patients with various cancers, including melanoma, lymphoma, and carcinomas of the lungs, kidneys, bladder, and head and neck. Promising immunotherapy approaches, such as chimeric antigen receptor (CAR) T cell therapy and therapeutic blockade of immune checkpoints, in particular cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 pathway (PD-1/PD-L1), have boosted the development of new therapeutic regimens for patients with cancer. Immunotherapeutic strategies for diffuse large B-cell lymphoma (DLBCL) include monoclonal anti-CD20 antibody (rituximab), monoclonal anti-PD-1 antibodies (nivolumab and pembrolizumab), monoclonal anti-PD-L1 antibodies (avelumab, durvalumab, and atezolizumab) and chimeric antigen receptor (CAR) T cell therapy. In this review, we outline the latest highlights and progress in using immunotherapy to treat patients with DLBCL, with a focus on the therapeutic blockade of PD-1/PD-L1 and CAR T cell therapy in DLBCL. We also discuss current clinical trials of PD-1/PD-L1 and CAR T cell therapy and review the challenges and opportunities of using immunotherapy for the treatment of DLBCL.

CD83 Antibody Inhibits Human B Cell Responses to Antigen as well as Dendritic Cell-Mediated CD4 T Cell Responses

Anti-CD83 Ab capable of Ab-dependent cellular cytotoxicity can deplete activated CD83+ human dendritic cells, thereby inhibiting CD4 T cell-mediated acute graft-versus-host disease. As CD83 is also expressed on the surface of activated B lymphocytes, we hypothesized that anti-CD83 would also inhibit B cell responses to stimulation. We found that anti-CD83 inhibited total IgM and IgG production in vitro by allostimulated human PBMC. Also, Ag-specific Ab responses to immunization of SCID mice xenografted with human PBMC were inhibited by anti-CD83 treatment. This inhibition occurred without depletion of all human B cells because anti-CD83 lysed activated CD83+ B cells by Ab-dependent cellular cytotoxicity and spared resting (CD83-) B cells. In cultured human PBMC, anti-CD83 inhibited tetanus toxoid-stimulated B cell proliferation and concomitant dendritic cell-mediated CD4 T cell proliferation and expression of IFN-γ and IL-17A, with minimal losses of B cells (<20%). In contrast, the anti-CD20 mAb rituximab depleted >80% of B cells but had no effect on CD4 T cell proliferation and cytokine expression. By virtue of the ability of anti-CD83 to selectively deplete activated, but not resting, B cells and dendritic cells, with the latter reducing CD4 T cell responses, anti-CD83 may be clinically useful in autoimmunity and transplantation. Advantages might include inhibited expansion of autoantigen- or alloantigen-specific B cells and CD4 T cells, thus preventing further production of pathogenic Abs and inflammatory cytokines while preserving protective memory and regulatory cells.

Development of specific nanobodies (VHH) for CD19 immuno-targeting of human B-lymphocytes

OBJECTIVES

CD19 is a transmembrane glycoprotein of immunoglobulin superfamily. In order to treat lymphoma, monoclonal antibodies (mAb) can target different antigens, including CD19, CD20 and CD22 on the surface of B-cells. Along with biotechnology progress, a new generation of antibodies is introduced, with the purpose of eliminating the defects of the previous generation. Among the most developed one are nanobodies (Nb). Nbs are a unique kind of camelid single domain antibody fragments with a broad range of medical applications. Unique physicochemical properties of Nbs have made them ideal candidates for therapeutic and diagnostic applications.

MATERIALS AND METHODS

An immune gene library was created, and several CD19 specific Nbs were selected through antigen panning process, and their molecular properties as well as specificity, sensitivity, affinity and immunoreactivity against CD19 positive and negative cells were evaluated.

RESULTS

The Nb library was prepared with 7.2 x107 members. We managed to isolate a panel of CD19-specific Nbs after the last round of selection with the affinity of isolated Nbs being estimated at the standard range of 15-35 nM. Sequence analysis of positive clones was indicative of the fact that 12 variable sequences were confirmed. Of all these 12 clones, 2 clones with the greatest level signal in ELISA underwent subsequent analysis. Our sequencing results indicated high sequence homology (approximately 90%) between the Nb and Homa variable immunoglobulin domains.

CONCLUSION

Specific Nbs possess the potential to be used as novel therapeutic approaches in order to treat autoimmune diseases and B-cell lymphoma.

Bruton tyrosine kinase inhibitor ONO/GS-4059: from bench to bedside

The Bruton tyrosine kinase (BTK) inhibitor, ibrutinib, has been approved for the treatment of chronic lymphocytic leukemia, mantle cell lymphoma, and Waldenstroms macroglobulinemia. Acquired resistance to ibrutinib due to BTK C481S mutation has been reported. Mutations in PLC?2 can also mediate resistance to ibrutinib. Untoward effects due to off-target effects are also disadvantages of ibrutinib. More selective and potent BTK inhibitors (ACP-196, ONO/GS-4059, BGB-3111, CC-292) are being investigated. This review summarized the preclinical research and clinical data of ONO/GS-4059.

Patient's Natural Killer Cells in the Era of Targeted Therapies: Role for Tumor Killers

Natural killer (NK) cells are potent antitumor effectors, involved in hematological malignancies and solid tumor immunosurveillance. They infiltrate various solid tumors, and their numbers are correlated with good outcome. The function of NK cells extends their lytic capacities toward tumor cells expressing stress-induced ligands, through secretion of immunoregulatory cytokines, and interactions with other immune cells. Altered NK cell function due to tumor immune escape is frequent in advanced tumors; however, strategies to release the function of NK infiltrating tumors are emerging. Recent therapies targeting specific oncogenic mutations improved the treatment of cancer patients, but patients often relapse. The actual development consists in combined therapeutic strategies including agents targeting the proliferation of tumor cells and others restorating functional antitumor immune effectors for efficient and durable efficacy of anticancer treatment. In that context, we discuss the recent results of the literature to propose hypotheses concerning the potential use of NK cells, potent antitumor cytotoxic effectors, to design novel antitumor strategies.

Second-generation inhibitors of Bruton tyrosine kinase

Bruton tyrosine kinase (BTK) is a critical effector molecule for B cell development and plays a major role in lymphoma genesis. Ibrutinib is the first-generation BTK inhibitor. Ibrutinib has off-target effects on EGFR, ITK, and Tec family kinases, which explains the untoward effects of ibrutinib. Resistance to ibrutinib was also reported. The C481S mutation in the BTK kinase domain was reported to be a major mechanism of resistance to ibrutinib. This review summarizes the clinical development of novel BTK inhibitors, ACP-196 (acalabrutinib), ONO/GS-4059, and BGB-3111.

Nanomedicine approaches in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the malignancy with the highest incidence amongst children (26% of all cancer cases), being surpassed only by the cancers of the brain and of the nervous system. The most recent research on ALL is focusing on new molecular therapies, like targeting specific biological structures in key points in the cell cycle, or using selective inhibitors for transmembranary proteins involved in cell signalling, and even aiming cell surface receptors with specifically designed antibodies for active targeting. Nanomedicine approaches, especially by the use of nanoparticle-based compounds for the delivery of drugs, cancer diagnosis or therapeutics may represent new and modern ways in the near future anti-cancer therapies. This review offers an overview on the recent role of nanomedicine in the detection and treatment of acute lymphoblastic leukemia as resulting from a thorough literature survey. A short introduction on the basics of ALL is presented followed by the description of the conventional methods used in the ALL detection and treatment. We follow our discussion by introducing some of the general nano-strategies used for cancer detection and treatment. The detailed role of organic and inorganic nanoparticles in ALL applications is further presented, with a special focus on gold nanoparticle-based nanocarriers of antileukemic drugs.

An update on current and prospective immunotherapies for chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common leukemia. Combined agent chemotherapy is the current standard front-line treatment for physically fit patients with CLL. Use of chemotherapy can be complicated by significant toxicity, especially in patients with advanced age or comorbid conditions. Moreover, patients may relapse and become refractory to further chemotherapy. Immunotherapy targets the aberrant immunological processes in CLL without the toxicity of chemotherapy. Immunotherapeutic strategies can also be combined with chemotherapy to improve response rates in this incurable disease. In this review, we evaluate current and future immune-based options in the treatment of CLL.

CCR9 in cancer: oncogenic role and therapeutic targeting

Cancer is currently one of the leading causes of death worldwide and is one of the most challenging major public health problems. The main challenges faced by clinicians in the management and treatment of cancer mainly arise from difficulties in early diagnosis and the emergence of tumor chemoresistance and metastasis. The structures of chemokine receptor 9 (CCR9) and its specific ligand chemokine ligand 25 (CCL25) have been elucidated, and, interestingly, a number of studies have demonstrated that CCR9 is a potential tumor biomarker in diagnosis and therapy, as it has been found to be highly expressed in a wide range of cancers. This expression pattern suggests that CCR9 may participate in many important biological activities involved in cancer progression. Researchers have shown that CCR9 that has been activated by its specific ligand CCL25 can interact with many signaling pathways, especially those involved in tumor chemoresistance and metastasis. This review, therefore, focuses on CCR9 induction activity and summarizes what is currently known regarding its role in cancers and its potential application in tumor-targeted therapy.

Bispecific antibodies and their applications

Bispecific antibodies (BsAbs) recognize two different epitopes. This dual specificity opens up a wide range of applications, including redirecting T cells to tumor cells, blocking two different signaling pathways simultaneously, dual targeting of different disease mediators, and delivering payloads to targeted sites. The approval of catumaxomab (anti-EpCAM and anti-CD3) and blinatumomab (anti-CD19 and anti-CD3) has become a major milestone in the development of bsAbs. Currently, more than 60 different bsAb formats exist, some of them making their way into the clinical pipeline. This review summarizes diverse formats of bsAbs and their clinical applications and sheds light on strategies to optimize the design of bsAbs.

ABT-199 (venetoclax) and BCL-2 inhibitors in clinical development

With the advent of new agents targeting CD20, Bruton's tyrosine kinase, and phosphoinositol-3 kinase for chronic lymphoid leukemia (CLL), more treatment options exist than ever before. B-cell lymphoma-2 (BCL-2) plays a major role in cellular apoptosis and is a druggable target. Small molecule inhibitors of BCL-2 are in active clinical studies. ABT-199 (venetoclax, RG7601, GDC-0199) has been granted breakthrough designation by FDA for relapsed or refractory CLL with 17p deletion. In this review, we summarized the latest clinical development of ABT-199/venetoclax and other novel agents targeting the BCL-2 proteins.

The roles of stem cell memory T cells in hematological malignancies

Adoptive cell therapy (ACT) is rapidly migrating from bench to clinical therapy for hematological malignancies. Recently, a new subtype of memory T cells, stem cell memory T (TSCM) cells, was shown to be one of the most favorable subsets for ACT. TSCM has high self-renewal capacity and is associated with superior T cell engraftment, persistence, and antitumor immunity. In this review, we focused on the characteristics of antigen-specific TSCM cells and discussed their potential for immunotherapy targeting hematological malignancies.

Redirection of CD4+ and CD8+ T lymphocytes via an anti-CD3 × anti-CD19 bi-specific antibody combined with cytosine arabinoside and the efficient lysis of patient-derived B-ALL cells

Background

B-acute lymphoblastic leukemia (B-ALL) is derived from B cell progenitors. Recently, the development of appropriate combinations of chemotherapy and immunotherapy represents a promising approach for eliminating cancer. We previously constructed an anti-CD3 × anti-CD19 bi-specific antibody in a diabody configuration and its disulfide-stabilized format (ds-diabody). The combination of the diabody or ds-diabody and Ara-C was highly effective in enhancing the cytotoxicity of T cells against the CD19+ human leukemia cell-line, Nalm-6, both in vitro and in vivo. This study verified whether B-ALL patient-derived cells were sensitive to the diabody or ds-diabody and low-dosage Ara-C combination.

Methods

This study aimed to detect the B7 family members B7.1 (CD80) and B7.2 (CD86) that were expressed in B-ALL patient-derived cells pre-treated by Ara-C (0.25 μM) and to determine the targeted killing ability of T cell subtypes induced by the diabody or ds-diabody combination with Ara-C both in vitro and in vivo. We also determined the levels of the cytokines that were released by activated CD4+ or CD8+ T cells during therapy.

Result

Low-dose Ara-C enhanced CD80 and CD86 expression in nearly 50 % of specimens of B-ALL patient-derived cells. A combination of diabody or ds-diabody and Ara-C enhanced T cell against B-ALL cells in vitro and in vivo. Both CD8+ and CD4+ T cells were potently activated. Expression of CD25 and CD69 was augmented equally by CD4+ or CD8+ T cells. However, CD8+ T cells made the major contribution by redirecting target cell lysis in a granzyme B and perforin-dependent mechanism. CD4+ T cells played an important immunomodulatory role by secreting IL2. Consequently, IL3, IL6, TNFα, and IFNγ were also released by CD4+ or CD8+ T cells following diabody-mediated T cell activation.

Conclusion

T cell therapy induced by diabody or ds-diabody combined with low dose of Ara-C was effective against cancer cell-lines and in clinical trials. In vivo, the ds-diabody was more efficient than its parent diabody due to its enhanced stability.

Blinatumomab: a bispecific T cell engager (BiTE) antibody against CD19/CD3 for refractory acute lymphoid leukemia

Targeted therapy has been the forefront of cancer treatment. Cancer immunotherapy is the most recent focus. In addition, novel immunotherapeutics targeting B cell receptor signaling (e.g., ibrutinib), T cell receptor ( e.g., CART19), and NK cells (e.g., AFM13) are being developed. This review summarized the new development in blinatumomab (MT103/MEDI-538), a first-in-class bispecific T engager (BiTE) antibody against CD19/CD3 in patients with relapsed/refractory precursor B cell acute lymphoid leukemia.

SAR650984 directly induces multiple myeloma cell death via lysosomal-associated and apoptotic pathways, which is further enhanced by pomalidomide

The anti-CD38 monoclonal antibody SAR650984 (SAR) is showing promising clinical activity in treatment of relapsed and refractory multiple myeloma (MM). Besides effector-mediated antibody-dependent cellular cytotoxicity and complement-mediated cytotoxicity, we here define molecular mechanisms of SAR-directed MM cell death and enhanced anti-MM activity triggered by SAR with Pomalidomide (Pom). Without Fc-cross-linking agents or effector cells, SAR specifically induces homotypic aggregation (HA)-associated cell death in MM cells dependent on the level of cell surface CD38 expression, actin cytoskeleton and membrane lipid raft. SAR and its F(ab)'2 fragments trigger caspase 3/7-dependent apoptosis in MM cells highly expressing CD38, even with p53 mutation. Importantly, SAR specifically induces lysosome-dependent cell death (LCD) by enlarging lysosomes and increasing lysosomal membrane permeabilization associated with leakage of cathepsin B and LAMP-1, regardless of the presence of interleukin-6 or bone marrow stromal cells. Conversely, the lysosomal vacuolar H+-ATPase inhibitor blocks SAR-induced LCD. SAR further upregulates reactive oxygen species. Pom enhances SAR-induced direct and indirect killing even in MM cells resistant to Pom/Len. Taken together, SAR is the first therapeutic monoclonal antibody mediating direct cytotoxicity against MM cells via multiple mechanisms of action. Our data show that Pom augments both direct and effector cell-mediated MM cytotoxicity of SAR, providing the framework for combination clinical trials.

Emerging immunological drugs for chronic lymphocytic leukemia

INTRODUCTION

Over the last few years, several new immunological drugs, particularly monoclonal antibodies (mAbs), immunomodulatory drugs and B-cell receptor (BCR) pathway inhibitors have been developed and investigated in chronic lymphocytic leukemia (CLL). This article summarizes recent discoveries regarding their mechanism of action, pharmacological properties, clinical activity and toxicity, as well as the emerging role of these agents in CLL.

AREAS COVERED

A literature review of mAbs, BCR pathway inhibitors and immunomodulating drugs was conducted of the MEDLINE database via PubMed for articles in English. Publications from 2000 through February 2015 were scrutinized. The search terms used were alemtuzumab, BI 836826, duvelisib ibrutinib, idelalisib, lenalidomide, monoclonal antibodies, MEDI-551, MOR208, obinutuzumab, ocaratuzumab, ofatumumab, ONO-4059, otlertuzumab, spebrutinib, veltuzumab and XmAb5574 in conjunction with CLL. Conference proceedings from the previous 5 years of the American Society of Hematology, European Hematology Association, American Society of Clinical Oncology, and ACR/ARHP Annual Scientific Meetings were searched manually. Additional relevant publications were obtained by reviewing the references from the chosen articles.

EXPERT OPINION

The use of mAbs, BCR inhibitors and immunomodulating drugs is a promising new strategy for chemotherapy-free treatment of CLL. However, definitive data from ongoing and future clinical trials will aid in better defining the status of immunological drugs in the treatment of this disease.

Current and emerging monoclonal antibody treatments for chronic lymphocytic leukemia: state of the art

Anti-CD20 monoclonal antibodies (mAbs), rituximab, ofatumumab and obinutuzumab, have a significant impact in the treatment of chronic lymphocytic leukemia (CLL), particularly in combination with chemotherapy. Over the last few years, several new mAbs have been developed and investigated in CLL. The most promising newer mAbs are directed against CD20, CD19, CD37 and CD40. Combinations of antibodies with targeted drugs like ibrutinib, idelalisib or lenalidomide will probably replace chemotherapy-based combinations in the near future. This review gives a critical overview of established mAbs as well as new antibodies potentially useful in CLL.