Mogamulizumab: first global approval

Chemokine receptors in allergic diseases

Under homeostatic conditions, as well as in various diseases, leukocyte migration is a crucial issue for the immune system that is mainly organized through the activation of bone marrow-derived cells in various tissues. Immune cell trafficking is orchestrated by a family of small proteins called chemokines. Leukocytes express cell-surface receptors that bind to chemokines and trigger transendothelial migration. Most allergic diseases, such as asthma, rhinitis, food allergies, and atopic dermatitis, are generally classified by the tissue rather than the type of inflammation, making the chemokine/chemokine receptor system a key point of the immune response. Moreover, because small antagonists can easily block such receptors, various molecules have been developed to suppress the recruitment of immune cells during allergic reactions, representing potential new drugs for allergies. We review the chemokines and chemokine receptors that are important in asthma, food allergies, and atopic dermatitis and their respectively developed antagonists.

Efficient Use of a Crude Drug/Herb Library Reveals Ephedra Herb As a Specific Antagonist for TH2-Specific Chemokine Receptors CCR3, CCR4, and CCR8

Chemokine receptors CCR3 and CCR4 are preferentially expressed by TH2 cells, mast cells, and/or eosinophils, all of which are involved in the pathogenesis of allergic diseases. Therefore, CCR3 and CCR4 have long been highlighted as potent therapeutic targets for allergic diseases. Japanese traditional herbal medicine Kampo consists of multiple crude drugs/herbs, which further consist of numerous chemical substances. Recent studies have demonstrated that such chemical substances appear to promising sources in the development of novel therapeutic agents. Based on these findings, we hypothesize that Kampo-related crude drugs/herbs would contain chemical substances that inhibit the cell migration mediated by CCR3 and/or CCR4. To test this hypothesis, we screened 80 crude drugs/herbs to identify candidate substances using chemotaxis assay. Among those tested, Ephedra Herb inhibited the chemotaxis mediated by both CCR3 and CCR4, Cornus Fruit inhibited that mediated by CCR3, and Rhubarb inhibited that mediated by CCR4. Furthermore, Ephedra Herb specifically inhibited the chemotaxis mediated by not only CCR3 and CCR4 but CCR8, all of which are selectively expressed by TH2 cells. This result led us to speculate that ephedrine, a major component of Ephedra Herb, would play a central role in the inhibitory effects on the chemotaxis mediated by CCR3, CCR4, and CCR8. However, ephedrine exhibited little effects on the chemotaxis. Therefore, we fractionated Ephedra Herb into four subfractions and examined the inhibitory effects of each subfraction. As the results, ethyl acetate-insoluble fraction exhibited the inhibitory effects on chemotaxis and calcium mobilization mediated by CCR3 and CCR4 most significantly. In contrast, chloroform-soluble fraction exhibited a weak inhibitory effect on the chemotaxis mediated by CCR8. Furthermore, maoto, one of the Kampo formulations containing Ephedra Herb, exhibited the inhibitory effects on the chemotaxis mediated by CCR3, CCR4, and CCR8. Taken together, our data suggest that these crude drugs/herbs might be useful sources to develop new drugs targeting TH2-mediated allergic diseases.

Pharmacological Therapy of Bronchial Asthma: The Role of Biologicals

Bronchial asthma is a heterogeneous, complex, chronic inflammatory and obstructive pulmonary disease driven by various pathways to present with different phenotypes. A small proportion of asthmatics (5-10%) suffer from severe asthma with symptoms that cannot be controlled by guideline therapy with high doses of inhaled steroids plus a second controller, such as long-acting β2 agonists (LABA) or leukotriene receptor antagonists, or even systemic steroids. The discovery and characterization of the pathways that drive different asthma phenotypes have opened up new therapeutic avenues for asthma treatment. The approval of the humanized anti-IgE antibody omalizumab for the treatment of severe allergic asthma has paved the way for other cytokine-targeting therapies, particularly those targeting interleukin (IL)-4, IL-5, IL-9, IL-13, IL-17, and IL-23 and the epithelium-derived cytokines IL-25, IL-33, and thymic stromal lymphopoietin. Knowledge of the molecular basis of asthma phenotypes has helped, and continues to help, the development of novel biologicals that target a diverse array of phenotype-specific molecular targets in patients suffering from severe asthma. This review summarizes potential therapeutic approaches that are likely to show clinical efficacy in the near future, focusing on biologicals as promising novel therapies for severe asthma.

Panoptic clinical review of the current and future treatment of relapsed/refractory T-cell lymphomas: Peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) tend to be aggressive and chemorefractory, with about 70% of patients developing relapsed/refractory disease. Prior to 2009, chemotherapies were the only options for relapsed/refractory PTCL, other than hematopoietic transplants. However, chemotherapy only improves survival by about 1 month compared with palliation. Four drugs are now approved in the US to treat relapsed/refractory PTCL: pralatrexate, romidepsin, belinostat, and brentuximab vedotin (for systemic anaplastic large cell lymphoma [sALCL]). Response rates with pralatrexate, romidepsin, and belinostat range from 25 to 54% in mixed relapsed/refractory PTCL populations, while 86% of sALCL patients respond to brentuximab vedotin. Here, we critically evaluate the evidence supporting the current drug treatment of relapsed/refractory PTCL, and look to the future to see how the treatment panorama may change with the advent of new targeted therapies, some of which (e.g., alisertib in PTCL and mogamulizumab in CCR4-positive adult T-cell leukemia/lymphoma) are already in phase 3 trials.

Optimizing Management of Patients with Adult T Cell Leukemia-Lymphoma

Adult T cell leukemia-lymphoma is a rare disease with a high mortality rate, and is challenging for the clinician. Early allogeneic stem cell transplant can confer durable remission. As novel therapeutic agents become available to treat T cell malignancies, it is increasingly important that medical oncologists, hematologists, and hematopathologists recognize and accurately diagnose adult T cell leukemia-lymphoma. There is no uniform standard of treatment of adult T cell leukemia-lymphoma, and clinical trials remain critical to improving outcomes. Here we present one management approach based on the recent advances in treatment for adult T cell leukemia-lymphoma patients.

Recent advances in primary cutaneous T-cell lymphoma

PURPOSE OF REVIEW

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of skin-homing T-cell neoplasms, which represent approximately 75% of all primary cutaneous lymphomas. Currently available drug therapies, when effective, simply control disease and the only option for curing CTCL is stem cell transplant.

RECENT FINDINGS

In the last year, there has been an incredible effort made to improve the understanding and treatment of CTCL. Recent findings indicate that epigenetic aberrations are integral to active disease. Furthermore, multiple tumor-derived immunological factors have also been shown to inhibit viability, proliferation, and cytokine production of nonmalignant T cells. Several novel targeted therapies show great potential, most promising being antibody drug conjugates targeting surface markers such as CD30 in some CTCL subtypes. Additional attractive targets involve the global modulation of epigenetic markers such as demethylation agents or HDAC inhibitors, either as single agents or in combination therapies.

SUMMARY

This is a concise review of recent advances in the field of CTCL with special focus on research articles over the preceding year.

Effect of trastuzumab interchain disulfide bond cleavage on Fcγ receptor binding and antibody-dependent tumour cell phagocytosis

The Fc domain of human IgG1 binds to Fcγ receptors (FcγRs) to induce effector functions such as phagocytosis. There are four interchain disulfide bonds between the H and L chains. In this study, the disulfide bonds within the IgG1 trastuzumab (TRA), which is specific for HER2, were cleaved by mild S-sulfonation or by mild reduction followed by S-alkylation with three different reagents. The cleavage did not change the binding activities of TRA to HER2-bearing SK-BR-3 cells. The binding activities of TRA to FcγRIIA and FcγRIIB were greatly enhanced by modification with mild reduction and S-alkylation with ICH2CONH2 or N-(4-aminophenyl) maleimide, while the binding activities of TRA to FcγRI and FcγRIIIA were decreased by any of the four modifications. However, the interchain disulfide bond cleavage by the different modifications did not change the antibody-dependent cell-mediated phagocytosis (ADCP) of SK-BR-3 cells by activated THP-1 cells. The order of FcγR expression levels on the THP-1 cells was FcγRII > FcγRI > FcγRIII and ADCP was inhibited by blocking antibodies against FcγRI and FcγRII. These results imply that the effect of the interchain disulfide bond cleavage on FcγRs binding and ADCP is dependent on modifications of the cysteine residues and the FcγR isotypes.

Tailored therapy for severe asthma

Patients with severe asthma or COPD have often a suboptimal symptom control due to inadequate treatment. A better understanding of pathogenetic mechanisms, phenotypes, endotypes and the new technologies available in the fields of molecular biology and immunogenetics have made it possible to synthesize specific monoclonal antibodies virtually able to interact with any target antigen, or to open a way for new therapeutic target options. At the moment, the only biologic drug available in clinical practice is omalizumab. To overcome the limits of omalizumab, the research has focused on new monoclonal antibodies presenting higher avidity for IgE (e.g. ligelizumab and lumiximab) and ability to interact also with low affinity IgE receptor (FcϵRII). At present, many new biological drugs with different mechanisms of action and targets are matter of research. It is very important to identify the asthmatic phenotype in order to select the most appropriate drug for the individual patient. The most promising agents are targeted against cytokines of Th2 pattern and related receptors, such as IL-2 (daclizumab) and IL-13 (lebrikizumab) or IL-5 in patients with hypereosinophilia (mepolizumab, reslizumab and benralizumab). Other interesting drugs have as a target TNF-α or its soluble receptor (infliximab, golimumab and etanercept) or IL-1 (canakinumab), a cytokine with an important systemic proinflammatory action. Finally, the discovery of increased levels of C5a in the airways of asthmatic patients has led to the synthesis of a specific monoclonal antibody (eculizumab). Further help should come from the identification of biomarkers that can guide in choosing the best treatment for the individual patient, such as IgE for omalizumab or periostin for lebrikizumab.

Fully human antagonistic antibodies against CCR4 potently inhibit cell signaling and chemotaxis

BACKGROUND

CC chemokine receptor 4 (CCR4) represents a potentially important target for cancer immunotherapy due to its expression on tumor infiltrating immune cells including regulatory T cells (Tregs) and on tumor cells in several cancer types and its role in metastasis.

METHODOLOGY

Using phage display, human antibody library, affinity maturation and a cell-based antibody selection strategy, the antibody variants against human CCR4 were generated. These antibodies effectively competed with ligand binding, were able to block ligand-induced signaling and cell migration, and demonstrated efficient killing of CCR4-positive tumor cells via ADCC and phagocytosis. In a mouse model of human T-cell lymphoma, significant survival benefit was demonstrated for animals treated with the newly selected anti-CCR4 antibodies.

SIGNIFICANCE

For the first time, successful generation of anti- G-protein coupled chemokine receptor (GPCR) antibodies using human non-immune library and phage display on GPCR-expressing cells was demonstrated. The generated anti-CCR4 antibodies possess a dual mode of action (inhibition of ligand-induced signaling and antibody-directed tumor cell killing). The data demonstrate that the anti-tumor activity in vivo is mediated, at least in part, through Fc-receptor dependent effector mechanisms, such as ADCC and phagocytosis. Anti-CC chemokine receptor 4 antibodies inhibiting receptor signaling have potential as immunomodulatory antibodies for cancer.

Therapeutic efficacy of an Fc-enhanced TCR-like antibody to the intracellular WT1 oncoprotein

PURPOSE

RMFPNAPYL (RMF), a Wilms' tumor gene 1 (WT1)-derived CD8 T-cell epitope presented by HLA-A*02:01, is a validated target for T-cell-based immunotherapy. We previously reported ESK1, a high avidity (Kd < 0.2 nmol/L), fully-human monoclonal antibody (mAb) specific for the WT1 RMF peptide/HLA-A*02:01 complex, which selectively bound and killed WT1(+) and HLA-A*02:01(+) leukemia and solid tumor cell lines.

EXPERIMENTAL DESIGN

We engineered a second-generation mAb, ESKM, to have enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) function due to altered Fc glycosylation. ESKM was compared with native ESK1 in binding assays, in vitro ADCC assays, and mesothelioma and leukemia therapeutic models and pharmacokinetic studies in mice. ESKM toxicity was assessed in HLA-A*02:01(+) transgenic mice.

RESULTS

ESK antibodies mediated ADCC against hematopoietic and solid tumor cells at concentrations below 1 μg/mL, but ESKM was about 5- to 10-fold more potent in vitro against multiple cancer cell lines. ESKM was more potent in vivo against JMN mesothelioma, and effective against SET2 AML and fresh ALL xenografts. ESKM had a shortened half-life (4.9 days vs. 6.5 days), but an identical biodistribution pattern in C57BL/6J mice. At therapeutic doses of ESKM, there was no difference in half-life or biodistribution in HLA-A*02:01(+) transgenic mice compared with the parent strain. Importantly, therapeutic doses of ESKM in these mice caused no depletion of total WBCs or hematopoetic stem cells, or pathologic tissue damage.

CONCLUSIONS

The data provide proof of concept that an Fc-enhanced mAb can improve efficacy against a low-density, tumor-specific, peptide/MHC target, and support further development of this mAb against an important intracellular oncogenic protein.

Development of a cell-based assay measuring the activation of FcγRIIa for the characterization of therapeutic monoclonal antibodies

Antibody-dependent cellular cytotoxicity (ADCC) is one of the important mechanisms of action of the targeting of tumor cells by therapeutic monoclonal antibodies (mAbs). Among the human Fcγ receptors (FcγRs), FcγRIIIa is well known as the only receptor expressed in natural killer (NK) cells, and it plays a pivotal role in ADCC by IgG1-subclass mAbs. In addition, the contributions of FcγRIIa to mAb-mediated cytotoxicity have been reported. FcγRIIa is expressed in myeloid effector cells including neutrophils and macrophages, and it is involved in the activation of these effector cells. However, the measurement of the cytotoxicity via FcγRIIa-expressing effector cells is complicated and inconvenient for the characterization of therapeutic mAbs. Here we report the development of a cell-based assay using a human FcγRIIa-expressing reporter cell line. The FcγRIIa reporter cell assay was able to estimate the activation of FcγRIIa by antigen-bound mAbs by a very simple method in vitro. The usefulness of this assay for evaluating the activity of mAbs with different abilities to activate FcγRIIa was confirmed by the examples including the comparison of the activity of the anti-CD20 mAb rituximab and its Fc-engineered variants, and two anti-EGFR mAbs with different IgG subclasses, cetuximab (IgG1) and panitumumab (IgG2). We also applied this assay to the characterization of a force-oxidized mAb, and we observed that oxidation significantly decreased the FcγRIIa activation by EGFR-bound cetuximab. These results suggest that our FcγRIIa reporter assay is a promising tool for the characterization of therapeutic mAbs, including Fc-engineered mAbs, IgG2-subclass mAbs, and their product-related variants.

Recent progress in the development of antagonists to the chemokine receptors CCR3 and CCR4

INTRODUCTION

The chemokine receptors CCR3 and CCR4 have been shown to be important therapeutic targets for the treatment of a variety of diseases. Although only two chemokine receptor inhibitors have been approved so far, there are numerous compounds that are in various stages of development.

AREAS COVERED

In this review article, the authors provide an update on the progress made in the identification of antagonists against the chemokine receptors CCR3 and CCR4 from 2009 to the present. The rationale of writing this review article is to cover the most important approaches to identifying antagonists to these two receptors, which could prove to be useful therapeutics in treating proinflammatory diseases.

EXPERT OPINION

Pharmaceutical companies have expended a considerable amount of money and effort to identify potent inhibitors of CCR3 and CCR4 for the treatment of asthma and atopic diseases. Although a variety of compounds have been described and several have progressed into the clinic, none have so far made it as approved drugs. There are, however, novel approaches such as mogamulizumab, a monoclonal antibody to CCR4 currently is in clinical trials for cancer and ASM8, an antisense nucleotide to CCR3, which is in Phase II clinical trials for asthma that might still prove to be successful new therapeutics.

Novel therapies for cutaneous T-cell lymphoma: what does the future hold?

INTRODUCTION

Cutaneous T-cell lymphomas (CTCLs) represent a group of extranodal non-Hodgkin lymphomas, of which mycosis fungoides (MF) is the most frequent. Standard therapeutic approaches are well established and often achieve stable disease. However, cure for MF is rare and thus novel therapies are needed.

AREAS COVERED

This review provides a discussion of the most promising new therapeutic approaches in the management of MF and other rare CTCLs. It includes targeted therapies with antibodies against surface molecules on malignant T cells (e.g., brentuximab), novel chemotherapeutic agents (e.g., pralatrexate), small-molecule compounds (e.g., panobinostat) and evidence of emerging targets in CTCLs (e.g., anti-IL-31). It also provides discussion of immune checkpoint inhibitors such as anti-PD1 that are worth considering in the treatment of leukaemic CTCL variants. Finally, it gives a brief overview of the possible use of stem-cell transplantation.

EXPERT OPINION

There is no doubt that progress has been made in the treatment of CTCLs with new, innovative and promising therapies approaching. However, there is still an urgent need to identify and test additional targets in well-designed clinical trials.

The changing landscape of peripheral T-cell lymphoma in the era of novel therapies

Peripheral T-cell lymphomas (PTCLs) are the most common sub-entity of mature T-cell lymphomas, and apart from particular presentations, share a poor prognosis with frequent short-term, agressive, and chemorefractory relapses. Because of the rarity and also the heterogeneity of the disease, we lack randomized clinical trials. However, to date, neither intensification of frontline chemotherapy or autologous transplant has led to any improvement of survival, and the standard CHOP (cyclophosphamide, doxorubicine, vincristine, and prednisone) regimen remains the most employed as induction therapy. In the past few years, new chemotherapeutic agents, with the capability to encompass the resistance to conventional chemotherapy, such as pralatrexate or bendamustine, have been evaluated. Furthermore, identification of cell surface molecular markers (CD52, CD30, CCR4) has led to the development of new monoclonal antibodies. Similarly, the better comprehension of physiopathological mechanisms and detection of deregulated intracellular pathways encouraged the use of novel therapies such as histone deacetylase inhibitors or immunomodulatory drugs. Some of these compounds have been approved for relapse, and are currently evaluated upfront in ongoing clinical trials. Despite these efforts, the global prognosis still remains much inferior to those of B-cell lymphomas, highlighting the necessity of multicenter clinical trials.