Resimmune, an anti-CD3ε recombinant immunotoxin, induces durable remissions in patients with cutaneous T-cell lymphoma

Baseline gene signatures of reactogenicity to Ebola vaccination: a machine learning approach across multiple cohorts

Introduction

The rVSVDG-ZEBOV-GP (Ervebo®) vaccine is both immunogenic and protective against Ebola. However, the vaccine can cause a broad range of transient adverse reactions, from headache to arthritis. Identifying baseline reactogenicity signatures can advance personalized vaccinology and increase our understanding of the molecular factors associated with such adverse events.

Methods

In this study, we developed a machine learning approach to integrate prevaccination gene expression data with adverse events that occurred within 14 days post-vaccination.

Results and Discussion

We analyzed the expression of 144 genes across 343 blood samples collected from participants of 4 phase I clinical trial cohorts: Switzerland, USA, Gabon, and Kenya. Our machine learning approach revealed 22 key genes associated with adverse events such as local reactions, fatigue, headache, myalgia, fever, chills, arthralgia, nausea, and arthritis, providing insights into potential biological mechanisms linked to vaccine reactogenicity.

Are we there yet? cellular therapies for cutaneous T cell lymphoma

Cutaneous T cell lymphomas (CTCLs) are a heterogenous group of skin-involved T-cell non-Hodgkin lymphoma which Mycosis Fungoides and Sezary Syndrome are the most common variants. Despite considerable progress in distinguishing the pathophysiology, the treatment options are still limited for advanced-stage disease. Recent approval of novel agents such as vorinostat, brentuximab vedotin and mogamulizumab paved a way. Allogeneic hematopoietic stem cell transplantation has been shown to be a feasible option in selected advanced-stage CTCL patients. Chimeric antigen receptor (CAR) T cells have been promising for the treatment of B-cell tumors and have been approved for second-line treatment in non-Hodgkin's lymphoma. Although several obstacles still need to be addressed, CAR T cell treatment for CTCLs seems not far off. This review discusses new discoveries in pathophysiology, the state of cellular therapies in current practice, challenges for cellular treatment in advanced CTCL, and how to overcome these challenges.

Targeting the Inside of Cells with Biologicals: Toxin Routes in a Therapeutic Context

Numerous toxins translocate to the cytosol in order to fulfil their function. This demonstrates the existence of routes for proteins from the extracellular space to the cytosol. Understanding these routes is relevant to multiple aspects related to therapeutic applications. These include the development of anti-toxin treatments, the potential use of toxins as shuttles for delivering macromolecular cargo to the cytosol or the use of drugs based on toxins. Compared with other strategies for delivery, such as chemicals as carriers for macromolecular delivery or physical methods like electroporation, toxin routes present paths into the cell that potentially cause less damage and can be specifically targeted. The efficiency of delivery via toxin routes is limited. However, low-delivery efficiencies can be entirely sufficient, if delivered cargoes possess an amplification effect or if very few molecules are sufficient for inducing the desired effects. This is known for example from RNA-based vaccines that have been developed during the coronavirus disease 2019 pandemic as well as for other approved RNA-based drugs, which elicited the desired effect despite their typically low delivery efficiencies. The different mechanisms by which toxins enter cells may have implications for their technological utility. We review the mechanistic principles of the translocation pathway of toxins from the extracellular space to the cytosol, the delivery efficiencies, and therapeutic strategies or applications that exploit toxin routes for intracellular delivery.

Integrating novel agents into the treatment of advanced mycosis fungoides and Sézary syndrome

Agents targeting the unique biology of mycosis fungoides and Sézary syndrome are quickly being incorporated into clinical management. With these new therapies, we are now capable of inducing more durable responses and even complete remissions in advanced disease, outcomes which were exceedingly rare with prior therapies. Yet, even this new generation of therapies typically produce objective responses in only a minority of patients. As our therapeutic options increase, we are now challenged with selecting treatments from a growing list of options. To gain the full benefit of these novel agents, we must develop strategies to match treatments for the patients most likely to benefit from them. Here, we consider both the current approaches to treatment selection based on clinical features and the future of molecular biomarker-guided therapy for patients with this heterogeneous disease.

Harnessing the immune system in the treatment of cutaneous T cell lymphomas

Cutaneous T cell lymphomas are a rare subset of non-Hodgkin's lymphomas with predilection for the skin with immunosuppressive effects that drive morbidity and mortality. We are now appreciating that suppression of the immune system is an important step in the progression of disease. It should come as no surprise that therapies historically and currently being used to treat these cancers have immune modulating functions that impact disease outcomes. By understanding the immune effects of our therapies, we may better develop new agents that target the immune system and improve combinatorial treatment strategies to limit morbidity and mortality of these cancers. The immune modulating effect of therapeutic drugs in use and under development for cutaneous T cell lymphomas will be reviewed.

Cutaneous T-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Harnessing the Potential of Chimeric Antigen Receptor T-Cell Therapy for the Treatment of T-Cell Malignancies: A Dare or Double Dare?

Historical standard of care treatments of T-cell malignancies generally entailed the use of cytotoxic and depleting approaches. These strategies are, however, poorly validated and record dismal long-term outcomes. More recently, the introduction and approval of chimeric antigen receptor (CAR)-T cell therapy has revolutionized the therapy of B-cell malignancies. Translating this success to the T-cell compartment has so far proven hazardous, entangled by risks of fratricide, T-cell aplasia, and product contamination by malignant cells. Several strategies have been utilized to overcome these challenges. These include the targeting of a selective cognate antigen exclusive to T-cells or a subset of T-cells, disruption of target antigen expression on CAR-T constructs, use of safety switches, non-viral transduction, and the introduction of allogeneic compounds and gene editing technologies. We herein overview these historical challenges and revisit the opportunities provided as potential solutions. An in-depth understanding of the tumor microenvironment is required to optimally harness the potential of the immune system to treat T-cell malignancies.

CD3e-immunotoxin spares CD62Llo Tregs and reshapes organ-specific T-cell composition by preferentially depleting CD3ehi T cells

CD3-epsilon(CD3e) immunotoxins (IT), a promising precision reagent for various clinical conditions requiring effective depletion of T cells, often shows limited treatment efficacy for largely unknown reasons. Tissue-resident T cells that persist in peripheral tissues have been shown to play pivotal roles in local and systemic immunity, as well as transplant rejection, autoimmunity and cancers. The impact of CD3e-IT treatment on these local cells, however, remains poorly understood. Here, using a new murine testing model, we demonstrate a substantial enrichment of tissue-resident Foxp3+ Tregs following CD3e-IT treatment. Differential surface expression of CD3e among T-cell subsets appears to be a main driver of Treg enrichment in CD3e-IT treatment. The surviving Tregs in CD3e-IT-treated mice were mostly the CD3e^dimCD62L^lo effector phenotype, but the levels of this phenotype markedly varied among different lymphoid and nonlymphoid organs. We also found notable variations in surface CD3e levels among tissue-resident T cells of different organs, and these variations drive CD3e-IT to uniquely reshape T-cell compositions in local organs. The functions of organs and anatomic locations (lymph nodes) also affected the efficacy of CD3e-IT. The multi-organ pharmacodynamics of CD3e-IT and potential treatment resistance mechanisms identified in this study may generate new opportunities to further improve this promising treatment.

Structure-Activity Relationship of the Dimeric and Oligomeric Forms of a Cytotoxic Biotherapeutic Based on Diphtheria Toxin

Protein aggregation is a well-recognized problem in industrial preparation, including biotherapeutics. These low-energy states constantly compete with a native-like conformation, which is more pronounced in the case of macromolecules of low stability in the solution. A better understanding of the structure and function of such aggregates is generally required for the more rational development of therapeutic proteins, including single-chain fusion cytotoxins to target specific receptors on cancer cells. Here, we identified and purified such particles as side products of the renaturation process of the single-chain fusion cytotoxin, composed of two diphtheria toxin (DT) domains and interleukin 13 (IL-13), and applied various experimental techniques to comprehensively understand their molecular architecture and function. Importantly, we distinguished soluble purified dimeric and fractionated oligomeric particles from aggregates. The oligomers are polydisperse and multimodal, with a distribution favoring lower and even stoichiometries, suggesting they are composed of dimeric building units. Importantly, all these oligomeric particles and the monomer are cystine-dependent as their innate disulfide bonds have structural and functional roles. Their reduction triggers aggregation. Presumably the dimer and lower oligomers represent the metastable state, retaining the native disulfide bond. Although significantly reduced in contrast to the monomer, they preserve some fraction of bioactivity, manifested by their IL-13RA2 receptor affinity and selective cytotoxic potency towards the U-251 glioblastoma cell line. These molecular assemblies probably preserve structural integrity and native-like fold, at least to some extent. As our study demonstrated, the dimeric and oligomeric cytotoxin may be an exciting model protein, introducing a new understanding of its monomeric counterpart’s molecular characteristics.

A diphtheria toxin-based nanoparticle achieves specific cytotoxic effect on CXCR4+ lymphoma cells without toxicity in immunocompromised and immunocompetent mice

High rates of relapsed and refractory diffuse large B-cell lymphoma (DLBCL) patients and life-threatening side effects associated with immunochemotherapy make an urgent need to develop new therapies for DLBCL patients. Immunotoxins seem very potent anticancer therapies but their use is limited because of their high toxicity. Accordingly, the self-assembling polypeptidic nanoparticle, T22-DITOX-H6, incorporating the diphtheria toxin and targeted to CXCR4 receptor, which is overexpressed in DLBCL cells, could offer a new strategy to selectively eliminate CXCR4⁺ DLBCL cells without adverse effects. In these terms, our work demonstrated that T22-DITOX-H6 showed high specific cytotoxicity towards CXCR4⁺ DLBCL cells at the low nanomolar range, which was dependent on caspase-3 cleavage, PARP activation and an increase of cells in early/late apoptosis. Repeated nanoparticle administration induced antineoplastic effect, in vivo and ex vivo, in a disseminated immunocompromised mouse model generated by intravenous injection of human luminescent CXCR4⁺ DLBCL cells. Moreover, T22-DITOX-H6 inhibited tumor growth in a subcutaneous immunocompetent mouse model bearing mouse CXCR4⁺ lymphoma cells in the absence of alterations in the hemogram, liver or kidney injury markers or on-target or off-target organ histology. Thus, T22-DITOX-H6 demonstrates a selective cytotoxicity towards CXCR4⁺ DLBCL cells without the induction of toxicity in non-lymphoma infiltrated organs nor hematologic toxicity.

Comparison of CD3e Antibody and CD3e-sZAP Immunotoxin Treatment in Mice Identifies sZAP as the Main Driver of Vascular Leakage

Anti-CD3-epsilon (CD3e) monoclonal antibodies (mAbs) and CD3e immunotoxins (ITs) are promising targeted therapy options for various T-cell disorders. Despite significant advances in mAb and IT engineering, vascular leakage syndrome (VLS) remains a major dose-limiting toxicity for ITs and has been poorly characterized for recent "engineered" mAbs. This study undertakes a direct comparison of non-mitogenic CD3e-mAb (145-2C11 with Fc-silentTM murine IgG1: S-CD3e-mAb) and a new murine-version CD3e-IT (saporin-streptavidin (sZAP) conjugated with S-CD3e-mAb: S-CD3e-IT) and identifies their distinct toxicity profiles in mice. As expected, the two agents showed different modes of action on T cells, with S-CD3e-mAb inducing nearly complete modulation of CD3e on the cell surface, while S-CD3e-IT depleted the cells. S-CD3e-IT significantly increased the infiltration of polymorphonuclear leukocytes (PMNs) into the tissue parenchyma of the spleen and lungs, a sign of increased vascular permeability. By contrast, S-CD3e-mAbs-treated mice showed no notable signs of vascular leakage. Treatment with control ITs (sZAP conjugated with Fc-silent isotype antibodies) induced significant vascular leakage without causing T-cell deaths. These results demonstrate that the toxin portion of S-CD3e-IT, not the CD3e-binding portion (S-CD3e-mAb), is the main driver of vascular leakage, thus clarifying the molecular target for improving safety profiles in CD3e-IT therapy.

Engineered Bifunctional Proteins for Targeted Cancer Therapy: Prospects and Challenges

Bifunctional proteins (BFPs) are a class of therapeutic agents produced through genetic engineering and protein engineering, and are increasingly used to treat various human diseases, including cancer. These proteins usually have two or more biological functions-specifically recognizing different molecular targets to regulate the related signaling pathways, or mediating effector molecules/cells to kill tumor cells. Unlike conventional small-molecule or single-target drugs, BFPs possess stronger biological activity but lower systemic toxicity. Hence, BFPs are considered to offer many benefits for the treatment of heterogeneous tumors. In this review, the authors briefly describe the unique structural feature of BFP molecules and innovatively divide them into bispecific antibodies, cytokine-based BFPs (immunocytokines), and protein toxin-based BFPs (immunotoxins) according to their mode of action. In addition, the latest advances in the development of BFPs are discussed and the potential limitations or problems in clinical applications are outlined. Taken together, future studies need to be centered on understanding the characteristics of BFPs for optimizing and designing more effective such drugs.

Clinical and preclinical tolerance protocols for vascularized composite allograft transplantation

The field of vascularized composite allografts (VCAs) has undergone significant advancement in recent decades, and VCAs are increasingly common and accepted in the clinical setting, bringing hope of functional recovery to patients with debilitating injuries. A major obstacle facing the widespread application of VCAs is the side effect profile associated with the current immunosuppressive regimen, which can cause a wide array of complications such as infection, malignancy, and even death. Significant concerns remain regarding whether the treatment outweighs the risk. The potential solution to this dilemma would be achieving VCA tolerance, which would allow recipients to receive allografts without significant immunosuppression and its sequelae. Promising tolerance protocols are being studied in kidney transplantation; four major trials have attempted to withdraw immunosuppressive treatment with various successes. The common theme in all four trials is the use of radiation treatment and donor cell transplantation. The knowledge gained from these trials can provide valuable insight into the development of a VCA tolerance protocol. Despite similarities, VCAs present additional barriers compared to kidney allografts regarding tolerance induction. VCA donors are likely to be deceased, which limits the time for significant pre-conditioning. VCA donors are also more likely to be human leukocyte antigen–mismatched, which means that tolerance must be induced across major immunological barriers. This review also explores adjunct therapies studied in large animal models that could be the missing element in establishing a safe and stable tolerance induction method.

Engineered antibody fusion proteins for targeted disease therapy

Since the FDA approval of the first therapeutic antibody 35 years ago, antibody-based products have gained prominence in the pharmaceutical market. Building on the early successes of monoclonal antibodies, more recent efforts have capitalized on the exquisite specificity and/or favorable pharmacokinetic properties of antibodies by developing fusion proteins that enable targeted delivery of therapeutic payloads which are otherwise ineffective when administered systemically. This review focuses on recent engineering and translational advances for therapeutics that genetically fuse antibodies to disease-relevant payloads, including cytokines, toxins, enzymes, neuroprotective agents, and soluble factor traps. With numerous antibody fusion proteins in the clinic and other innovative molecules poised to follow suit, these potent, multifunctional drug candidates promise to be a major player in the therapeutic development landscape for years to come.

CAR-T cell therapy in T-cell malignancies: Is success a low-hanging fruit?

Chimeric antigen receptor T-cell (CAR-T) therapy has been prosperous in the treatment of patients with various types of relapsed/refractory (R/R) B-cell malignancies including diffuse large B-cell lymphoma (DLBCL), B-cell acute lymphoblastic leukemia (B-ALL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and multiple myeloma (MM). However, this type of therapy has faced serious hindrances in combating T-cell neoplasms. R/R T-cell malignancies are generally associated with poor clinical outcomes, and the available effective treatment approaches are very limited. CAR-T therapy of T-cell malignancies has unique impediments in comparison with that of B-cell malignancies. Fratricide, T-cell aplasia, and product contamination with malignant T cells when producing autologous CAR-Ts are the most important challenges of CAR-T therapy in T-cell malignancies necessitating in-depth investigations. Herein, we highlight the preclinical and clinical efforts made for addressing these drawbacks and also review additional potent stratagems that could improve CAR-T therapy in T-cell malignancies.

CAR-T cell therapy in T-cell malignancies: Is success a low-hanging fruit?

Chimeric antigen receptor T-cell (CAR-T) therapy has been prosperous in the treatment of patients with various types of relapsed/refractory (R/R) B-cell malignancies including diffuse large B-cell lymphoma (DLBCL), B-cell acute lymphoblastic leukemia (B-ALL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and multiple myeloma (MM). However, this type of therapy has faced serious hindrances in combating T-cell neoplasms. R/R T-cell malignancies are generally associated with poor clinical outcomes, and the available effective treatment approaches are very limited. CAR-T therapy of T-cell malignancies has unique impediments in comparison with that of B-cell malignancies. Fratricide, T-cell aplasia, and product contamination with malignant T cells when producing autologous CAR-Ts are the most important challenges of CAR-T therapy in T-cell malignancies necessitating in-depth investigations. Herein, we highlight the preclinical and clinical efforts made for addressing these drawbacks and also review additional potent stratagems that could improve CAR-T therapy in T-cell malignancies.

Cutaneous T-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Plant-made immunotoxin building blocks: A roadmap for producing therapeutic antibody-toxin fusions

Molecular farming in plants is an emerging platform for the production of pharmaceutical proteins, and host species such as tobacco are now becoming competitive with commercially established production hosts based on bacteria and mammalian cell lines. The range of recombinant therapeutic proteins produced in plants includes replacement enzymes, vaccines and monoclonal antibodies (mAbs). But plants can also be used to manufacture toxins, such as the mistletoe lectin viscumin, providing an opportunity to express active antibody-toxin fusion proteins, so-called recombinant immunotoxins (RITs). Mammalian production systems are currently used to produce antibody-drug conjugates (ADCs), which require the separate expression and purification of each component followed by a complex and hazardous coupling procedure. In contrast, RITs made in plants are expressed in a single step and could therefore reduce production and purification costs. The costs can be reduced further if subcellular compartments that accumulate large quantities of the stable protein are identified and optimal plant growth conditions are selected. In this review, we first provide an overview of the current state of RIT production in plants before discussing the three key components of RITs in detail. The specificity-defining domain (often an antibody) binds cancer cells, including solid tumors and hematological malignancies. The toxin provides the means to kill target cells. Toxins from different species with different modes of action can be used for this purpose. Finally, the linker spaces the two other components to ensure they adopt a stable, functional conformation, and may also promote toxin release inside the cell. Given the diversity of these components, we extract broad principles that can be used as recommendations for the development of effective RITs. Future research should focus on such proteins to exploit the advantages of plants as efficient production platforms for targeted anti-cancer therapeutics.

Expression of Viral microRNAs in Serum and White Blood Cells of Cows Exposed to Bovine Leukemia Virus

Bovine leukemia virus (BLV) affects the health and productivity of cattle. The virus causes abnormal immune function and immunosuppression. MicroRNAs (miRNAs) are involved in gene expression, having been associated with stress and immune response, tumor growth, and viral infection. The objective of this study was to determine the expression of circulating miRNAs produced by BLV in animals exposed to the virus. Sera from 14 animals were collected to establish IgG reactivity to BLV by ELISA, where seven animals were seropositive and seven were seronegative for BLV exposure. White blood cells (WBC) from each animal were also collected and miRNAs were identified by sequencing from sera and WBC. The seropositive group had higher counts of BLV miRNAs when compared to seronegative group in sera and WBC. Blv-miR-1-3p, blv-miR-B2-5p, blv-miR-B4-3p, and blv-miR-B5-5p were statistically significant (P < 0.00001) in serum with an average of 7 log2 fold difference between seropositive and seronegative groups. Blv-miR-B1-3p, blv-miR-B1-5p, blv-miR-B3, blv-miR-B4-3p, blv-miR-B4-5p, blv-miR-B5-5p were statistically significant (P < 1.08e⁻⁹) in WBC with an average of 7 log2 fold difference between the seropositive and the seronegative groups. Blv-miR-B2-3p and blv-miR-B2-5p were also statistically significant in WBC (P < 2.79e-17), with an average of 27 log2 fold difference between the seropositive and the seronegative groups. There were 18 genes identified as being potential targets for blv-miR-B1-5p, and 3 genes for blv-miR-B4-5p. Gene ontology analysis indicated that the target genes are mainly involved in the response to stress and in the immune system process. Several of the identified genes have been associated with leukemia development in humans and cattle. Differential expression of genes targeted by BLV miRNAs should be evaluated to determine their effect in BLV replication.

Rapid Assembly and Screening of Multivalent Immune Cell-Redirecting Therapies for Leukemia

Therapies that bind with immune cells and redirect their cytotoxic activity toward diseased cells represent a promising and versatile approach to immunotherapy with applications in cancer, lupus, and other diseases; traditional methods for discovering these therapies, however, are often time-intensive and lack the throughput of related target-based discovery approaches. Inspired by the observation that the cytokine, IL-12, can enhance antileukemic activity of the clinically approved T cell redirecting therapy, blinatumomab, here we describe the structure and assembly of a chimeric immune cell-redirecting agent which redirects the lytic activity of primary human T cells toward leukemic B cells and simultaneously cotargets the delivery of T cell-stimulating IL-12. We further describe a novel method for the parallel assembly of compositionally diverse libraries of these bispecific T cell engaging cytokines (BiTEokines) and their high-throughput phenotypic screening, requiring just days for hit identification and the analysis of composition-function relationships. Using this approach, we identified CD19 × CD3 × IL12 compounds that exhibit ex vivo lytic activity comparable to current FDA-approved therapies for leukemia and correlated drug treatment with specific cell–cell contact, cytokine delivery, and leukemia cell lysis. Given the modular nature of these multivalent compounds and their rapid assembly/screening, we anticipate facile extension of this therapeutic approach to a wide range of immune cells, diseased cells, and soluble protein combinations in the future.

Development of Glypican-3 Targeting Immunotoxins for the Treatment of Liver Cancer: An Update

Hepatocellular carcinoma (HCC) accounts for most liver cancers and represents one of the deadliest cancers in the world. Despite the global demand for liver cancer treatments, there remain few options available. The U.S. Food and Drug Administration (FDA) recently approved Lumoxiti, a CD22-targeting immunotoxin, as a treatment for patients with hairy cell leukemia. This approval helps to demonstrate the potential role that immunotoxins can play in the cancer therapeutics pipeline. However, concerns have been raised about the use of immunotoxins, including their high immunogenicity and short half-life, in particular for treating solid tumors such as liver cancer. This review provides an overview of recent efforts to develop a glypican-3 (GPC3) targeting immunotoxin for treating HCC, including strategies to deimmunize immunotoxins by removing B- or T-cell epitopes on the bacterial toxin and to improve the serum half-life of immunotoxins by incorporating an albumin binding domain.

[Immunotoxins and immunocytokines]

Cytokines and biological toxins represent two potent classes of biomolecules that have long been explored for their potential as therapeutics. Considerable side effects and poor pharmacokinetics frequently observed with both have limited their broad application. Recombinant protein engineering has allowed the construction of immunocytokines and immunotoxins that seek to exploit the advantageous properties of immunoglobulins to address these issues. Whole antibodies, antibody fragments, constant domains and derivatives have been fused genetically to a range of cytokines and toxins. This review considers the strategies that have been employed and the problems sought to be resolved in the clinical evaluation of this class of biotherapeutic.

Critical Issues in the Development of Immunotoxins for Anticancer Therapy

Immunotoxins (ITs) are attractive anticancer modalities aimed at cancer-specific delivery of highly potent cytotoxic protein toxins. An IT consists of a targeting domain (an antibody, cytokine, or another cell-binding protein) chemically conjugated or recombinantly fused to a highly cytotoxic payload (a bacterial and plant toxin or human cytotoxic protein). The mode of action of ITs is killing designated cancer cells through the effector function of toxins in the cytosol after cellular internalization via the targeted cell-specific receptor-mediated endocytosis. Although numerous ITs of diverse structures have been tested in the past decades, only 3 ITs-denileukin diftitox, tagraxofusp, and moxetumomab pasudotox-have been clinically approved for treating hematological cancers. No ITs against solid tumors have been approved for clinical use. In this review, we discuss critical research and development issues associated with ITs that limit their clinical success as well as strategies to overcome these obstacles. The issues include off-target and on-target toxicities, immunogenicity, human cytotoxic proteins, antigen target selection, cytosolic delivery efficacy, solid-tumor targeting, and developability. To realize the therapeutic promise of ITs, novel strategies for safe and effective cytosolic delivery into designated tumors, including solid tumors, are urgently needed.

Targeted Diphtheria Toxin-Based Therapy: A Review Article

Cancer remains one of the leading causes of death worldwide. Conventional therapeutic strategies usually offer limited specificity, resulting in severe side effects and toxicity to normal tissues. Targeted cancer therapy, on the other hand, can improve the therapeutic potential of anti-cancer agents and decrease unwanted side effects. Targeted applications of cytolethal bacterial toxins have been found to be especially useful for the specific eradication of cancer cells. Targeting is either mediated by peptides or by protein-targeting moieties, such as antibodies, antibody fragments, cell-penetrating peptides (CPPs), growth factors, or cytokines. Together with a toxin domain, these molecules are more commonly referred to as immunotoxins. Targeting can also be achieved through gene delivery and cell-specific expression of a toxin. Of the available cytolethal toxins, diphtheria toxin (DT) is one of the most frequently used for these strategies. Of the many DT-based therapeutic strategies investigated to date, two immunotoxins, Ontak^TM and Tagraxofusp^TM, have gained FDA approval for clinical application. Despite some success with immunotoxins, suicide-gene therapy strategies, whereby controlled tumor-specific expression of DT is used for the eradication of malignant cells, are gaining prominence. The first part of this review focuses on DT-based immunotoxins, and it then discusses recent developments in tumor-specific expression of DT.

Mycosis fungoides and Sézary syndrome: 2019 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas (CTCL) are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, skin-directed therapies are preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies. These include biologic-response modifiers, histone deacetylase (HDAC) inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Immunotoxins Targeting B cell Malignancy-Progress and Problems With Immunogenicity

Few immunotoxins or targeted toxins have become mainline cancer therapies. Still immunotoxins continue to be of major interest and subject of research and development as alternative therapies for drug resistant cancer. A major matter of concern continues to be immunogenicity exemplified by the anti-toxin response of the treated patient. Since some of our most effective toxins are bacterial in nature and bacterial proteins are highly immunogenic, this review describes some efforts to address this pressing issue.

Systemic Treatment Options for Advanced-Stage Mycosis Fungoides and Sézary Syndrome

PURPOSE OF REVIEW

Cutaneous T-cell lymphoma (CTCL) is a rare form of non-Hodgkin lymphoma. Globally, the most common subtypes of CTCL are mycosis fungoides and Sézary syndrome. CTCL can confer significant morbidity and even mortality in advanced disease. Here we review the current and potential future treatments for advanced-stage CTCL.

RECENT FINDINGS

Heterogeneity of treatment choice has been demonstrated both in US and non-US centers. Systemic treatment choice is currently guided by prognostic features, incorporating stage, immunophenotypic and molecular findings, and patient-specific factors such as age and comorbidities. Randomized controlled studies are uncommon, and the literature is composed predominantly of retrospective, cohort, and early-phase studies. International consensus guidelines are available; however, the lack of comparative trials means that there is no clear algorithmic approach to treatment. This review article reports on the systemic treatment options in current use for advanced CTCL, and on the possible future therapies, acknowledging that an algorithmic approach is not yet forthcoming to guide treatment prioritization.

Current systemic therapeutic options for advanced mycosis fungoides and Sézary syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common cutaneous T-cell lymphomas (CTCLs). Both lack curative options, and advanced-stage carries a poor prognosis. Whilst there are a number of treatments available, achieving and maintaining a durable remission remains challenging. We review current systemic treatment options as monotherapy for advanced-stage MF (IIB-IV), appraising their mechanism of action, analyzing their efficacy, and describing toxicities. Individually, reported overall response rates (ORR) vary widely in the literature and duration of responses are typically short, ranging from 7.5 to 22.4 months. Combined therapy is frequently used in an effort to boost responses, although prospective studies comparing combinations to single agent therapies are rarely conducted. While recent translational research has led to increased understanding of the immunopathogenesis of MF and SS and the development of new treatments, current standard of care therapies are not curative and have low ORR for advanced-stage disease.

Protein-Based Therapeutic Killing for Cancer Therapies

The treatment of some high-incidence human diseases is based on therapeutic cell killing. In cancer this is mainly achieved by chemical drugs that are systemically administered to reach effective toxic doses. As an innovative alternative, cytotoxic proteins identified in nature can be adapted as precise therapeutic agents. For example, individual toxins and venom components, proapoptotic factors, and antimicrobial peptides from bacteria, animals, plants, and humans have been engineered as highly potent drugs. In addition to the intrinsic cytotoxic activities of these constructs, their biological fabrication by DNA recombination allows the recruitment, in single pharmacological entities, of diverse functions of clinical interest such as specific cell-surface receptor binding, self-activation, and self-assembling as nanoparticulate materials, with wide applicability in cell-targeted oncotherapy and theragnosis.

Cutaneous T-cell lymphoma: 2017 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors prior to escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Emerging antibody-drug conjugates for treating lymphoid malignancies

INTRODUCTION

Antibody-drug conjugates (ADC) are monoclonal antibodies (Mabs) attached to biologically active drugs through specialized chemical linkers. They deliver and release cytotoxic agents at the tumor site, reducing the likelihood of systemic exposure and therefore toxicity. These agents should improve the potency of chemotherapy by increasing the accumulation of cytotoxic the drug within or near the neoplastic cells with reduced systemic effects. Areas covered: A literature review was conducted of the MEDLINE database PubMed for articles in English examining Mabs, B-cell receptor pathway inhibitors and immunomodulating drugs. Publications from 2000 through April 2017 were scrutinized. Conference proceedings from the previous five 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: Newer ADCs show promise as treatment for several hematologic malignancies, especially lymphoma, multiple myeloma, and leukemia. However, definitive data from ongoing and future clinical trials will aid in better defining the status of these agents in the treatment of these diseases.

Safe and Effective Sarcoma Therapy through Bispecific Targeting of EGFR and uPAR

Sarcomas differ from carcinomas in their mesenchymal origin. Therapeutic advancements have come slowly, so alternative drugs and models are urgently needed. These studies report a new drug for sarcomas that simultaneously targets both tumor and tumor neovasculature. eBAT is a bispecific angiotoxin consisting of truncated, deimmunized Pseudomonas exotoxin fused to EGF and the amino terminal fragment of urokinase. Here, we study the drug in an in vivo "ontarget" companion dog trial as eBAT effectively kills canine hemangiosarcoma and human sarcoma cells in vitro We reasoned the model has value due to the common occurrence of spontaneous sarcomas in dogs and a limited lifespan allowing for rapid accrual and data collection. Splenectomized dogs with minimal residual disease were given one cycle of eBAT followed by adjuvant doxorubicin in an adaptive dose-finding, phase I-II study of 23 dogs with spontaneous, stage I-II, splenic hemangiosarcoma. eBAT improved 6-month survival from <40% in a comparison population to approximately 70% in dogs treated at a biologically active dose (50 μg/kg). Six dogs were long-term survivors, living >450 days. eBAT abated expected toxicity associated with EGFR targeting, a finding supported by mouse studies. Urokinase plasminogen activator receptor and EGFR are targets for human sarcomas, so thorough evaluation is crucial for validation of the dog model. Thus, we validated these markers for human sarcoma targeting in the study of 212 human and 97 canine sarcoma samples. Our results support further translation of eBAT for human patients with sarcomas and perhaps other EGFR-expressing malignancies. Mol Cancer Ther; 16(5); 956-65. ©2017 AACR.

Antibody-Based Cancer Therapy: Successful Agents and Novel Approaches

Since their discovery, antibodies have been viewed as ideal candidates or "magic bullets" for use in targeted therapy in the fields of cancer, autoimmunity, and chronic inflammatory disorders. A wave of antibody-dedicated research followed, which resulted in the clinical approval of a first generation of monoclonal antibodies for cancer therapy such as rituximab (1997) and cetuximab (2004), and infliximab (2002) for the treatment of autoimmune diseases. More recently, the development of antibodies that prevent checkpoint-mediated inhibition of T cell responses invigorated the field of cancer immunotherapy. Such antibodies induced unprecedented long-term remissions in patients with advanced stage malignancies, most notably melanoma and lung cancer, that do not respond to conventional therapies. In this review, we will recapitulate the development of antibody-based therapy, and detail recent advances and new functions, particularly in the field of cancer immunotherapy. With the advent of recombinant DNA engineering, a number of rationally designed molecular formats of antibodies and antibody-derived agents have become available, and we will discuss various molecular formats including antibodies with improved effector functions, bispecific antibodies, antibody-drug conjugates, antibody-cytokine fusion proteins, and T cells genetically modified with chimeric antigen receptors. With these exciting advances, new antibody-based treatment options will likely enter clinical practice and pave the way toward more successful control of malignant diseases.

Glypican-3 Targeting Immunotoxins for the Treatment of Liver Cancer

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, yet no effective therapeutics exist. This review provides an overview of the recent development of recombinant immunotoxins for the treatment of glypican-3 (GPC3) expressing HCC. GPC3 is a cell surface heparan sulfate proteoglycan that is overexpressed in HCC, but is absent from normal adult human tissues. Treatment of HCC with anti-GPC3 immunotoxins represents a new therapeutic option. Using phage display and hybridoma technologies, three high affinity antibodies (HN3, HS20 and YP7) have been generated against GPC3. Two of these antibodies (HN3 and HS20) have demonstrated the ability to inhibit Wnt/Yap signaling, leading to a reduction in liver cancer cell proliferation. By combining the HN3 antibody capable of inhibiting Wnt/Yap signaling with the protein synthesis inhibitory domain of the Pseudomonas exotoxin, a recombinant immunotoxin that exhibits a dual inhibitory mechanism was generated. This immunotoxin was found to be highly effective in the treatment of human HCCs in mouse xenograft models. Engineering of the toxin fragment to reduce the level of immunogenicity is currently being explored. The development of immunotoxins provides opportunities for novel liver cancer therapies.

Immunotherapy for non-small cell lung cancer: current concepts and clinical trials

Recent successes in immunotherapeutic strategies are being investigated to combat cancers that have less than ideal responses to standard of care treatment, such as non-small-cell lung cancer. In this paper, we summarize concepts and the current status of immunotherapy for non-small cell lung cancer, including salient features of the major categories of immunotherapy-monoclonal antibody therapy, immune checkpoint blockade, immunotoxins, anticancer vaccines, and adoptive cell therapy.

Cutaneous T-cell lymphoma: 2016 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors before escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.