Rituximab: review and clinical applications focusing on non-Hodgkin's lymphoma

Mechanisms and functions of SUMOylation in health and disease: a review focusing on immune cells

SUMOylation, which is a type of post-translational modification that involves covalent conjugation of small ubiquitin-like modifier (SUMO) proteins to target substrates, regulates various important molecular and cellular processes, including transcription, the cell cycle, cell signaling, and DNA synthesis and repair. Newly synthesized SUMO is immature and cleaved by the SUMO-specific protease family, resulting in exposure of the C-terminal Gly-Gly motif to become the mature form. In the presence of ATP, mature SUMO is conjugated with the activating enzyme E1 through the cysteine residue of E1, followed by transfer to the cysteine residue of E2-conjugating enzyme Ubc9 in humans that recognizes and modifies the lysine residue of a substrate protein. E3 SUMO ligases promote SUMOylation. SUMOylation is a reversible modification and mediated by SUMO-specific proteases. Cumulative studies have indicated that SUMOylation affects the functions of protein substrates in various manners, including cellular localization and protein stability. Gene knockout studies in mice have revealed that several SUMO cycling machinery proteins are crucial for the development and differentiation of various cell lineages, including immune cells. Aberrant SUMOylation has been implicated in several types of diseases, including cancers, cardiovascular diseases, and autoimmune diseases. This review summarizes the biochemistry of SUMO modification and the general biological functions of proteins involved in SUMOylation. In particular, this review focuses on the molecular mechanisms by which SUMOylation regulates the development, maturation, and functions of immune cells, including T, B, dendritic, and myeloid cells. This review also discusses the underlying relevance of disruption of SUMO cycling and site-specific interruption of SUMOylation on target proteins in immune cells in diseases, including cancers and infectious diseases.

Rheumatoid Factor: A Novel Determiner in Cancer History

Simple Summary

Rheumatoid factors are autoantibodies that characterize different autoimmune diseases, in particular rheumatoid arthritis, but that can also be found in the sera of the general healthy population. They have been mainly studied in the context of autoimmune diseases, but some evidence have suggested an association between their presence and the predisposition to develop cancer as well as a facilitation of cancer growth and progression in oncologic patients. In this review, for the first time we thus analyze and discuss the possible roles that these autoantibodies can assume in tumor history, from determiners of a heightened susceptibility of developing cancer to drivers of a reduced response to immunotherapies.

Abstract

The possible interplay between autoimmunity and cancer is a topic that still needs to be deeply explored. Rheumatoid factors are autoantibodies that are able to bind the constant regions (Fc) of immunoglobulins class G (IgGs). In physiological conditions, their production is a transient event aimed at contributing to the elimination of pathogens as well as limiting a redundant immune response by facilitating the clearance of antibodies and immune complexes. Their production can become persistent in case of different chronic infections or diseases, being for instance a fundamental marker for the diagnosis and prognosis of rheumatoid arthritis. Their presence is also associated with aging. Some studies highlighted how elevated levels of rheumatoid factors (RFs) in the blood of patients are correlated with an increased cancer risk, tumor recurrence, and load and with a reduced response to anti-tumor immunotherapies. In line with their physiological roles, RFs showed in different works the ability to impair in vitro anti-cancer immune responses and effector functions, suggesting their potential immunosuppressive activity in the context of tumor immunity. Thus, the aim of this review is to investigate the emerging role of RFs as determiners of cancer faith.

Ab locks for improving the selectivity and safety of antibody drugs

Monoclonal antibodies (mAbs) are a major targeted therapy for malignancies, infectious diseases, autoimmune diseases, transplant rejection and chronic inflammatory diseases due to their antigen specificity and longer half-life than conventional drugs. However, long-term systemic antigen neutralization by mAbs may cause severe adverse events. Improving the selectivity of mAbs to distinguish target antigens at the disease site from normal healthy tissue and reducing severe adverse events caused by the mechanisms-of-action of mAbs is still a pressing need. Development of pro-antibodies (pro-Abs) by installing a protease-cleavable Ab lock is a novel and advanced recombinant Ab-based strategy that efficiently masks the antigen binding ability of mAbs in the normal state and selectively "turns on" the mAb activity when the pro-Ab reaches the proteolytic protease-overexpressed diseased tissue. In this review, we discuss the design and advantages/disadvantages of different Ab lock strategies, focusing particularly on spatial-hindrance-based and affinity peptide-based approaches. We expect that the development of different masking strategies for mAbs will benefit the local reactivity of mAbs at the disease site, increase the therapeutic efficacy and safety of long-term treatment with mAbs in chronic diseases and even permit scientists to develop Ab drugs for formerly undruggable targets and satisfy the unmet medical needs of mAb therapy.

A coiled-coil masking domain for selective activation of therapeutic antibodies

The use of monoclonal antibodies in cancer therapy is limited by their cross-reactivity to healthy tissue. Tumor targeting has been improved by generating masked antibodies that are selectively activated in the tumor microenvironment, but each such antibody necessitates a custom design. Here, we present a generalizable approach for masking the binding domains of antibodies with a heterodimeric coiled-coil domain that sterically occludes the complementarity-determining regions. On exposure to tumor-associated proteases, such as matrix metalloproteinases 2 and 9, the coiled-coil peptides are cleaved and antigen binding is restored. We test multiple coiled-coil formats and show that the optimized masking domain is broadly applicable to antibodies of interest. Our approach prevents anti-CD3-associated cytokine release in mice and substantially improves circulation half-life by protecting the antibody from an antigen sink. When applied to antibody-drug conjugates, our masked antibodies are preferentially unmasked at the tumor site and have increased anti-tumor efficacy compared with unmasked antibodies in mouse models of cancer.

Immunology's Coming of Age

This treatise describes the development of immunology as a scientific discipline with a focus on its foundation. Toward the end of the nineteenth century, the study of immunology was founded with the discoveries of phagocytosis by Elias Metchnikoff, as well as by Emil Behring's and Paul Ehrlich's discovery of neutralizing antibodies. These seminal studies were followed by the discoveries of bacteriolysis by complement and of opsonization by antibodies, which provided first evidence for cooperation between acquired and innate immunity. In the years that followed, light was shed on the pathogenic corollary of the immune response, describing different types of hypersensitivity. Subsequently, immunochemistry dominated the field, leading to the revelation of the chemical structure of antibodies in the 1960s. Immunobiology was preceded by transplantation biology, which laid the ground for the genetic basis of acquired immunity. With the identification of antibody producers as B lymphocytes and the discovery of T lymphocytes as regulators of acquired immunity, lymphocytes moved into the center of immunologic research. T cells were shown to be genetically restricted and to regulate different leukocyte populations, including B cells and professional phagocytes. The discovery of dendritic cells as major antigen-presenting cells and their surface expression of pattern recognition receptors revealed the mechanisms by which innate immunity instructs acquired immunity. Genetic analysis provided in-depth insights into the generation of antibody diversity by recombination, which in principle was shown to underlie diversity of the T cell receptor, as well. The invention of monoclonal antibodies not only provided ultimate proof for the unique antigen specificity of the antibody-producing plasma cell, it also paved the way for a new era of immunotherapy. Emil Behring demonstrated cure of infectious disease by serum therapy, illustrating how clinical studies can stimulate basic research. The recent discovery of checkpoint control for cancer therapy illustrates how clinical application benefits from insights into basic mechanisms. Last not least, perspectives on immunology progressed from a dichotomy between cellular-unspecific innate immunity and humoral-specific acquired immunity, toward the concept of complementary binarity.

Inhibition of complement dependent cytotoxicity by anti-CD20 aptamers

SELEXed to protect: aptamers to B-lymphocyte antigen CD20 decrease cell damage inducedviaantibody-dependent complement dependent cytotoxicity.

Recent advances in the field of anti-cancer immunotherapy

Background

The main goal of anti-cancer therapy is to specifically inhibit the malignant activity of cancer cells, while leaving healthy cells unaffected. As such, for every proposed therapy, it is important to keep in mind the therapeutic index — the ratio of the toxic dose over the therapeutic dose. The use of immunotherapy has allowed a means to both specifically block protein–protein interaction and deliver cytotoxic events to a tumor-specific antigen.

Review scope

It is the objective of this review to give an overview on current immunotherapy treatment for cancers using monoclonal antibodies. We demonstrate three exciting targets for immunotherapy, TNF-α Converting Enzyme (TACE), Cathepsin S and Urokinase Plasmogen Activator and go over the advances made with one of the most used monoclonal antibodies in cancer therapy, Rituximab; as well as Herceptin, which is used for breast cancer therapy. Furthermore, we touch on other venues of immunotherapy, such as adaptive cell transfer, the use of nucleic acids and the use of dendritic cells. Finally, we summarize some ongoing studies that spell tentative advancements for anti-cancer immunotherapy.

General significance

Immunotherapy is at the forefront of anti-cancer therapies, allying both a high degree of specificity to general high effectiveness and fewer side-effects.

•

Current monoclonal antibodies for cancer immunotherapy have a bright future.

•

Immunotherapy presents opportunity to eliminate tumor growth that chemotherapy can't achieve.

•

Therapeutic antibodies for cancer immunotherapy show better results without undesirable side-effects.

Severe and fatal adverse events risk associated with rituximab addition to B-cell non-Hodgkin's lymphoma (B-NHL) chemotherapy: a meta-analysis

PURPOSE

Rituximab is a monoclonal antibody targetting the CD20 antigen with the ability to increase overall remission (OR) in B-cell non-Hodgkin's lymphoma (B-NHL). A systematic review and meta-analysis were conducted to determine the risk of the most clinically relevant severe and fatal adverse events (AEs) associated with the use of rituximab in the treatment of B-NHL.

PATIENTS AND METHODS

We included phase III clinical trials that used chemotherapy in combination with rituximab or chemotherapy alone as for B-NHL. Statistical analyses were conducted to calculate summary risk ratio (RR) of the relevant severe and fatal AEs related with rituximab.

RESULTS

Eight randomised controlled clinical trials were included in this meta-analysis. Summary RR obtained showed no statistically significant rituximab-associated increased risk in 13 severe adverse events (SAEs) (infection, fever, anaemia, thrombocytopaenia, granulocytopenia, liver toxicity, cardiac toxicity, neurologic toxicity, lung toxicity, mucositis, nausea/vomiting, diarrhoea, alopecia) except leukocytopenia (36.4% versus 31%; RR = 1.13; 95%CI, 1.01-1.27; P = 0.03). The incidences of fatal AEs showed noteworthy difference between rituximab group and control group (RR = 1.45; 95% CI, 1.04-2.02; P = 0.03).

CONCLUSION

This meta-analysis indicates that there was no proof of statistically higher incidence of most SAEs in rituximab containing group compared with chemotherapy alone. However, fatal infections were more frequently observed in patients who received rituximab. Considering the low-incidence infection-induced death during the treatment period, the effects of rituximab on infections need further investigation.

Childhood acute lymphoblastic leukaemia and relapse

Acute lymphoblastic leukaemia (ALL) is the most common childhood cancer. Treatment has improved but relapsed ALL remains more common than new cases of many 'common' paediatric malignancies. We have salvage regimens with substantial complete remission (CR) rates and increasing access to haematopoietic stem cell transplantation, but most patients who relapse die. We need better therapies. Insights into pharmacology may guide more effective use of existing agents. Novel agents with activity against resistant lymphoblasts offer an appealing strategy. However, most candidate agents fail, despite enthusiastic investigators, intriguing mechanisms of action and 'compelling' preclinical data. A number of existing combinations provide a 40% complete response rate in second or third relapse. Yet survival in third remission is <10%. Novel agents must, most likely, be integrated into multiagent combinations that provide a higher CR rate or better quality CR's than our conventional combinations in order to contribute substantially to cure. The march from bench to bedside requires careful consideration of the intermediate steps.

The diminishing role of surgery in the treatment of gastric lymphoma

OBJECTIVE

This article reviews the pathogenesis, diagnosis, and treatment of patients with primary gastric lymphoma, with special attention to the changing role of surgery.

SUMMARY BACKGROUND DATA

Primary gastric lymphomas are non-Hodgkin lymphomas that originate in the stomach and are divided into low-grade (or indolent) and high-grade (or aggressive) types. Low-grade lesions nearly always arise from mucosa-associated lymphoid tissue (MALT) secondary to chronic Helicobacter pylori (H. pylori) infection and disseminate slowly. High-grade lesions may arise from a low grade-MALT component or arise de novo and can spread to lymph nodes, adjacent organs and tissues, or distant sites.

METHODS

A review of the relevant English-language articles was performed on the basis of a MEDLINE search from January 1984 to August 2003.

RESULTS

About 40% of gastric lymphomas are low-grade, and nearly all these low-grade lesions are classified as MALT lymphomas. For low-grade MALT lymphomas confined to the gastric wall and without certain negative prognostic factors, H. pylori eradication is highly successful in causing lymphoma regression. More advanced low-grade lymphomas or those that do not regress with antibiotic therapy can be treated with combinations of H. pylori eradication, radiation therapy, and chemotherapy. Nearly 60% of gastric lymphomas are high-grade lesions with or without a low-grade MALT component. These lymphomas can be treated with chemotherapy and radiation therapy according to the extent of disease. Surgery for gastric lymphoma is now often reserved for patients with localized, residual disease after nonsurgical therapy or for rare patients with complications.

CONCLUSION

The treatment of gastric lymphoma continues to evolve, and surgical resection is now uncommonly a part of the initial management strategy.

Biotechnology and drug discovery: from bench to bedside

New biotechnology and drug discovery technologies are facilitating the rapid expansion of the clinical drug chest, empowering clinicians with a better understanding of disease as well as novel modalities for treating patients. Important research tools and themes include genomics, proteomics, ligand-receptor interaction, signal transduction, rational drug design, biochips, and microarrays. Emerging drug classes include monoclonal antibodies, cancer vaccines, gene therapy, antisense strands, enzymes, and proteins. In this article, we review these topics and illustrate their potential impact by presenting an overview of promising drugs in the pipeline. Clinicians who use these novel treatments must become familiar with these trends.

cAC10-vcMMAE, an anti-CD30-monomethyl auristatin E conjugate with potent and selective antitumor activity

The chimeric monoclonal antibody cAC10, directed against CD30, induces growth arrest of CD30+ cell lines in vitro and has pronounced antitumor activity in severe combined immunodeficiency (SCID) mouse xenograft models of Hodgkin disease. We have significantly enhanced these activities by conjugating to cAC10 the cytotoxic agent monomethyl auristatin E (MMAE) to create the antibody-drug conjugate cAC10-vcMMAE. MMAE, a derivative of the cytotoxic tubulin modifier auristatin E, was covalently coupled to cAC10 through a valine-citrulline peptide linker. The drug was stably attached to the antibody, showing only a 2% release of MMAE following 10-day incubation in human plasma, but it was readily cleaved by lysosomal proteases after receptor-mediated internalization. Release of MMAE into the cytosol induced G2/M-phase growth arrest and cell death through the induction of apoptosis. In vitro, cAC10-vcMMAE was highly potent and selective against CD30+ tumor lines (IC50 less than 10 ng/mL) but was more than 300-fold less active on antigen-negative cells. In SCID mouse xenograft models of anaplastic large cell lymphoma or Hodgkin disease, cAC10-vcMMAE was efficacious at doses as low as 1 mg/kg. Mice treated at 30 mg/kg cAC10-vcMMAE showed no signs of toxicity. These data indicate that cAC10-vcMMAE may be a highly effective and selective therapy for the treatment of CD30+ neoplasias.

Immunologic principles and immunotherapeutic approaches in ovarian cancer

Ovarian cancer is an immunogenic tumor, and numerous antigens have been identified in recent years. Several of these antigens are important in regulating tumor growth and may be ideal targets for the development of immune-based strategies. In the absence of immunologic intervention, tumors evade the immune system by several mechanisms, most notably tolerance and immunosuppression. As understanding of the immune response improves, strategies are being designed to circumvent T-cell tolerance to self-antigens through modulation of APC function. In addition, techniques are being developed to identify reverse ovarian cancer-induced immune evasion tactics. The type of the immune-based therapy to apply varies with disease burden. It is hoped that discoveries at the bench along with lessons learned in prior clinical trials soon will allow clinicians to develop rationally based immunologic strategies to treat and prevent ovarian cancer.

Development of potent monoclonal antibody auristatin conjugates for cancer therapy

We describe the in vitro and in vivo properties of monoclonal antibody (mAb)-drug conjugates consisting of the potent synthetic dolastatin 10 analogs auristatin E (AE) and monomethylauristatin E (MMAE), linked to the chimeric mAbs cBR96 (specific to Lewis Y on carcinomas) and cAC10 (specific to CD30 on hematological malignancies). The linkers used for conjugate formation included an acid-labile hydrazone and protease-sensitive dipeptides, leading to uniformly substituted conjugates that efficiently released active drug in the lysosomes of antigen-positive (Ag+) tumor cells. The peptide-linked mAb-valine-citrulline-MMAE and mAb-phenylalanine-lysine-MMAE conjugates were much more stable in buffers and plasma than the conjugates of mAb and the hydrazone of 5-benzoylvaleric acid-AE ester (AEVB). As a result, the mAb-Val-Cit-MMAE conjugates exhibited greater in vitro specificity and lower in vivo toxicity than corresponding hydrazone conjugates. In vivo studies demonstrated that the peptide-linked conjugates induced regressions and cures of established tumor xenografts with therapeutic indices as high as 60-fold. These conjugates illustrate the importance of linker technology, drug potency and conjugation methodology in developing safe and efficacious mAb-drug conjugates for cancer therapy.

Immunotherapy of glioblastoma multiforme

Glioblastoma multiforme is immunogenic and several glioblastoma multiforme-related antigens have now been identified. In addition, the immunologic characteristics of the tumor microenvironment that may affect tumor growth are becoming increasingly understood. The type of immune-based approach selected to treat glioblastoma multiforme will depend on the tumor burden. For minimal disease states, active vaccination may be useful for generating adequate protection from relapse. However, for more advanced stage disease states, more rigorous strategies may need to be applied, such as adoptive T-cell therapy, antibody therapy or a combination of different techniques. The immunosuppressive environment observed during advanced malignancy may need to be reversed for improved efficacy of immune-based therapies.

Macromolecular Therapeutics

Macromolecular drugs (also referred to as polymeric drugs) are a diverse group of drugs including polymer-conjugated drugs, polymeric micelles, liposomal drugs and solid phase depot formulations of various agents. In this review we will consider only water-soluble macromolecular drugs. In common, such drugs have high molecular weights, more than 40 kDa, which enables them to overcome renal excretion. Consequently, this group of drugs can attain prolonged plasma or local half-lives. The prolonged circulating time of these macromolecules enables them to utilise the vascular abnormalities of solid tumour tissues, a phenomenon called the enhanced permeability and retention (EPR) effect. The EPR effect facilitates extravasation of polymeric drugs more selectively at tumour tissues, and this selective targeting to solid tumour tissues may lead to superior therapeutic benefits with fewer systemic adverse effects. This contrasts with conventional low-molecular-weight drugs, where intratumour concentration diminishes rapidly in parallel with plasma concentration. The EPR effect is also operative in inflammatory tissues, which justifies the development and use of this class of drugs in infectious and inflammatory conditions. At the present time, several polymeric drugs have been approved by regulatory agencies. These include zinostatin stimalamer (copolymer styrene maleic acid-conjugated neocarzinostatin, or SMANCS) and polyethyleneglycol-conjugated interferon-alpha-2a. This article discusses these and other polymeric drugs in the setting of targeting to solid tumours.