The identification of irreversible rituximab-resistant lymphoma caused by CD20 gene mutations

Antibody and Cell-Based Therapies against Virus-Induced Cancers in the Context of HIV/AIDS

Infectious agents, notably viruses, can cause or increase the risk of cancer occurrences. These agents often disrupt normal cellular functions, promote uncontrolled proliferation and growth, and trigger chronic inflammation, leading to cancer. Approximately 20% of all cancer cases in humans are associated with an infectious pathogen. The International Agency for Research on Cancer (IARC) recognizes seven viruses as direct oncogenic agents, including Epstein-Barr Virus (EBV), Kaposi's Sarcoma-associated herpesvirus (KSHV), human T-cell leukemia virus type-1 (HTLV-1), human papilloma virus (HPV), hepatitis C virus (HCV), hepatitis B virus (HBV), and human immunodeficiency virus type 1 (HIV-1). Most viruses linked to increased cancer risk are typically transmitted through contact with contaminated body fluids and high-risk behaviors. The risk of infection can be reduced through vaccinations and routine testing, as well as recognizing and addressing risky behaviors and staying informed about public health concerns. Numerous strategies are currently in pre-clinical phases or undergoing clinical trials for targeting cancers driven by viral infections. Herein, we provide an overview of risk factors associated with increased cancer incidence in people living with HIV (PLWH) as well as other chronic viral infections, and contributing factors such as aging, toxicity from ART, coinfections, and comorbidities. Furthermore, we highlight both antibody- and cell-based strategies directed against virus-induced cancers while also emphasizing approaches aimed at discovering cures or achieving complete remission for affected individuals.

Combination of rituximab and short-term glucocorticoids in the treatment of anti-phospholipase A2 receptor antibody positive idiopathic membranous nephropathy

Rituximab (RTX) has been the first option in idiopathic membranous nephropathy (IMN). However, the clinical effect was not very satisfactory. This study aimed to explore the clinical efficacy and safety of the combination of RTX and glucocorticoids (GC) in anti-phospholipase A2 receptor (anti-PLA2R) antibody positive IMN. Sixty-six patients were randomly divided into RTX/GC group (RTX infusion plus short-term oral GC) and RTX group (RTX infusion alone) in this prospective cohort study. Complete remission (CR) and partial remission (PR) were the primary outcomes. Adverse events were the secondary outcomes. The laboratory index including serum albumin, 24 h urinary protein, serum creatinine, estimated glomerular filtration rate, and anti-PLA2R antibody titer were also monitored. All patients were followed for at least 12 months. During the 12-month follow-up, the composite remission rates in RTX/GC and RTX groups were 74.3% and 67.7%, and the CR rates were 34.3% and 19.4%, respectively. The median time of remission in RTX/GC group was shorter than the RTX group (P < 0.001). Compared with RTX monotherapy, the combination of RTX and GC significantly decreased the anti-PLA2R antibody titer (P = 0.028). No significant difference was observed in the incidence of adverse events. The results of the Kaplan-Meier survival analysis indicated that the cumulative CR rate and cumulative composite remission rate in RTX/GC group were all better than the RTX group (P = 0.043, P = 0.040, respectively). The combination of RTX and GC was better than RTX monotherapy without increasing the adverse events in the treatment of IMN.

A randomized, phase II study of sequential belimumab and rituximab in primary Sjögren's syndrome

BACKGROUNDPrimary Sjögren's syndrome (pSS) is characterized by B cell hyperactivity and elevated B-lymphocyte stimulator (BLyS). Anti-BLyS treatment (e.g., belimumab) increases peripheral memory B cells; decreases naive, activated, and plasma B cell subsets; and increases stringency on B cell selection during reconstitution. Anti-CD20 therapeutics (e.g., rituximab) bind and deplete CD20-expressing B cells in circulation but are less effective in depleting tissue-resident CD20+ B cells. Combined, these 2 mechanisms may achieve synergistic effects.METHODSThis 68-week, phase II, double-blind study (GSK study 201842) randomized 86 adult patients with active pSS to 1 of 4 arms: placebo, s.c. belimumab, i.v. rituximab, or sequential belimumab + rituximab.RESULTSOverall, 60 patients completed treatment and follow-up until week 68. The incidence of adverse events (AEs) and drug-related AEs was similar across groups. Infections/infestations were the most common AEs, and no serious infections of special interest occurred. Near-complete depletion of minor salivary gland CD20+ B cells and a greater and more sustained depletion of peripheral CD19+ B cells were observed with belimumab + rituximab versus monotherapies. With belimumab + rituximab, reconstitution of peripheral B cells occurred, but it was delayed compared with rituximab. At week 68, mean (± standard error) total EULAR Sjögren's syndrome disease activity index scores decreased from 11.0 (1.17) at baseline to 5.0 (1.27) for belimumab + rituximab and 10.4 (1.36) to 8.6 (1.57) for placebo.CONCLUSIONThe safety profile of belimumab + rituximab in pSS was consistent with the monotherapies. Belimumab + rituximab induced enhanced salivary gland B cell depletion relative to the monotherapies, potentially leading to improved clinical outcomes.TRIAL REGISTRATIONClinicalTrials.gov NCT02631538.FUNDINGFunding was provided by GSK.

Glycans as Targets for Drug Delivery in Cancer

Simple Summary

Alterations in glycosylation are frequently observed in cancer cells. Different strategies have been proposed to increase drug delivery to the tumor site in order to improve the therapeutic efficacy of anti-cancer drugs and avoid collateral cytotoxicity. The exploitation of drug delivery approaches directed to cancer-associated glycans has the potential to pave the way for better and more efficient personalized treatment practices. Such strategies taking advantage of aberrant cell surface glycosylation patterns enhance the targeting efficiency and optimize the delivery of clinically used drugs to cancer cells, with major potential for the clinical applications.

Abstract

Innovative strategies have been proposed to increase drug delivery to the tumor site and avoid cytotoxicity, improving the therapeutic efficacy of well-established anti-cancer drugs. Alterations in normal glycosylation processes are frequently observed in cancer cells and the resulting cell surface aberrant glycans can be used as direct molecular targets for drug delivery. In the present review, we address the development of strategies, such as monoclonal antibodies, antibody–drug conjugates and nanoparticles that specific and selectively target cancer-associated glycans in tumor cells. The use of nanoparticles for drug delivery encompasses novel applications in cancer therapy, including vaccines encapsulated in synthetic nanoparticles and specific nanoparticles that target glycoproteins or glycan-binding proteins. Here, we highlight their potential to enhance targeting approaches and to optimize the delivery of clinically approved drugs to the tumor microenvironment, paving the way for improved personalized treatment approaches with major potential importance for the pharmaceutical and clinical sectors.

Antigen Loss after Targeted Immunotherapy in Hematological Malignancies

Immunotherapy marked a milestone in cancer treatment and has shown unprecedented efficacy in a variety of hematological malignancies. Downregulation or loss of target antigens is commonly seen after immunotherapy, which often causes diagnostic dilemma and represents a key mechanism that tumor escapes from immunotherapy. The awareness of phenotypic changes after targeted immunotherapy is important to avoid misdiagnosis. Further understanding of the mechanisms of antigen loss is paramount for the development of therapeutic approaches that can prevent or overcome antigen escape in future immunotherapy.

A CRISPR Screen Reveals Resistance Mechanisms to CD3-Bispecific Antibody Therapy

CD3-bispecific antibodies represent an important therapeutic strategy in oncology. These molecules work by redirecting cytotoxic T cells to antigen-bearing tumor cells. Although CD3-bispecific antibodies have been developed for several clinical indications, cases of cancer-derived resistance are an emerging limitation to the more generalized application of these molecules. Here, we devised whole-genome CRISPR screens to identify cancer resistance mechanisms to CD3-bispecific antibodies across multiple targets and cancer types. By validating the screen hits, we found that deficiency in IFNγ signaling has a prominent role in cancer resistance. IFNγ functioned by stimulating the expression of T-cell killing-related molecules in a cell type-specific manner. By assessing resistance to the clinical CD3-bispecific antibody flotetuzumab, we identified core fucosylation as a critical pathway to regulate flotetuzumab binding to the CD123 antigen. Disruption of this pathway resulted in significant resistance to flotetuzumab treatment. Proper fucosylation of CD123 was required for its normal biological functions. In order to treat the resistance associated with fucosylation loss, flotetuzumab in combination with an alternative targeting CD3-bispecific antibody demonstrated superior efficacy. Together, our study reveals multiple mechanisms that can be targeted to enhance the clinical potential of current and future T-cell-engaging CD3-bispecific antibody therapies.

Mechanism and Treatment of Rituximab Resistance in Diffuse Large Bcell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype B non-Hodgkin lymphoma in adults. After rituximab being introduced to treat DLBCL, the current first-line treatment is R-CHOP regimen. This regimen greatly improves patient's prognosis, however, relapsed or refractory cases are commonly seen, mainly due to the resistance to rituximab. Although a large number of experiments have been conducted to investigate rituximab resistance, the exac mechanisms and solutions are still unclear. This review mainly explores the possible mechanisms oft rituximab resistance and current new effective treatments for rituximab resistance in DLBCL.

Monoclonal Antibodies in Cancer Therapy

Monoclonal antibody-based immunotherapy is now considered to be a main component of cancer therapy, alongside surgery, radiation, and chemotherapy. Monoclonal antibodies possess a diverse set of clinically relevant mechanisms of action. In addition, antibodies can directly target tumor cells while simultaneously promoting the induction of long-lasting anti-tumor immune responses. The multifaceted properties of antibodies as a therapeutic platform have led to the development of new cancer treatment strategies that will have major impacts on cancer care. This review focuses on the known mechanisms of action, current clinical applications for the treatment of cancer, and mechanisms of resistance of monoclonal antibody therapy. We further discuss how monoclonal antibody-based strategies have moved towards enhancing anti-tumor immune responses by targeting immune cells instead of tumor antigens as well as some of the current combination therapies.

Direct targeting of cancer cells with antibodies: What can we learn from the successes and failure of unconjugated antibodies for lymphoid neoplasias?

Following approval in 1997 of the anti-CD20 antibody rituximab for the treatment of B-NHL and CLL, many other unconjugated IgG1 MAbs have been tested in pre-clinical and clinical trials for the treatment of lymphoid neoplasms. Relatively few have been approved however and these are directed against a limited number of target antigens (CD20, CD52, CCR4, CD38, CD319). We review here the known biological properties of these antibodies and discuss which factors may have led to their success or may, on the contrary, limit their clinical application. Common factors of the approved MAbs are that the target antigen is expressed at relatively high levels on the neoplastic targets and their mechanism of action is mostly immune-mediated. Indeed most of these MAbs induce ADCC and phagocytosis by macrophages, and many also activate complement, leading to target cell lysis. In contrast direct cell death induction is not a common feature but may enhance efficacy in some cases. Interestingly, a key factor for the success of several MAbs appears to be their capacity to skew immunity towards an anti-tumour mode, by inhibiting/depleting suppressor cells and/or activating immune cells within the microenvironment, independently of FcγRs. We also expose here some of the strategies employed by industry to expand the clinical use of these molecules beyond their original indication. Interestingly, due to the central role of lymphocytes in the control of the immune response, several of the antibodies are now successfully used to treat many different autoimmune diseases and have also been formally approved for some of these new indications. There is little doubt that this trend will continue and that the precise mechanisms of therapeutic MAbs will be further dissected and better understood in the context of both tumour immunology and autoimmunity.

Genetic and Epigenetic Modulation of CD20 Expression in B-Cell Malignancies: Molecular Mechanisms and Significance to Rituximab Resistance

CD20 is a differentiation related cell surface phosphoprotein that is expressed during early pre-B cell stages until plasma cell differentiation, and is a suitable molecular target for B-cell malignancies by monoclonal antibodies such as rituximab, ofatumumab, obinutuzumab and others. CD20 expression is confirmed in most B-cell malignancies; however, the protein expression level varies in each patient, even in de novo tumors, and down-modulation of CD20 expression after chemoimmunotherapy with rituximab, resulting in rituximab resistance, has been recognized in the clinical setting. Recent reports suggest that genetic and epigenetic mechanisms are correlated with aberrantly low CD20 expression in de novo tumors and relapsed/refractory disease after using rituximab. Furthermore, some targeting drugs, such as lenalidomide, bortezomib and ibrutinib, directly or indirectly affect CD20 protein expression. CD20-negative phenotypically-changed DLBCL after rituximab use tends to show an aggressive clinical course and poor outcome with resistance to not only rituximab, but also conventional salvage chemo-regimens. Understanding of the mechanisms of CD20-negative phenotype may contribute to establish strategies for overcoming chemo-refractory B-cell malignancies. In this manuscript, recent progress of research on molecular and clinical features of CD20 protein and CD20-negative B-cell malignancies was reviewed.

Human lymphocytic B-leukemia cell line treatment with the bacterial toxin listeriolysin O and rituximab (anti-CD20 antibody): Effects of similar localization of their receptors

Small B-cell lymphocytic lymphoma/chronic lymphocytic leukemia, which typically affects elderly people, is a group of conditions that are not clinically uniform. It has been suggested that using the combined activity of the monoclonal antibody anti-CD20 (rituximab) and Listeria monocytogenes toxin listeriolysin O (LLO) for this condition could produce an enhanced treatment effect. Here, we tested the effect of the joint activity of rituximab and LLO, which is a cell membrane toxin, in human leukemia cell lines. The human B-leukemia Raji cell line, which expresses CD20, and the T-cell Jurkat cell line, which does not express CD20, for comparison were used in model tests. Cell cytotoxicity of rituximab or LLO and both applied jointly to the cell lines was compared in the presence of human plasma complement. Optimal cytotoxic effects dependent on rituximab or LLO concentration were tested separately. LD50 values were determined and used for optimal application of a mixture of the two factors. The cytotoxic effect on Raji cells of both rituximab and LLO was more than 2.5 times that of LLO alone and 1.5 times that of rituximab alone. At the highest tested concentrations, a mixture of the tested factors had a non-specific cytotoxic effect on the Jurkat cell line, as well. The rituximab and LLO binding sites appear to be in a similar region of the Raji leukemia cell membrane, suggesting an effective interaction of both factors. The joint interaction of these compounds in cell membrane pore formation suggests an explanation for the more effective cytotoxic activity that their combination was observed in this experiment.

Action and resistance of monoclonal CD20 antibodies therapy in B-cell Non-Hodgkin Lymphomas

Anti-CD20 monoclonal antibodies (mAbs) have improved patient's survival with Non-Hodgkin Lymphoma, when combined with chemotherapy. Several mechanisms of action have been reported, including antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity and induction of apoptosis. Despite the large amount of studies and published data, the role each mechanism played in vivo is not fully understood. Furthermore, the reason why a significant percentage of patients are refractory or resistant remains unknown. Several activated intracellular signaling pathways have been implicated in the mechanisms of resistance of rituximab. In the present manuscript, we review those mechanisms and new anti-CD20 mAbs, as well as the efforts being accomplished to overcome it, focusing on new drugs targeting pathways implicated in resistance to rituximab.

Update on obinutuzumab in the treatment of B-cell malignancies

INTRODUCTION

The anti-CD20 mAb rituximab has revolutionized the treatment of B-cell malignancies, improving outcome for patients. Despite these improvements, the majority of patients still relapse and become refractory to rituximab. Further efforts to improve anti-CD20 mAb efficacy have recently focused on obinutuzumab /GA101, a novel anti-CD20 mAb glycoengineered to display enhanced Fc-mediated effector mechanisms and induce direct cell death.

AREAS COVERED

We provide an overview of the current insights into the mechanisms of action of obinutuzumab focusing on how structural modifications and differences to rituximab led to designation of obinutuzumab as a type II antibody. We summarize data from preclinical studies and recent clinical trials including the Phase III trial in chronic lymphocytic leukemia (CLL), which led to FDA approval in November 2013.

EXPERT OPINION

Clinical data are now emerging confirming the promise of the initial preclinical data that demonstrated superior efficacy of obinutuzumab over rituximab at similar dosing. The emerging randomized Phase III data from older comorbid patients with previously untreated CLL demonstrated significant improvements in molecular remission rates and median progression-free survival of obinutuzumab plus chlorambucil versus rituximab plus chlorambucil. This emerging data provide reasons to be optimistic that outcomes for patients with B-cell malignancies can be further improved with obinutuzumab.

De novo diffuse large B-cell lymphoma with a CD20 immunohistochemistry-positive and flow cytometry-negative phenotype: molecular mechanisms and correlation with rituximab sensitivity

CD20 is expressed in most B-cell lymphomas and is a critical molecular target of rituximab. Some B-cell lymphomas show aberrant CD20 expression, and rituximab use in these patients is controversial. Here we show both the molecular mechanisms and the clinical significance of de novo diffuse large B-cell lymphomas (DLBCL) that show a CD20 immunohistochemistry (IHC)-positive and flow cytometry (FCM)- negative (IHC[+]/FCM[−]) phenotype. Both IHC and FCM using anti-CD20 antibodies L26 and B1, respectively, were analyzed in 37 of the 106 cases of de novo DLBCL; 8 (22%) of these cases were CD79a(+)/CD20(+) with IHC and CD19(+)/CD20(−) with FCM. CD20 (MS4A1) mRNA expression was significantly lower in IHC(+)/FCM(−) cells than in IHC(+)/FCM(+) cells (P = 0.0005). No genetic mutations were detected in MS4A1 promoter and coding regions. Rituximab-mediated cytotoxicity in the CDC assay using IHC(+)/FCM(−) primary cells was significantly lower than in IHC(+)/FCM(+) cells (P < 0.05); however, partial effectiveness was confirmed. FCM using rituximab detected CD20 more efficiently than B1. No significant difference was observed between IHC(+)/FCM(−) and IHC(+)/FCM(+) patients in overall survival (P = 0.664). Thus, lower expression of CD20 mRNA is critical for the CD20 IHC(+)/FCM(−) phenotype. Lower CD20 expression with FCM does not rule out rituximab use in these patients if expression is confirmed with IHC. FCM using rituximab may be more informative than B1 for predicting rituximab effectiveness in IHC(+)/FCM(−) cases.

Detection of the Helicobacter pylori CagA protein in gastric mucosa-associated lymphoid tissue lymphoma cells: clinical and biological significance

We previously reported that CagA can be translocated into B cells in Helicobacter pylori (HP) coculture media, and the translocation appears biologically significant as activation of the relevant cellular pathways was noticed. In this study, we further explore if CagA can be detected in malignant B cells of HP-positive gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Expression of CagA was evaluated by immunohistochemistry. CagA expression was further confirmed by western blot analysis. The association between CagA expression in malignant B cells and tumor response to HP eradication therapy (HPE) was evaluated in 64 stage IE gastric MALT lymphoma patients. We detected CagA expression in 31 (48.4%) of 64 patients: 26 (68.4%) of the 38 HP-dependent cases and 5 (19.2%) of the 26 HP-independent cases (P<0.001). Patients with CagA expression responded to HPE quicker than those without (median time to complete remission, 3.0 vs 6.5 months, P=0.025). Our results indicated that CagA can be translocated into malignant B cells of MALT lymphoma, and the translocation is clinically and biologically significant.