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1.  Statins Impair Antitumor Effects of Rituximab by Inducing Conformational Changes of CD20 
PLoS Medicine  2008;5(3):e64.
Background
Rituximab is used in the treatment of CD20+ B cell lymphomas and other B cell lymphoproliferative disorders. Its clinical efficacy might be further improved by combinations with other drugs such as statins that inhibit cholesterol synthesis and show promising antilymphoma effects. The objective of this study was to evaluate the influence of statins on rituximab-induced killing of B cell lymphomas.
Methods and Findings
Complement-dependent cytotoxicity (CDC) was assessed by MTT and Alamar blue assays as well as trypan blue staining, and antibody-dependent cellular cytotoxicity (ADCC) was assessed by a 51Cr release assay. Statins were found to significantly decrease rituximab-mediated CDC and ADCC of B cell lymphoma cells. Incubation of B cell lymphoma cells with statins decreased CD20 immunostaining in flow cytometry studies but did not affect total cellular levels of CD20 as measured with RT-PCR and Western blotting. Similar effects are exerted by other cholesterol-depleting agents (methyl-β-cyclodextrin and berberine), but not filipin III, indicating that the presence of plasma membrane cholesterol and not lipid rafts is required for rituximab-mediated CDC. Immunofluorescence microscopy using double staining with monoclonal antibodies (mAbs) directed against a conformational epitope and a linear cytoplasmic epitope revealed that CD20 is present in the plasma membrane in comparable amounts in control and statin-treated cells. Atomic force microscopy and limited proteolysis indicated that statins, through cholesterol depletion, induce conformational changes in CD20 that result in impaired binding of anti-CD20 mAb. An in vivo reduction of cholesterol induced by short-term treatment of five patients with hypercholesterolemia with atorvastatin resulted in reduced anti-CD20 binding to freshly isolated B cells.
Conclusions
Statins were shown to interfere with both detection of CD20 and antilymphoma activity of rituximab. These studies have significant clinical implications, as impaired binding of mAbs to conformational epitopes of CD20 elicited by statins could delay diagnosis, postpone effective treatment, or impair anti-lymphoma activity of rituximab.
Jakub Golab and colleagues found that statins significantly decrease rituximab-mediated complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity against B cell lymphoma cells.
Editors' Summary
Background.
Lymphomas are common cancers of the lymphatic system, the tissues and organs that produce and store the white blood cells (lymphocytes) that fight infections. In healthy people, the cells in the lymph nodes (collections of lymphocytes in the armpit, groin, and neck) and other lymphatic organs divide to form new cells only when the body needs them. Lymphomas form when a T or B lymphocyte starts to divide uncontrollably. The first sign of lymphoma is often a painless swelling in the armpit, groin, or neck caused by lymphocyte overgrowth in a lymph node. Eventually, the abnormal (malignant) lymphocytes, which provide no protection against infectious diseases, spread throughout the body. Treatments for lymphoma include chemotherapy (drugs that kill rapidly dividing cells) and radiotherapy. In addition, a drug called rituximab was recently developed for the treatment of some types of B cell lymphoma. Rituximab is a monoclonal antibody, a laboratory-produced protein. It binds to a protein called CD20 that is present on the surface of both normal and malignant B lymphocytes and induces cell killing through processes called “complement-dependent cytotoxity” (CDC) and “antibody-dependent cellular cytotoxity” (ADCC).
Why Was This Study Done?
Although rituximab lengthens the lives of patients with some types of B cell lymphoma, it is not a cure—the lymphoma usually recurs. Researchers are trying to increase the effectiveness of rituximab by combining it with other anticancer agents. One group of drugs that might be combined with rituximab is the “statins,” drugs that reduce the risk of heart disease by lowering the level of cholesterol (a type of fat) in the blood. In laboratory experiments, statins kill some cancer cells, in part by altering the fat composition of their outer (plasma) membrane. In addition, some population-based studies suggest that statin treatment might slightly decrease the risk of developing some kinds of cancer, including lymphoma. Statins are already undergoing clinical evaluation in combination with chemotherapy for the treatment of lymphoma, but in this study, the researchers investigate the influence of statins on rituximab-induced killing of B cell lymphomas.
What Did the Researchers Do and Find?
When the researchers tested the ability of rituximab and statin combinations to kill B cell lymphoma cells growing in dishes, they found that statins decreased rituximab-dependent CDC and ADCC of these cells. Statin treatment, they report, did not alter the total amount of CD20 made by the lymphoma cells or the amount of CD20 in their plasma membranes, but it did reduce the binding of another anti-CDC20 monoclonal antibody to the cells. Because both this antibody and rituximab bind to a specific three-dimensional structure in CD20 (a “conformational epitope”), the researchers hypothesized that statins might alter rituximab-induced killing by affecting the shape of the CD20 molecule on the lymphoma cell surface. To test this idea, they used two techniques—atomic force microscopy and limited proteolysis. The data obtained using both approaches confirmed that statins induce shape changes in CD20. Finally, the researchers took B cells from five patients who had taken statins for a short time and showed that this treatment had reduced the amount of anti-CD20 monoclonal antibody able to bind to these cells.
What Do These Findings Mean?
These findings indicate that statins change the shape of the CD20 molecules on the surface of normal and malignant B lymphocytes, probably by changing the amount of cholesterol in the cell membrane. This effect of statins has several clinical implications, which means that cancer specialists should check whether patients with known or suspected B cell lymphoma are taking statins to treat high cholesterol. First, the impaired binding of monoclonal antibodies to conformational epitopes of CD20 in patients being treated with statins might delay the diagnosis of B cell lymphomas (CD20 binding to lymphocytes is used during the diagnosis of lymphomas). Second, some patients with B cell lymphoma may receive an incorrect diagnosis and may not be offered rituximab. Finally, because statins impair the anti-lymphoma activity of rituximab, a possibility that needs to be investigated in clinical studies, cancer specialists should check that patients with B cell lymphoma are not taking statins before prescribing rituximab.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050064.
The MedlinePlus has an encyclopedia page on lymphoma and a list of links to other sources of information on lymphoma (in English and Spanish)
The US National Cancer Institute provides information about lymphoma and about statins and cancer prevention (in English and Spanish)
The UK charity Cancerbackup provides information for patients and caregivers on different types of B-cell lymphoma and on rituximab
The US Leukemia and Lymphoma Society also provides information for patients and caregivers about lymphoma
doi:10.1371/journal.pmed.0050064
PMCID: PMC2270297  PMID: 18366248
2.  Rituximab for the treatment of rheumatoid arthritis: an update 
Rituximab is a chimeric monoclonal antibody that targets the CD20 molecule expressed on the surface of B cells. It was first used in the treatment of non-Hodgkin’s lymphoma and later approved for the treatment of rheumatoid arthritis (RA) that does not respond adequately to disease-modifying antirheumatic drugs, including the anti-tumor-necrosis-factor (TNF) biologics. Sustained efficacy in RA can be achieved by repeated courses of rituximab. However, the optimal dose and retreatment schedule of rituximab in RA remains to be established. Seropositivity, complete B cell depletion shortly after treatment, and previous failure to no more than one anti-TNF agent are three factors associated with greater clinical benefits to rituximab. Infusion reaction to the first dose of rituximab occurs in approximately 25% of RA patients, and the incidence reduces with subsequent exposure. Immunogenicity to the chimeric compound occurs in 11% of RA patients, but this does not correlate with its efficacy in B cell depletion. Extended observation of randomized controlled trials in RA does not reveal a significant increase in the incidence of serious infections related to rituximab compared to placebo groups, and the infection rate remains static over time. Repeated treatment with rituximab is associated with hypogammaglobulinemia, which may increase the risk of serious, but rarely opportunistic, infections. Reactivation of occult hepatitis B infection has been reported in RA patients receiving rituximab, but no increase in the incidence of tuberculosis was observed. Screening for baseline serum immunoglobulin G level and hepatitis B status (including occult infection) is important, especially in Asian countries where hepatitis B infection is prevalent. The rare but fatal progressive multifocal leukoencephalopathy linked to the use of rituximab has to be noted. Postmarketing surveillance and registry data, particularly in Asia, are necessary to establish the long-term efficacy and safety of rituximab in the treatment of RA.
doi:10.2147/DDDT.S41645
PMCID: PMC3883598  PMID: 24403823
biologics; B-cell depletion; rheumatoid arthritis; prognosis
3.  Role of rituximab in first-line treatment of chronic lymphocytic leukemia 
Chronic lymphocytic leukemia (CLL) is a biologically heterogeneous illness that primarily afflicts the elderly. For many decades, the initial therapy for most patients requiring treatment was limited to single-agent alkylator therapy. Within the last two decades, we have seen remarkable progress in understanding the biology of CLL and the development of more effective treatment strategies that have employed monoclonal antibodies, such as rituximab (anti-CD20). Furthermore, recognition of the synergy between fludarabine, cyclophosphamide, and rituximab (FCR) prompted investigators to explore the clinical activity of FCR in Phase II and III trials in patients with relapsed/refractory or previously untreated CLL. On the basis of these findings, the US Food and Drug Administration (FDA) recently approved rituximab in combination with fludarabine and cyclophosphamide for the treatment of patients with relapsed/refractory or previously untreated CD20-postive CLL. Recent data from a randomized Phase III trial has confirmed improved overall survival with FCR in patients with previously untreated CLL. However, FCR is not for everyone. More tolerable regimens using rituximab for the elderly and less fit patients are being pursued in clinical trials. Recent Phase II trials have explored potentially less myelosuppressive approaches by using lower doses of fludarabine and cyclophosphamide, replacing fludarabine with pentostatin, and combining rituximab with chlorambucil. Furthermore new biomarkers predictive of early disease progression have prompted investigators to explore the benefits of early treatment with rituximab combined with other agents. In addition to the proven utility of rituximab as a frontline agent for CLL, rituximab has a favorable toxicity profile both as a single agent and in combination with chemotherapy. The majority of adverse events are Grade 1 and 2 infusion-related reactions (fevers, chills, and rigors) and occur with the first dose of rituximab. The improved tolerability observed with second and subsequent infusions allows for shorter infusion times. Rituximab’s proven activity and favorable toxicity profile has made it an ideal agent for expanding treatment options for patients with CLL, the majority of whom are elderly.
doi:10.2147/TCRM.S5855
PMCID: PMC3039008  PMID: 21339937
rituximab; tolerability; chronic lymphocytic leukemia; fludarabine; pentostatin; chlorambucil; elderly
4.  Analysis of innate and acquired resistance to anti-CD20 antibodies in malignant and nonmalignant B cells 
PeerJ  2013;1:e31.
The anti-CD20 monoclonal antibody, rituximab, provides a significant therapeutic benefit for patients with B-cell disorders. However, response to therapy varies and relapses are common, so an understanding of both inherited and acquired rituximab resistance is needed. In order to identify mechanisms of inherited resistance, sensitive versus resistant individuals were selected from a survey of 92 immortalized lymphoblastoid B-cell lines from normal individuals. Levels of CD20 protein and surface expression were lower in the resistant group. In contrast, CD20 mRNA levels were not correlated with susceptibility, suggesting regulation at a post-transcriptional level. To examine acquired resistance, resistant sublines were selected from both lymphoblastoid as well as lymphoma cell lines. Confirming previous findings, there was significant down-regulation of CD20 protein expression in all the resistant sublines. CD20 mRNA splice variants are reported to be associated with development of resistance. Three splice variants were observed in our cell lines, each lacking the binding epitope for rituximab, but none were associated with rituximab resistance. The second generation anti-CD20 mAb, ofatumumab, was more active compared with rituximab in vitro in the survey of all B-cell lines, mirroring results that have been reported previously with malignant B-cells. These studies show that normal B-lymphoblastoid cell lines can be used to model both innate and acquired mechanisms of resistance. They validate the important role of CD20 expression and enable future genetic studies to identify additional mediators of anti-CD20 mAb resistance.
doi:10.7717/peerj.31
PMCID: PMC3628892  PMID: 23638367
Rituximab; Ofatumumab; CD20 expression; mRNA splice variants; Complement-dependent cytotoxicity; Drug resistance; Lymphoblastoid cell line
5.  Expanded use of rituximab in the management of non-Hodgkin lymphoma 
OncoTargets and therapy  2009;2:189-197.
Rituximab is a chimeric monoclonal antibody targeting the B cell antigen CD20. Since its first approval for clinical use in 1997, rituximab has become an inherent part of the treatment of CD20-positive lymphoma. In previously untreated non-Hodgkin lymphoma (NHL) conventional chemotherapy supplemented by rituximab (R-chemotherapy) was shown to be more effective than chemotherapy alone. This holds true for indolent as well as aggressive NHL. Rituximab was also shown to be beneficial when used as maintenance therapy or part of salvage and re-induction regimens in relapsed NHL. Administration of rituximab is generally well tolerated. The most common side effects including fever, urticaria and bronchospasm are mostly mild, treatable and restricted to the infusion period. Thus, rituximab can usually be administered in an outpatient setting. Due to its favorable effect/side effect ratio, clinical trials are currently evaluating a possible role for rituximab in several other diseases such as Hodgkin lymphoma (HL) and non-malignant autoimmune disorders. This review aims at giving an overview of the pharmacological properties of rituximab and summarizing key publications and recent literature on its use in NHL.
PMCID: PMC2886316  PMID: 20616906
rituximab; non-Hodgkin lymphoma; immunochemotherapy
6.  The potential utility of B cell-directed biologic therapy in autoimmune diseases 
Rheumatology International  2007;28(3):205-215.
Increasing awareness of the importance of aberrant B cell regulation in autoimmunity has driven the clinical development of novel B cell-directed biologic therapies with the potential to treat a range of autoimmune disorders. The first of these drugs—rituximab, a chimeric monoclonal antibody against the B cell-specific surface marker CD20—was recently approved for treating rheumatoid arthritis in patients with an inadequate response to other biologic therapies. The aim of this review is to discuss the potential use of rituximab in the management of other autoimmune disorders. Results from early phase clinical trials indicate that rituximab may provide clinical benefit in systemic lupus erythematosus, Sjögren’s syndrome, vasculitis, and thrombocytopenic purpura. Numerous case reports and several small pilot studies have also been published reporting the use of rituximab in conditions such as myositis, antiphospholipid syndrome, Still’s disease, and multiple sclerosis. In general, the results from these preliminary studies encourage further testing of rituximab therapy in formalized clinical trials. Based on results published to date, it is concluded that rituximab, together with other B cell-directed therapies currently under clinical development, is likely to provide an important new treatment option for a number of these difficult-to-treat autoimmune disorders.
doi:10.1007/s00296-007-0471-x
PMCID: PMC2134974  PMID: 17957371
Biologic therapies; B-lymphocytes; CD20; Lupus; Rituximab; Sjögren’s syndrome; Thrombocytopenic purpura; Vasculitis
7.  Trial Watch 
Oncoimmunology  2014;3:e27048.
In 1997, for the first time in history, a monoclonal antibody (mAb), i.e., the chimeric anti-CD20 molecule rituximab, was approved by the US Food and Drug Administration for use in cancer patients. Since then, the panel of mAbs that are approved by international regulatory agencies for the treatment of hematopoietic and solid malignancies has not stopped to expand, nowadays encompassing a stunning amount of 15 distinct molecules. This therapeutic armamentarium includes mAbs that target tumor-associated antigens, as well as molecules that interfere with tumor-stroma interactions or exert direct immunostimulatory effects. These three classes of mAbs exert antineoplastic activity via distinct mechanisms, which may or may not involve immune effectors other than the mAbs themselves. In previous issues of OncoImmunology, we provided a brief scientific background to the use of mAbs, all types confounded, in cancer therapy, and discussed the results of recent clinical trials investigating the safety and efficacy of this approach. Here, we focus on mAbs that primarily target malignant cells or their interactions with stromal components, as opposed to mAbs that mediate antineoplastic effects by activating the immune system. In particular, we discuss relevant clinical findings that have been published during the last 13 months as well as clinical trials that have been launched in the same period to investigate the therapeutic profile of hitherto investigational tumor-targeting mAbs.
doi:10.4161/onci.27048
PMCID: PMC3937194  PMID: 24605265
bevacizumab; brentuximab vedotin; cetuximab; nimotuzumab; trastuzumab; tumor-associated antigen
8.  A general process for the development of peptide-based immunoassays for monoclonal antibodies 
Purpose
Monoclonal antibodies (mAb) are an important and growing class of cancer therapeutics, but pharmacokinetic analyses have in many cases been constrained by the lack of standard and robust pharmacologic assays. The goal of this project was to develop a general method for the production of immunoassays that can measure the levels of therapeutic monoclonal antibodies in biologic samples at relevant concentrations.
Methods
Alemtuzumab and rituximab are monoclonal approved for the treatment of B-cell malignancies and were used as a model system. Phage-displayed peptide libraries were screened for peptide sequences recognized by alemtuzumab (anti-CD52) or rituximab (anti-CD20). Synthetic biotinylated peptides were used in enzyme-linked immunosorbent assays (ELISA). Peptides directly synthesized on polymer resin beads were used in an immunofluorescent-based assay.
Results
Peptide mimetope sequences were recovered for both mAb and confirmed by competitive staining and kinetic measurements. A peptide-based ELISA method was developed for each. The assay for rituximab had a limit of detection of 4 μg/ml, and the assay for alemtuzumab had a limit of detection of 1 μg/ml. Antibody-specific staining of peptide conjugated beads could be seen in a dose-dependent manner.
Conclusion
Phage-displayed peptide libraries can be a source of highly specific mimetopes for therapeutic mAb. The biotinylated forms of those peptides are compatible with conventional ELISA methods with sensitivities comparable to other assay methods and sufficient for pharmacological studies of those mAb given at high dose. The process outlined here can be applied to any mAb to enable improved pharmacokinetic analysis during the development and clinical use of this class of therapies.
Electronic supplementary material
The online version of this article (doi:10.1007/s00280-009-1240-1) contains supplementary material, which is available to authorized users.
doi:10.1007/s00280-009-1240-1
PMCID: PMC2921063  PMID: 20087593
Immunoassay; Monoclonal antibody; Peptide; ELISA; Phage display
9.  A novel anti-CD19 monoclonal antibody (GBR 401) with high killing activity against B cell malignancies 
Background
CD19 is a B cell lineage specific surface receptor whose broad expression, from pro-B cells to early plasma cells, makes it an attractive target for the immunotherapy of B cell malignancies. In this study we present the generation of a novel humanized anti-CD19 monoclonal antibody (mAb), GBR 401, and investigate its therapeutic potential on human B cell malignancies.
Methods
GBR 401 was partially defucosylated in order to enhance its cytotoxic function. We analyzed the in vitro depleting effects of GBR 401 against B cell lines and primary malignant B cells from patients in the presence or in absence of purified NK cells isolated from healthy donors. In vivo, the antibody dependent cellular cytotoxicity (ADCC) efficacy of GBR 401 was assessed in a B cell depletion model consisting of SCID mice injected with healthy human donor PBMC, and a malignant B cell depletion model where SCID mice are xenografted with both primary human B-CLL tumors and heterologous human NK cells. Furthermore, the anti-tumor activity of GBR 401 was also evaluated in a xenochimeric mouse model of human Burkitt lymphoma using mice xenografted intravenously with Raji cells. Pharmacological inhibition tests were used to characterize the mechanism of the cell death induced by GBR 401.
Results
GBR 401 exerts a potent in vitro and in vivo cytotoxic activity against primary samples from patients representing various B-cell malignancies. GBR 401 elicits a markedly higher level of ADCC on primary malignant B cells when compared to fucosylated similar mAb and to Rituximab, the current anti-CD20 mAb standard immunotherapeutic treatment for B cell malignancies, showing killing at 500 times lower concentrations. Of interest, GBR 401 also exhibits a potent direct killing effect in different malignant B cell lines that involves homotypic aggregation mediated by actin relocalization.
Conclusion
These results contribute to consolidate clinical interest in developing GBR 401 for treatment of hematopoietic B cell malignancies, particularly for patients refractory to anti-CD20 mAb therapies.
doi:10.1186/1756-8722-7-33
PMCID: PMC4021825  PMID: 24731302
B cell malignancies; GBR 401; Anti-CD19 monoclonal antibody; ADCC; Therapeutic antibody
10.  Common variable immunodeficiency unmasked by treatment of immune thrombocytopenic purpura with Rituximab 
BMC Hematology  2013;13:4.
Background
Hypogammaglobulinemia may be part of several different immunological or malignant conditions, and its origin is not always obvious. Furthermore, although autoimmune cytopenias are known to be associated with common variable immunodeficiency (CVID) and even may precede signs of immunodeficiency, this is not always recognized. Despite novel insight into the molecular immunology of common variable immunodeficiency, several areas of uncertainty remain. In addition, the full spectrum of immunological effects of the B cell depleting anti-CD20 antibody Rituximab has not been fully explored. To our knowledge this is the first report of development of CVID in a patient with normal immunoglobulin prior to Rituximab treatment.
Case presentation
Here we describe the highly unusual clinical presentation of a 34-year old Caucasian male with treatment refractory immune thrombocytopenic purpura and persistent lymphadenopathy, who was splenectomized and received multiple courses of high-dose corticosteroid before treatment with Rituximab resulted in a sustained response. However, in the setting of severe pneumococcal meningitis, hypogammaglobulinemia was diagnosed. An extensive immunological investigation was performed in order to characterize his immune status, and to distinguish between a primary immunodeficiency and a side effect of Rituximab treatment. We provide an extensive presentation and discussion of the literature on the basic immunology of CVID, the mechanism of action of Rituximab, and the immunopathogenesis of hypogammaglobulinemia observed in this patient.
Conclusions
We suggest that CVID should be ruled out in any patient with immune cytopenias in order to avoid diagnostic delay. Likewise, we stress the importance of monitoring immunoglobulin levels before, during, and after Rituximab therapy to identify patients with hypogammaglobulinemia to ensure initiation of immunoglobulin replacement therapy in order to avoid life-threatening invasive bacterial infections. Recent reports indicate that Rituximab is not contra-indicated for the treatment of CVID-associated thrombocytopenia, however concomitant immunoglobulin substitution therapy is of fundamental importance to minimize the risk of infections. Therefore, lessons can be learned from this case report by clinicians caring for patients with immunodeficiencies, haematological diseases or other autoimmune disorders, particularly, when Rituximab treatment may be considered.
doi:10.1186/2052-1839-13-4
PMCID: PMC3776283  PMID: 24499503
Hypogammaglobulinemia; Common variable immunodeficiency; Immune thrombocytopenic purpura; Rituximab
11.  The spectrum of use of rituximab in chronic lymphocytic leukemia 
OncoTargets and therapy  2010;3:227-246.
The monoclonal chimeric anti-CD20 antibody, rituximab, has considerably improved therapeutic outcome in B-cell chronic lymphocytic leukemia. Rituximab has limited clinical activity when used as a single agent. The combination of the monoclonal antibody with fludarabine-based regimens clearly demonstrated, in Phase II and randomized trials, an increase in clinical efficacy in previously untreated and pretreated patients. Furthermore the addition of rituximab enabled the eradication of minimal residual disease, which is correlated with the prognosis in a high proportion of patients. Although the combination of rituximab with fludarabine-based regimens increased myelosuppression and immunosuppression, incidence of infections did not increase. The benefit of adding rituximab to other purine analogs or other chemotherapeutic combination regimens has also been explored. Moreover there could be a role for achieving better quality of responses with the combination of different monoclonal antibodies, considering that they target different antigens and exert different mechanism of action. Although the role of rituximab as maintenance therapy in low grade non-Hodgkin’s lymphomas has been determined, the benefit and optimal schedule in chronic lymphocytic leukemia are still under investigation. This review brings together knowledge of the pharmacokinetics, mechanism of action and clinical use of rituximab in chronic lymphocytic leukemia.
doi:10.2147/OTT.S8151
PMCID: PMC3024887  PMID: 21289858
rituximab; B-cell chronic lymphocytic leukemia; first-line treatment; refractory/relapsed
12.  Rituximab Resistance 
Rituximab has become a ubiquitous component of treatment regimens for follicular non-Hodgkin lymphoma. Despite widespread clinical use, the mechanisms by which tumor cells resist rituximab-mediated destruction remain unclear. Rituximab relies in part on immune effector mechanisms for its antitumor effect, and thus resistance may be mediated not only by intrinsic tumor-cell alterations but also by the host immunological environment. In this article, we explore the mechanisms of action of rituximab, the incidence of rituximab resistance, and potential mechanisms of resistance. Finally, we discuss novel approaches to modulate the antibody, the tumor cell, and the host immunologic environment to overcome rituximab resistance. Further research into the mechanisms of rituximab resistance will be essential to improving the efficacy of anti-CD20 therapy in NHL, and may also pay dividends in the optimization of monoclonal antibody therapy across a wide range of diseases.
doi:10.1016/j.beha.2011.02.009
PMCID: PMC3113665  PMID: 21658619
Lymphoma; Follicular; Antibodies; Monoclonal; Drug Resistance; Neoplasm; Pharmacokinetics
13.  Safety and clinical outcomes of rituximab therapy in patients with different autoimmune diseases: experience from a national registry (GRAID) 
Introduction
Evidence from a number of open-label, uncontrolled studies has suggested that rituximab may benefit patients with autoimmune diseases who are refractory to standard-of-care. The objective of this study was to evaluate the safety and clinical outcomes of rituximab in several standard-of-care-refractory autoimmune diseases (within rheumatology, nephrology, dermatology and neurology) other than rheumatoid arthritis or non-Hodgkin's lymphoma in a real-life clinical setting.
Methods
Patients who received rituximab having shown an inadequate response to standard-of-care had their safety and clinical outcomes data retrospectively analysed as part of the German Registry of Autoimmune Diseases. The main outcome measures were safety and clinical response, as judged at the discretion of the investigators.
Results
A total of 370 patients (299 patient-years) with various autoimmune diseases (23.0% with systemic lupus erythematosus, 15.7% antineutrophil cytoplasmic antibody-associated granulomatous vasculitides, 15.1% multiple sclerosis and 10.0% pemphigus) from 42 centres received a mean dose of 2,440 mg of rituximab over a median (range) of 194 (180 to 1,407) days. The overall rate of serious infections was 5.3 per 100 patient-years during rituximab therapy. Opportunistic infections were infrequent across the whole study population, and mostly occurred in patients with systemic lupus erythematosus. There were 11 deaths (3.0% of patients) after rituximab treatment (mean 11.6 months after first infusion, range 0.8 to 31.3 months), with most of the deaths caused by infections. Overall (n = 293), 13.3% of patients showed no response, 45.1% showed a partial response and 41.6% showed a complete response. Responses were also reflected by reduced use of glucocorticoids and various immunosuppressives during rituximab therapy and follow-up compared with before rituximab. Rituximab generally had a positive effect on patient well-being (physician's visual analogue scale; mean improvement from baseline of 12.1 mm).
Conclusions
Data from this registry indicate that rituximab is a commonly employed, well-tolerated therapy with potential beneficial effects in standard of care-refractory autoimmune diseases, and support the results from other open-label, uncontrolled studies.
doi:10.1186/ar3337
PMCID: PMC3218885  PMID: 21569519
14.  Subcutaneous administration of rituximab (MabThera) and trastuzumab (Herceptin) using hyaluronidase 
British Journal of Cancer  2013;109(6):1556-1561.
Background:
Rituximab and trastuzumab were the first therapeutic monoclonal antibodies (mAbs) approved in oncology. Both antibodies are delivered by the intravenous (IV) route, but recently subcutaneous (SC) formulations have been developed. Subcutaneous administration of mAbs can offer substantial patient and resource benefits compared with IV, but SC administration of some mAbs can be limited by drug volume. Recombinant human hyaluronidase (rHuPH20) temporarily degrades hyaluronan, allowing SC delivery of drug volumes that might not otherwise be feasible.
Methods:
Clinical trials assessing coformulation of rituximab or trastuzumab with rHuPH20 for SC administration were reviewed.
Results:
Phase I trials of rituximab SC maintenance therapy in patients with follicular lymphoma and trastuzumab SC in healthy volunteers and patients with early breast cancer have demonstrated substantially shorter administration times and comparable tolerability and pharmacokinetics compared with IV formulations. Rituximab SC 1400-mg and trastuzumab SC 600-mg doses were identified for further study. Phase III clinical data for rituximab SC 1400 mg have shown comparable efficacy to rituximab IV, and initial clinical data suggest comparable efficacy of trastuzumab SC 600 mg and the IV formulation.
Conclusion:
Coformulation with rHuPH20 may enable effective, well-tolerated, cost-effective, and convenient SC administration of rituximab and trastuzumab. Additional studies are ongoing.
doi:10.1038/bjc.2013.371
PMCID: PMC3776971  PMID: 24002601
breast cancer; hyaluronidase; lymphoma; subcutaneous administration; rituximab; trastuzumab
15.  Targeted treatment for chronic lymphocytic leukemia: clinical potential of obinutuzumab 
Introduction of targeted agents revolutionized the treatment of chronic lymphocytic leukemia (CLL) in the past decade. Addition of chimeric monoclonal anti-CD20 antibody rituximab to chemotherapy significantly improved efficacy including overall survival (OS) in untreated fit patients; humanized anti-CD52 antibody alemtuzumab and fully human anti-CD20 antibody ofatumumab lead to improvement in refractory disease. Novel small molecule inhibitors such as ibrutinib and idelalisib demonstrated excellent activity and were very recently licensed in relapsed/refractory CLL. Obinutuzumab (GA101) is the newest monoclonal antibody approved for the treatment of CLL. This novel, glycoengineered, type II humanized anti-CD20 antibody is characterized by enhanced antibody-dependent cellular cytotoxicity and direct induction of cell death compared to type I antibodies. Combination of obinutuzumab and chlorambucil yielded significantly better OS in comparison to chlorambucil monotherapy in untreated comorbid patients. These results led to approval of obinuzutumab for the treatment of CLL. Numerous clinical trials combining obinutuzumab with other cytotoxic drugs and novel small molecules are currently under way. This review focuses on the role of obinutuzumab in the treatment of CLL.
doi:10.2147/PGPM.S55501
PMCID: PMC4325625
chronic lymphocytic leukemia; anti-CD20 antibodies; chlorambucil; rituximab; ofatumumab; obinutuzumab; overall survival
16.  Rituximab Therapy for Myopathy Associated with Anti-Signal Recognition Particle Antibodies: A Case Series 
Arthritis care & research  2010;62(9):1328-1334.
Objective
The myopathy associated with anti-signal recognition particle (SRP) is a severe necrotizing immune-mediated disease characterized by rapidly progressive proximal muscle weakness, markedly elevated serum creatine kinase (CK) levels, and poor responsiveness to traditional immunosuppressive therapies. Reports on the efficacy of B cell depletion therapy for anti-SRP associated myopathy are mixed. We describe eight patients with anti-SRP associated myopathy and their response to treatment with the anti-CD20 monoclonal antibody rituximab.
Methods
We identified eight patients with myopathy who tested positive for anti-SRP antibodies by immunoprecipitation and were treated with rituximab as part of clinical care. We reviewed their medical records to assess clinical, serologic, and histologic characteristics and response to therapy. In five patients, serum was collected before and after rituximab therapy. Autoantibodies were detected by immunoprecipitation and quantitated by densitometry, and the percent decreases in anti-SRP autoantibody levels were calculated.
Results
Six of eight patients who had been refractory to standard immunosuppressive therapy demonstrated improved manual muscle strength and/or decline in CK levels as early as two months after rituximab treatment. Three patients sustained the response for twelve to eighteen months after initial dosing. All patients were continued on adjunctive corticosteroids, but dosages were substantially reduced after rituximab. Quantitative levels of serum anti-SRP antibodies also decreased after rituximab treatment.
Conclusions
B cell depletion therapy with rituximab is effective for patients with myopathy associated with anti-SRP. The substantial decrease in anti-SRP antibody levels after rituximab treatment also suggests that B cells and anti-SRP antibodies may play a role in the pathogenesis of this myopathy.
doi:10.1002/acr.20219
PMCID: PMC3107255  PMID: 20506493
17.  Safety of rituximab in the treatment of B cell malignancies: implications for rheumatoid arthritis 
Arthritis Research & Therapy  2003;5(Suppl 4):S12-S16.
The chimeric anti-CD20 monoclonal antibody rituximab has been used extensively in the treatment of B cell malignancies, and more recently it has emerged as a potential treatment for rheumatoid arthritis (RA), via selective B lymphocyte depletion. Experience in oncology shows that rituximab is well tolerated in a variety of settings, with mild-to-moderate infusion related reactions following the first infusion being the most common adverse event. Current data suggest that the safety profile of rituximab in patients with RA is similar to that in oncology, but that the adverse events are less frequent and less severe in patients with RA.
doi:10.1186/ar1008
PMCID: PMC2833440  PMID: 15180892
B cell depletion; oncology; rheumatoid arthritis; rituximab; safety
18.  Rituximab in Relapsing and Progressive Forms of Multiple Sclerosis: A Systematic Review 
PLoS ONE  2013;8(7):e66308.
Background
Rituximab is an anti-CD20 monoclonal antibody approved for non Hodgkin lymphoma and rheumatoid arthritis. It is being considered for the treatment of MS.
Objectives
To evaluate the efficacy and safety of rituximab for MS treatment.
Data collection
Studies were selected if they were clinical trials, irrespective of the dosage or combination therapies.
Main results
Four studies with a total of 599 patients were included. One assessed the efficacy of rituximab for primary progressive (PP) MS while the other three focused on relapsing-remitting (RR) MS. In the PPMS study, rituximab delayed time to confirmed disease progression (CDP) in pre-planned sub-group analyses. The increase in T2 lesion volume was lower in the rituximab group at week 96 compared with placebo. For the RRMS studies, an open-label phase I study found that rituximab reduced the annualized relapse rate to 0.25 from pre-therapy baseline to week 24, while in the randomized placebo-controlled phase II trial, annualized relapse rates were 0.37 in the rituximab group and 0.84 in the placebo group (p = 0.04) at week 24. Rituximab dramatically reduced the number of gadolinium-enhancing lesions on brain MRI scans for both RRMS studies. Off-label rituximab as an add-on therapy in patients with breakthrough disease on first-line agents was associated with an 88% reduction when comparing the mean number of gadolinium-enhancing lesions prior to and after the treatment. Although frequent adverse events classified as mild or moderate occurred in up to 77% of the patients, there were no grade 4 infusion-related adverse events.
Author’s conclusion
Despite the frequent mild/moderate adverse events related to the drug, rituximab appears overall safe for up to 2 years of therapy and has a substantial impact on the inflammatory disease activity (clinical and/or radiological) of RRMS. The effect of rituximab on disease progression in PPMS appears to be marginal.
doi:10.1371/journal.pone.0066308
PMCID: PMC3699597  PMID: 23843952
19.  Monoclonal antibody therapy in multiple sclerosis 
mAbs  2010;2(6):670-681.
Therapeutic approaches to multiple sclerosis (MS) are based on altering the functions of the immune system, either by using broad immunosuppressive drugs used for transplantation rejection and rheumatology, or by modulating them more discreetly with beta interferon and synthetic amino-acid copolymers. These strategies are only partially successful, have important safety and tolerability limitations, and have shown to be mostly effective in earlier stages of the disease, in which acute relapses dominate the clinical picture. For progressive phenotypes of MS there are currently no effective therapeutic options. As very specific and potent immunosuppressive agents, monoclonal antibodies (mAbs) may offer considerable advantages over other therapies for MS. During the last decade, anti-a4 integrin natalizumab became the first approved mAb for treatment of relapsing MS, after convincingly demonstrating clinically significant effects on two large Phase 3 trials. Moreover, the concept of disease remission was introduced for the first time to describe patients who show no signs of clinical or imaging markers of disease activity during therapy with natalizumab. Of the mAbs under development for MS, alemtuzumab and rituximab have also shown promising evidence of effectiveness and potentially expanded the therapeutic horizon to reversal of disease progression in early relapsing patients and progressive patients who previously had not been studied. However, the appearance of progressive multifocal leukoencephalopathy (PML) in natalizumab-treated MS patients, as well as in patients with lymphoma, lupus and rheumatoid arthritis, treated with rituximab and autoimmune-type complications in alemtuzumab-treated MS patients underlines the fact that extended efficacy comes with significant clinical risks. The challenge is then how best to utilize therapies that have evidently superior efficacy in a chronic disease of young adults to obtain the best benefit-risk ratio and how to monitor and prevent emergent safety concerns.
doi:10.4161/mabs.2.6.13270
PMCID: PMC3011221  PMID: 21124072
monoclonal; antibody; multiple sclerosis; therapy; natalizumab; rituximab; alemtuzumab
20.  Application of a novel inhibitor of human CD59 for the enhancement of complement-dependent cytolysis on cancer cells 
Many monoclonal antibodies (mAbs) have been extensively used in the clinic, such as rituximab to treat lymphoma. However, resistance and non-responsiveness to mAb treatment have been challenging for this line of therapy. Complement is one of the main mediators of antibody-based cancer therapy via the complement-dependent cytolysis (CDC) effect. CD59 plays a critical role in resistance to mAbs through the CDC effect. In this paper, we attempted to investigate whether the novel CD59 inhibitor, recombinant ILYd4, was effective in enhancing the rituximab-mediated CDC effect on rituximab-sensitive RL-7 lymphoma cells and rituximab-induced resistant RR51.2 cells. Meanwhile, the CDC effects, which were mediated by rituximab and anti-CD24 mAb, on the refractory multiple myeloma (MM) cell line ARH-77 and the solid tumor osteosarcoma cell line Saos-2, were respectively investigated. We found that rILYd4 rendered the refractory cells sensitive to the mAb-mediated CDC effect and that rILYd4 exhibited a synergistic effect with the mAb that resulted in tumor cells lysis. This effect on tumor cell lysis was apparent on both hematological tumors and solid tumors. Therefore, rILYd4 may serve as an adjuvant for mAb mediated-tumor immunotherapy.
doi:10.1038/cmi.2010.35
PMCID: PMC4003131  PMID: 21258360
CD59; complement; lymphoma; multiple myeloma; rituximab
21.  Anti-CD47 antibody synergizes with rituximab to promote phagocytosis and eradicate non-Hodgkin lymphoma 
Cell  2010;142(5):699-713.
Summary
Monoclonal antibodies are standard therapeutics for several cancers including the anti-CD20 antibody rituximab for B cell non-Hodgkin lymphoma (NHL). Rituximab and other antibodies are not curative, and must be combined with cytotoxic chemotherapy for clinical benefit. Here we report the eradication of human NHL solely with a monoclonal antibody therapy combining rituximab with a blocking anti-CD47 antibody. We identified increased expression of CD47 on human NHL cells, and determined that higher CD47 expression independently predicted adverse clinical outcomes in multiple NHL subtypes. Blocking anti-CD47 antibodies preferentially enabled phagocytosis of NHL cells and synergized with rituximab. Treatment of human NHL-engrafted mice with anti-CD47 antibody reduced lymphoma burden and improved survival, while combination treatment with rituximab led to elimination of lymphoma and cure. These antibodies synergized through a mechanism combining Fc receptor (FcR)-dependent and FcR-independent stimulation of phagocytosis that might be applicable to many other cancers.
doi:10.1016/j.cell.2010.07.044
PMCID: PMC2943345  PMID: 20813259
22.  Identification of a novel BET bromodomain inhibitor-sensitive, gene regulatory circuit that controls Rituximab response and tumour growth in aggressive lymphoid cancers 
EMBO Molecular Medicine  2013;5(8):1180-1195.
Immuno-chemotherapy elicit high response rates in B-cell non-Hodgkin lymphoma but heterogeneity in response duration is observed, with some patients achieving cure and others showing refractory disease or relapse. Using a transcriptome-powered targeted proteomics screen, we discovered a gene regulatory circuit involving the nuclear factor CYCLON which characterizes aggressive disease and resistance to the anti-CD20 monoclonal antibody, Rituximab, in high-risk B-cell lymphoma. CYCLON knockdown was found to inhibit the aggressivity of MYC-overexpressing tumours in mice and to modulate gene expression programs of biological relevance to lymphoma. Furthermore, CYCLON knockdown increased the sensitivity of human lymphoma B cells to Rituximab in vitro and in vivo. Strikingly, this effect could be mimicked by in vitro treatment of lymphoma B cells with a small molecule inhibitor for BET bromodomain proteins (JQ1). In summary, this work has identified CYCLON as a new MYC cooperating factor that autonomously drives aggressive tumour growth and Rituximab resistance in lymphoma. This resistance mechanism is amenable to next-generation epigenetic therapy by BET bromodomain inhibition, thereby providing a new combination therapy rationale for high-risk lymphoma.
The nuclear factor CYCLON is a new MYC cooperating factor that drives tumor growth and Rituximab resistance in lymphoma. This resistance mechanism can be targeted by next-generation epigenetic therapy by BET bromodomain inhibition downstream of MYC.
doi:10.1002/emmm.201202034
PMCID: PMC3944460  PMID: 23828858
cancer-testis factor; CCDC86; CD40; double-hit B-cell non-Hodgkin's lymphoma; R-CHOP
23.  Rituximab for the treatment of patients with autoimmune hepatitis who are refractory or intolerant to standard therapy 
BACKGROUND:
Although most patients with autoimmune hepatitis (AIH) respond to treatment with prednisone and/or azathioprine, some patients are intolerant or refractory to standard therapy. Rituximab is an anti-CD20 monoclonal antibody that depletes B cells and has demonstrated efficacy in other autoimmune conditions.
AIMS:
To evaluate the safety and efficacy of rituximab in patients with refractory AIH in an open-label, single-centre pilot study.
METHODS:
Six patients with definite, biopsy-proven AIH who failed prednisone and azathioprine treatment received two infusions of rituximab 1000 mg two weeks apart and were followed for 72 weeks.
RESULTS:
Rituximab was well tolerated with no serious adverse events. By week 24, mean (± SD) aspartate aminotransferase (AST) levels had significantly improved (90.0±23.3 U/L versus 31.3±4.2 U/L; P=0.03) and mean immunoglobulin G levels had fallen (16.4±2.0 g/L versus 11.5±1.1 g/L; P=0.056). The prednisone dose was weaned in three of four subjects, with one subject flaring after steroid withdrawal. Inflammation grade improved in all four subjects who underwent repeat liver biopsy at week 48. Regulatory T cell levels examined by FoxP3 immunohistochemistry paralleled inflammatory activity and did not increase on follow-up biopsies. There was no significant change in serum chemokine or cytokine levels from baseline to week 24 (n=5), although interferon-gamma-induced protein 10 levels improved in three of five subjects.
CONCLUSIONS:
Rituximab was safe, well tolerated and resulted in biochemical improvement in subjects with refractory AIH. These results support further investigation of rituximab as a treatment for AIH.
PMCID: PMC3735730  PMID: 23712302
Anti-CD20 monoclonal antibody; Azathioprine; B cell; Prednisone; Safety
24.  A study of hepatitis B virus reactivation associated with rituximab therapy in real-world clinical practice: a single-center experience 
Background/Aims
The widespread use of cytotoxic chemotherapy and immunosuppressants has resulted in reactivation of hepatitis B virus (HBV) recently becoming an issue. Although rituximab (an anti-CD20 monoclonal antibody) has revolutionized the treatment of lymphoma, recent reports have suggested that rituximab therapy increases the risk of viral-mediated complications, and particularly HBV reactivation. This study analyzed real clinical practice data for rituximab-related HBV reactivation.
Methods
Between January 2005 and December 2011, 169 patients received treatment with rituximab. Screening status of the HBV infection and frequency of preemptive therapy were determined in these patients, and the clinical features of HBV reactivation were analyzed.
Results
Seventy-nine of the 169 patients with chronic or past HBV infection were selected for evaluation of HBV reactivation. Of the 90 patients who were excluded, 22 (13.0%) were not assessed for HBsAg and anti-HBc, and 14 (8.3%) were not assessed for anti-HBc due to seronegativity for HBsAg. The selected patients were divided into those with chronic HBV infection (n=12) and those with past HBV infection (n=67); six patients (7.6%) experienced HBV reactivation. Eight patients received preemptive therapy, but three patients (37.5%) underwent HBV reactivation. Although HBsAg seropositivity was an independent risk factor for HBV reactivation (P=0.038), of the six patients with HBV reactivation, two (33.3%) had past HBV infection and three (50%) died of liver failure.
Conclusions
The findings of this study demonstrate that adherence to guidelines for screening and preemptive therapy for HBV reactivation was negligent among the included cohort. Attention should be paid to HBV reactivation in patients with past as well as chronic HBV infection during and after rituximab therapy.
doi:10.3350/cmh.2013.19.1.51
PMCID: PMC3622856  PMID: 23593610
Hepatitis B virus; Immunosuppressant; Rituximab
25.  Assessment of rituximab’s immunomodulatory synovial effects (ARISE trial). 1: clinical and synovial biomarker results 
Annals of the rheumatic diseases  2007;67(3):402-408.
Objective
Treatment with the anti-CD20 monoclonal antibody (mAb) rituximab is effective in rheumatoid arthritis (RA). Marked depletion of circulating B cells, seen in almost all patients, does not correlate with efficacy. The potential synovial immunomodulatory effects of rituximab have not been fully defined.
Methods
The ARISE trial is an open label, serial synovial biopsy (pre-treatment and 8 weeks) study of rituximab, given 1 g intravenously on days 0 and 14 without peri-infusional steroids, in active RA patients on concomitant methotrexate (MTX). Synovial tissue was analysed by immunohistochemistry with digital image analysis and gene expression by real-time PCR.
Results
The mean (SD) baseline DAS28 score was 6.5 (0.4), and mean MTX dose 17.3 mg/week. Of 13 patients, 11 had failed prior tumour necrosis factor (TNF) inhibitor therapy. With treatment, all patients experienced near complete depletion of circulating B cell numbers. During the 6 months after treatment, 7/13 patients achieved an American College of Rheumatology (ACR) 20% improvement (ACR20) response, 3/13 an ACR50 response and 2/13 an ACR70 response. There was a significant decrease in synovial B cells after treatment, but only a small trend towards greater reduction among clinical responders. Among the three patients with ACR50 responses there was a significant decrease in synovial immunoglobulin synthesis.
Conclusions
These data suggest that unlike those in circulation, synovial B cells are decreased but are not eliminated by rituximab therapy. Patients with higher levels of response may have more consistent depletion of synovial B cells, and may also have an alteration in synovial B cell function, as indicated by decreases in synovial immunoglobulin synthesis. Thus, effects on synovial B cells may be necessary but not sufficient for inducing clinical efficacy. Other effects, such as on primary lymph organ B cell antigen presentation or cytokine production, may be operative.
doi:10.1136/ard.2007.074229
PMCID: PMC2754142  PMID: 17644541

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