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.
Lymphoma; Follicular; Antibodies; Monoclonal; Drug Resistance; Neoplasm; Pharmacokinetics
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.
B cell depletion; oncology; rheumatoid arthritis; rituximab; safety
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.
rituximab; non-Hodgkin lymphoma; immunochemotherapy
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.
rituximab; B-cell chronic lymphocytic leukemia; first-line treatment; refractory/relapsed
Primary biliary cirrhosis (PBC) is a progressive liver disease for which limited therapies are recommended. Rituximab, an anti-CD20 monoclonal antibody, is expected to be a useful therapeutic regimen for PBC. Previous studies indicated biochemical and immunological improvement in PBC after rituximab treatment. Although rituximab shows therapeutic potential for PBC, few cases have been reported and histological improvement and long-term outcome remain uncertain. Here, we report a case of PBC in a 66-year-old Japanese female patient who presented with a gastric lymphoma and who had been treated with a regimen containing rituximab for incidental malignant lymphoma. She showed biochemical and immunological improvements, and liver histology before and after rituximab treatment confirmed a decrease in liver inflammation. However, she developed liver cirrhosis a short time after rituximab treatment without biochemical or immunological worsening. Rituximab treatment for PBC might be considered and careful observation is required after treatment.
Primary biliary cirrhosis; Rituximab; Transforming growth factor beta
Besides traditional cytostatic drugs the introduction of monoclonal antibodies has substantially influenced current treatment concepts of non-Hodgkin’s lymphoma (NHL). Rituximab, a monoclonal anti-CD20 chimeric antibody, now has been widely evaluated in the various B-cell lymphatic neoplasms. Large phase III studies helped to prove the value of this drug in follicular lymphoma as part of induction or relapse treatment as well as maintenance treatment. The addition of rituximab to the well established CHOP regimens has increased achievable cure rates in diffuse large cell lymphoma, and this combination is now accepted worldwide as standard of care. Although conflicting results are available, rituximab is widely used for the treatment of mantle cell lymphoma. For the less frequent lymphoma entities phase 2 studies show a considerable efficiency for most of these B-NHL variants. Current research focuses on combined chemoimmunotherapy approaches, optimization of dosing regimens, and combination with novel agents.
non-Hodgkin’s lymphoma; rituximab; monoclonal-antibody; targeted therapy
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.
Monoclonal antibodies have been the most successful therapeutics ever brought to cancer treatment by immune technologies. The use of monoclonal antibodies in B-cell Non-Hodgkin's lymphomas (NHL) represents the greatest example of these advances, as the introduction of the anti-CD20 antibody rituximab has had a dramatic impact on how we treat this group of diseases today. Despite this success, several questions about how to optimize the use of monoclonal antibodies in NHL remain open. The best administration schedules, as well as the optimal duration of rituximab treatment, have yet to be determined. A deeper knowledge of the mechanisms underlying resistance to rituximab is also necessary in order to improve the activity of this and of similar therapeutics. Finally, new antibodies and biological agents are entering the scene and their advantages over rituximab will have to be assessed. We will discuss these issues and present an overview of the most significant clinical studies with monoclonal antibodies for NHL treatment carried out to date.
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.
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.
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.
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.
Hepatitis B virus; Immunosuppressant; Rituximab
The introduction of the monoclonal antibodies rituximab (anti-CD20) and alemtuzumab (anti-CD52) has revolutionized the treatment of chronic lymphocytic leukemia (CLL). Both antibodies were first studied as single agents in relapsed CLL, but rituximab is increasingly used in combination chemoimmunotherapy regimens in previously untreated patients. Phase II studies demonstrated that the addition of rituximab to fludarabine-based chemotherapy improves complete response (CR) rates and progression-free survival (PFS), but long-term survival benefit has not been shown. Alemtuzumab is less commonly used, due to its greater infusion, hematologic and immune toxicity. Subcutaneous (SC) administration significantly reduces infusion toxicity, but hematologic and infectious complications, most notably cytomegalovirus (CMV) reactivation, still occur with SC dosing. Alemtuzumab’s unique clinical properties include its clinical activity in relapsed CLL patients with del(17p13) and its ability to eradicate minimal residual disease (MRD) in bone marrow. Its use as consolidation therapy to eradicate MRD after nucleoside analog therapy is under active study. Several investigational monoclonal antibodies are in preclinical or clinical studies, most notably lumiliximab (anti-CD23) and ofatumumab (HuMax CD20), and are briefly discussed in this review.
Primary biliary cirrhosis (PBC) is a progressive autoimmune liver disease of unknown etiology that affects almost exclusively women. Ursodeoxycholic acid (UDCA) is currently the only approved drug by Food and Drug Administration for patients with PBC. Although the precise pathogenesis of PBC remains unclear, it has been postulated that many cell populations, including B cells, are involved in the ongoing inflammatory process, which implicates, not surprisingly, a potential therapeutic target of depleting B cell to treat this disorder. Rituximab is a chimeric anti-CD20 monoclonal antibody that has been approved for the treatment of lymphoma and some autoimmune diseases such as rheumatoid arthritis. Whether it is effective in the treatment of PBC has not been evaluated. Recently, Tsuda et al demonstrated that B cell depletion with rituximab significantly reduced the number of anti-mitochondrial antibodies (AMA)-producing B cells, AMA titers, the plasma levels of immunoglobulins (IgA, IgM and IgG) as well as serum alkaline phosphatase, and it was well tolerated by all the treated patients with no serious adverse events. This observation provides a novel treatment option for the patients with PBC who have incomplete response to UDCA.
Primary biliary cirrhosis; Rituximab; B cell depletion; Anti-mitochondrial antibodies
Chronic lymphocytic leukemia (CLL) is an indolent but incurable disease. Despite the improvement of the available therapies, the management of heavily-treated CLL patients represents a challenge for modern practitioners. Ofatumumab is a second-generation, fully human anti-CD20 monoclonal antibody that has shown activity in CLL patients who have failed very effective therapies such as fludarabine, alemtuzumab and rituximab. Potential benefits of ofatumumab include powerful complement-dependent cytotoxicity, less immunogenicity, faster infusions and activity in resistant CLL patients. Recently, the FDA has approved ofatumumab for the treatment of CLL patients who have failed fludarabine and alemtuzumab-based regimens. The aim of this review is to summarize the current knowledge regarding pharmacology, mechanism of action, pre-clinical and clinical development, and the role of ofatumumab for the treatment of CLL patients who have failed previous therapies. Further research is necessary to further define the role of ofatumumab in the treatment of CLL.
ofatumumab; CLL; chronic lymphocytic leukemia; monoclonal antibodies; CD20
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.
Biologic therapies; B-lymphocytes; CD20; Lupus; Rituximab; Sjögren’s syndrome; Thrombocytopenic purpura; Vasculitis
Rituximab is an anti-CD20 monoclonal antibody approved for non Hodgkin lymphoma and rheumatoid arthritis. It is being considered for the treatment of MS.
To evaluate the efficacy and safety of rituximab for MS treatment.
Studies were selected if they were clinical trials, irrespective of the dosage or combination therapies.
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.
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.
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.
rituximab; tolerability; chronic lymphocytic leukemia; fludarabine; pentostatin; chlorambucil; elderly
Therapy for non-Hodgkin’s lymphoma has progressed significantly over the last decades. However, the majority of patients remain incurable, and novel therapies are needed. Because immunotherapy ideally offers target selectivity, an ever increasing number of immunotherapies, both passive and active, are undergoing development. The champion of passive immunotherapy to date is the anti-CD20 monoclonal antibody rituximab that revolutionized the standard of care for lymphoma. The great success of rituximab catalyzed the development of new passive immunotherapy strategies that are currently undergoing clinical evaluation. These include improvement of rituximab efficacy, newer generation anti-CD20 antibodies, drug-conjugated and radio labeled anti-CD20 antibodies, monoclonal antibodies targeting non-CD20 lymphoma antigens, and bispecific antibodies. Active immunotherapy aims at inducing long-lasting antitumor immunity, thereby limiting the likelihood of relapse. Current clinical studies of active immunotherapy for lymphoma consist largely of vaccination and immune checkpoint blockade. A variety of protein- and cell-based vaccines are being tested in ongoing clinical studies. Recently completed phase III clinical trials of an idiotype protein vaccine suggest that the vaccine may have clinical activity in a subset of patients. Efforts to enhance the efficacy of active immunotherapy are ongoing with an emphasis on optimization of antigen delivery and presentation of vaccines and modulation of the immune system toward counteracting immunosuppression, using antibodies against immune regulatory checkpoints. This article discusses results of the various immunotherapy approaches applied to date for B-cell lymphoma and the ongoing trials to improve their effect.
anti-CD20; clinical trials; idiotype; immunotherapy; lymphoma; monoclonal antibodies; vaccines
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.
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.
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.
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.
Immunoassay; Monoclonal antibody; Peptide; ELISA; Phage display
Although the use of monoclonal antibodies as single agents has had a tremendous impact on the care of patients with non-Hodgkin’s lymphoma (NHL), the greatest benefit has been generated by the addition of monoclonal antibodies to conventional cytotoxic chemotherapy. Rituximab is the monoclonal antibody responsible for all clinical improvement noted to date. The addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy (R-CHOP regimen) improves the response rate, progression-free survival (PFS), and overall survival (OS) in diffuse large B-cell lymphoma (DLBCL). Adding rituximab to CHOP chemotherapy improves response rates and PFS in mantle cell lymphoma (MCL). Finally, the addition of rituximab to a variety of chemotherapy regimens improves the response rates, PFS, and OS in follicular lymphoma (FL). Several other (epratuzumab, bevacizumab, alemtuzumab) monoclonal antibody–chemotherapy combinations are currently under study in NHL. This review will summarize the data supporting the addition of rituximab to chemotherapy in NHL and discuss preliminary data regarding the use of other monoclonal antibodies in combination with chemotherapy.
A rapid infusion rituximab over 90 minutes is well tolerated and safe when administered as the second and subsequent infusions in the course of therapy.
Rituximab is a chimeric anti-CD20 monoclonal antibody. We aimed to explore the safety and tolerability of rapid infusion rituximab, (over 90 minutes) in patients with non-Hodgkin's lymphoma at Hacettepe University Department of Medical Oncology.
Patients and Methods:
Adult patients diagnosed with non-Hodgkin's lymphoma who were to receive rituximab were included in the study. The schedule of administration for cycle 1 was unaltered and delivered according to the product monograph. All subsequent cycles were administered over a total infusion time of 90 minutes (20% of the dose in the first 30 minutes, then the remaining 80% over 60 minutes, total dose delivered in 500 mL). All patients were observed for infusion-related reactions during the rituximab infusion, and vital signs were recorded every 15 minutes.
From July 2006 to December 2008, 75 patients with non-Hodgkin's lymphoma were treated with rituximab-based chemotherapy. A total of 372 infusions were administered. The majority of patients were treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone, or rituximab only. The 90-minute rituximab infusion schedule was well tolerated, with no grade 3 or 4 infusion-related adverse events observed.
A rapid infusion rituximab over 90 minutes is well tolerated and safe when administered as the second and subsequent infusions in the course of therapy.
Rituximab (Mabthera, Rituxan) is a chimeric human/murine monoclonal antibody against CD-20 surface antigen expressed on B-cells. Rituximab, by causing B-cell depletion, appears to be effective in several autoimmune disorders; it has been approved for rheumatoid arthritis and is a promising new agent in the treatment of several autoimmune neurological disorders. A controlled study in patients with relapsing remitting multiple sclerosis has shown that rituximab significantly reduces the number of new MRI lesions and improves clinical outcome; it also showed some promise in a subset of patients with primary progressive MS. The drug is also effective in a number of patients with Devic’s disease, myasthenia gravis, autoimmune neuropathies, and inflammatory myopathies. The apparent effectiveness of rituximab has moved B-cells into the center stage of clinical and laboratory investigation of autoimmune neurological disorders. We review the evidence-based effectiveness of rituximab in neurological disorders based on controlled trials and anecdotal reports, including our own experience, and address the immunobiology of B-cells in autoimmune central nervous system (CNS) and peripheral nervous system (PNS) disorders. In addition, we provide practical guidelines on how best to use this drug in clinical practice and highlight its potential toxicity.
rituximab; B-cells; autoimmune neurological disorders; practical guidelines; toxicity; immunotherapy; B cell depletion
Rituximab is a monoclonal antibody directed against CD20 cell surface antigen of B-lymphocytes. Recent studies have demonstrated effectivity in recalcitrant bullous pemphigoid. The data available on other types of autoimmune bullous disease is more scant.
Here we report on the successful adjuvant use of rituximab in mucous membrane pemphigoid and pemphigus vulgaris in two patients with the most refractory course of disease. Both patients achieved a good clinical response.
Rituximab is a third line treatment of patients with pemphigus vulgaris and mucous membrane pemphigoid. In contrast to bullous pemphigoid, other bullous diseases do not always respond to a monotherapy with this monoclonal antibody. Nevertheless, biological therapy seems to work faster than established treatment in such cases. Risks and benefits of the treatment are discussed.
monoclonal antibody; rituximab; bullous pemphigoid; mucous membrane pemphigoid; pemphigus vulgaris
The management of chronic lymphocytic leukemia (CLL) has dramatically improved in the past decade with the addition of anti-CD20 monoclonal antibodies to the treatment armamentarium. Ofatumumab is a novel anti-CD20 monoclonal antibody recently approved in the US and Europe for the treatment of CLL refractory to alemtuzumab and fludarabine. Preclinical data showed improved complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity compared with rituximab. Clinical studies have shown single-agent activity for ofatumumab in CLL and in other low-grade non-Hodgkin’s lymphomas. Combination studies are being conducted to enhance the therapeutic efficacy of ofatumumab. This paper reviews some of the key clinical studies that led to approval of ofatumumab, and future directions.
ofatumumab; chronic lymphocytic leukemia; efficacy; safety
The relationship between antiCD20 therapy with rituximab and the lymphocytes phenotype in patients with rheumatoid arthritis was investigated, with an attempt to establish a relationship between commonly used clinical activity indices and variations in leukocyte count, in particular natural killer (NK) lymphocytes.
Patients with seropositive (cyclic citrullinated peptides and rheumatoid factor positive) rheumatoid arthritis (according to the American College of Rheumatology 1987 criteria) refractory to conventional and antitumor necrosis factor-alpha agents who were subsequently treated with rituximab, a chimeric monoclonal antibody directed against CD20, were enrolled between January 2009 and September 2009. All subjects were treated with rituximab standard rheumatologic dose of 1.0 g on days 1 and 15 every 6 months for at least 2 years. A clinical evaluation was performed at baseline and subsequently every 3 months thereafter. At each assessment activated NK (CD56+/CD16+/CD54bright) cell count was collected and disease activity was assessed using Disease Activity Score in 28 Joints and the Simplified Disease Activity Index (SDAI).
Thirty-four patients were enrolled (mean age ± standard deviation: 54.8 ± 12.8 years). Basal SDAI was 21.75 ± 5.4 and NK cell count mean value was 157.6 ± 90. After 24 months, SDAI was 14 ± 1.2 and NK cell count mean value was 301.7 ± 21 (P < 0.05). An inverted correlation between SDAI and NK count was observed at 3 months (r = −0.36, P < 0.05), 6 months (r = −0.48, P < 0.45), 9 months (r = −0.47, P < 0.05), 12 months (r = −0.41, P < 0.01), 15 months (r = −0.58, P < 0.05), 18 months (r = −0.53, P < 0.05), 21 months (r = −0.68, P < 0.05), and 24 months (r = −0.61, P < 0.05). A linear regression model between all variables collected and SDAI/Disease Activity Score in 28 Joints at 6 months and 12 months confirmed a significant relationship between SDAI/Disease Activity Score in 28 Joints and NK cell count.
The data confirm the clinical efficacy of rituximab and suggests the use of NK cells as a predictor of clinical response in patients with rheumatoid arthritis.
NK cells; rituximab; predictor; response; rheumatoid arthritis
Rituximab is a mainstay in the therapy for a broad variety of B-cell malignancies. Despite its undeniable therapeutic value, we still do not fully understand the mechanisms of action responsible for rituximab's anti-tumor effects. Direct signaling, complement dependent cellular cytotoxicity and antibody dependent cellular cytotoxicity all appear to play a role in rituximab efficacy. In vitro, animal model and clinical data addressing each of these mechanisms of action are reviewed, as are data speaking to the complexity of interactions between these mechanisms. Taken together, these data suggest different mechanisms are likely important in different scenarios. Study of the complex mechanisms of action that contribute to the clinical efficacy of rituximab have led to novel clinical trials including novel combinations, schedules, and generation of additional antibodies designed to have even greater effect. Such studies need to be accompanied by rigorous correlative analysis if we are to understand the importance of various mechanisms of action of rituximab and use that information to improve on what is already an indispensable approach to therapy.
The association between non-Hodgkin lymphomas and autoimmune disorders is a well-known event. Also autoimmune hemolytic anemia (AHA), although much more frequent in patients with chronic lymphocytic leukemia (CLL), has been described in this group of patients. In recent years, among the more traditional therapeutic options, rituximab, an anti-CD20 monoclonal antibody, has shown interesting results in the treatment of primary AHA. Although this drug has been frequently used for AHA in patients with CLL, much less data are available on its use in NHL patients. However, considering that the main pathogenetic mechanism of AHA in course of lymphoproliferative disorders seems to be an antibody production directly or indirectly mediated by the neoplastic clone, this monoclonal antibody represents an ideal therapeutic approach. In this paper we will briefly describe some biological and clinical features of NHL-patients with AHA. We will then analyze some studies focusing on rituximab in primary AHA, finally reviewing the available literature on the use of this drug in NHL related AHA.