Single-agent monoclonal antibody efficacy in bulky non-Hodgkin's lymphoma: results of a phase II trial of rituximab

Dual antigen-targeted off-the-shelf NK cells show durable response and prevent antigen escape in lymphoma and leukemia

Substantial numbers of B cell leukemia and lymphoma patients relapse due to antigen loss or heterogeneity after anti-CD19 chimeric antigen receptor (CAR) T cell therapy. To overcome antigen escape and address antigen heterogeneity, we engineered induced pluripotent stem cell-derived NK cells to express both an NK cell-optimized anti-CD19 CAR for direct targeting and a high affinity, non-cleavable CD16 to augment antibody-dependent cellular cytotoxicity. In addition, we introduced a membrane-bound IL-15/IL-15R fusion protein to promote in vivo persistence. These engineered cells, termed iDuo NK cells, displayed robust CAR-mediated cytotoxic activity that could be further enhanced with therapeutic antibodies targeting B cell malignancies. In multiple in vitro and xenogeneic adoptive transfer models, iDuo NK cells exhibited robust anti-lymphoma activity. Furthermore, iDuo NK cells effectively eliminated both CD19+ and CD19- lymphoma cells and displayed a unique propensity for targeting malignant cells over healthy cells that expressed CD19, features not achievable with anti-CAR19 T cells. iDuo NK cells combined with therapeutic antibodies represent a promising approach to prevent relapse due to antigen loss and tumor heterogeneity in patients with B cell malignancies.

Factors Influencing Infusion-Related Reactions Following Dosing of Reference Rituximab and PF-05280586, a Rituximab Biosimilar

BACKGROUND

Infusion-related reactions (IRRs) are the most common adverse event (AE) associated with infusion of rituximab, an anti-CD20 monoclonal antibody.

OBJECTIVE

Our objective was to evaluate the impact of dosing/infusion patterns and certain baseline characteristics on IRR occurrence during the first rituximab infusion administered as the biosimilar PF-05280586 (RTX-PF) or reference rituximab sourced from the EU (RTX-EU, MabThera^®) in patients with CD20+ low-tumor-burden follicular lymphoma.

PATIENTS AND METHODS

Rituximab (RTX-PF, n=196; RTX-EU, n=198) was administered (375 mg/m²) on days 1, 8, 15, and 22 (one cycle), with a follow-up period through 52 weeks. The relationships between infusion rate, drug exposure, and IRR incidence were assessed by logistic regression analysis and pharmacokinetic modeling and simulation. Baseline CD20 level, antidrug antibody (ADA) status, and tumor burden according to IRR occurrence (yes/no) were compared descriptively.

RESULTS

Median rituximab infusion duration on day 1 was 3.50 h for each of the two groups. There was a positive correlation between infusion rate and all-grade IRRs occurring within 24 h after infusion (p < 0.0001). Patients who developed IRRs had a higher median baseline CD20+ level. IRR incidence was unaffected by baseline ADA status. Drug exposure did not predict IRR incidence. Baseline tumor burden was similar between patients with and without IRRs.

CONCLUSIONS

Results of this analysis provide a better understanding of IRRs after the first rituximab (RTX-PF or RTX-EU) infusion and demonstrate a potential correlation of infusion rate and other factors with IRR at the individual and population levels. Infusion-rate escalation steps continue to be needed to manage IRRs.

TRIAL REGISTRATION (DATE OF REGISTRATION)

ClinicalTrials.gov Identifier: NCT02213263 (11 August 2014); and EudraCT: 2014-000132-41 (10 October 2014).

Pathogenesis of chronic lymphocytic leukemia and the development of novel therapeutic strategies

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries and is characterized by the clonal expansion of mature CD5⁺ B cells. There have been substantial advances in the field of CLL research in the last decade, including the identification of recurrent mutations, and clarification of clonal architectures, signaling molecules, and the multistep leukemogenic process, providing a comprehensive understanding of CLL pathogenesis. Furthermore, the development of therapeutic approaches, especially that of molecular target therapies against CLL, has markedly improved the standard of care for CLL. This review focuses on the recent insights made in CLL leukemogenesis and the development of novel therapeutic strategies.

Evolving role of biomaterials in diagnostic and therapeutic radiation oncology

Radiation therapy to treat cancer has evolved significantly since the discovery of x-rays. Yet, radiation therapy still has room for improvement in reducing side effects and improving control of cancer. Safer and more effective delivery of radiation has led us to novel techniques and use of biomaterials. Biomaterials in combination with radiation and chemotherapy have started to appear in pre-clinical explorations and clinical applications, with many more on the horizon. Biomaterials have revolutionized the field of diagnostic imaging, and now are being cultivated into the field of theranostics, combination therapy, and tissue protection. This review summarizes recent development of biomaterials in radiation therapy in several application areas.

The Use of 20% Subcutaneous Immunoglobulin Replacement Therapy in Patients With B Cell Non-Hodgkin Lymphoma With Humoral Immune Dysfunction After Treatment With Rituximab

BACKGROUND

Rituximab is an anti-CD20 chimeric antibody used to treat autoimmune conditions and B cell neoplasms. We characterized immunoglobulin (Ig) levels and vaccine responses in rituximab-treated B cell non-Hodgkin lymphoma (NHL) patients. Patients with impaired vaccine responses were offered therapy with 20% subcutaneous (subq) Ig.

PATIENTS AND METHODS

Patients with a biopsy-proven diagnosis of B cell NHL who had received rituximab within the past 24 months were eligible for the study and underwent the following immune evaluation: serum IgG, IgM, IgA, IgE, T/B cell lymphocyte panel, and pre/post vaccine IgG titers to diphtheria, tetanus, and streptococcus pneumoniae. Patients were vaccinated with tetanus, diphtheria and pneumococcal polysaccharide vaccine. Patients with abnormal vaccine responses were offered prophylactic subq Ig for 52 weeks.

RESULTS

Fifteen patients with NHL were enrolled in the study. The median IgG was 628 mg/dL [interquartile range, 489-718 mg/dL]. Three (20%) of 15 patients responded to diphtheria vaccination, 1 (6.7%) of 15 responded to tetanus vaccination, and 3 (20%) of 15 responded to vaccination to streptococcus pneumoniae. Thirteen (86.7%) of 15 met criteria for humoral immunodeficiency. Ten patients received subq Ig, and experienced a significant increase in serum IgG (P = .008). There were no serious adverse events, and there was a decrease in nonneutropenic infections while on subq Ig therapy.

CONCLUSIONS

Patients with NHL treated with rituximab may have significant humoral immunodeficiency as defined by abnormal vaccine responses even in the setting of relatively normal IgG levels. For these patients, subq Ig replacement therapy is well-tolerated and efficacious in improving serum IgG, and may decrease reliance on antibiotics for the treatment of nonneutropenic infections.

Premedication with montelukast and rupatadine decreased rituximab infusion time, rate, severity of reactions and use of rescue medications

Rituximab-associated infusion reactions (IRs) are significant burdens on oncology patients, caregivers and healthcare providers. We evaluated whether montelukast and rupatadine improve rituximab delivery, decrease frequency/severity of IRs and the number of medications used to control IRs. Using a nonrandomized clinical study design, we assessed adult rituximab naïve patients with B-cell lymphoid malignancies from January 2017 to July 2019. Prior to the first rituximab infusion patients received one of the premedication regimens: (i) standard premedications, diphenhydramine hydrochloride and acetaminophen ("SP" group); (ii) SP + montelukast ("M" group); (iii) SP + rupatadine ("R" group); (iv) SP + rupatadine + montelukast Schedule 1 ("M + R Schedule 1" group); (v) SP + rupatadine + montelukast Schedule 2 ("M + R Schedule 2" group). A total of 223 patients with a median age of 69 years were assessed. Demographics and treatment groups were comparable among all five groups. Mean rituximab infusion time was 290 min in the SP group versus 273, 261, 243 and 236 min in the M, R, M + R Schedule 1 and M + R Schedule 2 groups, respectively. The incidence of rituximab IRs was 75% in the SP group versus 44, 41, 22 and 22% in the M, R, M + R Schedule 1 and M + R Schedule 2 groups, respectively. The median reaction grade was 2 in the SP group and 0 in all other groups. The median number of rescue medications was 3 in the SP group and 0 in all other groups. In conclusion, montelukast and rupatadine significantly improved rituximab delivery, decreased the rate and severity of IRs and reduced the need for rescue medications.

Management of Adverse Events From the Combination of Rituximab and Lenalidomide in the Treatment of Patients With Follicular and Low-Grade Non-Hodgkin Lymphoma

Frontline treatment for patients with indolent non-Hodgkin lymphoma often includes immunochemotherapy. Although the disease of most patients responds to initial treatment, relapse is common. Recent results from the phase 3 Augment trial showed that combining rituximab with the immunomodulatory drug lenalidomide (R²) significantly improved efficacy over rituximab monotherapy in patients with recurrent non-Hodgkin lymphoma. As a result of these data, R² was approved in the US (Food and Drug Administration) and Japan (Pharmaceuticals and Medical Devices Agency) for previously treated adult patients with follicular and marginal zone lymphoma; and by the European Medicine Agency and the Swiss Agency for Therapeutic Products (Swissmedic) for previously treated adult patients with follicular lymphoma. R² has also been studied as initial treatment, where results have been comparable, but not superior, to chemoimmunotherapy. The resulting expanded use of R² reinforces the need for a detailed review of its safety profile and management, as presented here. Tolerability of R² has been consistent among trials, with most adverse events (AEs) being predictable and manageable. Hematologic AEs, particularly grade 3/4 neutropenia; low-grade cutaneous reactions, such as rash; and gastrointestinal AEs represent the most common AEs associated with R². The general R² safety profile and optimal strategies for AE management are discussed.

Secondary Hypogammaglobulinemia: An Increasingly Recognized Complication of Treatment with Immunomodulators and After Solid Organ Transplantation

Secondary hypogammaglobulinemia is a common development in patients treated with immunomodulatory agents for autoimmune, connective tissue, and malignant diseases. It has been observed in the medical management of patients undergoing hematopoietic stem cell and solid organ transplantation. Some patients have preexisting immunodeficiency associated with these illnesses; immunosuppressive treatment magnifies their immune defect. This article reviews immunosuppressive medications, including biological treatments that cause secondary hypogammaglobulinemia. It summarizes risk factors for rituximab-induced hypogammaglobulinemia, such as preexisting low immunoglobulin G levels, CD19 levels, host factors, and additive effect of all immunomodulatory drugs used. The evaluation and management of secondary hypogammaglobulinemia are discussed.

Immune precision medicine for cancer: a novel insight based on the efficiency of immune effector cells

Cancer cell growth is associated with immune surveillance failure. Nowadays, restoring the desired immune response against cancer cells remains a major therapeutic strategy. Due to the recent advances in biological knowledge, efficient therapeutic tools have been developed to support the best bio-clinical approaches for immune precision therapy. One of the most important successes in immune therapy is represented by the applicational use of monoclonal antibodies, particularly the use of rituximab for B-cell lymphoproliferative disorders. More recently, other monoclonal antibodies have been developed, to inhibit immune checkpoints within the tumor microenvironment that limit immune suppression, or to enhance some immune functions with immune adjuvants through different targets such as Toll-receptor agonists. The aim is to inhibit cancer proliferation by the diminishing/elimination of cancer residual cells and clinically improving the response duration with no or few adverse effects. This effect is supported by enhancing the number, functions, and activity of the immune effector cells, including the natural killer (NK) lymphocytes, NKT-lymphocytes, γδ T-lymphocytes, cytotoxic T-lymphocytes, directly or indirectly through vaccines particularly with neoantigens, and by lowering the functions of the immune suppressive cells. Beyond these new therapeutics and their personalized usage, new considerations have to be taken into account, such as epigenetic regulation particularly from microbiota, evaluation of transversal functions, particularly cellular metabolism, and consideration to the clinical consequences at the body level. The aim of this review is to discuss some practical aspects of immune therapy, giving to clinicians the concept of immune effector cells balancing between control and tolerance. Immunological precision medicine is a combination of modern biological knowledge and clinical therapeutic decisions in a global vision of the patient.

Role of obinutuzumab exposure on clinical outcome of follicular lymphoma treated with first-line immunochemotherapy

AIMS

Obinutuzumab (G) is a humanized type II, Fc-glycoengineered anti-CD20 monoclonal antibody used in various indications, including patients with previously untreated front-line follicular lymphoma. We investigated sources of variability in G exposure and association of progression-free survival (PFS) with average concentration over induction (C_meanIND ) in front-line follicular lymphoma patients treated with G plus chemotherapy (bendamustine, CHOP, or CVP) in the GALLIUM trial.

METHODS

Individual exposures (C_meanIND ) were obtained from a previously established population pharmacokinetic model updated with GALLIUM data. Multivariate Cox proportional hazard models and univariate Kaplan-Meier plots investigated relationships of PFS with exposure and other potential prognostic factors.

RESULTS

Overall, G exposure was lower in high body-weight patients and in males, and slightly lower in patients with high baseline tumour burden. Analysis of clinical outcomes showed that variability in G exposure did not impact PFS in G-bendamustine-treated patients; PFS was inferior in males and patients with FCGR2a/2b T232 T low-affinity receptor variant, and superior in patients with FCGR2a/2b I232T variant. In G-CHOP/CVP arms, PFS improved with increasing C_meanIND (hazard ratio = 1.74 and 0.394 at 5^th and 95^th percentile compared to median C_meanIND ) and was inferior in patients with high baseline tumour size and B symptoms.

CONCLUSIONS

It remains unclear whether for G-CHOP/CVP patients lower G exposure is a consequence of adverse disease biology and/or resistance to chemotherapy backbone (higher clearance in nonresponder patients, as demonstrated for rituximab) rather than being the cause of poorer clinical outcome. A study with >1 dose level of G could help resolve this uncertainty.

Anti-CD20 monoclonal antibodies: reviewing a revolution

Since the inception of rituximab in the 1990s, anti-CD20 monoclonal antibodies have revolutionised the treatment of B cell hematological malignancies and have become a cornerstone of modern gold-standard practice. Additionally, the potent efficacy of these agents in depleting the B cell compartment has been used in the management of a broad array of autoimmune diseases. Multiple iterations of these agents have been investigated and are routinely used in clinical practice. In this review, we will discuss the physiology of CD20 and its attractiveness as a therapeutic target, as well as the pharmacology, pre-clinical and clinical data for the major anti-CD20 monoclonal antibodies: rituximab, obinutuzumab and ofatumumab.

Infusion reactions associated with rituximab treatment for childhood-onset complicated nephrotic syndrome

BACKGROUND

Infusion reaction (IR) is defined as an adverse event within 24 h after monoclonal antibody infusion. In non-Hodgkin lymphoma, IR incidence following rituximab treatment is high (77-80%), but there are no data in complicated nephrotic syndrome.

METHODS

Records of rituximab infusions in patients with complicated nephrotic syndrome between February 2006 and December 2014 at the National Center for Child Health and Development were reviewed. Rituximab was administered at doses of 375 mg/m². The severity of IR was evaluated using the Common Terminology Criteria for Adverse Events ver. 4.0.

RESULTS

For 309 rituximab infusions in 159 patients (male, 110; median age, 12 years), IR was observed in 165 infusions (53.4%). Respiratory symptoms were most common (66% of all events). Ninety-five percent of the IR was observed within 3 h after rituximab infusion initiation. Sixty-eight percent of the events were classified as grade 1 and others classified as grade 2. Only 18% required medical intervention. CD20 cell count in patients with IR was significantly higher than in patients without IR. Incidence of IR was similar in subsequent rituximab treatment after B-cell recovery. Patients who experienced IR at first rituximab treatment were more likely to experience recurrent IR with subsequent treatments compared to those not having IR at initial treatment (odds ratio 3.64; p < 0.001).

CONCLUSIONS

In patients with complicated nephrotic syndrome, respiratory symptoms were the major type of IR, mostly observed within 3 h of infusion. Incidence of IR was lower and its severity milder in patients with complicated nephrotic syndrome than those with lymphoma.

Resistance to anticancer immunity in cancer patients: potential strategies to reverse resistance

In the 1990s, the application of immunotherapy approaches to target cancer cells resulted in significant clinical responses in patients with advanced malignancies who were refractory to conventional therapies. While early immunotherapeutics were focused on T cell-mediated cytotoxic activity, subsequent efforts were centered on targeted antibody-mediated anticancer therapy. The initial success with antibody therapy encouraged further studies and, consequently, there are now more than 25 FDA-approved antibodies directed against a range of targets. Although both T cell and antibody therapies continue to result in significant clinical responses with minimal toxicity, a significant subset of patients does not respond to immunotherapy and another subset develops resistance following an initial response. This review is focused on describing examples showing that cancer resistance to immunotherapies indeed occurs. In addition, it reviews the mechanisms being used to overcome the resistance to immunotherapies by targeting the tumor cell directly and/or the tumor microenvironment.

Rituximab in B-Cell Hematologic Malignancies: A Review of 20 Years of Clinical Experience

Rituximab is a human/murine, chimeric anti-CD20 monoclonal antibody with established efficacy, and a favorable and well-defined safety profile in patients with various CD20-expressing lymphoid malignancies, including indolent and aggressive forms of B-cell non-Hodgkin lymphoma. Since its first approval 20 years ago, intravenously administered rituximab has revolutionized the treatment of B-cell malignancies and has become a standard component of care for follicular lymphoma, diffuse large B-cell lymphoma, chronic lymphocytic leukemia, and mantle cell lymphoma. For all of these diseases, clinical trials have demonstrated that rituximab not only prolongs the time to disease progression but also extends overall survival. Efficacy benefits have also been shown in patients with marginal zone lymphoma and in more aggressive diseases such as Burkitt lymphoma. Although the proven clinical efficacy and success of rituximab has led to the development of other anti-CD20 monoclonal antibodies in recent years (e.g., obinutuzumab, ofatumumab, veltuzumab, and ocrelizumab), rituximab is likely to maintain a position within the therapeutic armamentarium because it is well established with a long history of successful clinical use. Furthermore, a subcutaneous formulation of the drug has been approved both in the EU and in the USA for the treatment of B-cell malignancies. Using the wealth of data published on rituximab during the last two decades, we review the preclinical development of rituximab and the clinical experience gained in the treatment of hematologic B-cell malignancies, with a focus on the well-established intravenous route of administration. This article is a companion paper to A. Davies, et al., which is also published in this issue.

FUNDING

F. Hoffmann-La Roche Ltd., Basel, Switzerland.

Rituximab exposure is influenced by baseline metabolic tumor volume and predicts outcome of DLBCL patients: a Lymphoma Study Association report

High variability in patient outcome after rituximab-based treatment is partly explained by rituximab concentrations, and pharmacokinetic (PK) variability could be influenced by tumor burden. We aimed at quantifying the influence of baseline total metabolic tumor volume (TMTV₀) on rituximab PK and of TMTV₀ and rituximab exposure on outcome in patients with diffuse large B-cell lymphoma (DLBCL). TMTV₀ was measured by ¹⁸F-fluorodeoxyglucose-positron emission tomography-computed tomography in 108 previously untreated DLBCL patients who received four 375 mg/m² rituximab infusions every 2 weeks in combination with chemotherapy in 2 prospective trials. A 2-compartment population model allowed describing rituximab PK and calculating rituximab exposure (area under the concentration-time curve; AUC). The association of TMTV₀ and AUC with metabolic response after 4 cycles, as well as progression-free survival (PFS) and overall survival (OS), was assessed using logistic regression and Cox models, respectively. Cutoff values for patient outcome were determined using receiver operating characteristic curve analysis. Exposure to rituximab decreased as TMTV₀ increased (R² = 0.41, P < .0001). A high AUC in cycle 1 (≥9400 mg × h per liter) was associated with better response (odds ratio, 5.56; P = .0006) and longer PFS (hazard ratio [HR], 0.38; P = .011) and OS (HR, 0.17; P = .001). A nomogram for rituximab dose needed to obtain optimal AUC according to TMTV₀ was constructed, and the 375 mg/m² classical dose would be suitable for patients with TMTV₀ <281 cm³ In summary, rituximab exposure is influenced by TMTV₀ and correlates with response and outcome of DLBCL patients. Dose individualization according to TMTV₀ should be evaluated in prospective studies. These studies were registered at www.clinicaltrials.gov as #NCT00498043 and #NCT00841945.

Outcome differences between children and adolescents and young adults with non-Hodgkin lymphoma following stem cell transplantation

Several studies of patients with acute lymphoblastic leukemia and acute myeloid leukemia who received stem cell transplantation (SCT) have reported that adolescents and young adults (AYAs) experience higher transplant-related mortality than that in younger children. However, to the best of our knowledge, there have been no reports of a similar comparison of non-Hodgkin lymphoma (NHL) patients who received SCT. We analyzed 918 patients aged 30 years and younger who received their first stem cell transplantation for NHL. Of the allogeneic transplant patients, children and AYAs did not significantly differ in survival rate, event-free survival rate, relapse rate, or transplant-related mortality. However, 5-year transplant-related mortality after autologous transplantation was significantly higher in children than in AYAs (5.1% in children vs. 0.8% in AYAs, P = 0.0043). The cause of transplant-related death in three of four children was interstitial pneumonitis. In NHL patients, transplantation results in AYAs were not inferior than those in children.

Elevation of Activated Platelet-Dependent Chemokines in Patients With Anti-CD20 Monoclonal Antibody (Rituximab)−Treated Non-Hodgkin's Lymphoma

.ocn.ne.jp. This study measured and compared levels of some chemokines in patients with rituximab-treated non-Hodgkin lymphoma because they may participate in the mechanism of efficacy of rituximab in non-Hodgkin lymphoma patients. Monocytic chemotactant protein-1, RANTES (regulated on activation, normally T-cell expressed and secreted), eotaxin, interleukin-8, neutrophil-activating protein-78, stromal cell-derived factor-1, and growth-regulating oncogene-α in patients with rituximab-treated non-Hodgkin lymphoma were measured by enzyme-linked immunosorbent assay. Levels of RANTES were higher in non-Hodgkin lymphoma patients than in controls. Levels of monocytic chemotactant protein-1, RANTES, and neutrophil-activating protein-78 were significantly elevated before and after chemotherapy with rituximab treatment. However, the level of stromal cell-derived factor-1 did not exhibit a significant change. Before to after chemotherapy without rituximab treatment, all chemokine levels did not exhibit significant changes. These findings suggest that activated platelet-dependent chemokines such as RANTES and neutrophil-activating protein-78 may modulate the efficacy of rituximab in antibody-dependent cellular cytotoxity.

Population pharmacokinetics of Reditux™, a biosimilar Rituximab, in diffuse large B-cell lymphoma

PURPOSE

Rituximab (MabThera™, Roche) is a chimeric IgG1 monoclonal antibody targeting the CD20 surface antigen on normal and neoplastic B cells. It revolutionized the treatment of non-Hodgkin's lymphoma with superior progression-free and overall survival. However, its prohibitively high cost makes it inaccessible to majority of patients in developing countries. Reditux™ (Dr. Reddy's Laboratories, India), a biosimilar, was introduced in India in 2007 at nearly half the price of the innovator. However, there is a dearth of data regarding the pharmacokinetics and efficacy of Reditux™.

METHODS

Twenty-one patients of diffuse large B-cell lymphoma on R-CHOP regimen were enrolled for the study. Reditux™ was administered as a slow intravenous infusion at a dose of 375 mg/m(2) on day 1 of a 21-day cycle. Pharmacokinetic sampling was performed at pre-dose, post-infusion, 24, 48 h, 7 and 21 days. Rituximab levels were estimated by ELISA. Population pharmacokinetics was performed using NONMEM. In addition, B-cell count was determined at baseline and days 3 and 21 of the first cycle. Survival analysis was performed using Kaplan-Meier plots.

RESULTS

The volume of distribution of central compartment and clearance of Reditux™ were estimated at 0.95 L and 5.98 mL/h, respectively. No covariate effects were seen. B-cell count was completely depleted by day 3 and remained so on day 21. Overall survival was 84.6 % at a median follow-up of 36 months.

CONCLUSION

The pharmacokinetic profile and B-cell response to Reditux™ are comparable with those reported for MabThera™. Thus, MabThera™ can be substituted with Reditux™ for the treatment of B-cell lymphomas.

Phase I study of chimeric anti-CD20 monoclonal antibody in Chinese patients with CD20-positive non-Hodgkin's lymphoma

OBJECTIVE

This study was designed to determine the safety, pharmacokinetics and biologic effects of a human-mouse chimeric anti-CD20 monoclonal antibody (SCT400) in Chinese patients with CD20-positive B-cell non-Hodgkin's lymphoma (CD20(+) B-cell NHL). SCT400 has an identical amino acid sequence as rituximab, with the exception of one amino acid in the CH1 domain of the heavy chain, which is common in Asians.

METHODS

Fifteen patients with CD20(+) B-cell NHL received dose-escalating SCT400 infusions (250 mg/m(2): n=3; 375 mg/m(2): n=9; 500 mg/m(2): n=3) once weekly for 4 consecutive weeks with a 24-week follow-up period. The data of all patients were collected for pharmacokinetics and pharmacodynamics analyses.

RESULTS

No dose-limiting toxicities were observed. Most drug-related adverse events were grade 1 or 2. Two patients had grade 3 or 4 neutropenia. Under premedication, the drug-related infusion reaction was mild. A rapid, profound and durable depletion of circulating B cells was observed in all dose groups without significant effects on T cell count, natural killer (NK) cell count or immunoglobulin levels. No patient developed anti-SCT400 antibodies during the course of the study. SCT400 serum half-life (T1/2), maximum concentration (Cmax) and area under the curve (AUC) generally increased between the first and fourth infusions (P<0.05). At the 375 mg/m(2) dose, the T1/2 was 122.5±46.7 h vs. 197.0±75.0 h, respectively, and the Cmax was 200.6±20.2 g/mL vs. 339.1±71.0 g/mL, respectively. From 250 mg/m(2) to 500 mg/m(2), the Cmax and AUC increased significantly in a dose-dependent manner (P<0.05). Patients with a high tumor burden had markedly lower serum SCT400 concentrations compared with those without or with a low tumor burden. Of the 9 assessable patients, 1 achieved complete response and 2 achieved partial responses.

CONCLUSIONS

SCT400 is well-tolerated and has encouraging preliminary efficacy in Chinese patients with CD20(+) B-cell NHL.

Randomized Phase II Trial Comparing Obinutuzumab (GA101) With Rituximab in Patients With Relapsed CD20+ Indolent B-Cell Non-Hodgkin Lymphoma: Final Analysis of the GAUSS Study

PURPOSE

Obinutuzumab (GA101), a novel glycoengineered type II anti-CD20 monoclonal antibody, demonstrated responses in single-arm studies of patients with relapsed/refractory non-Hodgkin lymphoma. This is the first prospective, randomized study comparing safety and efficacy of obinutuzumab with rituximab in relapsed indolent lymphoma. The primary end point of this study was the overall response rate (ORR) in patients with follicular lymphoma after induction and safety in patients with indolent lymphoma.

PATIENTS AND METHODS

A total of 175 patients with relapsed CD20(+) indolent lymphoma requiring therapy and with previous response to a rituximab-containing regimen were randomly assigned (1:1) to four once-per-week infusions of either obinutuzumab (1,000 mg) or rituximab (375 mg/m(2)). Patients without evidence of disease progression after induction therapy received obinutuzumab or rituximab maintenance therapy every 2 months for up to 2 years.

RESULTS

Among patients with follicular lymphoma (n = 149), ORR seemed higher for obinutuzumab than rituximab (44.6% v 33.3%; P = .08). This observation was also demonstrated by a blinded independent review panel that measured a higher ORR for obinutuzumab (44.6% v 26.7%; P = .01). However, this difference did not translate into an improvement in progression-free survival. No new safety signals were observed for obinutuzumab, and the incidence of adverse events was balanced between arms, with the exception of infusion-related reactions and cough, which were higher in the obinutuzumab arm.

CONCLUSION

Obinutuzumab demonstrated a higher ORR without appreciable differences in safety compared with rituximab. However, the clinical benefit of obinutuzumab in this setting remains unclear and should be evaluated within phase III trials.

Obinutuzumab in hematologic malignancies: lessons learned to date

The routine use of anti-CD20 monoclonal antibodies (mAbs) has improved patient outcomes in CD20-positive non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL). Despite the clinical success achieved with rituximab, relapses are still common with further improvements in anti-CD20 mAb efficacy required. Many novel anti-CD20 antibodies are in development, but obinutuzumab is currently the only type II glycoengineered anti-CD20 mAb in clinical testing. Obinutuzumab has increased antibody-dependent cell-mediated cytotoxicity, reduced complement-dependent cytotoxicity and enhanced direct non-apoptotic cell death. In preclinical models, obinutuzumab induced superior tumor remission compared with rituximab at the equivalent dose levels, and was active in rituximab-refractory tumors. Obinutuzumab exhibits encouraging efficacy as monotherapy in NHL, and combined with chemotherapy in relapsed/refractory NHL and treatment-naïve symptomatic CLL. In a recent randomized, phase III trial in patients with untreated comorbid CLL, overall response rate was significantly greater (78% vs. 65%, P<0.0001) and median progression-free survival was significantly prolonged (26.7 vs. 15.2months, P<0.0001) for obinutuzumab plus chlorambucil vs. rituximab plus chlorambucil. Obinutuzumab is a type II anti-CD20 antibody that utilizes distinct mechanisms of action relative to type I antibodies like rituximab and has led to significant clinical improvement over rituximab in a phase III trial in CLL. Further trials are ongoing to determine whether such improvements in outcome will be seen in CD20-positive B-cell malignancies.

Chemotherapy-free treatment in patients with follicular lymphoma

The outcome of patients with follicular lymphoma (FL) has improved over the last two decades through the introduction of anti-CD20 monoclonal antibodies, usually used in combination with chemotherapy. However, patients with FL still experience multiple relapses, requiring several lines of treatment. Early toxicity of chemotherapy is a significant concern and as the life expectancy of patients with FL is increasing, late toxicities become an increasingly important concern. Progress made in understanding the biology of FL, especially dysregulation of intracellular pathways and immunological antitumor responses, recently allowed for the development of innovative chemo-free therapeutic approaches. In this report, different options such as new anti-CD20 antibodies, antibodies targeting other cell surface antigens, bi-specific antibodies, immunomodulation, idiotype vaccine and other targeted therapies are presented. The article also highlights how, although promising in early phase studies, the cost-effectiveness of new agents will have to be justified in Phase III trials. Furthermore, chemo-free regimen might not mean toxicity-free treatment and monitoring of early and late toxicities is required.

Transformed follicular non-Hodgkin lymphoma

Histologic transformation of follicular lymphoma to an aggressive non-Hodgkin lymphoma is a critical biologic event with profound implications on the natural history of this otherwise indolent disease. Recent insights into the genetic and epigenetic basis of transformation have been described, with the recognition of pivotal events governing the initiation and persistence of tumor evolution. Outcomes of patients with transformed lymphoma have historically been poor; however, several studies in the rituximab era suggest that survival may be more favorable than previously recognized. This review highlights our current understanding of transformed follicular lymphoma biology and pathogenesis, current treatment, and future directions.

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.

Postulated mechanisms of resistance of B-cell non-Hodgkin lymphoma to rituximab treatment regimens: strategies to overcome resistance

Antibody-mediated immunotherapy has gained significant momentum since 1997 when the US Food and Drug Administration approved the first monoclonal antibody (mAb) for the treatment of B-cell non-Hodgkin lymphoma (B-NHL), namely, rituximab (chimeric anti-CD20 mAb). Subsequently, more than 20 approved mAbs have been in use clinically for the treatment of various cancers and several non-cancer-related diseases. Further, the combination treatment of mAbs with chemotherapy, immunotherapy, proteaosome inhibitors, and other inhibitors has resulted in synergistic anti-tumor activity with significant objective clinical responses. Despite their successful clinical use, the underlying mechanisms of rituximab's in vivo activities remain elusive. Further, it is not clear why a subset of patients is initially unresponsive and many responding patients become refractory and resistant to further treatments; hence, the underlying mechanisms of resistance are not known, Attempts have been made to develop model systems to investigate resistance to mAb therapy with the hope to apply the findings in both the generation of new therapeutics and in their use as new prognostic biomarkers. This review focuses on the development of resistance to rituximab treatments and discusses possible underlying mechanisms of action, postulated mechanisms of resistance in model systems, and suggested means to overcome resistance. Several prior reviews on the subject of rituximab resistance have been published and the present review both complements as well as adds new topics of relevance.

Rituximab and immune deficiency: case series and review of the literature

BACKGROUND

As the indications and use of rituximab continue to expand, the reports of long-term effects of anti-CD20--mediated B-cell depletion on the immune system accumulate.

OBJECTIVE

We report a group of patients with immunodeficiency who were treated with rituximab and present their immunologic data.

METHODS

A retrospective chart review identified patients with immunodeficiency who received rituximab for treatment of their primary disease and required immunoglobulin replacement therapy (IGRT). Pre-IGRT immunoglobulins, specific antibodies, B-cells, and B-cell phenotype were recorded and analyzed.

RESULTS

We identified 11 patients with immunodeficiency who received rituximab and required IGRT. Two of these patients were diagnosed with common variable immunodeficiency before rituximab treatment. Nine other patients had hypogammaglobulinemia and did not achieve an adequate response to polysaccharide vaccine. There was a significant delay in B-cell recovery. B-cell phenotypes identified predominantly naive B cells in the blood of these patients with significant decrease in switched and memory B cells.

CONCLUSION

There are patients with persistent B-cell dysfunction long after rituximab treatment was discontinued. Some of these patients required IGRT. These patients should be distinguished from patients with primary immunodeficiency diseases. Routine baseline B-cell numbers and serum immunoglobulin levels before starting immunomodulatory therapy are required to help distinguish primary immunodeficiency diseases from secondary rituximab-induced, transient, and, at times, prolonged immune suppression. Periodic monitoring is prudent to identify immune recovery. Post-rituximab B-cell phenotyping may help identify the patients who will develop persistent immune dysfunction caused by an unidentified underlying disease or the prolonged effect of rituximab treatment.

A phase I study of PRO131921, a novel anti-CD20 monoclonal antibody in patients with relapsed/refractory CD20+ indolent NHL: correlation between clinical responses and AUC pharmacokinetics

PRO131921 is a third-generation, humanized anti-CD20 monoclonal antibody with increased antibody-dependent cytotoxicity and complement-dependent cytotoxicity compared to rituximab. In this phase I study, PRO131921 was administered as a single agent to patients with CD20+, relapsed or refractory, indolent non-Hodgkin lymphoma (NHL) who had been treated with a prior rituximab-containing regimen. The primary aim of this study was safety and tolerability of PRO131921. The secondary aim of the study, and focus of this report, was to determine the pharmacokinetics (PK) profile of PRO131921 and establish a correlation between drug exposure and clinical efficacy. Patients were treated with PRO131921 by intravenous infusion weekly for 4 weeks and the dose was escalated based on safety in a 3+3 design. Twenty-four patients were treated with PRO131921 at doses from 25mg/m(2) to 800 mg/m(2). Analysis of PK data demonstrated a correlation between higher normalized drug exposure (normalized AUC) and tumor shrinkage (p = .0035). Also, normalized AUC levels were higher among responders and subjects displaying tumor shrinkage versus subjects progressing or showing no regression (p = 0.030). In conclusion, PRO131921 demonstrated clinical activity in rituximab-relapsed and refractory indolent NHL patients. The observation that higher normalized AUC may be associated with improved clinical responses has potential implications in future trials of monoclonal antibody-based therapies, and emphasizes the importance of early PK studies to optimize antibody efficacy.

The optimal management of follicular lymphoma: an evolving field

Follicular lymphoma consists of a heterogeneous group of diseases that can vary dramatically in clinical course. As with other indolent lymphomas, follicular lymphoma is felt to be highly treatable, but ultimately incurable. The appropriate management of this disease ranges from close observation to chemoimmunotherapy based on presenting symptoms and comorbidities. In this article, we focus on the optimal management of follicular lymphoma, including prognostication, indications for treatment, and current treatment options. While a number of front-line chemoimmunotherapy options exist, R-CHOP (rituximab, cyclophosphamide, vincristine, prednisone) and BR (bendamustine, rituximab) tend to be favored due to efficacy and tolerability. Post-induction options include maintenance rituximab and radioimmunotherapy, but neither has demonstrated an overall survival benefit. In relapsed disease, patients can receive an alternative chemoimmunotherapy regimen or radioimmunotherapy, or participate in a clinical trial. There are a number of new biologic targeted therapies with promising activity in follicular lymphoma that have the potential to change our approach to this disease.

Update on front-line therapy for follicular lymphoma: chemo-immunotherapy with rituximab and survival

Over the last three decades, there has been a wide range of options in the management of follicular lymphoma, including observation (watching and waiting), single-agent or combination (e.g., alkylating agents, anthracyclines or purine nucleoside analogs) radiation therapy, immunotherapy alone or in combination with chemotherapy, and interferon. A number of trials studying the treatment of follicular lymphoma patients have investigated the benefit of adding rituximab either concurrently or sequentially to chemotherapy. In the current review, these studies were selected based on the fact that they were randomized Phase III studies with two arms comparing chemotherapy alone with rituximab-based chemo-immunotherapy regimens. In September 2006, the US FDA approved the use of rituximab (Rituxan) as front-line treatment of patients with follicular lymphoma in combination with cyclophosphamide, vincristine and prednisone (R-CVP) as well as for the treatment of patients with low-grade non-Hodgkin's Lymphoma who achieve stable disease or better following first-line treatment with the same chemotherapy regimen (CVP --> R). The European Medicines Agency also approved the use of rituximab (MabThera) as front-line treatment of patients with stage III-IV disease in combination with CVP chemotherapy. In conclusion, although the clinical studies discussed in this article provide evidence for a progression-free survival benefit, overall survival advantage was clearly shown for the first time in a recent update of the initial study in patients with follicular lymphoma.

Rituximab in the treatment of peripheral neuropathy associated with monoclonal gammopathy

Peripheral neuropathy associated with immunoglobulin (Ig)M gammopathy and anti-myelin-associated glycoprotein antibodies is frequently treatment-resistant and different treatment regimens carry substantial toxicity and side effects. More recently, the chimeric anti-CD20 monoclonal antibody rituximab has shown benefits in the treatment of peripheral neuropathy associated with IgM gammopathy with a favorable side-effect profile. There are no published reports of its use in the treatment of neuropathy associated with IgG and IgA gammopathies. Rituximab is usually given at 375 mg/m(2) intravenously with four weekly doses that may be repeated after 6-12 months. Large controlled studies are still pending but rituximab is an exciting and promising treatment offering another option in the treatment of peripheral neuropathy associated with IgM monoclonal gammopathy.

Interferon alpha with or without rituximab achieves a high response rate and durable responses in relapsed FL: 17 years' experience in a single centre

Maintenance interferon alpha (IFN-α) immunotherapy after induction chemotherapy prolongs progression-free survival (PFS) in untreated follicular lymphoma (FL). Little information is available about IFN-α use in relapsed FL. This study aims to evaluate the benefit of IFN-α as a treatment of low-burden FL relapse. This single-centre retrospective study identified 20 patients treated in 27 cases with IFN-α. We analysed all cases of IFN-α treatment in patients with low-burden FL in clinical relapse (11), partial response (5) or only with molecular minimal residual disease (MRD; 5). The treatment schedule was 3MIU IFN-α three times a week alone (16) or combined with four weekly rituximab (R; 11), according to the institution's policy. Except for the molecular relapses, responses were evaluated according to the IWG 1999 criteria. MRD was defined as a repeatedly detectable BCL2-IgH rearrangement in peripheral blood or bone marrow. In 22 cases of clinical relapses or partial responders, overall response rate was 68 %, with 55 % complete responses. Median PFS was 20.9 months (95 % confidence interval (95 % CI), 0-64.9) with 20.9 and 48.7 months in the IFN and R-IFN groups, respectively (p = 0.4). The median PFS of the five MRD cases was 133 months (95 % CI, 103-165). The Follicular Lymphoma International Prognostic Index score calculated at initiation of IFN-α treatment was predictive of time to relapse (p = 0.036). These results compare favourably with previous reports of the efficacy of R alone, and of R with IFN-α in relapse. Further research is required to explore the role of IFN-α in the management of FL.

Personalized dosimetry of 131I-rituximab radioimmunotherapy of non-hodgkin lymphoma defined by pharmacokinetics in bone marrow and blood

PURPOSE

To report a comparison of SPECT/CT technique with standard blood-based dosimetry methodology in a cohort of non-Hodgkin lymphoma (NHL) patients treated with 131I-rituximab anti-CD20 chimeric monoclonal antibody.

METHODOLOGY

Red marrow uptake was measured directly using serial quantitative whole-body imaging in conjunction with SPECT/CT in a cohort of 23 patients undergoing routine 131I-rituximab radioimmunotherapy of NHL. Absorbed dose measurements were then compared with radiation doses calculated using standard peripheral blood counting methodology.

RESULTS

Activity clearance from whole body of 88.7 hours measured by imaging 131I-rituximab was significantly slower (p<0.001) than the mean effective half-life clearance of 60.8 hours calculated from the sampling peripheral blood. The mean activity concentrations in bone marrow measured using SPECT/CT, and by blood sampling, extrapolated to the time of administration, were, however, concordant. The absorbed self-dose in red marrow, measured using imaging, was 1.02 Gy compared with the dose (0.81 Gy) calculated from blood sampling. Neutrophil toxicity correlated with absorbed dose by SPECT/CT imaging (p=0.01), whereas the blood sampling method demonstrated no correlation with any parameters of hematological toxicity.

CONCLUSION

Radiation dose to red marrow from 131I-rituximab is inherently underestimated by standard indirect peripheral blood counting methods. Personalized marrow dosimetry by quantitative gamma imaging more accurately predicts of hemopoietic myelotoxicity by direct measurement of the bone marrow activity concentration of 131I-rituximab.

The first antibody therapy for cancer: a personal experience

More than 100 years ago, Paul Ehrlich proposed that antibodies could be used for therapeutic purposes. Little progress was achieved until Köhler and Milstein developed hybridoma technology in the 1970s. In 1997, rituximab, the first antibody for the treatment of cancer, was approved. Its development (laboratory and clinical) broke records, provided proof of concept for antibodies as anticancer agents and opened the floodgates for research in the area. Rituximab, in combination with cyclophosphamide, hydroxydaunorubicin, oncovin and prednisone chemotherapy, was proven to increase the cure rate for patients with diffuse large cell lymphoma. Hopefully, over the next decades, we will find additional indications where antibodies in combination with other agents result in making patients cancer free, provide long-term survival and cures.

Phase I study of a modified regimen of ⁹⁰Yttrium-ibritumomab tiuxetan for relapsed or refractory follicular or transformed CD20+ non-Hodgkin lymphoma

Radioimmunotherapy capitalizes on the radiosensitivity of non-Hodgkin lymphoma (NHL) and the targeted nature of monoclonal antibodies. In an attempt to reverse bone marrow infiltration with B-cells and optimize the biodistribution of Yttrium-90 (⁹⁰Y)-ibritumomab tiuxetan, we conducted a phase I study combining a single course of ⁹⁰Y-ibritumomab tiuxetan after a 4-weekly course of rituximab in relapsed or refractory low-grade or transformed CD20+ B-cell NHLs with <25% marrow involvement. The 0.4 mCi/kg dose was associated with 80% grade-4 cytopenias. Dose escalation was held, and 6 patients were enrolled at a 0.3 mCi/kg cohort. As the 0.3 mCi/kg dose was well tolerated, the 0.4 mCi/kg cohort was expanded to 6 additional patients. In the expansion cohort, grade-4 cytopenia developed in 33%. Further dose escalation was held, and the maximum tolerated dose was determined at 0.4 mCi/kg. With this regimen, marrow involvement decreased in all patients with complete clearance in 50%. The overall response rate was 82%. With a median follow-up of 31.7 months, the median progression-free survival and time to next treatment were 12.3 and 10.9 months, respectively. Although this regimen was associated with a high response rate, the hematologic toxicity was higher than with the standard ⁹⁰Y-ibritumomab tiuxetan regimen.

Management of indolent lymphoma: where are we now and where are we going

Indolent lymphoma comprises a unique and challenging subset of non-Hodgkin lymphoma (NHL). While definitions of indolence will vary, the most common indolent NHL subtypes include follicular lymphoma, marginal zone lymphoma, and small lymphocytic lymphoma. Patients with indolent NHL (iNHL) excluding those with rare localized presentations are often met with an incurable but highly treatable NHL. In the rituximab era, response rates are approaching 90% with rituximab plus chemotherapy and time to next treatment are beginning to be measured in years. As a result of a prolonged natural history, we are encountering a gridlock of novel regimens and agents that appropriately fill peer-reviewed journals. In this review, we tackle a spectrum of topics in the management of indolent lymphoma including the initial approach to the newly diagnosed patient, approaches to first cytotoxic chemotherapy, maintenance and consolidation techniques, as well as highlight promising treatments on the horizon in iNHL. Clinicians continue to face tough choices in the management of iNHL. Through well-thought out clinical trials and peer-reviewed vetting of data we will continue to determine how to best manage the clinical continuum that is iNHL.

Antibody delivery of drugs and radionuclides: factors influencing clinical pharmacology

The therapeutic rationale of antibody conjugates is the selective delivery of a cytotoxin to tumor cells via binding and internalization of the monoclonal antibodies to a specific cell-surface antigen, thereby enhancing the therapeutic index of the cytotoxin. The key structural and functional components of an antibody conjugate are the antibody, the linker and the cytotoxin (chemical or radionuclide) with each component being critical for the successful development of the conjugate. Considerable efforts have been made in understanding the pharmacokinetics, pharmacodynamics, tissue distribution, metabolism and pharmacologic effects of these complex macromolecular entities. The purpose of this article is to discuss the properties and various structural components of antibody conjugates that influence their clinical pharmacology.

Rituximab-induced bronchiolitis obliterans organizing pneumonia

Rituximab-induced lung disease (R-ILD) is a rare entity that should be considered in patients treated with rituximab who present with dyspnea, fever, and cough, but no clear evidence of infection. A variety of pathologic findings have been described in this setting. Bronchiolitis obliterans organizing pneumonia (BOOP) is the most common clinicopathologic diagnosis, followed by interstitial pneumonitis, acute respiratory distress syndrome (ARDS), and hypersensitivity pneumonitis. Prompt diagnosis and treatment with corticosteroids are essential as discussed by Wagner et al. (2007). Here we present a case of an 82-year-old man who was treated with rituximab for recurrent marginal zone lymphoma. After the first infusion of rituximab, he reported fever, chills, and dyspnea. On computed tomography imaging, he was found to have bilateral patchy infiltrates, consistent with BOOP on biopsy. In our patient, BOOP was caused by single-agent rituximab, in the first week after the first infusion of rituximab. We reviewed the relevant literature to clarify the different presentations and characteristics of R-ILD and raise awareness of this relatively overlooked entity.

Spotlight on rituximab in chronic lymphocytic leukemia, low-grade or follicular lymphoma, and diffuse large B-cell lymphoma

Rituximab (MabThera®, Rituxan®) is a chimeric mouse anti-human CD20 monoclonal antibody. This article reviews the use of intravenous rituximab in the treatment of chronic lymphocytic leukemia (CLL), low-grade or follicular lymphoma, and diffuse large B-cell lymphoma. The addition of rituximab to fludarabine plus cyclophosphamide significantly prolonged progression-free survival both in previously untreated patients with CLL and in those with relapsed or refractory CLL, according to the results of two randomized, open-label, multicenter trials. In patients with previously untreated advanced follicular lymphoma, the addition of rituximab to chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone [CHOP]; cyclophosphamide, vincristine, and prednisone [CVP]; mitoxantrone, chlorambucil, and prednisolone; or cyclophosphamide, doxorubicin, etoposide, and prednisolone) was generally associated with better outcomes than chemotherapy alone in randomized, multicenter trials. In a similarly designed trial, progression-free survival was significantly longer in previously untreated patients with follicular lymphoma, other indolent lymphomas, or mantle-cell lymphoma who received rituximab plus bendamustine than in those receiving rituximab plus CHOP. Monotherapy with rituximab also demonstrated efficacy in patients with relapsed or refractory low-grade or follicular lymphoma, according to the results of noncomparative trials. In terms of maintenance therapy, progression-free survival was significantly prolonged with rituximab maintenance therapy versus observation alone in patients with advanced indolent lymphoma who had not progressed following first-line therapy with CVP and in patients with relapsed or refractory follicular lymphoma who had responded to CHOP (with or without rituximab), according to the results of randomized, open-label, multicenter trials. In four randomized, open-label, multicenter trials in younger or elderly patients with previously untreated diffuse large B-cell lymphoma, event-free survival, failure-free survival, progression-free survival, and overall survival were generally improved to a significant extent by the addition of rituximab to CHOP or CHOP-like chemotherapy. Intravenous rituximab was generally well tolerated in patients with CLL, low-grade or follicular lymphoma, or diffuse large B-cell lymphoma, both as monotherapy and when administered in combination with chemotherapy. Infusion reactions were one of the most commonly occurring adverse events in patients receiving intravenous rituximab. The results of pharmacoeconomic modeling analyses demonstrated that rituximab appears to be cost effective in patients with previously untreated follicular lymphoma, in patients with follicular lymphoma receiving rituximab maintenance therapy following treatment for relapsed or refractory disease, and in patients with previously untreated diffuse large B-cell lymphoma. In conclusion, rituximab remains a valuable therapy in patients with CLL, low-grade or follicular lymphoma, and diffuse large B-cell lymphoma and, in a variety of treatment settings, represents the standard of care.