Interindividual Variability of Response to Rituximab: From Biological Origins to Individualized Therapies

Multi-targeted immunotherapeutics to treat B cell malignancies

The concept of multi-targeted immunotherapeutic systems has propelled the field of cancer immunotherapy into an exciting new era. Multi-effector molecules can be designed to engage with, and alter, the patient's immune system in a plethora of ways. The outcomes can vary from effector cell recruitment and activation upon recognition of a cancer cell, to a multipronged immune checkpoint blockade strategy disallowing evasion of the cancer cells by immune cells, or to direct cancer cell death upon engaging multiple cell surface receptors simultaneously. Here, we review the field of multi-specific immunotherapeutics implemented to treat B cell malignancies. The mechanistically diverse strategies are outlined and discussed; common B cell receptor antigen targeting strategies are outlined and summarized; and the challenges of the field are presented along with optimistic insights for the future.

Update on the Application of Monoclonal Antibody Therapy in Primary Membranous Nephropathy

When first introduced, rituximab (RTX), a chimeric anti-CD20 monoclonal antibody, brought about an alternative therapeutic paradigm for primary membranous nephropathy (PMN). Rituximab was shown to be effective and safe in PMN patients with kidney dysfunction, with. patients receiving second-line rituximab therapy achieving remission as effectively as those patients who had not previously received immunotherapy. No safety issues were reported. The B cell-driven protocol seems to be as efficient as the 375 mg/m² × 4 regimen or 1 g × 2 regimen in achieving B cell depletion and remission, but patients with high M-type phospholipase A2 receptor (PLA2R) antibody levels may benefit from a higher dose of rituximab. While rituximab added another therapeutic option to the treatment regimen, it does have limitations as 20 to 40% of patients do not respond. Not all patients respond to RTX therapy for lymphoproliferative disorders either, therefore further novel anti-CD20 monoclonal antibodies have been developed and these may provide alternative therapeutic options for PMN. Ofatumumab, a fully human monoclonal antibody, specifically recognizes an epitope encompassing both the small and large extracellular loops of the CD20 molecule, resulting in increased complement-dependent cytotoxic activity. Ocrelizumab binds an alternative but overlapping epitope region to rituximab and displays enhanced antibody-dependent cellular cytotoxic (ADCC) activities. Obinutuzumab is designed to have a modified elbow-hinge amino acid sequence, leading to increased direct cell death induction and ADCC activities. In PMN clinical studies, ocrelizumab and obinutuzumab showed promising results, while ofatumumab displayed mixed results. However, there is a lack of randomized controlled trials with large samples, especially direct head-to-head comparisons. Alternative molecular mechanisms have been suggested in this context to explore novel therapeutic strategies. B cell activator-targeted, plasma cell-targeted and complement-directed treatments may lead to novel therapy paradigms for PMN. Exploratory strategies for the use of drugs with different mechanisms, such as a combination of rituximab and cyclophosphamide and a steroid, a combination of rituximab and a calcineurin inhibitor, may provide more rapid and efficient remission, but the combination of standard immunosuppression with rituximab could increase infection risk.

State of the Evidence: Drug Removal via Apheresis

Therapeutic apheresis refers to a diversity of procedures in which specific hematologic components (e.g., plasma, erythrocytes, leukocytes, etc.) with pathological associations are removed from circulation (with possible replacement) in order to treat a variety of disease processes. As pharmacologic agents also circulate with these components, their removal is sometimes incidental, or in the scenario of drug toxicity, a therapeutic goal. The corpus of published manuscripts on this subject has grown immensely over the past few decades; however, the breadth of diseases, methods, and drugs that co-exist in this space make it challenging to generate generalizable evidence regarding drug removal via apheresis. This review discusses factors worth considering when interpreting literature-reported data on drug removal by apheresis with examples from several notable studies and highlights topics in need of evidential improvement and growth as our palette of therapeutic agents continues to expand.

Monoclonal Antibody Monitoring: Clinically Relevant Aspects, A Systematic Critical Review

Monoclonal antibody (mAb) therapy does not usually lead to a clinical response in all patients and resistance may increase over time after repeated mAb administration. This lack or loss of response to the treatment may originate from different and little-known epigenetic, biomolecular, or pathophysiological mechanisms, although an inadequate serum concentration is perhaps the most likely cause, even if not widely recognized and investigated yet. Patient factors that influence the pharmacokinetics (PK) of a mAb should be taken into account. Multiple analyses of patient-derived PK data have identified various factors influencing the clearance of mAbs. These factors include the presence of antidrug antibodies, low serum albumin, high serum levels of C-reactive protein, high body weight, and gender differences among others. The same clearance processes involved in systemic clearance after intravenous administration are also involved in local first-pass catabolism after subcutaneous administration of mAbs. Therapeutic drug monitoring has been proposed as a way to understand and respond to the variability in clinical response and remission. For both classes of mAbs with anti-inflammatory and antitumor effects, dose-guided optimization based on the measurement of serum concentrations in individual patients could be the next step for a personalized and targeted mAb therapy.

Development, Validation, and Comparison of Two Mass Spectrometry Methods (LC-MS/HRMS and LC-MS/MS) for the Quantification of Rituximab in Human Plasma

Rituximab is a chimeric immunoglobulin G1-kappa (IgG1κ) antibody targeting the CD20 antigen on B-lymphocytes. Its applications are various, such as for the treatment of chronic lymphoid leukemia or non-Hodgkin’s lymphoma in oncology, and it can also be used in the treatment of certain autoimmune diseases. Several studies support the interest in therapeutic drug monitoring to optimize dosing regimens of rituximab. Thus, two different laboratories have developed accurate and reproductive methods to quantify rituximab in human plasma: one using liquid chromatography quadripolar tandem mass spectrometer (LC-MS/MS) and the other, liquid chromatography orbitrap tandem mass spectrometer (LC-MS/HRMS). For both assays, quantification was based on albumin depletion or IgG-immunocapture, surrogate peptide analysis, and full-length stable isotope-labeled rituximab. With LC-MS/MS, the concentration range was from 5 to 500 µg/mL, the within- and between-run precisions were <8.5%, and the limit of quantitation was 5 µg/mL. With LC-MS/HRMS, the concentration range was from 10 to 200 µg/mL, the within- and between-run accuracy were <11.5%, and the limit of quantitation was 2 µg/mL. Rituximab plasma concentrations from 63 patients treated for vasculitis were compared. Bland–Altman analysis and Passing–Bablok regression showed the interchangeability between these two methods. Overall, these methods were robust and reliable and could be applied to routine clinical samples.

Macrophage imaging and subset analysis using single-cell RNA sequencing

Macrophages have been associated with drug response and resistance in diverse settings, thus raising the possibility of using macrophage imaging as a companion diagnostic to inform personalized patient treatment strategies. Nanoparticle-based contrast agents are especially promising because they efficiently deliver fluorescent, magnetic, and/or radionuclide labels by leveraging the intrinsic capacity of macrophages to accumulate nanomaterials in their role as professional phagocytes. Unfortunately, current clinical imaging modalities are limited in their ability to quantify broad molecular programs that may explain (a) which particular cell subsets a given imaging agent is actually labeling, and (b) what mechanistic role those cells play in promoting drug response or resistance. Highly multiplexed single-cell approaches including single-cell RNA sequencing (scRNAseq) have emerged as resources to help answer these questions. In this review, we query recently published scRNAseq datasets to support companion macrophage imaging, with particular focus on using dextran-based nanoparticles to predict the action of anti-cancer nanotherapies and monoclonal antibodies.

Personalized Medicine for PLA2R1-Related Membranous Nephropathy: A Multicenter Randomized Control Trial

Background: Membranous Nephropathy (MN) is a rare autoimmune disease related to PLA2R1 antibodies in 70% of cases. One third of patients enter in spontaneous remission. PLA2R1 epitopes in MN have been characterized in four different domains of PLA2R1 and a mechanism of epitope spreading from the immunodominant CysR domain to CTLD1 and/or CTLD7 and/or CTLD8 domains has been associated with poor prognosis. Epitope spreading could predict spontaneous remission (45% in non-spreader patients vs. 0.05% in spreader patients). The comparison of different regimens of rituximab dosing showed that: (i) early remission rate depends on rituximab dosing, (ii) low dose could be enough for patients with anti-PLA2R1 activity restricted to CysR, (iii) high dose may be required for spreader patients. This study aims to evaluate the efficacy of personalized treatment in PLA2R1-related MN depending on the epitope spreading status, in comparison to the established GEMRITUX protocol.

Methods: A multicenter, randomized, controlled, prospective clinical trial will be conducted in 22 French hospitals. Sixty-four consecutive patients with PLA2R1-related MN will be randomly assigned to either the control group following the GEMRITUX protocol (symptomatic treatment for 6 months, if the nephrotic syndrome (NS) persists at month-6, two 375 mg/m² rituximab infusions at 1 week interval) or the personalized treatment group (patients with no epitope spreading at month-0 will be treated with symptomatic treatment for 6 months, if NS persists at month-6, two 375 mg/m² rituximab infusions at 1 week interval; patients with epitope spreading at month-0 or month-6 with persistent NS will be treated immediately with two 1 g rituximab infusions at 2 week interval). The primary study outcome is the rate of clinical remission at month-12. The secondary outcomes include complete and partial remissions, immunological remissions, relapses, proteinuria, albuminuria, serum creatinine, eGFR, PLA2R1 antibody titers, severe infections, lymphocyte counts and lymphocyte phenotype, residual rituximab levels at month-3 and neutralizing anti-rituximab antibodies at month-6 and month-12 after rituximab treatment.

Discussion: The results of this trial will confirm whether personalized treatment of PLA2R1-driven nephrotic MN is more efficient to induce clinical remission than the established GEMRITUX protocol, and may thus contribute to improved remission rates and reduced relapse rates.

Trial registration: NCT 03804359 trial number. Registered on 15th January 2019.

Neutralizing Anti-Rituximab Antibodies and Relapse in Membranous Nephropathy Treated With Rituximab

Membranous Nephropathy (MN) is an autoimmune disease associated with antibodies against podocyte proteins: M-type phospholipase A2 receptor (PLA2R1) or thrombospondin type-1 domain-containing 7A (THSD7A) in 70 and 3% of patients, respectively. Antibody titer is correlated with disease activity: rising during active disease and decreasing before remission. Therefore, decreasing PLA2R1-Antibodies titer has become an important goal of therapy. Rituximab a chimeric monoclonal antibody induces remission in 60-80% of primary MN patients. All monoclonal antibodies such as rituximab can elicit antidrug antibodies, which may interfere with therapeutic response. We aim to analyze the relevance of anti-rituximab antibodies on the outcome of MN after a first course of rituximab. Forty-four MN patients were included and treated with two 1 g infusions of rituximab at 2-weeks interval. Anti-rituximab antibodies, CD19 count, and clinical response were analyzed. Then, we (i) analyzed the association of anti-rituximab antibodies at month-6 with response to treatment: remission, relapse and the need for another rituximab course; (ii) confirmed if anti-rituximab antibodies could neutralize rituximab B-cells depletion; and (iii) tested whether anti-rituximab antibodies could cross-inhibit new humanized anti-CD20 therapies. Anti-rituximab antibodies were detected in 10 patients (23%). Seventeen patients received a second rituximab course after a median time of 12 months (7-12), following nine cases of resistance and eight relapses. Anti-rituximab antibodies were significantly associated with faster B-cell reconstitution at month-6 (75 [57-89] vs. 2 [0-41] cells/μl, p = 0.006), higher proteinuria 12 months after rituximab infusion (1.7 [0.7; 5.8] vs. 0.6 [0.2; 3.4], p = 0.03) and before treatment modification (3.5 [1.6; 7.1] vs. 1.7 [0.2; 1.7] p = 0.0004). Remission rate 6 months after rituximab was not different according to anti-rituximab status (p > 0.99) but the rate of relapse was significantly higher for patients with anti-rituximab antibodies (p < 0.001). These patients required more frequently a second course of rituximab infusions (7/10 vs. 10/34, p = 0.03). Anti-rituximab antibodies neutralized rituximab activity in 8/10 patients and cross-reacted with other humanized monoclonal antibodies in only two patients. Three patients with anti-rituximab antibodies were successfully treated with ofatumumab. Anti-rituximab antibodies could neutralize rituximab B cells cytotoxicity and impact clinical outcome of MN patients. Humanized anti-CD20 seems to be a satisfying therapeutic alternative for patients with anti-rituximab antibodies and resistant or relapsing MN.

High-Dose Rituximab and Early Remission in PLA2R1-Related Membranous Nephropathy

BACKGROUND AND OBJECTIVES

Different rituximab protocols are used to treat membranous nephropathy. We compared two rituximab protocols in patients with membranous nephropathy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Twenty-eight participants from the NICE cohort received two infusions of 1-g rituximab at 2-week intervals, whereas 27 participants from the Prospective Randomized Multicentric Open Label Study to Evaluate Rituximab Treatment for Membranous Nephropathy (GEMRITUX) cohort received two infusions of 375 mg/m² at 1-week interval. We measured serum rituximab levels and compared remission at month 6 and before any treatment modification and analyzed factors associated with remission and relapses.

RESULTS

Remissions occurred in 18 (64%) versus eight (30%) from the NICE and GEMRITUX cohort (P=0.02) at month 6, respectively, and in 24 (86%) versus 18 (67%) participants (P=0.12) before treatment modification, respectively. Median time to remission was 3 [interquartile range (IQR), 3-9] and 9 [IQR, 6-12] months for NICE and GEMRITUX cohorts respectively (P=0.01). Participants from the NICE cohort had higher circulating level of rituximab and lower CD19 counts (3.3 µg/L [IQR, 0.0-10.8] versus 0.0 [IQR, 0.0-0.0] P<0.001 and 0.0 [IQR, 0.0-2.0] versus 16.5 [IQR, 2.5-31.0] P<0.001) at month 3, lower level of anti-PLA2R1 antibodies at month 6 (0.0 [IQR, 0.0-8.0] versus 8.3 [IQR, 0.0-73.5] P=0.03). In the combined study population, lower epitope spreading at diagnosis and higher rituximab levels at month 3 were associated with remissions at month 6 (13/26 (50%) versus 22/29 (76%) P=0.05 and 2.2 µg/ml [IQR, 0.0-10.9] versus 0.0 µg/ml [IQR, 0.0-0.0] P<0.001 respectively). All non-spreaders entered into remission whatever the protocol. Eight of the 41 participants who reached remission had relapses. Epitope spreading at diagnosis (8/8 (100%) versus 16/33 (48%) P=0.01) and incomplete depletion of anti-PLA2R1 antibodies at month 6 (4/8 (50%) versus 5/33 (9%) P=0.05) were associated with relapses.

CONCLUSIONS

Our work suggests that higher dose rituximab protocol is more effective on depletion of B-cells and lack of epitope spreading is associated with remission of membranous nephropathy.

Role of Calcium Signaling in GA101-Induced Cell Death in Malignant Human B Cells

GA101/obinutuzumab is a novel type II anti-CD20 monoclonal antibody (mAb), which is more effective than rituximab (RTX) in preclinical and clinical studies when used in combination with chemotherapy. Ca²⁺ signaling was shown to play a role in RTX-induced cell death. This report concerns the effect of GA101 on Ca²⁺ signaling and its involvement in the direct cell death induced by GA101. We reveal that GA101 triggered an intracellular Ca²⁺ increase by mobilizing intracellular Ca²⁺ stores and activating Orai1-dependent Ca²⁺ influx in non-Hodgkin lymphoma cell lines and primary B-Cell Chronic Lymphocytic Leukemia (B-CLL) cells. According to the cell type, Ca²⁺ was mobilized from two distinct intracellular compartments. In Raji, BL2, and B-CLL cells, GA101 induced a Ca²⁺ release from lysosomes, leading to the subsequent lysosomal membrane permeabilization and cell death. Inhibition of this calcium signaling reduced GA101-induced cell death in these cells. In SU-DHL-4 cells, GA101 mobilized Ca²⁺ from the endoplasmic reticulum (ER). Inhibition of ER replenishment, by blocking Orai1-dependent Ca²⁺ influx, led to an ER stress and unfolded protein response (UPR) which sensitized these cells to GA101-induced cell death. These results revealed the central role of Ca²⁺ signaling in GA101’s action mechanism, which may contribute to designing new rational drug combinations improving its clinical efficacy.

Cardiovascular Adverse Events Complicating the Administration of Rituximab: Report of Two Cases

Rituximab is a murine/human chimeric monoclonal antibody directed against the CD20 antigen. It is widely used in combination with polychemotherapy regimens for the treatment of hematological disorders. There is no evidence of direct cardiotoxicity of the drug but a few cases of cardiovascular adverse events have been reported in the literature.

We report on two patients affected by stage IV non-Hodgkin lymphoma with bone marrow infiltration and peripheral blood involvement who experienced cardiovascular accidents temporally related to rituximab infusion. In both cases the monoclonal antibody was administered in association with a polychemotherapy regimen but administration was postponed several days later in order to avoid severe cytokine release syndrome because of the high tumor burden.

The first case concerns an episode of atrial fibrillation in a patient with a diagnosis of small B-cell lymphoma. The episode happened immediately after rituximab infusion. In the second case there was an episode of chest pain associated with fever and chills during rituximab infusion in a patient with a diagnosis of mantle cell lymphoma. In both cases we noticed an unusual correlation between symptom recurrence and the speed of rituximab infusion. Both patients presented several cardiovascular risk factors but preliminary cardiac function assessment excluded signs of heart dysfunction.

The pathogenesis of cardiovascular events during rituximab infusion remains unclear. A key role might be played by cytokine release from B cells as a consequence of rituximab activity. Moreover, pre-existing silent cardiac damage could be co-responsible for the clinical manifestations we reported.

We consider our clinical experience relevant because it raises an issue of good clinical practice: despite rituximab's good tolerability profile, patients with cardiovascular risk factors should undergo accurate cardiac assessment so that silent heart disease can be detected. If the suspicion of cardiac damage is high, more extensive cardiac assessment is recommended.

Characterizing CD137 upregulation on NK cells in patients receiving monoclonal antibody therapy

Background

In the era of personalized cancer medicine, identifying techniques for effectively matching patients to efficacious treatments is a critical step in the treatment process. The advent of anti-cancer immunotherapies necessitates novel approaches to biomarker identification beyond traditional genomic profiling. One promising approach is incorporation of nomograms into treatment decisions. Nomograms are prediction tools, based on statistical modeling, designed to predict treatment outcomes. As a first step toward developing a nomogram, we conducted analyses to predict CD137 expression of natural killer cells after monoclonal antibody (mAb) treatment.

Patients and methods

Patient, tumor and immune characteristics were collected from 199 patients with breast cancer (N = 62), head/neck cancers (N = 46) and non-Hodgkin's lymphoma (NHL) (N = 91), who were receiving mAb therapy as part of clinical trials. The difference in CD137 expression before and after mAb therapy was assessed by flow cytometry. To evaluate those who respond to mAb therapy via increased CD137 expression, we applied classification and regression trees (CART), multivariable lasso regression tools and Random Forest.

Results

The CD137 expression was significantly different for each cancer type [mean (SD): Breast: 6.6 (6.5); Head/Neck: 11.0 (7.0); NHL: 7.5 (7.1), P < 0.0001]. For breast cancer and NHL, FcR polymorphism and baseline CD137 expression were significant predictors of increased CD137 expression; for head/neck cancer, FcR polymorphism and age were significant predictors of increased expression.

Conclusions

Our preliminary results suggest that FcR polymorphism, pre-treatment CD137 expression and age are significant predictors of CD137 upregulation in patients. This study demonstrates that the development of a nomogram for therapy response is feasible. Further work validating our models in an independent cohort will provide the next steps in developing a nomogram that may be used to individualize this therapeutic approach for patients (NCT01114256).

An improved method to quantify human NK cell-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) per IgG FcR-positive NK cell without purification of NK cells

Natural killer (NK) lymphocyte ADCC supports anti-viral protection and monoclonal antibody (mAb) anti-tumor therapies. To predict in vivo ADCC therapeutic responses of different individuals, measurement of both ADCC cellular lytic capacity and their NK cellular receptor recognition of antibodies on 'target' cells are needed, using clinically available amounts of blood. Twenty ml of blood provides sufficient peripheral blood mononuclear cells (PBMCs) for the new assay for lytic capacity described here and for an antibody EC₅₀ assay for Fc-receptor recognition. For the lytic capacity assay, we employed flow cytometry to quantify the CD16A IgG Fc-receptor positive NK effector cells from PBMCs to avoid loss of NKs during isolation. Targets were ⁵¹Cr-labeled Daudi B cells pretreated with excess obinutuzumab type 2 anti-CD20 mAb and washed; remaining free mAb was insufficient to convert B cells in the PBMCs into 'targets'. We calculated: the percentage Daudis killed at a 1:1 ratio of CD16A-positive NK cells to Daudis (CX1:1); lytic slopes; and ADCC₅₀ lytic units. Among 27 donors, we detected wide ranges in CX1:1 (16-73% targets killed) and in lytic slopes. Slope variations prevented application of lytic units. We recommend CX1:1 to compare individuals' ADCC capacity. CX1:1 was similar for purified NK cells vs. PBMCs and independent of CD16A V & F genotypes and antibody EC₅₀s. With high mAb bound onto targets and the high affinity of obinutuzumab Fc for CD16A, CX1:1 measurements discern ADCC lytic capacity rather than antibody recognition. This assay allows ADCC to be quantified without NK cell isolation and avoids distortion associated with lytic units.

A "Prozone-Like" Effect Influences the Efficacy of the Monoclonal Antibody ABT-700 against the Hepatocyte Growth Factor Receptor

ABT-700 is a therapeutic antibody against the hepatocyte growth factor receptor (MET). At doses or regimens that lead to exposures exceeding optimum in vivo, the efficacy of ABT-700 is unexpectedly reduced. We hypothesized that this reduction in efficacy was due to a "prozone-like" effect in vivo. A prozone-like effect, which is a reduction in efficacy beyond optimum exposure, is caused due a mechanism similar to the generation of false negative flocculation tests by excessive antibody titres. In vitro, we demonstrate that at higher ABT-700 concentrations, this "prozone-like" effect is mediated by a progressive conversion from bivalent to ineffective monovalent binding of the antibody. In vivo, the efficacy of ABT-700 is dependent on an optimum range of exposure as well. Our data suggest that the "prozone-like" effect is operative and independent of target expression. ABT-700 dose, regimen, exposure, and tumor burden are interdependent variables influencing the "prozone-like" effect and mediating and in vivo efficacy. By optimization of dosage and regimen we demonstrate that the "prozone-like" effect can be alleviated and ABT-700 efficacy at varying tumor loads can be further extended in combination with cisplatin. Our results suggest that optimization of exposure taking tumor burden into account may alleviate "prozone-like" effects without compromising efficacy.

Converting Lymphoma Cells into Potent Antigen-Presenting Cells for Interferon-Induced Tumor Regression

Anti-hCD20 is a therapeutic mAb that is clinically used to treat B-cell lymphoma. Some lymphomas are resistant to anti-hCD20; others relapse after treatment with anti-hCD20. Using a syngeneic immunocompetent mouse model, we observed that targeting lymphoma with interferon-α (IFNα) abolished resistance of B-cell lymphoma to anti-CD20 while limiting interferon (IFN)-associated systemic toxicity in the host. Control of tumors by a fusion of anti-CD20 and IFNα (anti-CD20-IFNα) depended on existing tumor-infiltrating CD8⁺ T cells. Although lymphomas were resistant to IFN-directed killing, IFN-exposed tumor cells became the dominant antigen-presenting cells (APC) for the reactivation of tumor-infiltrating CD8⁺ T cells that then controlled those lymphomas. Anti-CD20-IFNα also abolished checkpoint blockade resistance in advanced B-cell lymphoma. Our findings indicate that anti-CD20-IFNα eradicates B-cell lymphoma by employing tumor cells as APCs to reactivate tumor-infiltrating CD8⁺ T cells and synergizing with anti-PD-L1 treatment. Cancer Immunol Res; 5(7); 560-70. ©2017 AACR.

Analysis of the prognostic value of BMI and the difference in its impact according to age and sex in DLBCL patients

Studies that have evaluated the prognostic value of body mass index (BMI) in patients with diffuse large B-cell lymphoma have recently been reported. However, the impact of BMI on survival outcomes remains controversial. We retrospectively analyzed the data of 406 diffuse large B-cell lymphoma patients treated with R-CHOP or R-CHOP-like regimens. The number (%) of patients that were categorized into 1 of 4 groups according to BMI were underweight (<18.5 kg/m² ), 58 (14.3%); normal weight (≥18.5 to <25 kg/m² ), 262 (64.5%); overweight (≥25 to <30 kg/m² ), 75 (18.5%); and obese (≥30.0 kg/m² ), 11 (2.7%). While the prognosis of overweight patients was good, being similar to that of normal weight, underweight, and obese patients had a worse prognosis (5-y overall survival [OS] was 57.9%, 74.3%, 73.4%, and 40.9% for underweight, normal weight, overweight, and obese patients, respectively; P = .004). In multivariate analysis, underweight and obesity were independent prognostic factors for OS compared with normal weight (hazard ratios 2.90 and 5.17, respectively). In elderly female patients (≥70 y), patients with a low BMI (<25 kg/m² ) had significantly inferior OS than those with a high BMI (≥25 kg/m² ) (5-y OS, 61.5% vs 85.7%; P = .039). In contrast, in young female patients (<70 years), patients with a low BMI had significantly better OS than those with a high BMI (5-y OS, 88.6% vs 46.4%; P < .001). In male patients, there were no differences in the effect of BMI on OS between young and elderly patients. In this study, we demonstrated that being underweight and obese were independent prognostic factors compared with being normal weight. In female patients, BMI had a different impact on the prognosis of young and elderly patients, whereas in male patients, there was no difference in the effect of BMI on prognosis according to age.

miR-125b and miR-532-3p predict the efficiency of rituximab-mediated lymphodepletion in chronic lymphocytic leukemia patients. A French Innovative Leukemia Organization study

The underlying in vivo mechanisms of rituximab action remain incompletely understood in chronic lymphocytic leukemia. Recent data suggest that circulating micro-ribonucleic acids correlate with chronic lymphocytic leukemia progression and response to rituximab. Our study aimed at identifying circulating micro-ribonucleic acids that predict response to rituximab monotherapy in chronic lymphocytic leukemia patients. Using a hierarchical clustering of micro-ribonucleic acid expression profiles discriminating 10 untreated patients with low or high lymphocyte counts, we found 26 micro-ribonucleic acids significantly deregulated. Using individual real-time reverse transcription polymerase chain reaction, the expression levels of micro-ribonucleic acids representative of these two clusters were further validated in a larger cohort (n=61). MiR-125b and miR-532-3p were inversely correlated with rituximab-induced lymphodepletion (P=0.020 and P=0.001, respectively) and with the CD20 expression on CD19⁺ cells (P=0.0007 and P<0.0001, respectively). In silico analyses of genes putatively targeted by both micro-ribonucleic acids revealed a central role of the interleukin-10 pathway and CD20 (MS4A1) family members. Interestingly, both micro-ribonucleic acids were negatively correlated with MS4A1 expression, while they were positively correlated with MS4A3 and MSA47 Our results identify novel circulating predictive biomarkers for rituximab-mediated lymphodepletion efficacy in chronic lymphocytic leukemia, and suggest a novel molecular mechanism responsible for the rituximab mode of action that bridges miR-125b and miR-532-3p and CD20 family members. (clinicaltrials.gov Identifier: 01370772).

CTLA-4 Limits Anti-CD20-Mediated Tumor Regression

PURPOSE

The inhibition of tumor growth by anti-CD20 antibody (Ab) treatment is mediated by Ab- and complement-dependent cytotoxicity in xenograft tumor models. In addition, anti-CD20 therapy for B-cell lymphoma can result in intrinsic and extrinsic tumor resistance to further Ab treatment. However, adaptive immune response-related resistance has not been well studied in anti-CD20-mediated tumor control, and adaptive immunity has long been underestimated. The purpose of this study was to explore whether T cells are involved in mediating the effects of anti-CD20 therapy and what factors contribute to adaptive immune response-related resistance.

EXPERIMENTAL DESIGN

Using a syngeneic mouse B-cell lymphoma model, we investigated the role of CD8⁺ T cells in anti-CD20-mediated tumor regression. Furthermore, we revealed how the tumor-specific T-cell response was initiated by anti-CD20. Finally, we studied adaptive immune response-related resistance in advanced B-cell lymphoma.

RESULTS

CD8⁺ T cells played an essential role in anti-CD20-mediated tumor regression. Mechanistically, anti-CD20 therapy promoted dendritic cell (DC)-mediated cross-presentation. Importantly, macrophages were also necessary for the increase in the tumor-specific CTL response after anti-CD20 treatment, via the production of type I IFN to activate DC function. Furthermore, adaptive resistance is gradually developed through the CTLA-4 pathway in Treg cells in larger lymphomas. Further blockade of CTLA-4 can synergize with anti-CD20 treatment in antitumor activities.

CONCLUSIONS

The therapeutic function of anti-CD20 depends on tumor-specific CD8⁺ T-cell responses initiated by anti-CD20 through macrophages and DCs. CTLA-4 blockade can synergize with anti-CD20 to overcome adaptive immune response-related resistance in advanced B-cell lymphoma. Clin Cancer Res; 23(1); 193-203. ©2016 AACR.

Optimising B-cell depletion in autoimmune disease: is obinutuzumab the answer?

In Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE), B-cell depletion therapy using rituximab results in variable clinical responses between individuals, which likely relates to variable B-cell depletion in the presence of immune defects. Outcomes in clinical trials with other type I anti-CD20 mAbs, ocrelizumab and ofatumumab, are comparable to rituximab. A mechanistically different type II mAb, obinutuzumab (OBZ), with greater capacity for B-cell depletion, has recently entered clinical trials in SLE. Here we consider whether type II anti-CD20 mAbs will provide mechanistic advantages to overcome the disease-related immune defects in autoimmune diseases such as SLE.

FCGR3A/2A polymorphisms and diffuse large B-cell lymphoma outcome treated with immunochemotherapy: a meta-analysis on 1134 patients from two prospective cohorts

Single nucleotide polymorphisms (SNPs) in FCγ-receptor genes FCGR3A (rs396991) and FCGR2A (rs1801274) influence the affinity of the Fc portion of anti-CD20 immunoglobulin G1 monoclonal antibody. Their roles in diffuse large B-cell lymphoma (DLBCL) treated with rituximab in combination with anthracycline-based chemotherapy remain controversial. To address this question, we genotyped FCGR2A and FCGR3A SNPs in two prospective DLBCL cohorts from Lymphoma Study Association trials (N = 554) and Iowa/Mayo Specialized Program Of Research Excellence (N = 580). Correlations with treatment response and hematological toxicity were assessed in Lymphoma Study Association. Correlation with event-free survival (EFS) and overall survival (OS) was performed in both cohorts, followed by a meta-analysis to increase power. Our study shows the absence of correlation between these SNPs and treatment response. Grades 3 and 4 febrile neutropenia during treatment was more frequently observed in FCGR3A VV (39%) than VF (29%) and FF (32%) carriers (p = 0.04). Our analysis for EFS and OS shows that FCGR3A was not associated with outcome. In a meta-analysis using an ordinal model, FCGR2A (per R allele) was associated with a better EFS (hazard ratio = 0.87; 95%CI, 0.76-0.99; p = 0.04) and OS (hazard ratio = 0.86; 95%CI, 0.73-1.00; p = 0.05) which was not altered after adjustment for the International Prognostic Index. Overall, our data demonstrate that patients with DLBCL with the low-affinity FCγRIIA RR had an unexpectedly better outcome than FCγRIIA H carriers. Whether rituximab efficacy is improved in FCγRIIA RR patients due a clearance reduction or other functions of FCγRIIA in DLBCL should be investigated (clinicaltrials.gov identifiers: NCT00135499, NTC00135499 NCT00140595, NCT00144807, NCT00144755, NCT01087424, and NCT00301821). Copyright © 2016 John Wiley & Sons, Ltd.

Obinutuzumab for relapsed or refractory indolent non-Hodgkin's lymphomas

The use of anti-CD20 monoclonal antibodies (mAbs), such as rituximab, in CD20-positive B-cell malignancies has dramatically improved the outcome of chronic lymphoid leukemia and non-Hodgkin's lymphomas (NHL). However, the occurrence of relapse and development of rituximab-refractory disease highlight the need to develop novel anti-CD20 mAbs, with improved mechanisms of action. Obinutuzumab is the first humanized type II glycoengineered anti-CD20 mAb. In vitro and in vivo data suggested several differences compared with rituximab, including a low level of complement-dependent cytotoxicity and an increased direct nonapoptotic cell death. Moreover, the glycoengineered Fc-linked nonfucosylated oligosaccharide enhanced the Fc-Fcγ receptor (FcγR) IIIa interaction, resulting in improved antibody-dependent cellular cytotoxicity and phagocytosis. Preclinical models suggested that these differences translate into superior survival in murine lymphoma models. Phase I/II trials in monotherapy in relapsed or refractory B-cell NHL demonstrated that obinutuzumab has an acceptable safety profile, infusion-related reactions being the most common adverse event. In rituximab-refractory indolent NHL, the recent randomized phase III GADOLIN study demonstrated an improved median progression-free survival for patients treated with obinutuzumab plus bendamustine rather than bendamustine alone. Further trials are ongoing to determine the role of obinutuzumab as a first-line agent in the treatment of follicular lymphoma.

Post-transplant lymphoproliferative disorder in adult renal transplant recipients: survival and prognosis

Post-transplant lymphoproliferative disorder (PTLD) is a rare, serious complication following solid organ transplantation, with an incidence of 2.6 cases per 1000 patient years. Optimal treatment strategies and risk stratifications specific to kidney transplantation are lacking and PTLD mortality remains high. This study investigated survival and prognosis in 89 cases of PTLD presenting over 44 years at Manchester Royal Infirmary. Patient survival following diagnosis was 72% at 6 months, 67% at 1 year and 54% at 3 years. In multivariate analysis, a poorer 3 year survival was associated with acute kidney injury at diagnosis (p = 0.0001), impaired renal function (p = 0.04), early onset (p = 0.02), T cell disease (p = 0.02) and previous treatment with anti-thymocyte globulin (p = 0.04). The inclusion of graft function adds prognostic value to risk stratification and should be explored further. Strategies to improve survival should include timing and choice of immuno-chemotherapy, preparation for dialysis and aggressive surveillance for sepsis and treatment toxicity.

New developments in the treatment of chronic lymphocytic leukemia: role of obinutuzumab

Obinutuzumab is a novel glycoengineered type II anti-CD20 monoclonal antibody with a higher affinity for CD20 epitope, enhanced antibody-dependent cellular cytotoxicity and direct cell death, leading to superior cytotoxicity compared with rituximab. The approval of obinutuzumab by US Food and Drug Administration was based on a pivotal, phase III, randomized trial of chlorambucil monotherapy (n=118), chlorambucil plus obinutuzumab (n=333), or chlorambucil plus rituximab (n=330) in previously untreated patients with CLL. Obinutuzumab was administered intravenously as 1,000 mg on days 1, 8, and 15 of cycle 1 and day 1 of subsequent cycles. Obinutuzumab plus chlorambucil was associated with an overall response rate of 78% and a median progression-free survival of 26.7 months. Overall, obinutuzumab was fairly well tolerated in this pivotal study. The incidence of grade 3 or higher adverse events was infusion-related reactions (20%), neutropenia (33%), thrombocytopenia (10%), and infections (7%). Obinutuzumab in combination with chlorambucil is a safe and effective new treatment option for previously untreated elderly patients with CLL. It should become the new standard of care for these patients with significant co-morbidities who are not candidates for fludarabine-based therapy. Obinutuzumab combination therapy with several agents that inhibit kinases involved in the B-cell receptor signaling pathway, as well as many other agents utilized in the frontline and relapsed/refractory setting, is currently under investigation. As the results from these studies become available, the role of obinutuzumab is expected to expand to other settings.

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.

Clinical role of obinutuzumab in the treatment of naive patients with chronic lymphocytic leukemia

The introduction of targeted therapy against CD20⁺ with the monoclonal antibody rituximab has dramatically improved the survival of B-cell non-Hodgkin lymphoma including chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma. Unfortunately, CLL remains incurable with chemoimmunotherapy, with many patients having refractory or relapsing disease after rituximab-containing therapy. Obinutuzumab (GA101) is a novel humanized Type II anti-CD20 monoclonal antibody that has been investigated and compared to rituximab. Here, we provide an overview of obinutuzumab, including its mechanisms of action, preclinical data, and Phase I to III clinical studies. Preclinical data illustrate obinutuzumab’s higher potency compared to rituximab through antibody-dependent cellular cytotoxicity and direct cell death. Recently, the CLL11 study presented a significant benefit from obinutuzumab chemoimmunotherapy and supports its use for treatment-naive unfit CLL patients. Herein, we review that obinutuzumab is both a safe and effective alternative to rituximab.

Body mass index and other anthropometric parameters in patients with diffuse large B-cell lymphoma: physiopathological significance and predictive value in the immunochemotherapy era

Diffuse large B-cell lymphoma (DLBCL) is the most common form of aggressive non-Hodgkin lymphoma, accounting for 30-40% of newly diagnosed cases. Obesity is a well-defined risk factor for DLBCL. However, the impact of body mass index (BMI) on DLBCL prognosis is controversial. Recent studies suggest that skeletal muscle wasting (sarcopenia) or loss of fat mass can be detected by computed tomography (CT) images and is useful for predicting the clinical outcome in several types of cancer including DLBCL. Several hypotheses have been proposed to explain the differences in DLBCL outcome according to BMI or weight that include tolerance to treatment, inflammatory background and chemotherapy or rituximab metabolism. In this review, we summarize the available literature, addressing the impact and physiopathological relevance of simple anthropometric tools including BMI and tissue distribution measurements. We also discuss their relationship with other nutritional parameters and their potential role in the management of patients with DLBCL.

Synergistic anti-tumor activity of acadesine (AICAR) in combination with the anti-CD20 monoclonal antibody rituximab in in vivo and in vitro models of mantle cell lymphoma

Mantle cell lymphoma (MCL) is considered one of the most challenging lymphoma, with limited responses to current therapies. Acadesine, a nucleoside analogue has shown antitumoral effects in different preclinical cancer models as well as in a recent phase I/II clinical trial conducted in patients with chronic lymphocytic leukemia. Here we observed that acadesine exerted a selective antitumoral activity in the majority of MCL cell lines and primary MCL samples, independently of adverse cytogenetic factors. Moreover, acadesine was highly synergistic, both in vitro and in vivo, with the anti-CD20 monoclonal antibody rituximab, commonly used in combination therapy for MCL. Gene expression profiling analysis in harvested tumors suggested that acadesine modulates immune response, actin cytoskeleton organization and metal binding, pointing out a substantial impact on metabolic processes by the nucleoside analog. Rituximab also induced changes on metal binding and immune responses. The combination of both drugs enhanced the gene signature corresponding to each single agent, showing an enrichment of genes involved in inflammation, metabolic stress, apoptosis and proliferation. These effects could be important as aberrant apoptotic and proinflammatory pathways play a significant role in the pathogenesis of MCL. In summary, our results suggest that acadesine exerts a cytotoxic effect in MCL in combination with rituximab, by decreasing the proliferative and survival signatures of the disease, thus supporting the clinical examination of this strategy in MCL patients.

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.

Monoclonal antibodies: Pharmacokinetics as a basis for new dosage regimens?

Complete monoclonal IgG antibodies which are in use in clinical practice share some pharmacological properties resulting in high concentrations in plasma. This fact is reflected in their low volumes of distribution, which can also be correlated with a high molecular weight and water solubility. This feature allows a novel approach to be applied to the dosing schedule for this group of drugs with fixed doses being used instead of the initially developed weight- or body surface-adjusted dosing schedules. In addition, the development of a new formulation containing hyaluronidase allows a subcutaneous route of administration to be used, because hyaluronidase creates a space in the subcutaneous tissue that helps antibody absorption. This method requires higher doses, but has allowed testing the feasibility of administering a fixed dose, with no individual dose adjustments based on weight or body surface. Moreover, loading doses are not needed, because the first dose results, within 3 weeks, in minimum concentrations that are higher than effective concentrations.

Fcγ-receptor IIIA polymorphism p.158F has no negative predictive impact on rituximab therapy with and without sequential chemotherapy in CD20-positive posttransplant lymphoproliferative disorder

We retrospectively analyzed the p.V158F polymorphism of Fcγ-receptor IIIA (FCGR3A, CD16) in patients with PTLD treated with rituximab monotherapy. Previous reports had indicated that the lower affinity F allele affects rituximab-mediated antibody-dependent cellular cytotoxicity (ADCC) and is linked to inferior outcome of rituximab monotherapy in B cell malignancies. 25 patients with PTLD after solid organ transplantation were included in this analysis. They had received 4 weekly doses of rituximab as part of two clinical trials, which had a rituximab monotherapy induction regimen in common. 16/25 patients received further treatment with CHOP-21 after rituximab monotherapy (PTLD-1, NCT01458548). The FCGR3A status was correlated to the response after 4 cycles of rituximab monotherapy. Response to rituximab monotherapy was not affected by F carrier status. This is in contrast to previous findings in B cell malignancies where investigators found a predictive impact of FCGR3A status on outcome to rituximab monotherapy. One explanation for this finding could be that ADCC is impaired in transplant recipients receiving immunosuppression. These results suggest that carrying a FCRG3A F allele does not negatively affect rituximab therapy in immunosuppressed patients.

Efficacy and safety of rituximab plus low-dose oral fludarabine and cyclophosphamide as first-line treatment of elderly patients with indolent non-Hodgkin lymphomas

Indolent non-Hodgkin lymphomas (iNHLs) are B-cell neoplasms for which no consensus is available about optimal first-line therapy. Chemoimmunotherapy with fludarabine, cyclophospamide and rituximab is very effective, but may give severe hematological and non-hematological toxicity at standard doses, especially in elderly patients. In this phase II study, 25 untreated elderly patients with iNHL received rituximab (375 mg/m(2)) plus low-dose oral fludarabine (25 mg/m(2) for 4 consecutive days) and cyclophosphamide (150 mg/m(2) for 4 consecutive days) for four monthly cycles. Twenty-three patients were responsive (92%) and 12 patients achieved a complete remission (48%). Twenty-one patients (84%) were alive, median follow-up was 30 months and median event-free survival (EFS) was not reached. Patients who we previously treated with chemotherapy alone had a shorter EFS (median 20 months). Compliance was good, with mild toxicity. This regimen is effective for elderly patients with iNHL. The addition of rituximab results in long EFS without affecting toxicity.

Monitoring NK cell activity in patients with hematological malignancies

Natural killer (NK) cells are lymphocytes of the innate immune system that can recognize and kill various types of malignant cells. Monitoring the activity of peripheral NK cells in patients affected by hematological malignancies may provide prognostic information or unveil ongoing tumor-specific immune responses. Moreover, further insights into the biology of NK cells might also promote the development of novel strategies for stimulating their anticancer activity. Here, we review the main methods to monitor phenotypic and functional NK cell properties in cancer patients, focusing on individuals affected by multiple myeloma, a hematological malignancy currently treated with immunomodulatory drugs.

Mature B-cell lymphoma and leukemia in children and adolescents-review of standard chemotherapy regimen and perspectives

Mature B-cell non-Hodgkin lymphoma (B-NHL) comprises more than 50% of all non-Hodgkin lymphoma (NHL) in children and adolescents. Many B-NHL subtypes frequently observed in adults are rarely diagnosed in children and adolescents. In this age group, Burkitt lymphoma (BL), Burkitt leukemia or FAB L3 leukemia (B-AL), diffuse large B-cell lymphoma (DLBCL), primary mediastinal large B-cell lymphoma (PMLBL), follicular lymphoma (FL), and aggressive mature B-NHL not further classifiable (B-NHL nfc) are the most common subtypes. Diverse clinical trials demonstrated similar results of current combination chemotherapy regimens succeeding in overall survival rates of more than 80%. However, treatment-related toxicity and the poor prognosis of relapse are serious concerns. Furthermore, specific histological B-NHL subtypes are rare in children and optimal treatment is not established. New treatment modalities are urgently needed for these patient groups. Rituximab, a monoclonal antibody that is already established in the treatment of adults with mature B-NHL, demonstrated promising results in pediatric patients. The definitive role of rituximab in the treatment of children and adolescents with B-NHL needs to be evaluated in prospective controlled clinical trials. This review provides a comprehensive overview of chemotherapy regimens and the perspectives for children and adolescents with mature B-cell lymphoma and leukemia.

Lessons for the clinic from rituximab pharmacokinetics and pharmacodynamics

The anti-CD20 antibody rituximab (RTX; Rituxan®, MabThera®) was the first anti-cancer antibody approved by the US Food and Drug Administration in 1997 and it is now the most-studied unconjugated therapeutic antibody. The knowledge gained over the past 15 y on the pharmacodynamics (PD) of this antibody has led to the development of a new generation of anti-CD20 antibodies with enhanced efficacy in vitro. Studies on the pharmacokinetics (PK) properties and the effect of factors such as tumor load and localization, antibody concentration in the circulation and gender on both PK and clinical response has allowed the design of optimized schedules and novel routes of RTX administration. Although clinical results using newer anti-CD20 antibodies, such as ofatumumab and obinutuzumab, and novel administration schedules for RTX are still being evaluated, the knowledge gained so far on RTX PK and PD should also be relevant for other unconjugated monoclonal antibody therapeutics, and will be critically reviewed here.

Correlation of HER2, FCGR2A, and FCGR3A gene polymorphisms with trastuzumab related cardiac toxicity and efficacy in a subgroup of patients from UNICANCER-PACS 04 trial

The purpose of this study was to investigate, in the context of a prospective node-positive-breast cancer trial HER2 containing-regimen (UNICANCER-PACS 04 trial), the predictive value of HER2, FCGRIIA, and FCGRIIIA gene polymorphisms for cardiac toxicity and efficacy of trastuzumab. We analyzed HER2-I655V, FCGR2A-H131R, and FCGR3A-V158F single nucleotide polymorphisms in patients in adjuvant setting treated by six courses of either fluorouracil 500 mg/m(2), epirubicin 100 mg/m(2) and cyclophosphamide 500 mg/m(2), or epirubicin 75 mg/m(2) and docetaxel 75 mg/m(2) every 3 weeks then randomly assigned, in case of HER2 overexpressing tumor, to either trastuzumab for 1 year or nothing. Left ventricular ejection fraction and clinical examination were monitored in each patient, seven times throughout the study to detect congestive heart failure or asymptomatic subclinical cardiac toxicity. All genotypes were analyzed in relation to cardiac toxicity, EFS, and OS. One hundred and thirty-two HER2-positive breast cancer patients were analyzed. The HER2-I655V genotype was significantly associated with cardiac toxicity (p = 0.025). The FCGR2A-131 H/H genotype was significantly correlated with a shorter EFS (p = 0.027). The FCGR3A-158 V/V genotype was not correlated with EFS nor OS. These results might be useful in making a treatment choice of HER2 blockers in adjuvant setting by with an increase in efficacy and decrease in toxicity.

Higher World Health Organization grades of follicular lymphoma correlate with better outcome in two Nordic Lymphoma Group trials of rituximab without chemotherapy

Abstract A common treatment for follicular lymphoma is rituximab monotherapy. To identify patients for whom this regimen is adequate as first-line therapy, we applied the World Health Organization (WHO) classification for grading follicular lymphoma in a prospective central pathology review of the biopsies of previously untreated patients in two randomized trials of rituximab without chemotherapy. In the first trial (n₁ = 53), higher WHO grades correlated with longer time to next treatment, independently of clinical prognostic factors (p = 0.030); the finding was replicated in the second trial (n₂ = 221; p = 0.019). Higher grades were associated with better treatment responses (p = 0.018). Furthermore, also grades externally confirmed by independent local pathologists correlated with time to next treatment (p = 0.048). Flow cytometry in a separate patient series showed that the intensity of CD20 increased with the malignant cell size (p < 0.00005). In conclusion, WHO grade 1 follicular lymphoma correlates with inferior outcome after rituximab monotherapy. WHO grading might provide a clinically useful tool for personalized therapy.

Reduction of complement factor H binding to CLL cells improves the induction of rituximab-mediated complement-dependent cytotoxicity

A main effector mechanism of rituximab (RTX) is the induction of complement-dependent cytotoxicity (CDC). However, this effector function is limited, because CLL cells are protected from complement-induced damage by regulators of complement activation (RCAs). A prominent RCA in fluid phase is factor H (fH), which has not been investigated in this context yet. Here, we show that fH binds to CLL cells and that human recombinant fH-derived short-consensus repeat 18–20 (hSCR18–20) interferes with this binding. In complement-based lysis assays, CLL cells from therapy-naive patients were differently susceptible to RTX-induced CDC and were defined as CDC responder or CDC non-responder, respectively. In CDC responders, but notably also in non-responders, hSCR18–20 significantly boosted RTX-induced CDC. Killing of the cells was specific for CD20⁺ cells, whereas CD20⁻ cells were poorly affected. CDC resistance was independent of expression of the membrane-anchored RCAs CD55 and CD59, although blocking of these RCAs further boosted CDC. Thus, inhibition of fH binding by hSCR18–20 sensitizes CLL cells to CDC and may provide a novel strategy for improving RTX-containing immunochemotherapy of CLL patients.

Therapeutic options in post-transplant lymphoproliferative disorders

Post-transplantation lymphoproliferative disorders (PTLD) are the second most frequent malignancies after solid organ transplantation and cover a wide spectrum ranging from polyclonal early lesions to monomorphic lymphoma. Available treatment modalities include immunosuppression reduction, immunotherapy with anti-B-cell monoclonal antibodies, chemotherapy, antiviral therapy, cytotoxic T-cell therapy as well as surgery and irradiation. Owing to the small number of cases and the heterogeneity of PTLD, current treatment strategies are mostly based on case reports and small, often retrospective studies. Moreover, many studies on the treatment of PTLD have involved a combination of different treatment options, complicating the evaluation of individual treatment components. However, there has been significant progress over the last few years. Three prospective phase II trials on the efficacy of rituximab monotherapy have shown significant complete remission rates without any relevant toxicity. A prospective, multicenter, international phase II trial evaluating sequential treatment with rituximab and CHOP-based chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone) is ongoing and preliminary results have been promising. Cytotoxic T-cell therapy targeting Epstein-Barr virus (EBV)-infected B cells has shown low toxicity and high efficacy in a phase II trial and will be a future therapeutic option at specialized centers. Here, we review the currently available data on the different treatment modalities with a focus on PTLD following solid organ transplantation in adult patients.