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

B-cell depletion in SLE: clinical and trial experience with rituximab and ocrelizumab and implications for study design

B cells are believed to be central to the disease process in systemic lupus erythematosus (SLE), making them a target for new therapeutic intervention. In recent years there have been many publications regarding the experience in SLE of B-cell depletion utilising rituximab, an anti-CD20 mAb that temporarily depletes B cells,reporting promising results in uncontrolled open studies and in routine clinical use. However, the two large randomised controlled trials in extra-renal lupus (EXPLORER study) and lupus nephritis (LUNAR study) failed to achieve their primary endpoints. Based on the clinical experience with rituximab this failure was somewhat unexpected and raised a number of questions and concerns, not only into the true level of benefit of B-cell depletion in a broad population but also how to test the true level of effectiveness of an investigational agent as we seek to improve the design of therapeutic trials in SLE. A better understanding of what went wrong in these trials is essential to elucidate the underlying reasons for the disparate observations noted in open studies and controlled trials. In this review, we focus on various factors that may affect the ability to accurately and confidently establish the level of treatment effect of the investigational agent, in this case rituximab, in the tw studies and explore hurdles faced in the randomised controlled trials investigating the efficacy of ocrelizumab, the humanised anti-CD20 mAb, in SLE. Further, based on the lessons learned from the clinical trials, we make suggestions that could be implemented in future clinical trial design to overcome the hurdles faced.

A critical review of the role of Fc gamma receptor polymorphisms in the response to monoclonal antibodies in cancer

Antibody-dependent cellular cytotoxicity (ADCC) is a major mechanism of action of therapeutic monoclonal antibodies (mAbs) such as cetuximab, rituximab and trastuzumab. Fc gamma receptors (FcgR) on human white blood cells are an integral part of the ADCC pathway. Differential response to therapeutic mAbs has been reported to correlate with specific polymorphisms in two of these genes: FCGR2A (H131R) and FCGR3A (V158F). These polymorphisms are associated with differential affinity of the receptors for mAbs. This review critically examines the current evidence for genotyping the corresponding single nucleotide polymorphisms (SNPs) to predict response to mAbs in patients with cancer.

Sex differences in the drug therapy for oncologic diseases

There are clear gender-dependent differences in response rates and the probability of side effects in patients treated with chemotherapy. Sex-biased expression levels of metabolic enzymes and transporters in liver and kidney leading to different pharmacokinetics have been described for most common anti-cancer drugs. In women, half-life is often longer, which is associated with improved survival, but also increased toxicity.Some chemotherapy protocols lead to a better response rate in women without increasing toxicity (e.g., cisplatin and irinotecan), while others only increase toxicity, but do not improve response rates in women (e.g., 5-fluorouracil). The increased toxicity often correlates with different pharmacokinetics, but women also show a higher sensitivity to some agents with shorter half-life (e.g., steroids). Organ-specific toxicities like cardiac toxicity after doxorubicin treatment or neurotoxicity associated with ifosfamide are more severe in women due to gender-specific changes in gene expression. Novel therapies like tyrosine kinase inhibitors or monoclonal antibodies show very complex, but clinical significant differences depending on gender. Antibodies often have a longer half-life in women, which is associated with an improved response to therapy.Side effects appear to be highly dependent on different tissue properties, as women have a higher incidence of oral mucositis, but lower rates of gut toxicity. Nausea and vomiting is a greater problem in females during therapy due to the lower activity of anti-emetic drugs. Nausea and vomiting pose a bigger challenge in female patients, as anti-emetic drugs seem to be less effective.

What lessons can be learned from γδ T cell-based cancer immunotherapy trials?

During the last several years, research has produced a significant amount of knowledge concerning the characteristics of human γδ T lymphocytes. Findings regarding the immune functions of these cells, particularly their natural killer cell-like lytic activity against tumor cells, have raised expectations for the therapeutic applications of these cells for cancer. Pharmaceutical companies have produced selective agonists for these lymphocytes, and several teams have launched clinical trials of γδ T cell-based cancer therapies. The findings from these studies include hematological malignancies (follicular lymphoma, multiple myeloma, acute and chronic myeloid leukemia), as well as solid tumors (renal cell, breast and prostate carcinomas), consisting of samples from more than 250 patients from Europe, Japan and the United States. The results of these pioneering studies are now available, and this short review summarizes the lessons learned and the role of γδ T cell-based strategies in the current landscape of cancer immunotherapies.

Ofatumumab is more efficient than rituximab in lysing B chronic lymphocytic leukemia cells in whole blood and in combination with chemotherapy

Ofatumumab (OFA) is a human anti-CD20 Ab approved for treatment of fludarabine-refractory B chronic lymphocytic leukemia (B-CLL). The efficacy of different immunotherapeutic strategies is best investigated in conditions that are as physiologic as possible. We have therefore compared the activity OFA and rituximab (RTX), alone or in combination with chemotherapeutic agents in unmanipulated whole blood assays, using flow cytometry. OFA (10-100 μg/ml) lysed B-CLL targets in whole blood more efficiently and with faster kinetics than RTX, with a mean 56% lysis at 24 h compared with 16%. This activity of OFA was fully complement dependent, as shown by >99% inhibition by anti-C5 Ab eculizumab and a lack of NK cell activation in whole blood. OFA-mediated NK cell activation was blocked by complement. OFA-mediated lysis could be increased an additional 15% by blocking CD55 and CD59 complement inhibitors. Interestingly, OFA-mediated lysis correlated significantly with CD20 expression levels (r(2) = 0.79). OFA showed overlapping dose response curves similar to those for RTX in phagocytosis assays using either human macrophages or neutrophils. However, phagocytosis was inhibited in the presence of serum or whole blood. Finally, combined treatment with mafosfamide and fludarabine showed that these therapeutic drugs are synergistic in B-CLL whole blood assays and show superior activity when combined with OFA compared with RTX. These results confirm in B-CLL samples and in physiologic conditions the superior complement mediated cytotoxicity induced by OFA alone compared with RTX, the lack of NK cell activation, and phagocytosis in these conditions and suggest effective chemoimmunotherapy strategies using this new generation anti-CD20 Ab.

Brain tumor immunotherapy: seeing the brain in the body

Brain tumor immunotherapy is often interpreted in terms of immune privilege and the blood-brain barrier (BBB), but a broader view is warranted. The delicate regulatory balance of the immune system is relevant at any site, as are the heterogeneity and plasticity of tumor growth. Criteria for tumor antigens, and often the antigens themselves, cut across tumor types. Here, this broader view, complemented by current understanding of privilege and the BBB, provides the context for review. Future success is likely to exploit simplified methods, used in combination; and similarities - more than differences - between the brain and other sites.

Association of the FCGR3A-158F/V gene polymorphism with the response to rituximab treatment in Spanish systemic autoimmune disease patients

Rituximab is being used as treatment for systemic autoimmune diseases. The objective of this study was to determine whether the genetic variant in the Fc gamma-receptor III a (FCGR3A) gene, 158F/V, contributes to the observed variation in response to rituximab in patients with systemic autoimmune diseases. DNA samples from 132 Spanish patients with different systemic autoimmune diseases receiving rituximab were genotyped for FCGR3A-158F/V (rs396991) gene polymorphism using the TaqMan(®) allelic discrimination technology. Six months after infusion with rituximab we evaluated the response to the drug: 61% of the patients showed a complete response, partial 27% and 12% did not respond to the treatment. A statistically significant difference was observed in V allele frequency between responder (38%) and nonresponder (16%) patients (p=0.01; odds ratio [OR]=3.24, 95% confidence interval [CI] 1.17-11.1). Rituximab was also more effective in V allele carriers (94%) than in homozygous FF patients (81%): p=0.02; OR=3.96, 95% CI 1.10-17.68. These results suggest that FCGR3A-158F/V (rs396991) gene polymorphism play a role in the response to rituximab in autoimmune diseases. Validation of these findings in independent cohorts is warranted.

Prognostic role of gender in diffuse large B-cell lymphoma treated with rituximab containing regimens: a Fondazione Italiana Linfomi/Grupo de Estudos em Moléstias Onco-Hematológicas retrospective study

Male gender was recently reported as an adverse prognostic factor in patients with diffuse large B-cell lymphoma (DLBCL) treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone). We conducted a retrospective study of adult patients with DLBCL initially treated with rituximab containing regimens between 2001 and 2007. Patients were identified from the clinical archives of 43 Italian and Brazilian institutions. The principal endpoint was overall survival (OS). One thousand seven hundred and ninety-three patients were fully eligible for the study. Thirty-eight percent, 27%, 22% and 12% of patients had an International Prognostic Index (IPI) score of 0-1, 2, 3 and 4-5, respectively; 53% were males. After a median follow-up of 36 months (1-106), the 5-year OS was 76% (95% confidence interval 74-78%). In univariate analysis, male gender was an adverse prognostic factor with a hazard ratio of 1.52. In multivariate analysis, when adjusted by IPI, again gender maintained its prognostic relevance, showing an independent additive effect. In conclusion, in patients with DLBCL treated with rituximab containing regimens, gender may increase the predictive power of the IPI. Based on these results, given possible differences in blood clearance of rituximab between males and females, the benefit of higher doses of rituximab in males should be explored.

The future role of monoclonal antibody therapy in childhood acute leukaemias

Leukaemia is the single most common childhood malignancy. With modern treatment regimens, survival in acute lymphoblastic leukaemia (ALL) approaches 90%. Only about 70% of children with acute myeloid leukaemia (AML) achieve long term survival. Patients who relapse have a dismal prognosis. Novel therapeutic approaches are needed to improve treatment outcomes in newly-diagnosed patients with a poor prognosis and for patients with relapsed/refractory disease that have limited treatment options. One promising approach in treating haematological malignancies has been the use of monoclonal antibodies to target cell surface antigens expressed on malignant cells. Most success with monoclonal antibody therapy in the treatment of haematological malignancies has come in the setting of adult B-cell non-Hodgkin lymphoma with the addition of the anti-CD20 monoclonal antibody rituximab to standard treatment regimens. In order to further advance treatment of haematological malignancies, novel monoclonal antibodies continue to be developed that target a variety of cell surface antigens. Several antibodies continue to be investigated in childhood leukaemias. This review will discuss the development of monoclonal antibodies that target a variety of cell surface antigens for the treatment of childhood ALL and the use of the anti-CD33 antibody gemtuzumab ozogamicin in the treatment of childhood AML.

Clinical outcome of patients with follicular lymphoma receiving chemoimmunotherapy in the PRIMA study is not affected by FCGR3A and FCGR2A polymorphisms

In patients with follicular lymphoma treated with single-agent rituximab, single nucleotide polymorphisms in the FCGR3A gene are known to influence response and progression-free survival. The prognostic role of FCGR3A and FCGR2A polymorphisms in patients with follicular lymphoma treated with rituximab and chemotherapy combination remains controversial and has not been evaluated in the context of rituximab maintenance. FCGR3A and FCGR2A single nucleotide polymorphisms were evaluated in, respectively, 460 and 455 patients treated in the PRIMA study to investigate whether these were associated with response rate and patient outcome after rituximab chemotherapy induction and 2-year rituximab maintenance. In this representative patient cohort, complete and unconfirmed complete responses after rituximab chemotherapy were observed in 65%, 67%, 66% (P = .86) and 60%, 72%, 66% (P = .21) of FCGR3A VV, VF, FF and FCGR2A HH, HR, RR carriers, respectively. After 2 years of rituximab maintenance (or observation), response rates did not differ among the different genotypes. Progression-free survival measured from either treatment initiation or randomization to observation or maintenance was not influenced by these polymorphisms. These data indicate that FCGR3A and FCGR2A polymorphisms do not influence response rate and outcome when rituximab is combined with chemotherapy or used as maintenance treatment. The PRIMA study is registered at www.clinicaltrials.gov as NCT00140582.

7th cancer scientific forum of theCancéropôle Lyon Auvergne Rhône-Alpes: March 20-21, 2012, Lyon, France

The Innovative Approaches in Anti-Cancer Monoclonal Antibodies meeting, held on March 20, 2012 in Lyon, was organized by Cancéropôle Lyon Auvergne-Rhône-Alps in partnership with the French competitiveness cluster Lyonbiopôle. CLARA is one of the seven cancer research clusters within France in charge of facilitating Translational Oncology Research by taking into account the objectives of the French National Cancer Plans I and II and, in coordination with the French National Cancer Institute and local authorities (mainly Grand Lyon, Rhône County and Rhône-Alpes Region), to perform economic development of research findings. The contribution of lectures by outstanding speakers as described in this report, the organization of two-round tables: "Antibody treatment in cancer: Unmet needs in solid tumors and hematological malignancies," and "From chimeric to more than human antibodies," together with face-to-face meetings, was shared by over 230 participants. The lectures provided an overview of the commercial pipeline of monoclonal antibody (mAb) therapeutics for cancer; discussion of the distinction between biosimilar, biobetter and next generation therapeutic antibodies for cancer; updates on obinutuzumab and the use of mAbs in lymphoma; and discussion of antibody-drug conjugates.

Aurora A inhibitor (MLN8237) plus vincristine plus rituximab is synthetic lethal and a potential curative therapy in aggressive B-cell non-Hodgkin lymphoma

PURPOSE

Aurora A and B are oncogenic serine/threonine kinases that regulate mitosis. Overexpression of Auroras promotes resistance to microtubule-targeted agents. We investigated mechanistic synergy by inhibiting the mitotic spindle apparatus in the presence of MLN8237 [M], an Aurora A inhibitor with either vincristine [MV] or docetaxel [MD] in aggressive B-cell non-Hodgkin lymphoma (B-NHL). The addition of rituximab [R] to MV or MD was evaluated for synthetic lethality.

EXPERIMENTAL DESIGN

Aggressive B-NHL cell subtypes were evaluated in vitro and in vivo for target modulation and anti-NHL activity with single agents, doublets, and triplets by analyzing cell proliferation, apoptosis, tumor growth, survival, and mechanisms of response/relapse by gene expression profiling with protein validation.

RESULTS

MV is synergistic whereas MD is additive for cell proliferation inhibition in B-NHL cell culture models. Addition of rituximab to MV is superior to MD, but both significantly induce apoptosis compared with doublet therapy. Mouse xenograft models of mantle cell lymphoma showed modest single-agent activity for MLN8237, rituximab, docetaxel, and vincristine with tumor growth inhibition (TGI) of approximately 10% to 15%. Of the doublets, MV caused tumor regression, whereas TGI was observed with MD (approximately 55%-60%) and MR (approximately 25%-50%), respectively. Although MV caused tumor regression, mice relapsed 20 days after stopping therapy. In contrast, MVR was curative, whereas MDR led to TGI of approximately 85%. Proliferation cell nuclear antigen, Aurora B, cyclin B1, cyclin D1, and Bcl-2 proteins of harvested tumors confirmed response and resistance to therapy.

CONCLUSIONS

Addition of rituximab to MV is a novel therapeutic strategy for aggressive B-NHL and warrants clinical trial evaluation.

Antibody-induced nonapoptotic cell death in human lymphoma and leukemia cells is mediated through a novel reactive oxygen species-dependent pathway

Monoclonal antibodies (mAbs) have revolutionized the treatment of B-cell malignancies. Although Fc-dependent mechanisms of mAb-mediated tumor clearance have been extensively studied, the ability of mAbs to directly evoke programmed cell death (PCD) in the target cell and the underlying mechanisms involved remain under-investigated. We recently demonstrated that certain mAbs (type II anti-CD20 and anti-HLA DR mAbs) potently evoked PCD through an actin-dependent, lysosome-mediated process. Here, we reveal that the induction of PCD by these mAbs, including the type II anti-CD20 mAb GA101 (obinutuzumab), directly correlates with their ability to produce reactive oxygen species (ROS) in human B-lymphoma cell lines and primary B-cell chronic lymphocytic leukemia cells. ROS scavengers abrogated mAb-induced PCD indicating that ROS are required for the execution of cell death. ROS were generated downstream of mAb-induced actin cytoskeletal reorganization and lysosome membrane permeabilization. ROS production was independent of mitochondria and unaffected by BCL-2 overexpression. Instead, ROS generation was mediated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. These findings provide further insights into a previously unrecognized role for NADPH oxidase-derived ROS in mediating nonapoptotic PCD evoked by mAbs in B-cell malignancies. This newly characterized cell death pathway may potentially be exploited to eliminate malignant cells, which are refractory to conventional chemotherapy and immunotherapy.

Sequential treatment with rituximab followed by CHOP chemotherapy in adult B-cell post-transplant lymphoproliferative disorder (PTLD): the prospective international multicentre phase 2 PTLD-1 trial

BACKGROUND

Post-transplantation lymphoproliferative disorder (PTLD) develops in 1-10% of transplant recipients and can be Epstein-Barr virus (EBV) associated. To improve long-term efficacy after rituximab monotherapy and to avoid the toxic effects of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy seen in first-line treatment, we initiated a phase 2 trial to test whether the subsequent use of rituximab and CHOP would improve the outcome of patients with PTLD.

METHODS

In this international multicentre open-label phase 2 trial, treatment-naive adult solid-organ transplant recipients diagnosed with CD20-positive PTLD who had failed to respond to upfront immunosuppression reduction received four courses of rituximab (375 mg/m(2) intravenously) once a week followed by 4 weeks without treatment and four cycles of CHOP every 3 weeks. In case of disease progression during rituximab monotherapy, CHOP was started immediately. Supportive therapy with granulocyte-colony stimulating factor after chemotherapy was mandatory and antibiotic prophylaxis was recommended. The primary endpoint was treatment efficacy measured as response rates in all patients who completed treatment with rituximab and CHOP, per protocol, and response duration, in all patients who completed all planned therapy and responded. Secondary endpoints were frequency of infections, treatment-related mortality, and overall survival. This study is registered at ClinicalTrials.gov, number NCT01458548.

FINDINGS

74 patients were enrolled between Dec 12, 2002 and May 5, 2008, of whom 70 patients were eligible to receive treatment. PTLD was of late type in 53 (76%) of 70 patients, monomorphic in 67 (96%) of 70, and histologically EBV associated in 29 (44%) of 66 cases. Four of 70 patients did not receive CHOP. 53 of 59 patients had a complete or partial response (90%, 95% CI 79-96), of which 40 (68%, 55-78) were complete responses. At data cutoff (June 1, 2011) median response duration in the 53 patients who had responded to treatment had not yet been reached (>79·1 months). The main adverse events were grade 3-4 leucopenia in 42 of 62 patients (68%, 55-78) and infections of grade 3-4 in 26 of 64 patients (41%, 29-53). Seven of 66 patients (11%, 5-21) had CHOP-associated treatment-related mortality. Median overall survival was 6·6 years (95% CI 2·8-10·4; n=70).

INTERPRETATION

Our results support the use of sequential immunochemotherapy with rituximab and CHOP in PTLD.

FUNDING

F Hoffmann-La Roche, Amgen Germany, Chugaï France.

Mechanisms regulating enhanced human leukocyte antigen class II-mediated CD4 + T cell recognition of human B-cell lymphoma by resveratrol

Malignant B-cells express measurable levels of human leukocyte antigen (HLA) class II proteins, but often escape immune recognition by CD4 + T cells. Resveratrol (Resv) has been the focus of numerous investigations due to its potential chemopreventive and anti-cancer effects, but it has never been tested in the regulation of immune components in B-cell tumors. Here, we show for the first time that Resv treatment enhances HLA class II-mediated immune detection of B-cell lymphomas by altering immune components and class II presentation in tumor cells. Resv treatment induced an up-regulation of both classical and non-classical HLA class II proteins (DR and DM) in B-lymphoma cells. Resv also altered endolysosomal cathepsins (Cat S, B and D) and a thiol reductase (GILT), increasing HLA class II-mediated antigen (Ag) processing in B-cell lymphomas and their subsequent recognition by CD4 + T cells. Mechanistic study demonstrated that Resv treatment activated the recycling class II pathway of Ag presentation through up-regulation of Rab 4B protein expression in B-lymphoma cells. These findings suggest that HLA class II-mediated immune recognition of malignant B-cells can be improved by Resv treatment, thus encouraging its potential use in chemoimmunotherapy of B-cell lymphoma.

Rituximab: as first-line maintenance therapy following rituximab-containing therapy for follicular lymphoma

Rituximab is a recombinant chimeric murine/human monoclonal IgG(1-κ) antibody. It binds specifically to the CD20 antigen on normal and malignant B lymphocytes and produces complement-dependent and antibody-dependent cytotoxicity and induces apoptosis in these cells. Prolonged treatment with rituximab in patients with follicular lymphoma results in a sustained reduction in circulating B lymphocytes. Two years of single-agent maintenance therapy with rituximab significantly prolonged progression-free survival (primary endpoint) compared with observation in patients with follicular lymphoma who were responsive to first-line induction therapy with rituximab plus chemotherapy. Furthermore, maintenance therapy with rituximab significantly delayed the time to the next antilymphoma treatment and the next chemotherapy compared with observation in these patients. Rituximab had an acceptable tolerability profile as single-agent maintenance therapy in patients with follicular lymphoma with no new or unexpected adverse events compared with induction therapy.