Safety and efficacy of ofatumumab, a fully human monoclonal anti-CD20 antibody, in patients with relapsed or refractory B-cell chronic lymphocytic leukemia: a phase 1-2 study

Single arm NCRI phase II study of CHOP in combination with Ofatumumab in induction and maintenance for patients with newly diagnosed Richter's syndrome

BACKGROUND

Transformation of B-cell chronic lymphocytic leukaemia (B-CLL) to diffuse large B cell lymphoma (DLBCL) (Richter's syndrome (RS)) is a rare (2-15% of patients) but catastrophic complication of B-CLL. Dose-intense chemotherapy regimens investigated in small single institution trials, but with the exception of bone marrow transplantation for a minority of patients, little has improved the median overall survival of patients with RS beyond eight months. Patients are often elderly, immunosuppressed, possess co-morbidities and have a deteriorating performance status. TP53 disruption is a common molecular abnormality noted in RS and contributes to the tumour's chemotherapy resistance. Ofatumumab is a fully human anti-CD20 monoclonal IgG1κ antibody that targets a unique epitope on B lymphocytes. It has displayed increased binding affinity and a longer dissociation time when compared to rituximab resulting in improved complement dependent cellular cytotoxicity (CDCC); a mechanism with the potential to overcome apoptosis-resistance in TP53 disruption. Given the prevalence of TP53 disruption in RS, Ofatumumab was considered a relatively non-toxic agent with a sound rationale to test in a prospective multicentre trial as an adjunct to CHOP induction and subsequent ofatumumab maintenance therapy in responding patients.

METHODS/DESIGN

The CHOP-OR study is a prospective phase II study to evaluate the safety, feasibility and activity of a CHOP chemotherapy in combination with ofatumumab in induction and subsequent maintenance for patients with newly diagnosed RS. The primary objective will be the overall response rate (ORR) in patients with RS after six cycles of CHOP-O. The secondary objectives include feasibility of recruitment, progression free survival (PFS), overall survival (OS) and toxicity. The study will be accompanied by exploratory analysis of the genomic landscape of RS in newly diagnosed patients.

DISCUSSION

The CHOP-OR trial evaluates the safety, feasibility and activity of CHOP plus Ofatumumab induction and Ofatumumab maintenance in new RS patients. The study is currently recruiting and has met the interim analysis criteria, with more than 7 of the first 25 participants achieving a CR or PR after six cycles of CHOP-O. The study has the potential to identify predictive biomarkers for this treatment modality.

TRIAL REGISTRATION

NCT01171378.

Ofatumumab in poor-prognosis chronic lymphocytic leukemia: a phase IV, non-interventional, observational study from the European Research Initiative on Chronic Lymphocytic Leukemia

We report the largest retrospective, phase IV non-interventional, observational study of ofatumumab therapy in heavily pre-treated patients with poor-prognosis chronic lymphocytic leukemia. Total number of patients was 103; median age was 65 years (range 39-85). Median number of prior lines of therapy was 4 (range 1-13), including, in most cases, rituximab-, fludarabine- and alemtuzumab-based regimens; 13 patients had been allografted. Of 113 adverse events, 28 (29%) were considered to be directly related to ofatumumab. Grade 3-4 toxicities included neutropenia (10%), thrombocytopenia (5%), anemia (3%), pneumonia (17%), and fever (3%). Two heavily pre-treated patients developed progressive multifocal leukoencephalopathy. On an intention-to-treat analysis, the overall response rate was 22% (3 complete response, 1 incomplete complete response). Median progression-free and overall survival times were 5 and 11 months, respectively. This study confirms in a daily-life setting the feasibility and acceptable toxicity of ofatumumab treatment in advanced chronic lymphocytic leukemia. The complete response rate, however, was low. Therefore, treatment with ofatumumab should be moved to earlier phases of the disease. Ideally, this should be done in combination with other agents, as recently approved for ofatumumab plus chlorambucil as front-line treatment for patients unfit for fludarabine. This study is registered at clinicaltrials.gov identifier:01453062.

Ibrutinib: a new frontier in the treatment of chronic lymphocytic leukemia by Bruton's tyrosine kinase inhibition

Chronic lymphocytic leukemia (CLL) is characterized by progressive accumulation of nonfunctional mature B cells in blood, bone marrow and lymphoid tissues. In the last decade, our understanding of CLL and consequently our diagnostic and therapeutic approaches have changed dramatically. Conventional fludarabine based chemotherapy has led to improved disease response and longer survival in young patients with CLL. However its application in elderly patients has been restricted by substantial myelosuppression and infection. Treatment of CLL is now moving towards targeted therapy. The success of new class of agents such as monoclonal antibodies, proteasome inhibitors and immunomodulatory derivatives has sparked further search for treatment agents with novel targets to inhibit. The B cell receptor activating pathway involving the Bruton’s tyrosine kinase (BTK) is crucial in B cell production and maintenance and is an attractive therapeutic target. Ibrutinib is an oral covalent inhibitor of the BTK pathway that induces apoptosis of B cells. Early phase studies with Ibrutinib either as a single agent or in combination regimens have shown promising results with an excellent safety profile in patients with high-risk, refractory or relapsed CLL and elderly treatment-naïve patients. This review summarizes the current knowledge of Ibrutinib in the treatment of CLL.

Target Therapy in Hematological Malignances: New Monoclonal Antibodies

Apart from radio- and chemotherapy, monoclonal antibodies (MoAbs) represent a new, more selective tool in the treatment of hematological malignancies. MoAbs bind with the specific antigens of the tumors. This interaction is a basis for targeted therapies which exhibit few side effects and significant antitumor activity. This review provides an overview of the functional characteristics of MoAbs, with some examples of their clinical application. The promising results in the treatment of hematological malignancies have led to the more frequent usage of MoAbs in the therapy. Development of MoAbs is a subject of extensive research. They are a promising method of cancer treatment in the future.

Monoclonal antibody (mAb)-based cancer therapy: Is it time to reevaluate dosing strategies?

Compelling evidence indicates Type I CD20 immunotherapeutic mAbs promote targeted tumor cell elimination exclusively via immune effector functions, which can be exhausted/saturated. mAb dosing paradigms should therefore take into account the capacity of these cytotoxic mechanisms, leading to the conclusion that lower doses, given frequently, may be far more effective.

Role of allogeneic transplantation in patients with chronic lymphocytic leukemia in the era of novel therapies: a review

Chronic lymphocytic leukemia (CLL) is the most common form of adult leukemia and is characterized by a highly variable clinical course. In the past decade, several prognostic risk factors have been identified facilitating the classification of CLL into various risk groups. Patients with poor risk disease, such as poor cytogenetics or relapsing after purine-based analogues, had limited therapeutic options, with allogeneic hematopoietic cell transplantation (allo-SCT) the only known therapy with curative potential. More recently, the introduction of novel agents inhibiting the B-cell receptor pathway, and the early success with chimeric antigen receptor T cells offers an effective and relatively safe option for this poor prognostic group which holds promise in the future. Alternatively, the use of reduced intensity conditioning regimens in the allo-SCT setting has led to a significant decrease in nonrelapse mortality to 16-23%, making it an attractive therapeutic option. No recent guidelines have been developed since these novel therapies became available regarding the optimal time to allo-SCT in this patient population. The advent of these novel and highly active therapeutic agents, therefore, warrants a reappraisal of the role and timing of allo-SCT in patients with CLL. In this article, we summarize the literature regarding the novel therapeutic agents available today as well as focus on the efficacy and safety of allo-SCT.

Personalized medicine in CLL: current status and future perspectives

Chronic lymphocytic leukemia (CLL) is the most common hematologic malignancy in the Western Hemisphere. Despite advances in research and the development of effective treatment regimens, CLL is still largely an incurable disease. Although several prognostic factors have been identified in recent years, most of the new prognostic factors are not utilized, and treatment decisions are still based on clinical staging and limited use of cytogenetic analysis. Patients with advanced disease are treated at diagnosis, whereas others, regardless of their prognostic indicators, are offered treatment only at disease progression. Furthermore, treatment guidelines for elderly or "unfit" patients are unavailable because most CLL trials have included mostly younger, healthier patients. Given theheterogeneity of the clinical manifestations and prognosis of CLL, patients are likely to benefit from a personalized therapeutic approach. Recent advances in CLL pathobiology research, the use of high-throughput technologies, and most importantly, the introduction of novel targeted therapies with high efficacy and low toxicity are currently transforming the treatment of CLL. A personalized approach that includes early intervention in selected patients with CLL is likely to bring physicians closer to the goal of attaining cures in most patients with CLL.

Obinutuzumab (GA101) in relapsed/refractory chronic lymphocytic leukemia: final data from the phase 1/2 GAUGUIN study

GAUGUIN evaluated the safety and efficacy of obinutuzumab (GA101) monotherapy in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). In phase 1 (dose escalation), 13 patients received obinutuzumab 400 to 1200 mg (days 1 and 8 of cycle 1; day 1 of cycles 2-8). In phase 2, 20 patients received a fixed dose of 1000 mg (days 1, 8, and 15 of cycle 1; day 1 of cycles 2-8). Infusion-related reactions occurred in nearly all patients, but few were grade 3/4. Grade 3/4 neutropenia occurred in 7 patients in phase 1 (but was not dose-related) and in 4 patients in phase 2. Overall end-of-treatment response (all partial responses) was 62% (phase 1) and 15% (phase 2); best overall response was 62% and 30%, respectively. Phase 2 median progression-free survival was 10.7 months and median duration of response was 8.9 months. In summary, obinutuzumab monotherapy is active in patients with heavily pretreated relapsed/refractory CLL.

Ofatumumab in refractory chronic lymphocytic leukemia: experience through the French early access program

BACKGROUND

The Autorisation Temporaire d'Utilisation (ATU) is an early access program available in France for drugs aimed at treating severe diseases not yet covered by a marketing authorization, for patients without any other therapeutic option and who cannot be included in a clinical trial.

PATIENTS AND METHODS

This report presents the use of single-agent ofatumumab in 30 patients with advanced chronic lymphocytic leukemia (CLL) in the French ATU program.

RESULTS

These very-high-risk patients had received multiple previous treatments (median = 6), and most had disease that was fludarabine-refractory or alemtuzumab-refractory (or both) or was unsuitable for alemtuzumab treatment. In the intent-to-treat analysis, the overall response rate was 47% (4 of 30, complete response; 10 of 30, partial response). Of 13 patients with 17p deletion, 6 displayed response to ofatumumab, including 2 complete responses. Treatment was well tolerated, with 17 grade 3 or 4 adverse events; 4 cases of grade 3 or 4 infusion reactions were reported, with favorable immediate outcome. Among nonhematologic complications, infections were the most frequent.

CONCLUSION

The results confirm the efficacy and acceptable tolerability profile of ofatumumab as a single agent in severely ill patients with CLL. Attention should be paid to possible early infusion reactions to ofatumumab, as well as to the risk of infection.

Targeted biopharmaceuticals for cancer treatment

Cancer is a complex invasive genetic disease that causes significant mortality rate worldwide. Protein-based biopharmaceuticals have significantly extended the lives of millions of cancer patients. This article reviews the biological function and application of targeted anticancer biopharmaceuticals. We first discuss the specific antigens and core pathways that are used in the development of targeted cancer therapy. The innovative monoclonal antibodies, non-antibody proteins, and small molecules targeting these antigens or pathways are then reviewed. Finally, the current challenges in anticancer biopharmaceuticals development and the potential solutions to address these challenges are discussed.

Ofatumumab: a novel, fully human anti-CD20 monoclonal antibody for the treatment of chronic lymphocytic leukemia

Ofatumumab is a fully human, IgG anti-CD20 monoclonal antibody codeveloped by GlaxoSmithKline (Brentford, UK) and Genmab (Copenhagen, Denmark). In preclinical studies, ofatumumab exhibited more potent in vitro activity than rituximab against B-cell malignancies and prolonged survival in in vivo animal models compared with rituximab. Ofatumumab is clinically well tolerated with initial infusion reactions being the predominant associated toxicity. Ofatumumab has demonstrated efficacy in relapsed/refractory chronic lymphocytic leukemia (CLL) and has received regulatory approval in both Europe and the USA for treatment of fludarabine and alemtuzumab refractory disease. Single-agent ofatumumab has resulted in overall response rates of 42-51% in relapsed/refractory CLL and up to 80% when combined with chemotherapy. In de novo CLL, overall response rates of 77-78% have been achieved.

Population pharmacokinetics of ofatumumab in patients with chronic lymphocytic leukemia, follicular lymphoma, and rheumatoid arthritis

Ofatumumab is a human monoclonal antibody directed at CD20 approved for treatment of chronic lymphocytic leukemia. The population pharmacokinetics of intravenous ofatumumab were characterized in patients with relapsed/refractory chronic lymphocytic leukemia, relapsed/refractory follicular lymphoma, and rheumatoid arthritis, diseases with widely varying CD20⁺ B-cell counts in blood. Serum concentration data from a total of 477 patients who received ofatumumab doses ranging from 100 mg to 2000 mg in different dosing regimens were analyzed to determine the pharmacokinetic characteristics of ofatumumab across different patient groups and to identify factors contributing to the pharmacokinetic variability. Ofatumumab pharmacokinetics were well described by a linear two-compartment model component to represent non-specific monoclonal antibody clearance from the central compartment interacting with a model component representing the target-mediated clearance of ofatumumab by binding to CD20 expressed on B cells. The clearance (7.5 mL/h) and steady-state volume of distribution (5.3 L) for the linear, non-specific component were consistent with results obtained for other monoclonal antibodies. The target-mediated clearance component was related to the disease-specific number of circulating B cells, which will allow simulation of the contribution of target-mediated clearance to ofatumumab pharmacokinetics in untested disease states with data on B-cell counts and turnover.

Anti-CD20 monoclonal antibodies and associated viral hepatitis in hematological diseases

Over the past decade, the administration of anti-CD20 monoclonal antibodies such as rituximab has demonstrated various degrees of effectiveness and has improved patients’ outcomes during the treatment of autoimmune hematological disorders and hematological malignancies. However, the depletion of B-cells, the distribution of T-cell populations, and the reconstruction of host immunity resulting from the use of anti-CD20 monoclonal antibodies potentially lead to severe viral infections, such as hepatitis B virus (HBV), hepatitis C virus (HCV), parvovirus B19, and herpes viruses, in patients who are undergoing immune therapy or immunochemotherapy. Of these infections, HBV- and HCV-related hepatitis are a great concern in endemic areas because of the high morbidity and mortality rates in untreated patients. As a result, prophylaxis against HBV infection is becoming a standard of care in these areas. Parvovirus B19, a widespread pathogen that causes red blood cell aplasia in immunocompromised hosts, also causes hepatitis in healthy individuals. Recently, its association with hepatitis was recognized in a patient treated with rituximab. In addition, adenovirus, varicella-zoster virus, hepatitis E virus, and rituximab itself have been linked to the occurrence of hepatitis during or after rituximab treatments. The epidemiologies and pathogeneses of these etiologies remain unknown. Because of the increasing use of anti-CD20 monoclonal antibodies for the treatment of hematological malignancies or autoimmune hematological disorders, it is imperative that physicians understand and balance the risks of hepatotropic virus-associated hepatitis against the benefits of using anti-CD20 monoclonal antibodies.

Ofatumumab as front-line therapy in untreated chronic lymphocytic leukemia

ABSTRACT: 

Ofatumumab is a fully human IgG1 type I anti-CD20 monoclonal antibody that binds to both the small and large loop of the membrane antigen CD20. Much of its therapeutic efficacy is derived through complement-dependent cytotoxicity, although it also appears to operate via induction of caspase-dependent apoptosis and shows potent antibody-dependent cellular phagocytosis. CD20 is an important but sometimes difficult antigen to effectively target in chronic lymphocytic leukemia (CLL) secondary to its overall dim expression in CLL cells. Currently, ofatumumab is approved in the USA and EU for fludarabine- and alemtuzumab-refractory CLL patients. However, the experience with ofatumumab in untreated CLL patients is mounting and shows competitive response and survival rates with an acceptable adverse event profile. Herein, we outline the efficacy and toxicities of ofatumumab alone and in combination for the front-line treatment of CLL.

B-cell antigen receptor signaling in chronic lymphocytic leukemia: therapeutic targets and translational opportunities

B-cell chronic lymphocytic leukemia (CLL) is characterized by clonally expanded and molecularly heterogeneous populations of B lymphocytes with impaired apoptotic mechanisms. This occurs as a result of multiple genetic and epigenetic abnormalities, including chromosomal aberrations and enhancer region hypomethylation, often impinging on intracellular signaling pathways that are essential to normal B-cell activation, proliferation, and survival. The B-cell antigen receptor (BCR) signaling is one such pathway usurped by malignant B cells, as exemplified by the early phase clinical success achieved by small-molecule agents targeting key players involved in the pathway. Such new targeted agents, including those that inhibit the function of Spleen tyrosine kinase (SYK), Bruton's tyrosine kinase (BTK), phosphatidylinositol 3-kinases (PI3K), and B-cell lymphoma 2 (BCL-2), along with the current standard therapy comprising chemo-immunotherapies with or without B-cell depleting biologic agent rituximab (anti-CD20 monoclonal antibody), should expand the armamentarium for CLL therapy. We review the therapeutic agents currently in clinical development which target different effectors of the malignant BCR signaling, and discuss their overlapping and discriminating translational opportunities in the context of CLL treatment.

New treatment options for chronic lymphocytic leukemia

INTRODUCTION

Chemoimmunotherapy is the gold standard of therapy for patients with advanced chronic lymphocytic leukemia (CLL), resulting in high and durable complete response rates. However, all patients eventually relapse and CLL remains incurable. Newer and more rationally developed compounds are needed to improve CLL therapy, particularly in cases of refractory disease.

AREAS COVERED

Following a literature search on PubMed using 'chronic', 'lymphocytic', 'treatment' and 'therapy' as keywords, results obtained with novel agents were critically analyzed. Abstracts presented during 2013 at ASH, EHA, ICML, IWCLL and ASCO meetings were also included in the search.

EXPERT OPINION

New monoclonal antibodies, lenalidomide, B-cell receptor-signal transduction inhibitors and pro-apoptotic molecules have shown efficacy in patients with relapsed or refractory disease. Hopefully, the combined use of these molecules in risk-adapted treatment strategies will improve the outcome of patients with CLL and pave the way for their long-term control.

Induced resistance to ofatumumab-mediated cell clearance mechanisms, including complement-dependent cytotoxicity, in chronic lymphocytic leukemia

Ofatumumab (OFA), a human CD20-targeting mAb, kills B lymphocytes using the innate immune system including complement-dependent cytotoxicity (CDC). The efficacy of OFA in patients with chronic lymphocytic leukemia (CLL) is limited by drug resistance, which is not well characterized. To better understand mechanisms of resistance, we prospectively studied CLL cells isolated from blood samples collected before and after in vivo exposure to the initial dose of OFA therapy in 25 patients undergoing their first treatment for progressive CLL. As previously reported, OFA therapy rapidly decreased the absolute lymphocyte count, CD20 expression by CLL cells, and serum complement levels. We now show that after administration of the first dose of OFA, there was a modest rebound in the absolute lymphocyte count and serum complement levels, but substantial ongoing loss of CD20 expression by CLL cells. These post-OFA treatment CLL cells were highly resistant to OFA-mediated CDC but retained sensitivity to alemtuzumab-mediated CDC in vitro. Posttherapy serum OFA levels correlated inversely with both the amount of pretreatment circulating cell-bound CD20 and with the decrease in this value following treatment. In vitro OFA-mediated CDC did not predict clinical responses, and the patients with first-dose reactions to OFA did not have markers of increased complement activation in vivo. We propose that optimal efficacy of CD20- targeted therapy for CLL requires determining an mAb dose size and frequency that optimizes CLL killing without exceeding the capacity of the cytotoxic mechanisms and thus minimizes loss of CD20 expression in the surviving CLL cells.

Treatment challenges in the management of relapsed or refractory non-Hodgkin's lymphoma - novel and emerging therapies

Over the last few decades, advances in immunochemotherapy have led to dramatic improvement in the prognosis of non-Hodgkin's lymphoma (NHL). Despite these advances, relapsed and refractory disease represents a major treatment challenge. For both aggressive and indolent subtypes of NHL, there is no standard of care for salvage regimens, with prognosis after relapse remaining relatively poor. Nevertheless, there are multiple emerging classes of targeted therapies for relapsed/refractory disease, including monoclonal antibodies, antibody- drug conjugates, radioimmunotherapy, small-molecule inhibitors of cell-growth pathways, and novel chemotherapy agents. This review will discuss treatment challenges of NHL, current available salvage regimens for relapsed/refractory NHL, and the safety and efficacy of novel emerging therapies.

Combination of two anti-CD5 monoclonal antibodies synergistically induces complement-dependent cytotoxicity of chronic lymphocytic leukaemia cells

The treatment of chronic lymphocytic leukaemia (CLL) has been improved by introduction of monoclonal antibodies (mAbs) that exert their effect through secondary effector mechanisms. CLL cells are characterized by expression of CD5 and CD23 along with CD19 and CD20, hence anti-CD5 Abs that engage secondary effector functions represent an attractive opportunity for CLL treatment. Here, a repertoire of mAbs against human CD5 was generated and tested for ability to induce complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) both as single mAbs and combinations of two mAbs against non-overlapping epitopes on human CD5. The results demonstrated that combinations of two mAbs significantly increased the level of CDC compared to the single mAbs, while no enhancement of ADCC was seen with anti-CD5 mAb combinations. High levels of CDC and ADCC correlated with low levels of Ab-induced CD5 internalization and degradation. Importantly, an anti-CD5 mAb combination enhanced CDC of CLL cells when combined with the anti-CD20 mAbs rituximab and ofatumumab as well as with the anti-CD52 mAb alemtuzumab. These results suggest that an anti-CD5 mAb combination inducing CDC and ADCC may be effective alone, in combination with mAbs against other targets or combined with chemotherapy for CLL and other CD5-expressing haematological or lymphoid malignancies.

Complement factor H-derived short consensus repeat 18-20 enhanced complement-dependent cytotoxicity of ofatumumab on chronic lymphocytic leukemia cells

The antitumor activity of monoclonal antibodies in the treatment of chronic lymphocytic leukemia is mediated mainly by antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. Unfortunately, the efficacy of complement-dependent cytotoxicity is strongly restricted due to the expression and acquisition of regulators of complement activation by lymphocytic leukemia cells. Whereas the role of membrane regulators of complement activation, such as CD55 and CD59, has been investigated in detail in chronic lymphocytic leukemia, the involvement of soluble regulators of complement activation, such as complement factor H, has not yet been reported. Propidium iodide staining was performed to investigate the efficacy of ofatumumab and factor H-derived short-consensus-repeat 18-20 in the induction of complement-dependent cytotoxicity on primary chronic lymphocytic leukemia cells from 20 patients. Deposition of complement C3 fragments was monitored by western blot analysis. Expression of CD20, CD55 or CD59 was determined by FACS analysis. Replacement of factor H with short consensus repeat 18-20 significantly increased the susceptibility of primary chronic lymphocytic leukemia cells to ofatumumab-induced complement-dependent cytotoxicity. More importantly, addition of short-consensus-repeat 18-20 was able to overcome complement- resistance occurring during treatment with ofatumumab alone. Use of short consensus repeat 18-20 is likely to prolong the turnover time of active C3b fragments generated on the target cells following ofatumumab-induced complement activation, thereby improving specific killing of chronic lymphocytic leukemia cells by complement-dependent cytotoxicity. The relative contribution of factor H to the protection of chronic lymphocytic leukemia cells against complement-dependent cytotoxicity was comparable to that of CD55. Our data suggest that, by abrogating factor H function, short consensus repeat 18-20 may provide a novel approach that improves the complement-dependent efficacy of therapeutic monoclonal antibodies.

Developing strategies in the immunotherapy of leukemias

BACKGROUND

In the current treatment paradigms for leukemias, hematopoietic stem cell transplant (HSCT) is considered the best option with a curative potential although more often than not it simply delays disease progression. Advances are needed, both in current therapies and in the development of new strategies. Partly from studying the nuances of the curative potential of stem cell transplant, we have come to appreciate the relevance of the immune response and the potential of immunotherapy.

METHODS

This review article summarizes the recent advances in the field of immunology and immunotherapy for leukemia.

RESULTS

In passive immunotherapy, recent progress in chimeric T-cell antigen receptor technology has been encouraging. In active immunotherapy, a cancer vaccine may potentially enhance HSCT. An overview of various clinical studies of peptide vaccination strategies focusing on molecular targets such as the Wilms' tumor gene 1 (WT1), proteinase 3 (PR3), and receptor for hyaluronan acid-mediated motility (RHAMM) is provided. Cell-based vaccination strategies are also briefly explored.

CONCLUSIONS

The immune system clearly has the capacity to recognize and react to leukemic cells, and recent evidence directs our attention to the importance of mounting inflammatory and CD4 T-cell responses to complement and support the cytotoxic activity elicited by peptide vaccines.

Ofatumumab in combination with ICE or DHAP chemotherapy in relapsed or refractory intermediate grade B-cell lymphoma

Standard treatment of transplant-eligible patients with relapsed diffuse large B-cell lymphoma (DLBCL) consists of rituximab and platinum-based chemotherapy, either ifosfamide, carboplatin, and etoposide (ICE) or dexamethasone, cytarabine, and cisplatin (DHAP), with autologous transplant consolidation for those with chemosensitive disease. Nonetheless, outcomes are suboptimal for patients failing rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). We performed a multi-center phase II trial investigating the safety and efficacy of ofatumumab, a monoclonal antibody against CD20, combined with ICE or DHAP second-line therapy in patients with relapsed or refractory DLBCL, grade 3b follicular lymphoma, or transformed follicular lymphoma. Sixty-one patients were treated with either ofatumumab-ICE (35) or ofatumumab-DHAP (26). The overall response rate (ORR) was 61%, and the complete response (CR) rate was 37%. In patients with 2 or 3 adverse risk factors according to the second-line, age-adjusted, international prognostic index, the ORR was 59% and CR 31%, and in patients with early-relapsing or primary refractory disease, the ORR was 55% and CR 30%. Toxicity was largely hematologic, and stem cell mobilization was successful in 43 of 45 patients. Substitution of ofatumumab for rituximab in standard second-line regimens following failure of R-CHOP is a promising approach. This trial was registered at www.clinicaltrials.gov as NCT00823719.

Ibrutinib: an evidence-based review of its potential in the treatment of advanced chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with a variable course, and remains an incurable disease. Frequent relapses and eventual resistance to fludarabine characterize symptomatic CLL and portends a dismal prognosis for patients. Growing evidence has shown that signaling pathways such as the B cell receptor and NFkB are implicated in the survival and proliferation of the CLL cells which are ultimately associated with persistence of the disease. The Bruton's tyrosine kinase pathway regulates downstream activation of the B cell receptor and has emerged as an attractive target. Ibrutinib inhibits the Bruton's tyrosine kinase pathway, and consequently induces apoptosis of B cells. Phase I and II studies have shown impressive response rates with an excellent safety profile in patients with refractory/relapsed CLL and elderly treatment-naïve CLL patients. This paper reviews the preclinical and clinical data for ibrutinib when used in the treatment of CLL. Recent studies showing the benefit of combination therapy using ibrutinib, monoclonal antibodies, and chemoimmunotherapy are also discussed.

Challenges and approaches for the development of safer immunomodulatory biologics

Immunomodulatory biologics are a class of biotechnology-derived therapeutic products that are designed to engage immune-relevant targets and are indicated in the treatment and management of a range of diseases, including immune-mediated inflammatory diseases and malignancies.

Despite their high specificity and therapeutic advantages, immmunomodulatory biologics have been associated with adverse reactions such as serious infections, malignancies and cytokine release syndrome, which arise owing to the on-target or exaggerated pharmacological effects of these drugs. Immunogenicity resulting in the generation of antidrug antibodies is another unwanted effect that leads to loss of efficacy and — rarely — hypersensitivity reactions.

For some adverse reactions, mitigating and preventive strategies are in place, such as stratifying patients on the basis of responsiveness to therapy and the risk of developing adverse reactions. These strategies depend on the availability of robust biomarkers for therapeutic efficacy and the risk of adverse reactions: for example, seropositivity for John Cunningham virus is a risk factor for progressive multifocal leukoencephalopathy. The development of effective biomarkers will greatly aid these strategies.

The development and design of safer immunomodulatory biologics is reliant on a detailed understanding of the nature of the disease, target biology, the interaction of the target with the immunomodulatory biologic and the inherent properties of the biologic that elicit unwanted effects.

The availability of in vitro and in vivo models that can be used to predict adverse reactions associated with immunomodulatory biologics is central to the development of safer immunomodulatory biologics. Some progress has been made in developing in vitro and in silico tests for predicting cytokine release syndrome and immunogenicity, but there is still a lack of models for effectively predicting infections and malignancies.

Two pathways can be followed in designing and developing safer immunomodulatory biologics. The first pathway involves generating a biologic that engages an alternative target or mechanism to produce the desired pharmacodynamic effect without the associated adverse reaction, and is followed when the adverse reaction cannot be dissociated from the target biology. The second pathway involves redesigning the biologic to 'engineer out' components within the biologic structure that trigger adverse effects or to alter the nature of the target–biologic interactions.

Owing to their specificity, immunomodulatory biologics generally have better safety profiles than small-molecule drugs. However, adverse effects such as an increased risk of infections or cytokine release syndrome are of concern. Here, Park and colleagues discuss the current strategies used to predict and mitigate these adverse effects and consider how they can be used to inform the development of safer immunomodulatory biologics.

Immunomodulatory biologics, which render their therapeutic effects by modulating or harnessing immune responses, have proven their therapeutic utility in several complex conditions including cancer and autoimmune diseases. However, unwanted adverse reactions — including serious infections, malignancy, cytokine release syndrome, anaphylaxis and hypersensitivity as well as immunogenicity — pose a challenge to the development of new (and safer) immunomodulatory biologics. In this article, we assess the safety issues associated with immunomodulatory biologics and discuss the current approaches for predicting and mitigating adverse reactions associated with their use. We also outline how these approaches can inform the development of safer immunomodulatory biologics.

Safety and efficacy of ofatumumab in patients with fludarabine and alemtuzumab refractory chronic lymphocytic leukaemia

There are now many therapeutic CD20 monoclonal antibodies undergoing clinical trials for B-cell malignancy and autoimmune conditions; which is optimal for cancer therapy is not clear. The novel human IgG1 CD20 monoclonal antibody ofatumumab has shown significant activity in difficult to treat patients with chronic lymphocytic leukemia, namely those resistant or refractory to fludarabine and alemtuzumab and has now been licensed for this uncommon indication. This brief review summarizes the clinical data obtained with ofatumumab in CLL in terms of both efficacy and toxicity.

GA101 induces NK-cell activation and antibody-dependent cellular cytotoxicity more effectively than rituximab when complement is present

Both complement and antibody-dependent cellular cytotoxicity (ADCC) contribute to the clinical efficacy of anti-CD20 monoclonal antibody (mAb) therapy. Paradoxically, the C3b component of complement can block interaction between mAb and natural killer (NK) cells. The present study compared the effect of complement on the ability of two anti-CD20 mAbs, rituximab and GA101, to activate NK cells and mediate ADCC. Complement blocked adherence of NK cells to rituximab, but had little effect on NK binding to GA101. Target cells coated with rituximab or GA101 were able to activate NK cells in the absence of serum. Complement in serum blocked NK activation induced by rituximab, but not GA101. Complement blocked rituximab-induced NK-cell mediated ADCC, but not GA101-induced ADCC. These results demonstrate that the decreased ability of GA101 to fix complement relative to rituximab results in an enhanced ability of GA101 to bind to NK cells, activate NK cells and induce ADCC when serum is present.

Novel targeted treatment strategies for refractory chronic lymphocytic leukaemia

Patients with refractory chronic lymphocytic leukaemia (CLL) still have an unfavourable prognosis and novel treatment strategies are necessary, preferably adjusted to the patient's individual situation. Refractoriness is no longer limited just to fludarabine (F) but extends to F-combinations with other chemotherapeutic agents (e.g. cyclophosphamide [C] and FC) and antibodies (e.g. rituximab [R], FR, and FCR). Also, refractoriness to alemtuzumab is an increasing problem. New pharmacological developments provide promising approaches. This review focuses on novel therapies such as monoclonal antibodies and small molecules aiming at specific targets of the CLL cell in the refractory situation. Approved therapeutic regimens will be presented as well as investigational approaches. An overview of completed and current clinical trials is offered.

Phase I study of ofatumumab, a human anti-CD20 antibody, in Japanese patients with relapsed or refractory chronic lymphocytic leukemia and small lymphocytic lymphoma

Objectives

Ofatumumab is a human IgG1κ monoclonal antibody that targets a membrane proximal epitope encompassing the small and large loops of CD20. This Phase I study evaluated the safety, tolerability, efficacy and pharmacokinetics of ofatumumab monotherapy in Japanese patients with relapsed/refractory B-cell chronic lymphocytic leukemia and small lymphocytic lymphoma.

Methods

Ofatumumab was administered intravenously weekly for a total of eight doses (dose escalation: 500 and 1000 mg). Six patients (two chronic lymphocytic leukemia and four small lymphocytic lymphoma) were enrolled into two dose cohorts (500 mg, three patients; 1000 mg, three patients). All six patients received 300 mg ofatumumab at the first infusion and either 500 or 1000 mg at seven subsequent weekly infusions.

Results

No dose-limiting toxicities or serious adverse events were observed. Grade 3–4 adverse events observed were grade 3 lymphocytopenia (n = 1) and neutropenia (n = 1). Grade 1–2 infusion-related adverse events leading to temporary interruption of ofatumumab infusion were observed in all six patients on the first infusion day, and all patients completed the planned eight infusions. The overall response rate was 50% (3/6).

Conclusions

Ofatumumab was well tolerated at doses up to 1000 mg and showed preliminary evidence of activity in relapsed or refractory chronic lymphocytic leukemia/small lymphocytic lymphoma, warranting further investigations. This study was registered at ClinicalTrials.gov (NCT00742144).

Anti-CD20 monoclonal antibodies in chronic lymphocytic leukemia

INTRODUCTION

The last decade has witnesd immense progress in the treatment of chronic lymphocytic leukemia (CLL). Chemoimmunotherapy (CIT) combining rituximab and fludarabine with cyclophosphamide (FCR) in the frontline setting has clearly been shown to improve outcomes in patients with CLL. Building on the success achieved with rituximab, other anti-CD20 monoclonal antibodies (mAbs) are being investigated. Novel bioengineering techniques have helped in the development of anti-CD20 mAbs. One antibody, ofatumumab, was recently approved for the treatment of refractory CLL. A type II anti-CD20 mAb, GA-101 (obinutuzumab), is currently in clinical trials. This short review focuses on ongoing clinical trials of anti-CD20 mAbs in CLL.

AREAS COVERED

Literature search was performed using PubMed ( www.clinicaltrials.gov (till August 2012)), and recent American Society of Clinical Oncology (ASCO), American Society of Hematology (ASH), European Hematology association (EHA), International workshop on CLL (iwCLL) abstracts, using the primary search terms 'anti-CD20 monoclonal antibody' with/without CLL. Articles were chosen on the basis of relevance of anti-CD20 mAbs to CLL therapy.

EXPERT OPINION

Rituximab, the prototype anti-CD20 mAb, forms the core of CIT in CLL. The success of rituximab and ofatumumab has led investigators to evaluate other anti-CD20 mAbs in the treatment of CLL.

Emerging monoclonal antibodies and related agents for the treatment of chronic lymphocytic leukemia

Monoclonal antibodies (mAbs) – rituximab, ofatumumab and alemtuzumab – have been approved for use in the therapy of chronic lymphocytic leukemia (CLL). Recently, a new generation of anti-CD20 mAbs has become available for preclinical studies and clinical trials. These antibodies were engineered to have augmented antitumor activity by increasing complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity and Fc-binding affinity for the low-affinity variants of the Fcγ receptor IIIa. The most promising mAb directed against CD20 is obinutuzumab (GA-101). mAbs directed against CD22, CD37 and CD40 have also shown some activity in CLL. In addition, small modular immunopharmaceuticals – TRU-015 (anti-CD20) and TRU-016 (anti-CD37) – that retain Fc-mediated effector functions have been developed and investigated in preclinical studies and clinical trials. Antibody–drug conjugates and recombinant immunotoxins are also being evaluated in lymphoid malignancies. Further studies will elucidate the role of these agents in the treatment of CLL.

[Conventional therapeutic strategies for relapsed chronic lymphocytic leukemia]

The choice of salvage therapy for patients presenting relapsed chronic lymphocytic leukemia (CLL) has to take into account some factors influencing tumor resistance and comorbidities. Since 2010, new drugs targeting the tumor cells' signaling have been proposed for CLL patients. Waiting the results of various clinical trials evaluating these treatments, there is a need to describe the state-of-the-art concerning approved treatments such as chemotherapy and monoclonal antibodies.

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.

Rituximab, ofatumumab and other monoclonal anti-CD20 antibodies for chronic lymphocytic leukaemia

BACKGROUND

Chronic lymphocytic leukaemia (CLL) accounts for 25% of all leukaemias and is the most common lymphoid malignancy in western countries. Standard treatments include mono- or polychemotherapies, usually combined with monoclonal antibodies such as rituximab or alemtuzumab. However, the impact of these agents remains unclear, as there are hints for increased risk of severe infections.

OBJECTIVES

The objectives of this review are to provide an evidence-based answer regarding the clinical benefits and harms of monoclonal anti-CD20 antibodies (such as rituximab, ofatumumab, GA101) compared to no further therapy or to other anti-leukaemic therapies in patients with CLL, irrespective of disease status.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 12, 2011), MEDLINE (from January 1990 to 4 January 2012), and EMBASE (from 1990 to 20 March 2009) as well as conference proceedings (American Society of Hematology, American Society of Clinical Oncology, European Hematology Association and European Society of Medical Oncology) for randomised controlled trials (RCTs).

SELECTION CRITERIA

We included RCTs examining monoclonal anti-CD20 antibodies compared to no further therapy or to anti-leukaemic therapy such as chemotherapy or monoclonal antibodies in patients with newly diagnosed or relapsed CLL.

DATA COLLECTION AND ANALYSIS

We used hazard ratios (HR) as effect measures for overall survival (OS), progression-free survival (PFS) and time to next treatment, and risk ratios (RR) for response rates, treatment-related mortality (TRM) and adverse events (AEs). Two review authors independently extracted data and assessed quality of trials.

MAIN RESULTS

We screened a total of 1150 records. Seven RCTs involving 1763 patients were identified, but only five could be included in the two separate meta-analyses we performed. We judged the overall the quality of these trials as moderate to high. All trials were randomised and open-label studies. However, two trials were published as abstracts only, therefore we were unable to assess the potential risk of bias for these trials in detail.Three RCTs (N = 1421) assessed the efficacy of monoclonal anti-CD20 antibodies (i.e. rituximab) plus chemotherapy compared to chemotherapy alone. The meta-analyses showed a statistically significant OS (HR 0.78, 95% confidence interval (CI) 0.62 to 0.98, P = 0.03, the number needed to treat for an additional beneficial effect (NNTB) was 12) and PFS (HR 0.64, 95% CI 0.55 to 0.74, P < 0.00001) advantage for patients receiving rituximab. In the rituximab-arm occurred more AEs, World Health Organization (WHO) grade 3 or 4 (3 trials, N = 1398, RR 1.15, 95% CI 1.08 to 1.23, P < 0.0001; the number needed to harm for an additional harmful outcome (NNTH) was 9), but that did not lead to a statistically significant difference regarding TRM (3 trials, N = 1415, RR 1.19, 95% CI 0.70 to 2.01, P = 0.52).Two trials (N = 177) evaluated rituximab versus alemtuzumab. Neither study reported OS or PFS. There was no statistically significant difference between arms regarding complete response rate (CRR) (RR 1.21, 95% CI 0.94 to 1.58, P = 0.14) or TRM (RR 0.31, 95% CI 0.06 to 1.51, P = 0.15). However, the CLL2007FMP trial was stopped early owing to an increase in mortality in the alemtuzumab arm. More serious AEs occurred in this arm (43% with alemtuzumab versus 22% with rituximab; P = 0.006).Two trials assessed different dosages or time schedules of monoclonal anti-CD20 antibodies. One trial (N = 104) evaluated two different rituximab schedules (concurrent arm: fludarabine plus rituximab (Flu-R) plus rituximab consolidation versus sequential arm: fludarabine alone plus rituximab consolidation). The comparison of the concurrent versus sequential regimen of rituximab showed a statistically significant difference of the CRR with 33% in the concurrent-arm and 15% in the sequential-arm (P = 0.04), that did not lead to statistically significant differences regarding OS (HR 1.14, 95% CI 0.20 to 6.65, P = 0.30) or PFS (HR 0.96, 95% CI 0.43 to 2.15, P = 0.11). Furthermore results showed no differences in occurring AEs, except for neutropenia, which was more often observed in patients of the concurrent arm. The other trial (N = 61) investigated two different dosages (500 mg and 1000 mg) of ofatumumab in addition to FluC. The arm investigating ofatumumab did not assess OS and a median PFS had not been reached owing to the short median follow-up of eight months. It showed no statistically significant differences between arms regarding CRR (32% in the FCO500 arm versus 50% in the FCO1000 arm; P = 0.10) or AEs (anaemia, neutropenia, thrombocytopenia).

AUTHORS' CONCLUSIONS

This meta-analysis showed that patients receiving chemotherapy plus rituximab benefit in terms of OS as well as PFS compared to those with chemotherapy alone. Therefore, it supports the recommendation of rituximab in combination with FluC as an option for the first-line treatment as well as for the people with relapsed or refractory CLL. The available evidence regarding the other assessed comparisons was not sufficient to deduct final conclusions.

Diffuse large B-cell lymphoma: current strategies and future directions

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is the most common histology of non-Hodgkin lymphoma, representing 25% to 35% of new cases annually. The incidence of DLBCL has doubled in the past decades, highlighting the need for more effective treatment regimens.

METHODS

This article reviews the current protocols applicable to this aggressive lymphoma and discusses ongoing research that is focusing on molecular diagnostics, prognostic factors have also been defined for DLBCL.

RESULTS

Patients with DLBCL vary in clinical presentation, prognosis, and response to current therapies. While current therapy in the rituximab era has led to improved outcomes with reduced toxicity, novel treatment approaches for localized, advanced, and relapsed/refractory DLBCL are being pursued in clinical trials. Several studies have shown promise, such as trials involving proteasome inhibitors, lenalidomide, and antibody drug conjugates.

CONCLUSIONS

Recent discoveries in the spectrum of care for patients with DLBCL have prompted a renaissance for personalized cancer medicine and molecularly targeted therapy. Potential targets and novel drug combinations are undergoing continued study in the hope of achieving successful and personalized care of this disease.