Durable complete responses from therapy with combined epratuzumab and rituximab: final results from an international multicenter, phase 2 study in recurrent, indolent, non-Hodgkin lymphoma

Targeting CD22 for the Treatment of B-Cell Malignancies

Immunotherapeutic agents play an increasingly important role in the treatment of B-cell malignancies. CD19 and CD20 are common targets for lymphoid malignancies, though patients who relapse have few therapeutic options remaining. CD22 is a cell surface sialoglycoprotein uniquely present on B-cells and regulates B-cell function and proliferation. Thus, it is an appealing therapeutic target for autoimmune disorders and B-cell malignancies. A variety of therapies targeting CD22 have been developed, including monoclonal antibodies, antibody-drug conjugates, radioimmunoconjugates, chimeric antigen receptor T cells, and bispecific antibodies. Here, we review the biology of CD22 and key therapies targeting CD22 in lymphoid malignancies.

Invasive Fungal Diseases in Children with Hematological Malignancies Treated with Therapies That Target Cell Surface Antigens: Monoclonal Antibodies, Immune Checkpoint Inhibitors and CAR T-Cell Therapies

Since 1985 when the first agent targeting antigens on the surface of lymphocytes was approved (muromonab-CD3), a multitude of such therapies have been used in children with hematologic malignancies. A detailed literature review until January 2021 was conducted regarding pediatric patient populations treated with agents that target CD2 (alefacept), CD3 (bispecific T-cell engager [BiTE] blinatumomab), CD19 (denintuzumab mafodotin, B43, BiTEs blinatumomab and DT2219ARL, the immunotoxin combotox, and chimeric antigen receptor [CAR] T-cell therapies tisagenlecleucel and axicabtagene ciloleucel), CD20 (rituximab and biosimilars, 90Y-ibritumomab tiuxetan, ofatumumab, and obinutuzumab), CD22 (epratuzumab, inotuzumab ozogamicin, moxetumomab pasudotox, BiTE DT2219ARL, and the immunotoxin combotox), CD25 (basiliximab and inolimomab), CD30 (brentuximab vedotin and iratumumab), CD33 (gemtuzumab ozogamicin), CD38 (daratumumab and isatuximab), CD52 (alemtuzumab), CD66b (90Y-labelled BW 250/183), CD248 (ontuxizumab) and immune checkpoint inhibitors against CTLA-4 (CD152; abatacept, ipilimumab and tremelimumab) or with PD-1/PD-L1 blockade (CD279/CD274; atezolizumab, avelumab, camrelizumab, durvalumab, nivolumab and pembrolizumab). The aim of this narrative review is to describe treatment-related invasive fungal diseases (IFDs) of each category of agents. IFDs are very common in patients under blinatumomab, inotuzumab ozogamicin, basiliximab, gemtuzumab ozogamicin, alemtuzumab, and tisagenlecleucel and uncommon in patients treated with moxetumomab pasudotox, brentuximab vedotin, abatacept, ipilimumab, pembrolizumab and avelumab. Although this new era of precision medicine shows promising outcomes of targeted therapies in children with leukemia or lymphoma, the results of this review stress the necessity for ongoing surveillance and suggest the need for antifungal prophylaxis in cases where IFDs are very common complications.

Advances in targeted therapy for malignant lymphoma

The incidence of lymphoma has gradually increased over previous decades, and it ranks among the ten most prevalent cancers worldwide. With the development of targeted therapeutic strategies, though a subset of lymphoma patients has become curable, the treatment of refractory and relapsed diseases remains challenging. Many efforts have been made to explore new targets and to develop corresponding therapies. In addition to novel antibodies targeting surface antigens and small molecular inhibitors targeting oncogenic signaling pathways and tumor suppressors, immune checkpoint inhibitors and chimeric antigen receptor T-cells have been rapidly developed to target the tumor microenvironment. Although these targeted agents have shown great success in treating lymphoma patients, adverse events should be noted. The selection of the most suitable candidates, optimal dosage, and effective combinations warrant further investigation. In this review, we systematically outlined the advances in targeted therapy for malignant lymphoma, providing a clinical rationale for mechanism-based lymphoma treatment in the era of precision medicine.

Targeting indolent non-Hodgkin lymphoma

INTRODUCTION

Due to recent advancements in the understanding of the molecular pathogenesis of B-cell malignancies, there has been an explosion of innovative agents in development. The purpose of this review is to efficiently summarize novel therapies with activity in indolent non-Hodgkin lymphoma (iNHL) targeting surface antigens, signaling pathways, and the tumor microenvironment. Areas covered: A literature search was performed to identify preclinical data and clinical trials focused on the use of targeted therapies in iNHL subtypes including follicular lymphoma, marginal zone lymphoma, small lymphocytic lymphoma, and lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. Classes reviewed include monoclonal antibodies, antibody-drug conjugates, immunomodulatory agents, B-cell receptor pathway inhibitors, Bcl-2 inhibitors, checkpoint inhibitors, chromatin and epigenetic modulating agents, and CAR T-cells. Expert commentary: Opinions regarding strategies to address the prioritization of novel agents entering clinical development, the determination of rational combination therapy, the development of novel endpoints to expedite clinical development, and the movement towards novel consolidative approaches with immuno- and cellular therapy in an attempt to provide curative treatment options are provided. Also, the economic impact of indefinite therapy is discussed.

Novel agents in follicular lymphoma: choosing the best target

Outcomes in patients with follicular lymphoma (FL) have improved dramatically over the last decade. However, novel agents are greatly needed for those who exhibit treatment resistance, in order to minimize lifelong toxicity and to enable combinations that may allow us to achieve the elusive goal of cure. Biological advances have led to the discovery of a large number of potential therapeutic targets and the development of a plethora of novel agents designed to exploit these processes. Possible targets include tumor cell surface markers, key components of intracellular pathways and epigenetic mechanisms, and reactive cells of the microenvironment. Given the large number of candidate drugs and potential combinations, it will be crucial to prioritize evaluation based on sound preclinical and early clinical studies. Combinations that exploit driver mechanisms within tumor cells and target parallel pathways to minimize the development of drug resistance, as well as harness the potential of the immune system would seem most logical. In order to expedite progress, future studies will need to use innovative trial designs and employ surrogate end points. The development of validated prognostic tools to identify higher risk patients and reliable predictive markers to select subgroups most likely to benefit from targeted agents will be paramount. The potential for unexpected toxicity with novel combinations must be recognized, necessitating both short- and long-term vigilance. Finally, as a greater number of treatment options become available, optimal sequencing must be determined in order to both prolong life and maintain its quality.

New drugs for follicular lymphoma

Despite the improvement in prognosis since the advent of rituximab, follicular lymphoma is still incurable and remains the cause of death of most afflicted patients. With the expanding knowledge of the pathogenesis of B-cell malignancies, in the last few years a plethora of new therapies acting through a variety of mechanisms have shown promising results. This review attempts to analyze the evidence available on these new drugs, which include new monoclonal antibodies and immunoconjugates, the anti-angiogenic and immunomodulatory agent lenalidomide, the proteasome inhibitor bortezomib, inhibitors of B-cell receptor pathway enzymes, such as ibrutinib, idelalisib, duvelisib and entospletinib, BCL2 inhibitors and checkpoint inhibitors. We conclude that despite the high expectations around the new therapeutic options for patients with refractory disease, these new drugs have side effects that require caution with their use, particularly in light of the still short follow up and the lack of both randomized trials and data on combination regimens.

Suppression of Rituximab-resistant B-cell lymphoma with a novel multi-component anti-CD20 mAb nanocluster

Although the anti-CD20 antibody Rituximab has revolutionized the treatment of Non-Hodgkin Lymphoma (NHL), resistance to treatment still existed. Thus, strategies for suppressing Rituximab-resistant NHLs are urgently needed. Here, an anti-CD20 nanocluster (ACNC) is successfully constructed from its type I and type II mAb (Rituximab and 11B8). These distinct anti-CD20 mAbs are mass grafted to a short chain polymer (polyethylenimine). Compared with parental Rituximab and 11B8, the ACNC had a reduced “off-rate”. Importantly, ACNC efficiently inhibited Rituximab-resistant lymphomas in both disseminated and localized human NHL xenograft models. Further results revealed that ACNC is significantly potent in inducing caspase-dependent apoptosis and lysosome-mediated programmed cell death (PCD). This may help explain why ACNC is effective in suppressing rituximab-resistant lymphoma while Rituximab and 11B8 are not. Additionally, ACNC experienced low clearance from peripheral blood and high intratumor accumulation. This improved pharmacokinetics is attributed to the antibody-antigen reaction (active targeting) and enhanced permeability and retention (ERP) effect (passive targeting). This study suggested that ACNC might be a promising therapeutic agent for treatment of rituximab-resistant lymphomas.

The use of combinations of monoclonal antibodies in clinical oncology

Treatment with monoclonal antibodies is becoming increasingly important in clinical oncology. These antibodies specifically inhibit signaling pathways in tumor growth and/or induce immunological responses against tumor cells. By combining monoclonal antibodies several pathways may be targeted simultaneously, potentially leading to additive or synergistic effects. Theoretically, antibodies are very suitable for use in combination therapy, because of limited overlapping toxicity and lack of pharmacokinetic interactions. In this article an overview is given of preclinical and clinical data on twenty-five different combinations of antibodies in oncology. Some of these combinations have proven clinical benefit, for example the combination of trastuzumab and pertuzumab in HER2-positive breast cancer, which exemplifies an additive or synergistic effect on antitumor activity in clinical studies and the combination of nivolumab and ipilimumab, which results in significant increases in progression-free and overall survival in patients with advanced melanoma. However, other combinations may lead to unfavorable results, such as bevacizumab with cetuximab or panitumumab in advanced colorectal cancer. These combinations result in shorter progression-free survival and increased toxicity compared to therapy with a single antibody. In summary, the different published studies showed widely varying results, depending on the combination of antibodies, indication and patient population. More preclinical and clinical studies are necessary to unravel the mechanisms behind synergistic or antagonistic effects of combining monoclonal antibodies. Most research on combination therapies is still in an early stage, but it is expected that for several tumor types the use of combination therapy of antibodies will become standard of care in the near future.

Extensive crosslinking of CD22 by epratuzumab triggers BCR signaling and caspase-dependent apoptosis in human lymphoma cells

Epratuzumab has demonstrated therapeutic activity in patients with non-Hodgkin lymphoma, acute lymphoblastic leukemia, systemic lupus erythematosus, and Sjögren's syndrome, but its mechanism of affecting normal and malignant B cells remains incompletely understood. We reported previously that epratuzumab displayed in vitro cytotoxicity to CD22-expressing Burkitt lymphoma cell lines (Daudi and Ramos) only when immobilized on plates or combined with a crosslinking antibody plus a suboptimal amount of anti-IgM (1 μg/mL). Herein, we show that, in the absence of additional anti-IgM ligation, extensive crosslinking of CD22 by plate-immobilized epratuzumab induced intracellular changes in Daudi cells similar to ligating B-cell antigen receptor with a sufficiently high amount of anti-IgM (10 μg/mL). Specifically, either treatment led to phosphorylation of CD22, CD79a and CD79b, along with their translocation to lipid rafts, both of which were essential for effecting caspase-dependent apoptosis. Moreover, such immobilization induced stabilization of F-actin, phosphorylation of Lyn, ERKs and JNKs, generation of reactive oxygen species (ROS), decrease in mitochondria membrane potential (Δψ_m), upregulation of pro-apoptotic Bax, and downregulation of anti-apoptotic Bcl-xl and Mcl-1. The physiological relevance of immobilized epratuzumab was implicated by noting that several of its in vitro effects, including apoptosis, drop in Δψ_m, and generation of ROS, could be observed with soluble epratuzumab in Daudi cells co-cultivated with human umbilical vein endothelial cells. These results suggest that the in vivo mechanism of non-ligand-blocking epratuzumab may, in part, involve the unmasking of CD22 to facilitate the trans-interaction of B cells with vascular endothelium.

Randomized Trial of Lenalidomide Alone Versus Lenalidomide Plus Rituximab in Patients With Recurrent Follicular Lymphoma: CALGB 50401 (Alliance)

PURPOSE

Lenalidomide and rituximab (LR) are active agents in follicular lymphoma (FL). Combination regimens have not been previously assessed in randomized studies.

PATIENTS AND METHODS

The Cancer and Leukemia Group B (Alliance) 50401 trial is a randomized phase II trial studying rituximab (375 mg/m(2) weekly for 4 weeks), lenalidomide (15 mg per day on days 1 to 21, followed by 7 days of rest, in cycle 1 and then 20 mg per day on days 1 to 21, followed by 7 days of rest, in cycles 2 to 12), or LR. The rituximab-alone arm was discontinued as a result of poor accrual. Eligibility included recurrent FL and prior rituximab with time to progression of ≥ 6 months from last dose. Aspirin or heparin was recommended for patients at high thrombosis risk.

RESULTS

Ninety-one patients (lenalidomide, n = 45; LR, n = 46) received treatment; median age was 63 years (range, 34 to 89 years), and 58% were intermediate or high risk according to the Follicular Lymphoma International Prognostic Index. In the lenalidomide and LR arms, grade 3 to 4 adverse events occurred in 58% and 53% of patients, with 9% and 11% of patients experiencing grade 4 toxicity, respectively; grade 3 to 4 adverse events included neutropenia (16% v 20%, respectively), fatigue (9% v 13%, respectively), and thrombosis (16% [n = 7] v 4% [n = 2], respectively; P = .157). Thirty-six percent of lenalidomide patients and 63% of LR patients completed 12 cycles. Lenalidomide alone was associated with more treatment failures, with 22% of patients discontinuing treatment as a result of adverse events. Dose-intensity exceeded 80% in both arms. Overall response rate was 53% (20% complete response) and 76% (39% complete response) for lenalidomide alone and LR, respectively (P = .029). At the median follow-up of 2.5 years, median time to progression was 1.1 year for lenalidomide alone and 2 years for LR (P = .0023).

CONCLUSION

LR is more active than lenalidomide alone in recurrent FL with similar toxicity, warranting further study in B-cell non-Hodgkin lymphoma as a platform for addition of novel agents.

Re-induction chemoimmunotherapy with epratuzumab in relapsed acute lymphoblastic leukemia (ALL): Phase II results from Children's Oncology Group (COG) study ADVL04P2

BACKGROUND

Given the success of immunotherapeutic approaches in hematologic malignancies, the COG designed a phase I/II study to determine whether the addition of epratuzumab (anti-CD22) to an established chemotherapy platform improves rates of second remission (CR2) in pediatric patients with B-lymphoblastic leukemia (B-ALL) and early bone marrow relapse.

PROCEDURE

Therapy consisted of three established blocks of re-induction chemotherapy. Epratuzumab (360 mg/m(2)/dose) was combined with chemotherapy on weekly × 4 (B1) and twice weekly × 4 [eight doses] (B2) schedules during the first re-induction block. Remission rates and minimal residual disease (MRD) status were compared to historical rates observed with the identical chemotherapy platform alone.

RESULTS

CR2 was achieved in 65 and 66%, of the evaluable B1 (n = 54) and B2 patients (n = 60), respectively; unchanged from that observed historically without epratuzumab. Rates of MRD negativity (<0.01%) were 31% in B1 (P = 0.4128) and 39% in B2 patients (P = 0.1731), compared to 25% in historical controls. The addition of epratuzumab was well tolerated, with a similar toxicity profile to that observed with the re-induction chemotherapy platform regimen alone.

CONCLUSIONS

Epratuzumab was well tolerated in combination with re-induction chemotherapy. While CR2 rates were not improved compared to historical controls treated with chemotherapy alone, there was a non-significant trend towards improvement in MRD response with the addition of epratuzumab (twice weekly for eight doses) to re-induction chemotherapy.

Investigational therapies targeting lymphocyte antigens for the treatment of non-Hodgkin's lymphoma

INTRODUCTION

The advent of the anti-CD20 mAb rituximab has opened a new era in the treatment of non-Hodgkin's lymphomas (NHL), markedly altering standard treatment strategies. Moreover, the proof-of-concept that targeting a specific lymphocyte surface antigen may induce a highly effective and safe targeted killing of malignant cells has opened the door to the development of a plethora of novel mAbs directed towards different B- and T-cell-specific antigens.

AREAS COVERED

This review discusses the recent available clinical data about new-generation anti-CD20 mAbs characterized by increased antibody- (obinutuzumab) or complement-dependent cyotoxicity (ofatumumab) as well as novel investigational agents targeting other lymphocyte antigens (e.g., CD19, CD22, CD30, CD40, CD52, CCR4), which are currently under investigation for B- and T-cell NHL treatment. In addition, antibody-drug conjugates (inotuzumab ozogamicin, brentuximab vedotin, polatuzumab vedotin), bispecific T-cell engagers (blinatumomab) and a new class of antibodies targeting cytotoxic T-lymphocyte-associated antigen 4, programmed death 1 or programmed death ligand 1 (immune checkpoint inhibitors) are specifically considered.

EXPERT OPINION

Among the novel mAbs challenging rituximab, obinutuzumab seems to be in the most advanced phase, with the results of randomized trials awaited shortly. Brentuximab vedotin is increasing its role in T-cell NHL. Furthermore, immune checkpoint inhibitors have the potential to acquire a great relevance in NHL therapy.

The combination of milatuzumab, a humanized anti-CD74 antibody, and veltuzumab, a humanized anti-CD20 antibody, demonstrates activity in patients with relapsed and refractory B-cell non-Hodgkin lymphoma

As a result of the anti-tumour activity observed in vitro and in vivo with combined anti-CD20 and anti-CD74 antibodies, we initiated a phase I/II trial of veltuzumab and milatuzumab in patients with relapsed or refractory B-cell non-Hodgkin lymphoma (NHL). Patients received an induction of veltuzumab 200 mg/m(2) weekly combined with escalating doses of milatuzumab at 8, 16 and 20 mg/kg weekly for 4 weeks. Patients without disease progression could receive an extended induction with treatment on weeks 12, 20, 28 and 36. A total of 35 patients enrolled on the study. Median age was 63 years, median number of prior therapies was 3, and 63% of patients were rituximab refractory. No dose-limiting toxicities were observed in the phase I study. Related grade 3-4 toxicities included lymphopenia, leucopenia, neutropenia, anaemia, infusion reactions, hyperglycaemia, fatigue and atrial tachycardia. Median weeks of therapy was 12 and 29% of patients completed all 36 weeks of therapy. The overall response rate was 24%, median duration of response was 12 months, and responses were observed at all dose levels and in 50% of patients refractory to rituximab. Combination therapy with veltuzumab and milatuzumab demonstrated activity in a population of heavily pre-treated patients with relapsed or refractory indolent NHL.

WITHDRAWN: Effective suppression of Rituximab-resistant B-cell lymphoma by a comb-like anti-CD20 mAb nanocluster

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Chemotherapy-free treatment in patients with follicular lymphoma

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

Current therapeutic strategies and new treatment paradigms for follicular lymphoma

Follicular lymphoma (FL) is an indolent non-Hodgkin's lymphoma that remains an incurable disease for most patients. It is responsive to a variety of different treatments, however it follows a pattern of relapsing and remitting disease. Traditional therapeutic options for patients with untreated FL include expectant observation for asymptomatic and low tumor burden and multiagent cytotoxic chemotherapy for symptomatic and/or high tumor burden. Biologics have become an integral part of therapy with agents that target B lymphocytes, including monoclonal anti-CD20 antibodies and radiolabeled anti-CD20 antibodies. Treatment response to cytotoxic and biologic therapy is high initially; however, with subsequent treatments, response rate and remission duration typically decline and cumulative toxicities increase. The identification of novel targeted agents, use of stem cell transplantation, and new treatment combinations provide the opportunity to enhance patient outcomes. In this review, we critically examine standard treatment strategies for patients with newly diagnosed and relapsed or refractory FL and discuss established and emerging novel therapeutic approaches.

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.

New antibody approaches to lymphoma therapy

The CD20-directed monoclonal antibody rituximab established a new era in lymphoma therapy. Since then other epitopes on the lymphoma surface have been identified as potential targets for monoclonal antibodies (mAb). While most mAbs eliminate lymphoma cells mainly by antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity or direct cell death, others counter mechanisms utilized by malignant cells to evade immune surveillance. Expression of PD-L1 on malignant or stromal cells in the tumor environment for example leads to T-cell anergy. Targeting either PD-1 or PD-L1 via mAbs can indirectly eliminate cancer cells by unblocking the host intrinsic immune response. Yet another mechanism of targeted therapy with mAbs are bi-specific T-cell engagers (BiTE) such as blinatumomab, which directly engages the host immune cells. These examples highlight the broad spectrum of available therapies targeting the lymphoma surface with mAbs utilizing both passive and active immune pathways. Many of these agents have already demonstrated significant activity in clinical trials. In this review we will focus on novel CD20-directed antibodies as well as mAbs directed against newer targets like CD19, CD22, CD40, CD52 and CCR4. In addition we will review mAbs unblocking immune checkpoints and the BiTE blinatumomab. Given the success of mAbs and the expansion in active and passive immunotherapies, these agents will play an increasing role in the treatment of lymphomas.

A reevaluation of CD22 expression in human lung cancer

CD22 is a transmembrane glycoprotein expressed by mature B cells. It inhibits signal transduction by the B-cell receptor and its coreceptor CD19. Recent reports indicate that most human lung cancer cells and cell lines express CD22, making it an important new therapeutic target for lung cancer. The objective of our studies was to independently validate these results with the goal of testing the efficacy of our CD22 immunotoxins on lung cancer cell lines. As determined by quantitative real-time PCR analysis, we found that levels of CD22 mRNA in a panel of human lung cancer cell lines were 200 to 60,000-fold lower than those observed in the human CD22(+) Burkitt lymphoma cells, Daudi. Using flow cytometry with a panel of CD22 monoclonal antibodies and Western blot analyses, we could not detect surface or intracellular expression of CD22 protein in a panel of lung cancer cell lines. In addition, the in vitro proliferation of the lung tumor cell lines was not affected by either CD22 antibodies or our highly potent anti-CD22 immunotoxin. In contrast, CD22(+) Daudi cells expressed high levels of CD22 mRNA and protein, and were sensitive to our CD22 immunotoxin. Importantly, primary non-small cell lung cancers from more than 250 patient specimens did not express detectable levels of CD22 protein as assessed by immunohistochemistry. We conclude that CD22 is not expressed at measurable levels on the surface of lung cancer cells, and that these cells cannot be killed by anti-CD22 immunotoxins.

Anti-CD22/CD20 Bispecific antibody with enhanced trogocytosis for treatment of Lupus

The humanized anti-CD22 antibody, epratuzumab, has demonstrated therapeutic activity in clinical trials of lymphoma, leukemia and autoimmune diseases, treating currently over 1500 cases of non-Hodgkin lymphoma, acute lymphoblastic leukemias, Waldenström's macroglobulinemia, Sjögren's syndrome, and systemic lupus erythematosus. Because epratuzumab reduces on average only 35% of circulating B cells in patients, and has minimal antibody-dependent cellular cytotoxicity and negligible complement-dependent cytotoxicity when evaluated in vitro, its therapeutic activity may not result completely from B-cell depletion. We reported recently that epratuzumab mediates Fc/FcR-dependent membrane transfer from B cells to effector cells via trogocytosis, resulting in a substantial reduction of multiple BCR modulators, including CD22, CD19, CD21, and CD79b, as well as key cell adhesion molecules, including CD44, CD62L, and β7 integrin, on the surface of B cells in peripheral blood mononuclear cells obtained from normal donors or SLE patients. Rituximab has clinical activity in lupus, but failed to achieve primary endpoints in a Phase III trial. This is the first study of trogocytosis mediated by bispecific antibodies targeting neighboring cell-surface proteins, CD22, CD20, and CD19, as demonstrated by flow cytometry and immunofluorescence microscopy. We show that, compared to epratuzumab, a bispecific hexavalent antibody comprising epratuzumab and veltuzumab (humanized anti-CD20 mAb) exhibits enhanced trogocytosis resulting in major reductions in B-cell surface levels of CD19, CD20, CD21, CD22, CD79b, CD44, CD62L and β7-integrin, and with considerably less immunocompromising B-cell depletion that would result with anti-CD20 mAbs such as veltuzumab or rituximab, given either alone or in combination with epratuzumab. A CD22/CD19 bispecific hexavalent antibody, which exhibited enhanced trogocytosis of some antigens and minimal B-cell depletion, may also be therapeutically useful. The bispecific antibody is a candidate for improved treatment of lupus and other autoimmune diseases, offering advantages over administration of the two parental antibodies in combination.

Lenalidomide plus rituximab can produce durable clinical responses in patients with relapsed or refractory, indolent non-Hodgkin lymphoma

This phase II study evaluated the safety and efficacy of lenalidomide in combination with rituximab in patients with relapsed/refractory, indolent non-Hodgkin lymphoma (NHL). Patients were treated with daily lenalidomide in 28-d cycles and weekly rituximab for 4 weeks. Lenalidomide was continued until progression or unacceptable toxicity. Twenty-two patients were assessed for FCGR3A polymorphisms. Thirty patients were enrolled; 27 were evaluable for response. The overall response rate (ORR) was 74% including 44% complete responses (CR); median progression-free survival (PFS) was 12·4 months. The 13 rituximab refractory patients had an ORR of 61·5% (four CR/unconfirmed CR). The ORR was 77% in the 22 follicular lymphoma patients (nine CR/unconfirmed CR). At a median follow-up time of 43 months, the median duration of response and time to next therapy were 15·4 and 37·4 months, respectively. Most common grade 3/4 adverse events were lymphopenia (45%), neutropenia (55%), fatigue (23%) and hyponatraemia (9%). The ORR and PFS in patients with low-affinity FCGR3A polymorphisms (F/F and F/V) suggest that lenalidomide may improve the activity of rituximab in these patients. These data suggest that combining lenalidomide with rituximab can produce durable responses with acceptable toxicity in patients with indolent NHL.

Targeting CD22 in B-cell malignancies: current status and clinical outlook

CD22 is a B-cell-specific transmembrane glycoprotein found on the surface of most B cells; it modulates B-cell function, survival and apoptosis. CD22 has emerged as an ideal target for monoclonal antibody (mAb)-based therapy of B-cell malignancies including most lymphomas and many leukemias. Epratuzumab, an anti-CD22 mAb, has been developed in various forms, including as an unlabeled (naked) mAb, as a radioimmunotherapeutic, as an antibody drug conjugate (ADC), and as a vehicle for CD22-targeted nanoparticles. While clinical trials with unlabeled epratuzumab have demonstrated modest results, its combination with rituximab in phase II studies has been more encouraging. Based on the potential for CD22 to become internalized, CD22-targeted constructs carrying radioisotopes or toxins have generated promising results. Radioimmunotherapy, utilizing ⁹⁰Y-labeled epratuzumab, was shown to be highly effective in patients with follicular lymphoma, generating a complete response (CR) rate of 92 % and progression-free survival of more than 2 years. ADC therapy is a promising therapeutic approach to B-cell malignancies which includes the direct conjugation of mAbs with cytotoxic agents. Phase II studies of inotuzumab ozogamicin, an ADC which combines anti-CD22 mAb with calicheamicin, an enediyne antibiotic which mediates apoptosis, in patients with acute lymphoblastic leukemia have produced an overall response rate (ORR) of greater than 50 % in treatment-refractory patients. Phase I trials of moxetumomab pasudotox, an ADC which combines anti-CD22 with PE38, a fragment of Pseudomonas exotoxin A, have been completed in hairy cell leukemia with a ORR of 86 %. Finally, a review of CD22-targeted nanoparticles, that include a doxorubicin-containing lipid complex that uses synthetic high-affinity CD22 ligand mimetics as well as anti-CD22 mAb-coated pegylated liposomas doxorubin (PLD), has demonstrated promising results in pre-clinical models of human lymphoma. Moreover, novel anti-CD22 mAb that block CD22 ligand binding as well as second generation ADC that utilize biodegradable linkers and more potent toxins hold great hope for the future of CD22-targeted therapeutics that may translate into better outcomes for patients with CD22-positive malignancies.

The future of B cell-targeted therapies in Sjögren's syndrome

Primary Sjögren's syndrome is a systemic autoimmune disease characterized by progressive exocrine gland destruction, resulting clinically in eyes and mouth dryness. To date, no treatment has been proven effective to modify the course of this slow-evolving disease. B cells are now considered to play a central role in the pathogenesis of primary Sjögren's syndrome because their functions are not restrained to antibody production. Thus, several B-cell targeting therapies are under clinical investigation. Rituximab, a monoclonal antibody directed to CD20 and leading to transient blood B-cell depletion, has shown partial improvements in subjective and objective sicca symptoms in small studies. However, the results of two large controlled trials are awaited before considering its use in large populations of patients. Several other therapeutic strategies are being studied, targeting other B-cell surface proteins (epratuzumab and anti-CD22) or major cytokines of B-cell homeostasis (e.g., BAFF, IL-6 and lymphotoxin-β). Although great hope is generated by the trials of these specific therapies, another challenge for clinical researchers is the development of reliable tools to assess the activity of Sjögren's syndrome and its response to treatment.

A tale of two specificities: bispecific antibodies for therapeutic and diagnostic applications

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Recombinant DNA technologies are leading the rapid expansion of bispecific antibody formats.

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The therapeutic potential of bispecific antibodies is being realized through creative design.

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Bispecific antibodies are potentially underutilized reagents for diagnostics.

Artificial manipulation of antibody genes has facilitated the production of several unique recombinant antibody formats, which have highly important therapeutic and biotechnological applications. Although bispecific antibodies (bsAbs) are not new, they are coming to the forefront as our knowledge of the potential efficacy of antibody-based therapeutics expands. The next generation of bsAbs is developing due to significant improvements in recombinant antibody technologies. This review focuses on recent advances with a particular focus on improvements in format and design that are contributing to the resurgence of bsAbs, and in particular, on innovative structures applicable to next generation point-of-care (POC) devices with applicability to low resource environments.

The current status and future impact of targeted therapies in non-Hodgkin lymphoma

A number of new, biologic targeted therapies have been developed for the treatment of lymphoid malignancies. These include anti-CD20 monoclonal antibodies designed with greater binding affinities and different mechanisms of action profiles compared with rituximab. Other extracellular antigens on B cells and T cells are also being targeted. Monoclonal antibodies have been conjugated to radioisotopes and cellular toxins. In addition, several exciting new small-molecule kinase inhibitors are in development that target intracellular pathways that contribute to the pathogenesis of these diseases. Drugs that affect the tumor microenvironment are also under investigation. The advantage of these targeted agents compared with standard chemotherapy is greater tumor specificity, a more favorable toxicity profile, and, when combined with scientific rationale, and in the appropriate setting, perhaps a better long-term outcome.

A phase 2 trial of extended induction epratuzumab and rituximab for previously untreated follicular lymphoma: CALGB 50701

BACKGROUND

Rituximab combined with chemotherapy has improved the survival of previously untreated patients with follicular lymphoma (FL). Nevertheless, many patients neither want nor can tolerate chemotherapy, leading to interest in biological approaches. Epratuzumab is a humanized anti-CD22 monoclonal antibody with efficacy in relapsed FL. Because both rituximab and epratuzumab have single-agent activity in FL, the antibody combination was evaluated as initial treatment of patients with FL.

METHODS

Fifty-nine untreated patients with FL received epratuzumab 360 mg/m2 with rituximab 375 mg/m2 weekly for 4 induction doses. This combination was continued as extended induction in weeks 12, 20, 28, and 36. Response assessed by computed tomography was correlated with clinical risk factors, [18F]fluorodeoxyglucose positron emission tomography findings at week 3, Fcγ polymorphisms, immunohistochemical markers, and statin use.

RESULTS

Therapy was well-tolerated, with toxicities similar to expected with rituximab monotherapy. Fifty-two (88.2%) evaluable patients responded, including 25 complete responses (42.4%) and 27 partial responses (45.8%). At 3 years follow-up, 60% of patients remain in remission. Follicular Lymphoma International Prognostic Index (FLIPI) risk strongly predicted progression-free survival (P = .022).

CONCLUSIONS

The high response rate and prolonged time to progression observed with this antibody combination are comparable to those observed after standard chemoimmunotherapies and further support the development of biologic, nonchemotherapeutic approaches for these patients.

Novel agents in indolent lymphomas

Indolent non-Hodgkin's lymphomas (iNHLs) include follicular lymphomas (FL), marginal-zone lymphoma, lymphoplasmacytic lymphoma/Waldenström macroglobulinemia and small lymphocytic lymphoma. First-line standard therapy in advanced, symptomatic iNHL consists of rituximab-based immunochemotherapy. The recent rediscovery of the 'old' chemotherapeutic agent bendamustine, an alkylating agent with a peculiar mechanism of action, has added a new effective and well-tolerated option to the therapeutic armamentarium in iNHL, increasing response rates and duration. However, patients invariably relapse and subsequent active and well-tolerated agents are needed. In recent years a large number of new targeted agents have been tested in preclinical and clinical experimentation in FL and indolent nonfollicular lymphoma (iNFL), including the new monoclonal antibodies binding CD20 or other surface antigens, immunoconjugates and bispecific antibodies. Moreover novel agents directed against intracellular processes such as proteasome inhibitors, mTOR inhibitors and agents that target the tumour microenvironment, notably the immunomodulatory agent lenalidomide, are under active clinical investigation. The development of these new drugs may change in the near future the approach to iNHL patients, leading to better tolerated and effective therapy regimens.

Macrophage and NK-mediated killing of precursor-B acute lymphoblastic leukemia cells targeted with a-fucosylated anti-CD19 humanized antibodies

This work reports the tumoricidal effects of a novel investigational humanized anti-CD19 monoclonal antibody (Medi-551). An a-fucosylated antibody with increased affinity for human FcγRIIIA, Medi-551 is shown to mediate both antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). Medi-551/CD19 complexes internalize slowly (>5 h) and thus remain accessible to effector cells for prolonged periods. We evaluated in vitro ADCC and ADCP activities of primary human natural killer (NK) cells and macrophages against precursor-B (pre-B) acute lymphoblastic leukemia (ALL) cell lines and pediatric patient blasts. Fluorescent imaging studies document immunological synapses formed between anti-CD19-bound target leukemia cells and effector cells and capture the kinetics of both NK-mediated killing and macrophage phagocytosis. Genetic polymorphisms in FcγRIIIA-158F/V modulate in vitro activities of effector cells, with FcγRIIIA-158V homozygotes or heterozygotes showing the strongest activity. Medi-551 treatment of severe combined immunodeficiency (SCID) mice engrafted with human pre-B cells led to prolonged animal survival and markedly reduced disease burden in blood, liver and bone marrow. These data show that anti-CD19 antibodies effectively recruit immune cells to pre-B ALL cells and support a move forward to early phase trials in this disease.

Therapy of newly diagnosed follicular lymphoma

Newly diagnosed follicular lymphoma is relatively common and can be effectively treated with several differing approaches. Although the disease is often considered incurable, it is highly responsive to therapy when indicated. This review discusses the indications for treatment, risk stratification systems, treatment options with supporting clinical trial data, and expected therapeutic outcomes in newly diagnosed follicular lymphoma.

Changing role of stem cell transplantation in follicular lymphoma

Patients with advanced follicular lymphoma (FL) have numerous treatment options, including observation, radiotherapy, single-agent or combination chemotherapy, mAbs, and radioimmunoconjugates. These therapies can extend progression-free survival but none can provide a cure. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curable therapy for FL, with the field shifting more toward the use of reduced-intensity conditioning regimens because of the lower associated nonrelapse mortality compared with myeloablative regimens. However, GVHD and infection are still problematic in the allo-HSCT population. Autologous HSCT (auto-HSCT) confers high response rates and prolongs progression-free survival in relapsed patients who are chemosensitive, and an increasing amount of data suggest that auto-HSCT may be curative if offered to relapsed patients who are not heavily pretreated. Auto-HSCT has no role as consolidation therapy for patients in first remission based on the results from 3 large randomized trials. Novel conditioning regimens with radioimmunoconjugates have been used in both auto-HSCT and allo-HSCT regimens and results have shown efficacy even in chemorefractory patients. Therefore, with the exception of patients in first remission, the optimal timing for HSCT remains controversial. However, the outcomes seen after auto-HSCT and allo-HSCT continue to improve, and HSCT represents a treatment modality that should be considered in all FL patients, especially while their disease remains chemoresponsive.

RECRUIT-TandAbs: harnessing the immune system to kill cancer cells

Tandem diabodies (TandAbs) are tetravalent bispecific molecules comprised of antibody variable domains with two binding sites for each antigen. RECRUIT-TandAbs can simultaneously engage an immune system effector cell, such as a natural killer cell or a cytotoxic T cell, and an antigen expressed specifically on a cancer cell, thus leading to killing of the cancer cell. Recruitment of immune effector cells is highly specific and mediated via binding of the TandAb to molecules expressed on the surface of these cells. Furthermore, the absence of an Fc domain allows TandAbs to avoid certain IgG-mediated side effects. With a molecular weight of approximately 110 kDa, TandAbs are far above the first-pass renal clearance limit, offering a pharmacokinetic advantage compared with smaller bispecific antibody formats. This article reviews the RECRUIT-TandAb technology and the therapeutic potential of these molecules.

Follicular lymphoma: current management and future directions

BACKGROUND

Follicular lymphomas (FLs) are a heterogeneous group of lymphomas. No standard of care exists, and the management of these patients is highly individualized.

METHODS

After reviewing the scientific literature pertaining to the prognosis and management of FLs, we describe recent developments in treatment and discuss future trends in the care of patients with this disease.

RESULTS

With the exception of a subset of patients with limited-stage FL treated with radiation therapy, no curative treatment exists for the majority of patients with FL. The decision on when to start treatment is based on the presence of symptoms, bulky disease, or abnormalities in hematologic parameters that can be attributed to FL. Prognostic scoring systems such as the Follicular Lymphoma International Prognostic Index help in assessing prognosis but do not contribute to the decision on when to start treatment. There are numerous effective chemotherapeutic regimens for the treatment of advanced-stage FL, but none show a definitive improvement in overall survival. Maintenance and consolidation regimens have also been shown to be effective treatments of FL, with significant improvements in progression-free survival and possibly overall survival.

CONCLUSIONS

Newer prognostic tests are in development that may help to guide the decision on which patients may benefit from early treatment. In addition, newer targeted agents that may improve on existing outcomes with less toxicity are currently being evaluated.

Follicular lymphoma: 2012 update on diagnosis and management

DISEASE OVERVIEW

Follicular lymphoma (FL) is generally an indolent B-cell lymphoproliferative disorder of transformed follicular center B cells. FL is characterized by diffuse lymphoadenopathy, involvement of bone marrow, splenomegaly, and less commonly other extranodal sites of involvement. In general, cytopenias can occur but constitutional symptoms of fever, night sweats, and weight loss are uncommon.

DIAGNOSIS

Diagnosis is based on histology of preferably a biopsy of a lymph node. Immunohistochemical staining is positive in virtually all cases for cell surface CD19, CD20, CD10, and monoclonal immunoglobulin, as well as cytoplasmic expression of bcl-2 protein. The overwhelming majority of cases have the characteristic t(14;18) translocation involving the IgH/bcl-2 genes.

RISK STRATIFICATION

The FL International Prognostic Index prognostic model for FL uses five independent predictors of inferior survival: age > 60 years, hemoglobin < 12 g/dL, serum lactate dehydrogenase > normal, Ann Arbor stage III/IV, number of involved nodal areas > 4. The presence of 0, 1, 2, and ≥ 3 adverse factors defines low, intermediate, and high-risk disease with median 10-year survivals in the pre-rituximab era of ~71, 51, and 36 months, respectively. With the use of more modern therapies, specifically anti-CD20 monoclonal antibody, the outcome has improved.

RISK-ADAPTED THERAPY

Observation continues to be adequate for asymptomatic patients with low bulk disease and no cytopenias. For patients needing therapy, most patients are treated with chemotherapy plus rituximab, which has improved response rates, duration of response, and overall survival. Randomized studies have shown additional benefit for maintenance rituximab both following chemotherapy-rituximab and single-agent rituximab. Autologous stem cell transplantation (SCT) has not shown a survival benefit in first remission patients. SCT including both autologous and allogeneic SCT or experimental agent therapy is considered for recurrent disease.

Phase II trial of galiximab (anti-CD80 monoclonal antibody) plus rituximab (CALGB 50402): Follicular Lymphoma International Prognostic Index (FLIPI) score is predictive of upfront immunotherapy responsiveness

BACKGROUND

This phase II CALGB trial evaluated the activity and safety of an extended induction schedule of galiximab (G) plus rituximab (R) in untreated follicular lymphoma (FL).

PATIENTS AND METHODS

Patients with previously untreated FL (grades 1, 2, 3a) received 4 weekly infusions of G + R, followed by an additional dose every 2 months four times. International Workshop Response Criteria were used to evaluate response.

RESULTS

Sixty-one patients were treated and antibody infusions were well tolerated. The overall response rate (ORR) is 72.1% (95% confidence interval 59.2% to 82.9%): 47.6% complete response (CR)/unconfirmed complete response (CRu) and 24.6% partial response. At a median follow-up time of 4.3 years (range, 0.3-5.3 years) median progression-free survival (PFS) is 2.9 years. Notably, Follicular Lymphoma International Prognostic Index (FLIPI) correlated with ORR, CR rate, and PFS, and the low-risk FLIPI group (n = 12) achieved a 92% ORR, 75% CR/CRu rate, and 75% 3-year PFS.

CONCLUSIONS

An extended induction schedule of G + R in previously untreated FL is well tolerated and appears particularly efficacious in those patients with low-risk FLIPI scores. In addition, this trial served as the initial platform for additional CALGB 'doublet' combination regimes of rituximab plus other novel targeted agents.

Antibody therapy for acute lymphoblastic leukemia

Advances in chemotherapy administration have made acute lymphoblastic leukemia (ALL) a curable disease; however, most patients will relapse, despite readily attaining a complete remission. Treatment of relapse has shown dismal results with little advances made in the recent decades. Antigenic-directed therapy of ALL can complement cytotoxic chemotherapy and has shown encouraging results. This review will evaluate four antigens in ALL (CD20, CD22, CD52, and CD19) and therapeutic strategies to target them. We will review the clinical and preclinical data surrounding rituximab, epratuzumab, inotuzumab ozogamicin, alemtuzumab, blinatumomab, and chimeric antigen receptor-modified T-cell therapy.

B-cell depletion in the treatment of lupus nephritis

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that is clinically heterogeneous and affects multiple organs. Lupus nephritis is the most frequent severe manifestation of SLE. Conventional immunosuppressive therapy has increased the life expectancy of patients diagnosed with lupus nephritis, but only 70-80% of patients respond to this treatment and its adverse effects are considerable. B cells are central to the pathogenesis of SLE and are, therefore, an attractive therapeutic target. B-cell depletion has been used successfully to treat other autoimmune diseases, such as rheumatoid arthritis and antineutrophil cytoplasmic antibody-associated vasculitis, and many case reports and small nonrandomized trials of B-cell-depleting agents in patients with lupus nephritis have reported positive results. By contrast, two large placebo-controlled trials designed to investigate the efficacy of the B-cell-depleting agents rituximab and ocrelizumab as a treatment for lupus nephritis, failed to meet their primary efficacy end points (LUNAR and BELONG, respectively). This Review discusses the current evidence on the use of B-cell depletion in the treatment of lupus nephritis, which is derived from case studies and clinical trials including a total of over 800 patients.

Dual-targeting immunotherapy of lymphoma: potent cytotoxicity of anti-CD20/CD74 bispecific antibodies in mantle cell and other lymphomas

We describe the use of novel bispecific hexavalent Abs (HexAbs) to enhance anticancer immunotherapy. Two bispecific HexAbs [IgG-(Fab)4 constructed from veltuzumab (anti-CD20 IgG) and milatuzumab (anti-CD74 IgG)] show enhanced cytotoxicity in mantle cell lymphoma (MCL) and other lymphoma/leukemia cell lines, as well as patient tumor samples, without a crosslinking Ab, compared with their parental mAb counterparts, alone or in combination. The bispecific HexAbs have different properties from and are more potent than their parental mAbs in vitro. The juxtaposition of CD20 and CD74 on MCL cells by the HexAbs resulted in homotypic adhesion and triggered intracellular changes that include loss of mitochondrial transmembrane potential, production of reactive oxygen species, rapid and sustained phosphorylation of ERKs and JNK, down-regulation of pAkt and Bcl-xL, actin reorganization, and lysosomal membrane permeabilization, culminating in cell death. They also displayed different potencies in depleting lymphoma cells and normal B cells from whole blood ex vivo and significantly extended the survival of nude mice bearing MCL xenografts in a dose-dependent manner, thus indicating stability and antitumor activity in vivo. Such bispecific HexAbs may constitute a new class of therapeutic agents for improved cancer immunotherapy, as shown here for MCL and other CD20+/CD74+ malignancies.

Phase I study of anti-CD22 immunoconjugate inotuzumab ozogamicin plus rituximab in relapsed/refractory B-cell non-Hodgkin lymphoma

Inotuzumab ozogamicin (CMC-544), a humanized anti-CD22 antibody conjugated to the potent cytotoxic antibiotic calicheamicin, targets the CD22 antigen expressed on the majority of B-cell non-Hodgkin lymphomas. This phase I study assessed the tolerability, safety, pharmacokinetics, and preliminary efficacy of inotuzumab ozogamicin administered intravenously in combination with rituximab in Japanese patients with relapsed or refractory B-cell non-Hodgkin lymphoma. Ten patients were administered rituximab 375 mg/m(2) followed by inotuzumab ozogamicin at the maximum tolerated dose (1.8 mg/m(2)). Treatment was repeated every 28 days up to eight cycles, or until occurrence of disease progression or intolerable toxicity. The safety profile was similar to that of inotuzumab ozogamicin monotherapy, with hematologic adverse events occurring most frequently. The most common grade three or higher adverse events were thrombocytopenia (70%), neutropenia (50%), leukopenia (30%), and lymphopenia (30%). The overall response rate was 80% (8/10; 95% CI, 44-98%). Drug exposure increased with successive doses, similar to the pharmacokinetic profiles observed in previous phase I monotherapy studies. Efficacy results suggested promising antitumor activity, and the overall findings support the continued clinical development of this therapeutic regimen in patients with relapsed or refractory B-cell non-Hodgkin lymphoma. This trial was registered at www.ClinicalTrials.gov as NCT00724971.

Dual targeting strategies with bispecific antibodies

Monoclonal antibodies are widely used for the treatment of cancer, inflammatory and infectious diseases and other disorders. Most of the marketed antibodies are monospecific and therefore capable of interacting and interfering with a single target. However, complex diseases are often multifactorial in nature, and involve redundant or synergistic action of disease mediators or upregulation of different receptors, including crosstalk between their signaling networks. Consequently, blockade of multiple, different pathological factors and pathways may result in improved therapeutic efficacy. This result can be achieved by combining different drugs, or use of the dual targeting strategies applying bispecific antibodies that have emerged as an alternative to combination therapy. This review discusses the various dual targeting strategies for which bispecific antibodies have been developed and provides an overview of the established bispecific antibody formats.

Pharmacokinetics and tolerability of human mouse chimeric anti-CD22 monoclonal antibody in Chinese patients with CD22-positive non-Hodgkin lymphoma

The safety and pharmacokinetics assessment of antibodies targeting CD22 (e.g., epratuzumab) have been established in western Caucasian populations, but there are no reports of the effects in Chinese populations. This dose-escalation study examines the safety, pharmacokinetics and biologic effects of multiple doses of anti-CD22 human-murine chimeric monoclonal antibody SM03 in 21 Chinese patients with CD22-positive non-Hodgkin lymphoma. Most of drug-related adverse events (AEs) were mild and reversible. Two patients experienced serious AEs (hemorrhage); one patient had grade 4 neutropenia; one patient had asymptomatic grade III prolongation of activated partial thromboplastin time (APTT). Major AEs included fever (71%), prolongation of APTT (42.8%), leukocytopenia (44.4%), alanine transaminase elevation (28.6%), elevated serum creatinine (23.8%) and injection site skin redness (14.3%). Circulating B cells transiently decreased without significant effects on T cells or immunoglobulin levels. Pharmacokinetic data revealed that mean maximum observed SM03 concentration and mean AUC from time zero to infinity increased in a dose-dependent manner up to 360 mg/m (2) SM03. Mean clearance was similar at doses ≤ 360 mg/m (2) and decreased significantly at dose 480 mg/m (2), supporting saturation of B-cell binding at 360 mg/m (2). Across all dose levels and histologies, one patient achieved partial response at 480 mg/m (2) dose; 14 patients had stable disease as best response and four patients progressed. Overall, SM03 was tolerated at doses ranging from 60-480 mg/m (2) and had potential efficacy in Chinese patients with follicular lymphoma.

Fetal and Neonatal Illnesses Caused or Influenced by Maternal Transplacental IgG and/or Therapeutic Antibodies Applied During Pregnancy

The human fetus is protected by the mother’s antibodies. At the end of the pregnancy, the concentration of maternal antibodies is higher in the cord blood, than in the maternal circulation. Simultaneously, the immune system of the fetus begins to work and from the second trimester, fetal IgM is produced by the fetal immune system specific to microorganisms and antigens passing the maternal-fetal barrier. The same time the fetal immune system has to cope and develop tolerance and T_REG cells to the maternal microchimeric cells, latent virus-carrier maternal cells and microorganisms transported through the maternal-fetal barrier.

The maternal phenotypic inheritance may hide risks for the newborn, too. Antibody mediated enhancement results in dengue shock syndrome in the first 8 month of age of the baby.

A series of pathologic maternal antibodies may elicit neonatal illnesses upon birth usually recovering during the first months of the life of the offspring. Certain antibodies, however, may impair the fetal or neonatal tissues or organs resulting prolonged recovery or initiating prolonged pathological processes of the children.

The importance of maternal anti-idiotypic antibodies are believed to prime the fetal immune system with epitopes of etiologic agents infected the mother during her whole life before pregnancy and delivery.

The chemotherapeutical and biological substances used for the therapy of the mother will be transcytosed into the fetal body during the last two trimesters of pregnancy. The long series of the therapeutic monoclonal antibodies and conjugates has not been tested systematically yet. The available data are summarised in this chapter.

The innate immunity plays an important role in fetal defence. The concentration of interferon is relative high in the placenta. This is probably one reason, why the therapeutic interferon treatment of the mother does not impair the fetal development.

A glycoengineered anti-CD19 antibody with potent antibody-dependent cellular cytotoxicity activity in vitro and lymphoma growth inhibition in vivo

Human cluster of differentiation (CD) antigen 19 is a B cell-specific surface antigen and an attractive target for therapeutic monoclonal antibody (mAb) approaches to treat malignancies of B cell origin. MEDI-551 is an affinity-optimized and afucosylated CD19 mAb with enhanced antibody-dependent cellular cytotoxicity (ADCC). The results from in vitro ADCC assays with Natural Killer cells as effector cells, demonstrate that MEDI-551 is effective at lower mAb doses than rituximab with multiple cell lines as well as primary chronic lymphocytic leukaemia and acute lymphoblastic leukaemia samples. Targeting CD19 with MEDI-551 was also effective in several severe combined immunodeficiency lymphoma models. Furthermore, the combination of MEDI-551 with rituximab resulted in prolonged suppression of tumour growth, demonstrating that therapeutic mAbs with overlapping effector function can be combined for greater tumour growth inhibition. Together, the data demonstrate that MEDI-551 has potent antitumour activity in preclinical models of B cell malignancies. The results also suggest that the combination of the ADCC-enhanced CD19 mAb with an anti-CD20 mAb could be a novel approach for the treatment of B cell lymphomas.

Follicular lymphoma: 2011 update on diagnosis and management

DISEASE OVERVIEW

Follicular lymphoma (FL) is generally an indolent B-cell lymphoproliferative disorder of transformed follicular center B cells. FL is characterized by diffuse lymphoadenopathy, bone marrow involvement, splenomegaly, and less commonly other extranodal sites of involvement. In general, cytopenias can occur but constitutional symptoms of fever, nightsweats, and weight loss are uncommon.

DIAGNOSIS

Diagnosis is based on histology of preferably biopsy of a lymph node. Immunohistochemical staining is positive in virtually all cases for cell surface CD19, CD20, CD10 and monoclonal immunoglobulin, as well as cytoplasmic expression of bcl-2 protein. The overwhelming majority of cases have the characteristic t(14;18) translocation involving the IgH/bcl-2 genes.

RISK STRATIFICATION

The Follicular Lymphoma International Prognostic Index prognostic model for FL uses five independent predictors of inferior survival: age > 60 years, hemoglobin <12 g/dL, serum LDH > normal, Ann Arbor stage III/IV, number of involved nodal areas > 4. The presence of 0-1, 2, and ≥3 adverse factors defines low, intermediate, and high-risk disease with median 10 year survivals in the pre-rituximab era of approximately 71, 51, and 36 months, respectively. With the use of more modern therapies, specifically anti-CD20 monoclonal antibody, the outcome has improved.

RISK-ADAPTED THERAPY

Observation continues to be adequate for asymptomatic patients with low bulk disease and no cytopenias. For patients needing therapy, most patients are treated with chemotherapy plus rituximab, which has improved response rates, duration of response, and overall survival. Randomized studies have shown additional benefit for maintenance rituximab both following chemotherapy-rituximab and single agent rituximab. Autologous stem cell transplantation has not shown a survival benefit in first remission patients. Stem cell transplantation (SCT) including both autologous and allogeneic SCT or experimental agent therapy is considered for recurrent disease.

Emerging antibody combinations in oncology

The use of monoclonal antibodies (mAbs) has become a general approach for specifically targeting and treating human disease. In oncology, the therapeutic utility of mAbs is usually evaluated in the context of treatment with standard of care, as well as other small molecule targeted therapies. Many anti-cancer antibody modalities have achieved validation, including the targeting of growth factor and angiogenesis pathways, the induction of tumor cell killing or apoptosis, and the blocking of immune inhibitory mechanisms to stimulate anti-tumor responses. But, as with other targeted therapies, few antibodies are curative because of biological complexities that underlie tumor formation and redundancies in molecular pathways that enable tumors to adapt and show resistance to treatment. This review discusses the combinations of antibody therapeutics that are emerging to improve efficacy and durability within a specific biological mechanism (e.g., immunomodulation or the inhibition of angiogenesis) and across multiple biological pathways (e.g., inhibition of tumor growth and induction of tumor cell apoptosis).

Targeting siglecs--a novel pharmacological strategy for immuno- and glycotherapy

The immune system must be tightly held in check to avoid bystander tissue damage as well as autoreactivity caused by overwhelming immune reactions. A novel family of immunoregulatory, carbohydrate-binding receptors, the Siglecs (sialic acid binding immunoglobulin-like lectins), has received particular attention in light of their capacity to mediate cell death, anti-proliferative effects and to regulate a variety of cellular activities. Siglec receptors are mainly expressed on leukocytes in a cell type-specific and differentiation-dependent manner. Siglecs might potentially be exploited as targets of novel immune- and glycotherapeutics for cell-directed therapies in autoimmune and allergic diseases, as well as in haematologic malignancies. Here we present novel insights on structural and functional characteristics, expression patterns and evolutionary aspects of Siglecs and their ligands. Pharmacological strategies using Siglec agonistic cross-linking therapeutics, such as monoclonal or engineered antibodies, intravenous immunoglobulin (IVIG), or glycomimetics are discussed. Modulation of immune responses by targeting Siglecs using agonistic or antagonistic therapeutics may have important clinical implications and may pave the way for novel pharmacological avenues for the treatment of autoimmune and allergic diseases or for tumor immunotherapy.