Combination immunotherapy with rituximab and interleukin 2 in patients with relapsed or refractory follicular non-Hodgkin's lymphoma

T-cell help in the tumor microenvironment enhances rituximab-mediated NK-cell ADCC

ABSTRACT

Rituximab (RTX) and other monoclonal antibodies (mAbs) that bind directly to malignant cells are of great clinical value but are not effective for all patients. A major mechanism of action of RTX is antibody-dependent cellular cytotoxicity (ADCC) mediated by natural killer (NK) cells. Prior in vitro studies in our laboratory demonstrated that T cells contribute to maintaining the viability and cytotoxic potential of NK cells activated by anti-CD20-coated target B cells. Here, we conducted studies using a novel mouse model and clinical correlative analysis to assess whether T-cell help contribute to RTX-mediated NK-cell ADCC in the tumor microenvironment (TME) in vivo. A humanized mouse model was developed using Raji lymphoma cells and normal donor peripheral blood mononuclear cells that allows for control of T-cell numbers in the lymphoma TME. In this model, NK-cell viability and CD16 and CD25 expression dropped after RTX in the absence of T cells but increased in the presence of T cells. RTX therapy was more effective when T cells were present and was ineffective when NK cells were depleted. In patients with indolent lymphoma, fine needle aspirates were obtained before and ∼1 week after treatment with a RTX-containing regimen. There was a strong correlation between CD4+ T cells as well as total T cells in the pretherapy TME and an increase in NK-cell CD16 and CD25 expression after RTX. We conclude that T-cell help in the TME enhances RTX-mediated NK-cell viability and ADCC.

Contribution of natural killer cells in innate immunity against colorectal cancer

Natural killer cells are members of the innate immune system and promote cytotoxic activity against tumor or infected cells independently from MHC recognition. NK cells are modulated by the expression of activator/inhibitory receptors. The ratio of this activator/inhibitory receptors is responsible for the cytotoxic activity of NK cells toward the target cells. Owing to the potent anti-tumor properties of NK cells, they are considered as interesting approach in tumor treatment. Colorectal cancer (CRC) is the second most common cause of death in the world and the incidence is about 2 million new cases per year. Metastatic CRC is accompanied by a poor prognosis with less than three years of overall survival. Chemotherapy and surgery are the most adopted treatments. Besides, targeted therapy and immune checkpoint blockade are novel approach to CRC treatment. In these patients, circulating NK cells are a prognostic marker. The main target of CRC immune cell therapy is to improve the tumor cell's recognition and elimination by immune cells. Adaptive NK cell therapy is the milestone to achieve the purpose. Allogeneic NK cell therapy has been widely investigated within clinical trials. In this review, we focus on the NK related approaches including CAR NK cells, cell-based vaccines, monoclonal antibodies and immunomodulatory drugs against CRC tumoral cells.

Follicular lymphoma: 2023 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 lymphadenopathy, bone marrow involvement, and splenomegaly. Extranodal involvement is less common. Cytopenias are relatively common but constitutional symptoms of fever, night sweats, and weight loss are uncommon in the absence of transformation to diffuse large B cell lymphoma.

DIAGNOSIS

The diagnosis is based on histology from a biopsy of a lymph node or other affected tissue. Incisional biopsy is preferred over needle biopsies in order to give adequate tissue to assign grade and assess for transformation. 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 (FLIPI) 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. There are other clinical prognostic models but the FLIPI remains the most common. Other factors such as time to relapse of less than 2 years from chemoimmunotherapy and specific gene mutations may also be useful for prognosis. Regardless of the prognostic model used, modern therapies have demonstrably improved prognosis.

RISK-ADAPTED THERAPY

Observation continues to be appropriate for asymptomatic patients with low bulk disease and no cytopenias. There is no overall survival (OS) advantage for early treatment with either chemotherapy or single-agent rituximab. For patients needing therapy, most patients are treated with chemoimmunotherapy, which has improved overall response rates (ORR), DOR, and OS. Randomized studies have shown additional benefits for maintenance of rituximab. Lenalidomide was non-inferior to chemoimmunotherapy in a randomized front-line study and, when combined with rituximab, was superior to rituximab alone in relapsed FL. Kinase inhibitors, stem cell transplantation (SCT), and chimeric antigen receptor T cells (CAR-T) are also considered for recurrent disease.

Advancements on the Multifaceted Roles of Sphingolipids in Hematological Malignancies

Dysregulation of sphingolipid metabolism plays a complex role in hematological malignancies, beginning with the first historical link between sphingolipids and apoptosis discovered in HL-60 leukemic cells. Numerous manuscripts have reviewed the field including the early discoveries that jumpstarted the studies. Many studies discussed here support a role for sphingolipids, such as ceramide, in combinatorial therapeutic regimens to enhance anti-leukemic effects and reduce resistance to standard therapies. Additionally, inhibitors of specific nodes of the sphingolipid pathway, such as sphingosine kinase inhibitors, significantly reduce leukemic cell survival in various types of leukemias. Acid ceramidase inhibitors have also shown promising results in acute myeloid leukemia. As the field moves rapidly, here we aim to expand the body of literature discussed in previously published reviews by focusing on advances reported in the latter part of the last decade.

A rationally-engineered IL-2 improves the antitumor effect of anti-CD20 therapy

Anti-CD20 treatment represents a therapeutic benefit for patients with B-cell lymphomas, although more efficient therapies are needed for refractory or relapsing patients. Among them, the combination of anti-CD20 and IL-2 that induces T cell response has been hampered by the expansion of FoxP3⁺ Tregs that strongly express the high affinity IL-2 receptor (IL-2R αβγ). We explore here the anti-tumor effect of an anti-CD20 antibody combined with a mutated IL-2 (no-alpha mutein) which has a disrupted affinity for the IL-2R αβγ. We demonstrate that anti-CD20/no-alpha mutein combination significantly augments the survival rate of mice challenged with huCD20⁺ cells as compared to animals treated with anti-CD20 ± IL-2. Moreover, the combination with no-alpha mutein but not IL-2 provokes an increase of granzyme B and perforin in splenic NK and CD8⁺ T cells, a reduction of Tregs and an increase in activated macrophages. The former combination also induces a T helper profile different from that obtained with IL-2, with an earlier polarization to Th1 and no increase in Th17. The therapeutic effect of anti-CD20/no-alpha mutein was accompanied by an expansion of peripheral central (TCM) and effector (TEM) memory CD8⁺ T cell compartments. Last, as opposed to IL-2, no-alpha mutein administered at the beginning of anti-CD20 treatment did not dampen the long-term protection of surviving mice after tumor rechallenge. Thus, this study shows that the combination of anti-tumor antibodies and no-alpha mutein is a promising approach to improve the therapeutic effect of these antibodies by potentiating NK/macrophage-mediated innate immunity and the adaptive T-cell response.

Follicular lymphoma: 2020 update on diagnosis and management

DISEASE OVERVIEW

Follicular lymphoma (FL) is generally an indolent B cell lymphoproliferative disorder of transformed follicular center B cells. Follicular lymphoma is characterized by diffuse lymphadenopathy, bone marrow involvement, and splenomegaly. Extranodal involvement is less common. Cytopenias are relatively common but constitutional symptoms of fever, night sweats, and weight loss are uncommon in the absence of transformation to diffuse large B cell lymphoma.

DIAGNOSIS

The diagnosis is based on histology from a biopsy of a lymph node or other affected tissue. Incisional biopsy is preferred over needle biopsies in order to give adequate tissue to assign grade and assess for transformation. 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 (FLIPI) 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. There are other clinical prognostic models but the FLIPI remains the most common. Other factors such as time to relapse of less than 2 years from chemoimmunotherapy and specific gene mutations may also be useful for prognosis. Regardless of the prognostic model used, modern therapies have demonstrably improved prognosis.

RISK-ADAPTED THERAPY

Observation continues to be appropriate for asymptomatic patients with low bulk disease and no cytopenias. There is no overall survival advantage for early treatment with either chemotherapy or single agent rituximab. For patients needing therapy, most patients are treated with chemoimmunotherapy, which has improved response rates, duration of response and overall survival (OS). Randomized studies have shown additional benefit for maintenance rituximab. Lenalidomide was non-inferior to chemoimmunotherapy in a randomized front-line study and, when combined with rituximab, was superior to rituximab alone in relapsed FL. Kinase inhibitors, other immunotherapies, and stem cell transplantation (SCT) are also considered for recurrent disease.

A CS1-NKG2D Bispecific Antibody Collectively Activates Cytolytic Immune Cells against Multiple Myeloma

Multiple myeloma (MM) is an incurable hematologic malignancy of plasma cells, with an estimated 30,000 new cases diagnosed each year in the United States, signifying the need for new therapeutic approaches. We hypothesized that targeting MM using a bispecific antibody (biAb) to simultaneously engage both innate and adaptive cytolytic immune cells could present potent antitumor activity. We engineered a biAb by fusing an anti-CS1 single-chain variable fragment (scFv) and an anti-NKG2D scFv (CS1-NKG2D biAb). Although NKG2D is a potent activation receptor ubiquitously expressed on mostly cytolytic immune cells including NK cells, CD8⁺ T cells, γδ T cells, and NKT cells, the CS1 tumor-associated antigen on MM represents a promising target. CS1-NKG2D biAb engaged human MM cell lines and NKG2D⁺ immune cells, forming immune synapses. In effector cells, CS1-NKG2D biAb triggered the phosphorylation of AKT, a downstream protein kinase of the activated NKG2D-DAP10 complex. The EC₅₀ values of CS1-NKG2D biAb for CS1^high and for CS1^low MM cell lines with effector PBMCs were 10^-12 and 10^-9 mol/L, respectively. CS1-NKG2D biAb acted through multiple types of immune cells, and this induced cytotoxicity was both CS1- and NKG2D-specific. In vivo, survival was significantly prolonged using CS1-NKG2D biAb in a xenograft NOD-SCID^IL2γc-/- (NSG) mouse model engrafted with both human PBMCs and MM cell lines. Collectively, we demonstrated that the CS1-NKG2D biAb facilitated an enhanced immune synapse between CS1⁺ MM cells and NKG2D⁺ cytolytic innate and antigen-specific effector cells, which, in turn, activated these immune cells for improved clearance of MM. Cancer Immunol Res; 6(7); 776-87. ©2018 AACR.

A Dose-escalation Study of Recombinant Human Interleukin-18 in Combination With Ofatumumab After Autologous Peripheral Blood Stem Cell Transplantation for Lymphoma

Interleukin-18 (IL-18) is an immunostimulatory cytokine that augments antibody-dependent cellular cytotoxicity mediated by human natural killer cells against antibody-coated lymphoma cells in vitro and that has antitumor activity in animal models. Ofatumumab is a CD20 monoclonal antibody with activity against human B-cell lymphomas. A phase I study of recombinant human (rh) IL-18 given with ofatumumab was undertaken in patients with CD20 lymphoma who had undergone high-dose chemotherapy and autologous peripheral blood stem cell transplantation. Cohorts of 3 patients were given intravenous infusions of ofatumumab 1000 mg weekly for 4 weeks with escalating doses of rhIL-18 as a intravenous infusion weekly for 8 consecutive weeks. Nine male patients with CD20 lymphomas were given ofatumumab in combination with rhIL-18 at doses of 3, 10, and 30 μg/kg. No unexpected or dose-limiting toxicities were observed. The mean reduction from predose levels in the number of peripheral blood natural killer cells after the first rhIL-18 infusion was 91%, 96%, and 97% for the 3, 10, and 30 μg/kg cohorts, respectively. Serum concentrations of interferon-γ and chemokines transiently increased following IL-18 dosing. rhIL-18 can be given in biologically active doses by weekly infusions in combination with ofatumumab after peripheral blood stem cell transplantation to patients with lymphoma. A maximum tolerated dose of rhIL-18 plus ofatumumab was not determined. Further studies of rhIL-18 and CD20 monoclonal antibodies in B-cell malignancies are warranted.

Follicular lymphoma: 2018 update on diagnosis and management

DISEASE OVERVIEW

Follicular lymphoma is generally an indolent B cell lymphoproliferative disorder of transformed follicular center B cells. Follicular lymphoma (FL) is characterized by diffuse lymphadenopathy, 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 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 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 the use of more modern therapies, outcomes have improved.

RISK-ADAPTED THERAPY

Observation continues to be adequate for asymptomatic patients with low bulk disease and no cytopenias, with no survival advantage for early treatment with either chemotherapy or rituximab alone. 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. Experimental therapies as well as stem cell transplantation (SCT) are considered for recurrent disease.

Targeted Therapy for Hematologic Malignancies

Background:

The introduction of monoclonal antibodies, either as native molecules or conjugated to radioisotopes or other toxins, has led to new therapeutic options for patients with hematologic malignancies. In addition, the use of small molecules against specific cell surface receptors, enzymes, and proteins has become an important strategy in the treatment of such disorders.

Methods:

The author reviewed the published clinical trials of monoclonal antibody and other targeted therapies in hematologic malignancies.

Results:

Results from several trials demonstrate a therapeutic benefit for the use of monoclonal antibodies (either native or conjugated) and other targeted therapies, used alone or in combination with standard cytotoxic chemotherapy.

Conclusions:

Targeted therapy of hematologic malignancies seems to be an effective and less toxic approach to the treatment of such disorders. Nevertheless, additional studies are needed to determine where and when such management fits into a therapeutic regimen for any given disorder, whether upfront or as salvage therapy, alone or in combination with chemotherapy (concurrent or sequential).

Antibody-dependent cell cytotoxicity: immunotherapy strategies enhancing effector NK cells

Antibody-dependent cellular cytotoxicity (ADCC) is a set of mechanisms that target cells coated with IgG antibodies of the proper subclasses (IgG1 in the human) to be the prey of cell-to-cell cytolysis executed by immune cells expressing FcRIIIA (CD16A). These effectors include not only natural killer (NK) cells but also other CD16⁺ subsets such as monocyte/macrophages, NKT cells or γδ T cells. In cancer therapy, ADCC is exploited by antibodies that selectively recognize proteins on the surface of malignant cells. An approach to enhance antitumor activity is to act on effector cells so they are increased in their numbers or enhanced in their individual (on a cell per cell basis) ADCC performance. This enhancement can be therapeutically attained by cytokines (that is, interleukin (IL)-15, IL-21, IL-18, IL-2); immunostimulatory monoclonal antibodies (that is, anti-CD137, anti-CD96, anti-TIGIT, anti-KIR, anti-PD-1); TLR agonists or by adoptive infusions of ex vivo expanded NK cells which can be genetically engineered to become more efficient effectors. In conjunction with approaches optimizing IgG1 Fc affinity to CD16, acting on effector cells offers hope to achieve synergistic immunotherapy strategies.

Antibody-Based Cancer Therapy: Successful Agents and Novel Approaches

Since their discovery, antibodies have been viewed as ideal candidates or "magic bullets" for use in targeted therapy in the fields of cancer, autoimmunity, and chronic inflammatory disorders. A wave of antibody-dedicated research followed, which resulted in the clinical approval of a first generation of monoclonal antibodies for cancer therapy such as rituximab (1997) and cetuximab (2004), and infliximab (2002) for the treatment of autoimmune diseases. More recently, the development of antibodies that prevent checkpoint-mediated inhibition of T cell responses invigorated the field of cancer immunotherapy. Such antibodies induced unprecedented long-term remissions in patients with advanced stage malignancies, most notably melanoma and lung cancer, that do not respond to conventional therapies. In this review, we will recapitulate the development of antibody-based therapy, and detail recent advances and new functions, particularly in the field of cancer immunotherapy. With the advent of recombinant DNA engineering, a number of rationally designed molecular formats of antibodies and antibody-derived agents have become available, and we will discuss various molecular formats including antibodies with improved effector functions, bispecific antibodies, antibody-drug conjugates, antibody-cytokine fusion proteins, and T cells genetically modified with chimeric antigen receptors. With these exciting advances, new antibody-based treatment options will likely enter clinical practice and pave the way toward more successful control of malignant diseases.

Toll-like Receptor 4 Ligands Down-regulate Fcγ Receptor IIb (FcγRIIb) via MARCH3 Protein-mediated Ubiquitination

Monocytes and macrophages are critical for the effectiveness of monoclonal antibody therapy. Responses to antibody-coated tumor cells are largely mediated by Fcγ receptors (FcγRs), which become activated upon binding to immune complexes. FcγRIIb is an inhibitory FcγR that negatively regulates these responses, and it is expressed on monocytes and macrophages. Therefore, deletion or down-regulation of this receptor may substantially enhance therapeutic outcomes. Here we screened a panel of Toll-like receptor (TLR) agonists and found that those selective for TLR4 and TLR8 could significantly down-regulate the expression of FcγRIIb. Upon further examination, we found that treatment of monocytes with TLR4 agonists could lead to the ubiquitination of FcγRIIb protein. A search of our earlier microarray database of monocytes activated with the TLR7/8 agonist R-848 (in which FcγRIIb was down-regulated) revealed an up-regulation of membrane-associated ring finger (C3HC4) 3 (MARCH3), an E3 ubiquitin ligase. Therefore, we tested whether LPS treatment could up-regulate MARCH3 in monocytes and whether this E3 ligase was involved with LPS-mediated FcγRIIb down-regulation. The results showed that LPS activation of TLR4 significantly increased MARCH3 expression and that siRNA against MARCH3 prevented the decrease in FcγRIIb following LPS treatment. These data suggest that activation of TLR4 on monocytes can induce a rapid down-regulation of FcγRIIb protein and that this involves ubiquitination.

Follicular lymphoma: 2015 update on diagnosis and management

DISEASE OVERVIEW

Follicular lymphoma is generally an indolent B cell lymphoproliferative disorder of transformed follicular center B cells. Follicular lymphoma (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, 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 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 the use of more modern therapies, outcomes have improved.

RISK-ADAPTED THERAPY

Observation continues to be adequate for asymptomatic patients with low bulk disease and no cytopenias, with no survival advantage for early treatment with either chemotherapy or rituximab alone. 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. Experimental therapies as well as stem cell transplantation (SCT) are considered for recurrent disease.

A molecular perspective on rituximab: A monoclonal antibody for B cell non Hodgkin lymphoma and other affections

Rituximab (a chimeric anti-CD20 monoclonal antibody) is the first Food and Drug Administration approved anti-tumor antibody. Immunotherapy by rituximab, especially in combination-therapy, is a mainstay for a vast variety of B-cell malignancies therapy. Its therapeutic value is unquestionable, yet the mechanisms of action responsible for anti-tumor activity of rituximab and rituximab resistance mechanisms are not completely understood. Investigation of the mechanisms of action that contribute to the rituximab activity have eventually directed to a suite of novel combinations and novel treatment schedules, and also have resulted new generations of antibodies with more desired effects. Although, further investigations are needed to define the mechanisms of rituximab resistance and prominent effector activity of the altered next generation anti-CD20 to improve their efficacies and develop new anti-CD20 monoclonal antibodies in NHL treatment. This article focuses on the properties of CD20 which led scientists to select it as an effective therapeutic target and the molecular details of mechanisms of rituximab action and resistance. We also discuss about the impact of rituximab in monotherapy and in combination with chemotherapy regimens. Finally, we comparatively summarize the next generations of anti CD20 monoclonal antibodies to highlight their advantages relative to their ancestor: Rituximab.

Lymphoma: immune evasion strategies

While the cellular origin of lymphoma is often characterized by chromosomal translocations and other genetic aberrations, its growth and development into a malignant neoplasm is highly dependent upon its ability to escape natural host defenses. Neoplastic cells interact with a variety of non-malignant cells in the tumor milieu to create an immunosuppressive microenvironment. The resulting functional impairment and dysregulation of tumor-associated immune cells not only allows for passive growth of the malignancy but may even provide active growth signals upon which the tumor subsequently becomes dependent. In the past decade, the success of immune checkpoint blockade and adoptive cell transfer for relapsed or refractory lymphomas has validated immunotherapy as a possible treatment cornerstone. Here, we review the mechanisms by which lymphomas have been found to evade and even reprogram the immune system, including alterations in surface molecules, recruitment of immunosuppressive subpopulations, and secretion of anti-inflammatory factors. A fundamental understanding of the immune evasion strategies utilized by lymphomas may lead to better prognostic markers and guide the development of targeted interventions that are both safer and more effective than current standards of care.

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

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

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.

Follicular lymphoma: 2014 update on diagnosis and management

DISEASE OVERVIEW

Follicular lymphoma is generally an indolent B cell lymphoproliferative disorder of transformed follicular center B cells. Follicular lymphoma (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 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 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 the use of more modern therapies, outcomes have 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. Experimental therapies as well as stem cell transplantation (SCT) are considered for recurrent disease.

Synergistic enhancement of cancer therapy using a combination of ceramide and docetaxel

Ceramide (CE)-based combination therapy (CE combination) as a novel therapeutic strategy has attracted great attention in the field of anti-cancer therapy. The principal purposes of this study were to investigate the synergistic effect of CE in combination with docetaxel (DTX) (CE + DTX) and to explore the synergy mechanisms of CE + DTX. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and combination index (CI) assay showed that simultaneous administration of CE and DTX with a molar ratio of 0.5:1 could generate the optimal synergistic effect on murine malignant melanoma cell (B16, CI = 0.31) and human breast carcinoma cell (MCF-7, CI = 0.48). The apoptosis, cell cycle, and cytoskeleton destruction study demonstrated that CE could target and destruct the microfilament actin, subsequently activate Caspase-3 and induce apoptosis. Meanwhile, DTX could target and disrupt the microtubules cytoskeleton, leading to a high proportion of cancer cells in G2/M-phase arrest. Moreover, CE plus DTX could cause a synergistic destruction of cytoskeleton, which resulted in a significantly higher apoptosis and a significantly higher arrest in G2/M arrest comparing with either agent alone (p < 0.01). The in vivo antitumor study evaluated in B16 tumor-bearing mice also validated the synergistic effects. All these results suggested that CE could enhance the antitumor activity of DTX in a synergistic manner, which suggest promising application prospects of CE + DTX combination treatment.

A dose-escalation study of recombinant human interleukin-18 in combination with rituximab in patients with non-Hodgkin lymphoma

Interleukin-18 (IL-18) is an immunostimulatory cytokine with antitumor activity in preclinical models. Rituximab is a CD20 monoclonal antibody with activity against human B-cell lymphomas. A phase I study of recombinant human (rh) IL-18 given with rituximab was performed in patients with CD20+ lymphoma. Cohorts of 3-4 patients were given infusions of rituximab (375 mg/m2) weekly for 4 weeks with escalating doses of rhIL-18 as a 2-hour intravenous infusion weekly for 12 consecutive weeks. Toxicities were graded using standard criteria. Blood samples were obtained for safety, pharmacokinetic, and pharmacodynamic studies. Nineteen patients with CD20+ B-cell non-Hodgkin lymphoma were given rituximab in combination with rhIL-18 at doses of 1, 3, 10, 20, 30, and 100 μg/kg. Common side effects included chills, fever, headache, and nausea. Common laboratory abnormalities included transient, asymptomatic lymphopenia, hyperglycemia, anemia, hypoalbuminemia, and bilirubin and liver enzyme elevations. No dose-limiting toxicities were observed. Biologic effects of rhIL-18 included transient lymphopenia and increased expression of activation antigens on lymphocytes. Increases in serum concentrations of IFN-γ, GM-CSF, and chemokines were observed after dosing. Objective tumor responses were seen in 5 patients, including 2 complete and 3 partial responses. rhIL-18 can be given in biologically active doses by weekly infusions in combination with rituximab to patients with lymphoma. A maximum tolerated dose of rhIL-18 plus rituximab was not determined. Further studies of rhIL-18 and CD20 monoclonal antibodies in B-cell malignancies are warranted.

Immunocytokines: a review of molecules in clinical development for cancer therapy

The concept of therapeutically enhancing the immune system’s responsiveness to tumors is long standing. Several cytokines have been investigated in clinical trials for their therapeutic activity in cancer patients. However, substantial side effects and unfavorable pharmacokinetic properties have been a major drawback hampering the administration of therapeutically relevant doses. The use of recombinant antibody–cytokine fusion proteins promises to significantly enhance the therapeutic index of cytokines by targeting them to the site of disease. This review aims to provide a concise and complete overview of the preclinical data and clinical results currently available for all immunocytokines having reached clinical development.

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.

Interleukin-2 inhibits germinal center formation by limiting T follicular helper cell differentiation

T follicular helper (Tfh) cells promote T cell-dependent humoral immune responses by providing T cell help to B cells and by promoting germinal center (GC) formation and long-lived antibody responses. However, the cellular and molecular mechanisms that control Tfh cell differentiation in vivo are incompletely understood. Here we show that interleukin-2 (IL-2) administration impaired influenza-specific GCs, long-lived IgG responses, and Tfh cells. IL-2 did not directly inhibit GC formation, but instead suppressed the differentiation of Tfh cells, thereby hindering the maintenance of influenza-specific GC B cells. Our data demonstrate that IL-2 is a critical factor that regulates successful Tfh and B cell responses in vivo and regulates Tfh cell development.

Immunomodulating antibodies and drugs for the treatment of hematological malignancies

The aim of cancer immunotherapy is to induce immune cells to kill tumor and promote immunological memory that protects against tumor recurrence. Most current immunotherapies, such as monoclonal antibodies (mAb), target the tumor cells directly. Advances in our understanding of the immune system such as the role of co-stimulatory and co-inhibitory receptors, and the advent of new immunomodulatory agents provide new opportunities to target the immune system and enhance anti-tumor immune responses. These promising agents include immunomodulating mAbs, Toll-like receptor agonists, IMiDs, and cytokines. In this review, we discuss the current results of immunomodulating agents in the treatment of hematological malignancies and propose applications that include targeting of the innate and adaptive immune systems as well as combinations with tumor-specific mAbs.

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.

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

Granulocyte-macrophage colony stimulating factor-induced immune priming of cyclophosphamide, doxorubicin, vincristine, and prednisone with rituximab chemoimmunotherapy in previously untreated patients with diffuse large B-cell lymphoma and mantle cell lymphoma

Granulocyte-macrophage colony stimulating factor (GM-CSF) has been shown to enhance CD20 antigen expression, augment antibody-dependent cell-mediated cytotoxicity, and stimulate immune cell proliferation. This may lead to an improved anti-tumor effect of rituximab while reducing the severity of chemotherapy-induced myelosuppression. We evaluated the safety and efficacy of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in sequential combination with GM-CSF priming and rituximab in previously untreated patients (n = 39) with diffuse-large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL). CHOP was administered every 21 days on day 1, GM-CSF 250 μg/m(2)/day on days 9 through 15, and rituximab 375 mg/m(2) on day 15 of each cycle. The overall response rate was 87%, with complete response in 64%. At a median follow-up of 84.3 months, the overall and progression-free survival rates were 54% and 49%, respectively. The most common toxicity was myelosuppression. Sequential combination of CHOP with GM-CSF priming and rituximab was feasible and effective, warranting further evaluation.

CD137 stimulation enhances the antilymphoma activity of anti-CD20 antibodies

Antibody-dependent cell-mediated cytotoxicity (ADCC), which is largely mediated by natural killer (NK) cells, is thought to play an important role in the efficacy of rituximab, an anti-CD20 monoclonal antibody (mAb) used to treat patients with B-cell lymphomas. CD137 is a costimulatory molecule expressed on a variety of immune cells after activation, including NK cells. In the present study, we show that an anti-CD137 agonistic mAb enhances the antilymphoma activity of rituximab by enhancing ADCC. Human NK cells up-regulate CD137 after encountering rituximab-coated tumor B cells, and subsequent stimulation of these NK cells with anti-CD137 mAb enhances rituximab-dependent cytotoxicity against the lymphoma cells. In a syngeneic murine lymphoma model and in a xenotransplanted human lymphoma model, sequential administration of anti-CD20 mAb followed by anti-CD137 mAb had potent antilymphoma activity in vivo. These results support a novel, sequential antibody approach against B-cell malignancies by targeting first the tumor and then the host immune system.

Phase II study of immunomodulation with granulocyte-macrophage colony-stimulating factor, interleukin-2, and rituximab following autologous stem cell transplant in patients with relapsed or refractory lymphomas

High-dose chemotherapy followed by autologous stem cell transplant (ASCT) leads to durable remissions in approximately half of patients with chemosensitive relapsed or refractory aggressive lymphomas; however, many will relapse despite ASCT secondary to persistent minimal residual disease (MRD) or malignant graft contamination. Post-transplant rituximab may eradicate MRD. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2) might enhance the efficacy of rituximab by augmenting antibody-dependent cellular cytotoxicity (ADCC). We hypothesized that given together, rituximab, GM-CSF, and IL-2 might eradicate MRD and improve event-free survival following ASCT. Forty-six patients with relapsed non-Hodgkin lymphoma (NHL) or Hodgkin lymphoma (HL) were enrolled. Stem cells were mobilized with G-CSF and GM-CSF following chemotherapy. Following BEAM conditioning, patients received GM-CSF until neutrophil engraftment. Between days + 30 and + 120, patients received one dose of rituximab 375 mg/m(2) (cycle 1), followed by three cycles of GM-CSF 250 microg/m(2)/day SQ days 1-5, IL-2 1.5 x 10(6) IU/m(2)/day SQ days 6-12, and rituximab 375 mg/m(2) IV day 9, repeated every 21 days. Thirty-eight patients were eligible for post-ASCT immunotherapy. Nine patients completed 1-2 cycles and 21 completed 3-4 cycles; eight patients did not receive post-ASCT immunotherapy. Grade 3-4 neutropenia and grade 3 thrombocytopenia were observed. With a median follow-up of 30 months, the estimated 5-year OS and EFS for all patients eligible for immunotherapy are 65% and 45%, respectively. Post-ASCT immunomodulation with rituximab, IL-2, and GM-CSF was feasible and safe, but not all patients were able to continue on to post-ASCT immunotherapy.

Rituximab in indolent lymphomas

Indolent non-Hodgkin lymphoma (NHL) comprises a group of incurable, generally slow-growing lymphomas highly responsive to initial therapy, with a relapsing and progressive course. Rituximab, an anti-CD20 antibody, has had a large impact on the treatment of indolent NHL. Its effectiveness as a single agent and in conjunction with known chemotherapy regimens has made it a standard of care in the treatment of NHL. Analysis of data obtained from NHL clinical trials, as well as data from the National Cancer Institute, indicate that the overall survival (OS) of patients with indolent NHL has improved since the discovery of rituximab. Given its effectiveness and tolerability, rituximab is currently being investigated as a maintenance agent with encouraging results. This review summarizes several landmark trials utilizing rituximab as a single agent and in combination with chemotherapy for treatment of NHL. In addition, a review of the studied rituximab maintenance dosing schedules and its impact on NHL will be presented. Overall, rituximab has changed the landscape for treatment of indolent NHL; however, additional research is necessary to identify the optimal dosing schedule, as well as patients most likely to respond to prolonged rituximab therapy.

Rituximab: mechanism of action

Rituximab is a mainstay in the therapy for a broad variety of B-cell malignancies. Despite its undeniable therapeutic value, we still do not fully understand the mechanisms of action responsible for rituximab's anti-tumor effects. Direct signaling, complement-mediated cytotoxicity (CMC), and antibody-dependent cellular cytotoxicity (ADCC) all appear to play a role in rituximab efficacy. In vitro, animal model and clinical data addressing each of these mechanisms of action are reviewed, as are data speaking to the complexity of interactions between these mechanisms. Taken together, these data suggest different mechanisms are likely important in different scenarios. Study of the complex mechanisms of action that contribute to the clinical efficacy of rituximab have led to novel clinical trials including novel combinations, schedules, and generation of additional antibodies designed to have even greater effect. Such studies need to be accompanied by rigorous correlative analysis if we are to understand the importance of various mechanisms of action of rituximab and use that information to improve on what is already an indispensable component of therapy.

Therapy of B-cell malignancies by anti-HLA-DR humanized monoclonal antibody, IMMU-114, is mediated through hyperactivation of ERK and JNK MAP kinase signaling pathways

A humanized IgG4 anti-HLA-DR monoclonal antibody (IMMU-114), engineered to avoid side effects associated with complement activation, was examined for binding and cytotoxicity on leukemia, lymphoma, and multiple myeloma cell lines and chronic lymphocytic leukemia (CLL) patient specimens, followed by evaluation of the effects of IMMU-114 on extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways. HLA-DR was expressed on the majority of these cells at markedly higher levels than CD20, CD22, and CD74. IMMU-114 was toxic to mantle cell lymphoma, CLL, acute lymphoblastic leukemia, hairy cell leukemia, non-Hodgkin lymphoma (including rituximab-resistant), and multiple myeloma cell lines, and also patient CLL cells. IMMU-114 induced disease-free survival in tumor-bearing SCID mice with early-stage disease and in models that are relatively resistant to anti-CD20 monoclonal antibodies. Despite positive staining, acute myelogenous leukemic cells were not killed by IMMU-114. The ability of IMMU-114 to induce activation of ERK and JNK signaling correlated with cytotoxicity and differentiates the mechanism of action of IMMU-114 from monoclonal antibodies against CD20 and CD74. Thus, antigen expression is not sufficient for cytotoxicity; antibody-induced hyperactivation of ERK and JNK mitogen activated protein kinase signaling pathways are also required.

Immunotherapy of cancer

Major advances have been made in the field of immunology in the past two decades. A better understanding of the molecular and cellular mechanisms controlling the immune system has opened the door to many innovative and promising new cancer therapies that manipulate the immune response. For instance, toll-like receptor agonists have been shown to boost immune responses toward tumors. Also, a wide array of cell-based immunotherapies utilizing T cells, NK cells, and dendritic cells have been established. Furthermore, a rapidly expanding repertoire of monoclonal antibodies is being developed to treat tumors, and many of the available antibodies have demonstrated impressive clinical responses. Here, we examine some of these immunotherapeutic approaches currently in use or testing to treat cancer, and we examine available evidence with regards to mechanism and efficacy of these treatments.

Intratumoral but not systemic delivery of CpG oligodeoxynucleotide augments the efficacy of anti-CD20 monoclonal antibody therapy against B cell lymphoma

The anti-CD20 monoclonal antibody rituximab (Rituxan) has become a mainstay in the treatment of B cell non-Hodgkin lymphomas. The mechanisms of action for rituximab include antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity, and apoptosis induction. Combination of anti-CD20 antibodies with immunostimulatory agents may improve their efficacy via enhancement of one or more of these mechanisms. Toll-like receptor 9 agonist CpG oligodeoxynucleotides administered systemically have been studied in clinical trials with and without rituximab. However, recent data suggest that intratumoral (IT) delivery of CpG has advantages in the treatment of tumors. Using a syngeneic murine B cell lymphoma line expressing human CD20, we found that IT, but not systemically administered CpG significantly improved the efficacy of rituximab against 7-day established tumors. Rituximab plus IT CpG could eradicate tumors from 42% of mice, whereas systemically administered CpG, with or without rituximab, did not achieve tumor eradication. Both natural killer cells and complement participated in the cure of tumors by rituximab plus IT CpG, apparently by increasing tumor cell sensitivity to complement and ADCC lysis, and by augmenting the cytotoxicity of ADCC effectors. No role for T cells in mediating tumor eradication was demonstrated in this model. These results suggest that previous clinical trials in B cell lymphoma combining systemic administration of CpG with rituximab may have employed suboptimal routes of CpG delivery. Future trials combining IT CpG with anti-CD20 antibodies or the antibody-mediated targeting of CpG directly to the sites of B cell lymphoma may thus be warranted.

Immunogenicity of the hu14.18-IL2 immunocytokine molecule in adults with melanoma and children with neuroblastoma

PURPOSE

Immunocytokine (IC) hu14.18-IL2 is a fusion protein of humanized antidisialoganglioside (GD2) antibody (hu14.18) and interleukin (IL)-2. Sixty-one melanoma and neuroblastoma patients received IC in phase I/Ib studies. Patient sera were examined in ELISA to determine if an anti-IC antibody response occurred during treatment.

EXPERIMENTAL DESIGN

Serum was assayed for anti-idiotypic antibody (anti-id Ab) based on ability to bridge biotinylated hu14.18 to plate-bound hu14.18 and ability to inhibit binding of hu14.18 to GD2 antigen and/or murine anti-idiotypic antibody. ELISA was also used to detect antibodies to the Fc-IL2 end of hu14.18-IL2.

RESULTS

Thirty-two patients (52%) developed an anti-idiotypic antibody response (absorbance, >0.7) in the bridge ELISA. Twelve patients (20%) had an intermediate response, whereas 17 patients (28%) were negative (adsorbance, <0.3). The development of antibody to hu14.18-IL2 detected in the bridge ELISA was not related to the dose of hu14.18-IL2. Twenty of 33 adult patients (61%) demonstrated an anti-idiotypic antibody response based on binding inhibition ELISA. The anti-idiotypic response was inversely correlated (P < 0.002) with IC measured during the second course of treatment, indicating that development of anti-idiotypic antibodies interfered with detection of circulating hu14.18-IL2. All patients developed some inhibitory activity in the binding inhibition assay designed to detect antibodies to the Fc-IL2 region of the IC. There was a positive correlation between the peak serum level of IC in course 1 and the anti-Fc-IL2 response.

CONCLUSIONS

Patients treated with hu14.18-IL2 developed anti-idiotypic antibodies and anti Fc-IL2 antibodies. No association was seen between development of anti-IC antibodies and clinical toxicity.

Phase II study of a TLR-9 agonist (1018 ISS) with rituximab in patients with relapsed or refractory follicular lymphoma

Toll-like receptor-9 (TLR-9) agonists have pleotropic effects on both the innate and adaptive immune systems, including increased antigen expression, enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and T helper cell type 1 shift in the immune response. We combined a TLR-9 agonist (1018 ISS, 0.2 mg/kg sc weekly x 4 beginning day 8) with standard rituximab (375 mg/m(2) weekly x 4) in patients (n = 23) with relapsed/refractory, histologically confirmed follicular lymphoma, and evaluated immunological changes following the combination. Treatment was well-tolerated with no significant adverse events attributable to therapy. Clinical responses were observed in 48% of patients; the overall median progression-free survival was 9 months. Biologically relevant increases in ADCC and circulating CD-3 positive T cells were observed in 35% and 39% of patients, respectively. Forty-five percent of patients had increased T cells and dendritic cells in skin biopsies of 1018 ISS injection sites 24 h post-therapy. Pre- and post-biopsies of tumour tissue demonstrated an infiltration of CD8(+) T cells and macrophages following treatment. This group of patients had favourable clinical outcome despite adverse prognostic factors. This study is the first to histologically confirm perturbation of the local immune microenvironment following systemic biological therapy of follicular lymphoma.

Understanding and circumventing resistance to anticancer monoclonal antibodies

With the widespread use of therapeutic monoclonal antibodies in the treatment of patients with cancer, resistance to these agents has become a major issue. Preclinical models of drug action or resistance have contributed to unravel the main mechanisms of resistance, involving both tumor-associated and host related factors. However our understanding of how a monoclonal antibody destroys cancer cells in a patient and why it one day stops being effective are still far from being complete. This review focuses on the available data on mechanisms of action and resistance to rituximab and includes some additional information for other monoclonal antibodies. Innovative approaches designed to overcome resistance, such as combination immunotherapy, costimulation with cytokines or growth factors are presented.

Vaccination with autologous tumor-loaded dendritic cells induces clinical and immunologic responses in indolent B-cell lymphoma patients with relapsed and measurable disease: a pilot study

Eighteen relapsed patients with measurable indolent non-Hodgkin lymphoma (NHL) were vaccinated with dendritic cells (DCs) loaded with killed autologous tumor cells. Six patients had objective clinical responses including 3 continuous complete responses (CRs) and 3 partial responses (PRs), with a median follow up of 50.5 months. Eight patients had stable disease, whereas 4 had progressive disease. Clinical responses were significantly associated with a reduction in CD4+CD25+FOXP3+ regulatory T cells, an increase in CD3−CD56dimCD16+ natural killer (NK) cells, and maturation of lymphocytes to the effector memory stage in either postvaccination peripheral blood or tumor specimen samples. In partial responding patients, vaccination significantly boosted the IFN-γ–producing T-cell response to autologous tumor challenge. In one HLA-A*0201+ patient who achieved CR, IL-4 release by circulating T cells in response to tumor-specific IgH-encoded peptides was also documented. Immunohistochemical analysis of tumor biopsies using biotin-conjugated autologous serum samples revealed a tumor-restricted humoral response only in the postvaccination serum from responding patients. Collectively these results demonstrate that vaccination with tumor-loaded DCs may induce both T- and B-cell responses and produces clinical benefits in indolent NHL patients with measurable disease. This study is registered with the Istituto Superiore di Sanità: http://www.iss.it with protocol number 7578-PRE 21-801.

Economic burden of follicular non-Hodgkin's lymphoma

Follicular non-Hodgkin's lymphoma (FNHL), a slow-growing cancer of the immune system, constitutes about 15-30% of all incident non-Hodgkin's lymphoma in developed countries. Its incidence is rising worldwide. Patients can live many years, but FNHL is considered incurable. We systematically reviewed the English-language MEDLINE-indexed and non-indexed economic literature published in the past 10 years on FNHL, identifying 23 primary economic studies. The economic burden of FNHL is significant, but available data are generally limited to retrospective considerations of hospital-based direct treatment costs, with little information available regarding societal cost of illness. Most direct cost information originates from the US, with one estimate of $US36 000 for the per-patient incremental cost of FNHL care during the first year following diagnosis. The most studied treatment is rituximab, which may offer similar overall costs to fludarabine considering higher resource use with fludarabine complications. Nearly all cost-effectiveness models identified by this review evaluated rituximab for relapsed/refractory FNHL responding to chemotherapy induction. Rituximab is supported as a cost-effective addition to standard chemotherapy by two models in the UK and one in the US, as maintenance therapy instead of stem-cell transplant by one UK model, and as maintenance therapy instead of observation alone by one model each in France, Spain and Canada. The UK National Institute for Health and Clinical Excellence updated guidance on rituximab in February 2008, concluding that it is cost effective when added to induction chemotherapy, and when used as maintenance therapy. No studies of per-patient or national indirect costs of illness were identified, with the only study of indirect costs a Canadian survey documenting lost work productivity. Across all study types identified by our review, the most common focus was on the direct costs of rituximab. As new treatments for FNHL come to market, more real-life cost data are imperative to calculate their relative cost effectiveness.

Complete eradication of human B-cell lymphoma xenografts using rituximab in combination with the immunocytokine L19-IL2

The antibody-mediated delivery of therapeutic agents to sites of angiogenesis is an attractive strategy for anticancer therapy, but is largely unexplored in hematologic malignancies. In the present study, we show that the extra domain B (EDB) of fibronectin, a marker of angiogenesis, is expressed in B-cell non-Hodgkin lymphoma (NHL) and that the human monoclonal anti-EDB antibody L19 can selectively localize to the lymphoma-associated subendothelial extracellular matrix. In vivo, the preferential accumulation of the antibody at the tumor site was confirmed by quantitative biodistribution analyses with radioiodinated antibody preparations. The fusion protein L19-IL2, which mediates the delivery of interleukin-2 (IL-2) to the neovasculature, displayed a superior antilymphoma activity compared with unconjugated IL-2 in localized and systemic xenograft models of NHL. When coadministered with rituximab, L19-IL2 induced complete remissions of established localized lymphomas and provided long-lasting protection from disseminated lymphoma. The combined use of rituximab and L19-IL2, which dramatically increases the infiltration of immune effector cells in lymphomas, may deserve clinical investigations, facilitated by the fact that L19-IL2 is currently being studied in phase II clinical trials in patients with solid tumors.

Antibody and immunomodulatory agents in the treatment of indolent non-Hodgkin's lymphoma

Immunomodulatory agents, including cytokines, CpG oligonucleotides, and anti-idiotype vaccines have properties that suggest they have the ability to augment rituximab in the treatment of non-Hodgkin's lymphoma (NHL). Although several clinical trials have shown promising results, no randomized trials of reasonable size have been reported to date, limiting the ability to discern whether combinations of immunomodulatory agents with rituximab impact clinical outcome. Until such trials are mature, we do not recommend using these agents in combination outside of the research setting.

Total body irradiation, etoposide, cyclophosphamide, and autologous peripheral blood stem-cell transplantation followed by randomization to therapy with interleukin-2 versus observation for patients with non-Hodgkin lymphoma: results of a phase 3 randomized trial by the Southwest Oncology Group (SWOG 9438)

To determine the effect of posttransplantation immunotherapy with IL-2 on the progression-free survival (PFS) and overall survival (OS) of patients with non-Hodgkin lymphoma (NHL) after autologous stem-cell transplantation (PBSCT), patients with previously treated NHL were treated with cyclophosphamide, etoposide, total body irradiation (TBI), and PBSCT. Twenty-eight to 80 days after PBSCT, patients were randomized to IL-2 versus observation. Three hundred seventy-six eligible patients were registered (with 4-year PFS of 34% and 4-year OS of 52%), and 194 eligible patients were randomized to continuous infusion intravenous IL-2 (9 million units/m(2)/day for 4 days followed 5 days later by 1.6 million units/m(2)/day for 10 days) versus observation. In randomized patients, there was no significant difference in PFS (hazard ratio of IL-2 to observation = 0.90; P =.56) or in OS (hazard ratio of IL-2 to observation = 0.88; P =.55). There were no deaths related to IL-2 treatment. Grade 4 IL-2-related toxicities (n = 14) were reversible. These results confirm earlier SWOG findings that cyclophosphamide, etoposide, TBI, and PBSCT can be administered to patients with relapsed/refractory NHL with encouraging PFS and OS. Posttransplantation IL-2 given at this dose and schedule of administration had no significant effect on PFS or OS. This study is registered at www.clinicaltrials.gov as NCT00002649.

The role of sargramostim (rhGM-CSF) as immunotherapy

GM-CSF stimulates the differentiation of hematopoietic progenitors to monocytes and neutrophils, and reduces the risk for febrile neutropenia in cancer patients. GM-CSF also has been shown to induce the differentiation of myeloid dendritic cells (DCs) that promote the development of T-helper type 1 (cellular) immune responses in cognate T cells. This review summarizes some of the immunological effects of GM-CSF relevant to antitumor immunity in cancer patients. GM-CSF has been used to augment the activity of rituximab in patients with follicular lymphoma and to induce autologous antitumor immunity in patients with hormone-refractory prostate cancer. GM-CSF causes upregulation of costimulatory molecule expression on leukemia blasts in vitro, enhancing their ability to present antigen to allogeneic T cells, and, in combination with interferon-alpha, can induce antitumor immune responses in patients whose acute leukemia has relapsed following allogeneic hematopoietic progenitor cell transplant. Tumor cells engineered to secrete GM-CSF are particularly effective as antitumor vaccines, and the addition of GM-CSF to standard vaccines may increase their effectiveness by recruiting DCs to the site of vaccination. However, a significant limitation in the use of GM-CSF as an immunostimulatory agent is that objective antitumor responses are infrequent, and are often not durable. Effective and durable antitumor immunity will likely require novel methods to eliminate counterregulatory immune responses that limit activation and expansion of cytotoxic T cells with antitumor activity.

Non-fucosylated therapeutic antibodies: the next generation of therapeutic antibodies

Therapeutic antibody IgG1 has two N-linked oligosaccharide chains bound to the Fc region. The oligosaccharides are of the complex biantennary type, composed of a trimannosyl core structure with the presence or absence of core fucose, bisecting N-acetylglucosamine (GlcNAc), galactose, and terminal sialic acid, which gives rise to structural heterogeneity. Both human serum IgG and therapeutic antibodies are well known to be heavily fucosylated. Recently, antibody-dependent cellular cytotoxicity (ADCC), a lytic attack on antibody-targeted cells, has been found to be one of the critical effector functions responsible for the clinical efficacy of therapeutic antibodies such as anti-CD20 IgG1 rituximab (Rituxan((R))) and anti-Her2/neu IgG1 trastuzumab (Herceptin((R))). ADCC is triggered upon the binding of lymphocyte receptors (FcgammaRs) to the antibody Fc region. The activity is dependent on the amount of fucose attached to the innermost GlcNAc of N-linked Fc oligosaccharide via an alpha-1,6-linkage, and is dramatically enhanced by a reduction in fucose. Non-fucosylated therapeutic antibodies show more potent efficacy than their fucosylated counterparts both in vitro and in vivo, and are not likely to be immunogenic because their carbohydrate structures are a normal component of natural human serum IgG. Thus, the application of non-fucosylated antibodies is expected to be a powerful and elegant approach to the design of the next generation therapeutic antibodies with improved efficacy. In this review, we discuss the importance of the oligosaccharides attached to the Fc region of therapeutic antibodies, especially regarding the inhibitory effect of fucosylated therapeutic antibodies on the efficacy of non-fucosylated counterparts in one medical agent. The impact of completely non-fucosylated therapeutic antibodies on therapeutic fields will be also discussed.