Clinical Outcome of Lymphoma Patients After Idiotype Vaccination Is Correlated With Humoral Immune Response and Immunoglobulin G Fc Receptor Genotype

Unique tumor antigens: evidence for immune control of genome integrity and immunogenic targets for T cell-mediated patient-specific immunotherapy

The molecular identification and characterization of antigenic epitopes recognized by T cells on human cancers has rapidly evolved since the cloning in 1991 of MAGEA1, the first gene reported to encode a CTL-defined human tumor antigen. In the expanding field of human tumor immunology, unique tumor antigens constitute a growing class of T cell-defined epitopes that exhibit strong immunogenicity. Some of these antigens, which often derive from mutation of genes that have relevant biological functions, are less susceptible to immunoselection and may be retained even in advanced tumors. Immunogenicity and constitutive expression of the unique tumor antigens provide a strong rationale for the design of novel, patient-tailored therapies that target such determinants. Here we discuss the immunologic relevance of unique tumor antigens in the light of the prospects for exploiting such epitopes as targets for patient-specific immune intervention strategies.

Dendritic cells loaded with apoptotic antibody-coated tumor cells provide protective immunity against B-cell lymphoma in vivo

The in vitro priming of tumor-specific T cells by dendritic cells (DCs) phagocytosing killed tumor cells can be augmented in the presence of antitumor monoclonal antibody (mAb). We investigated whether DCs phagocytosing killed lymphoma cells coated with tumor-specific antibody could elicit antitumor immunity in vivo. Irradiated murine 38C13 lymphoma cells were cocultured with bone marrow-derived DCs in the presence or absence of tumor-specific mAb. Mice vaccinated with DCs cocultured with mAb-coated tumor cells were protected from tumor challenge (60% long-term survival), whereas DCs loaded with tumor cells alone were much less effective. The opsonized whole tumor cell-DC vaccine elicited significantly better tumor protection than a traditional lymphoma idiotype (Id) protein vaccine, and in combination with chemotherapy could eradicate preexisting tumor. Moreover, the DC vaccine protected animals from both wild-type and Id-negative variant tumor cells, indicating that Id is not a major target of the induced tumor immunity. Protection was critically dependent upon CD8(+) T cells, with lesser contribution by CD4(+) T cells. Importantly, opsonized whole tumor cell-DC vaccination did not result in tissue-specific autoimmunity. Since opsonized whole tumor cell-DC and Id vaccines appear to target distinct tumor antigens, optimal antilymphoma immunity might be achieved by combining these approaches.

Therapeutic lymphoma vaccines: importance of T-cell immunity

The unique antigenic determinants, termed idiotype, of the immunoglobulin expressed on a given B-cell malignancy can serve as a tumor-specific antigen for active immunotherapy. Administration of autologous tumor-derived idiotype protein conjugated to a carrier protein, keyhole limpet hemocyanin, together with granulocyte-macrophage colony-stimulating factor to follicular lymphoma patients in complete clinical remission was associated with induction of tumor-specific cellular and humoral immunity, molecular remissions, and prolonged disease-free survival. Idiotype vaccination in patients with mantle cell lymphoma following rituximab-containing chemotherapy induced tumor-specific T-cell immunity in the absence of B cells, suggesting that vaccines may be used in combination with rituximab. Three double-blind, randomized, Phase III idiotype vaccine trials are currently ongoing to definitively determine the clinical benefit of idiotype-keyhole limpet hemocyanin plus granulocyte-macrophage colony-stimulating factor vaccination in patients with lymphoma. Results from early clinical trials with idiotype vaccines suggested that both humoral and cellular immune responses may be independently associated with tumor regression and improved progression-free survival. With the increased use of rituximab for the treatment of follicular lymphoma and other B-cell non-Hodgkin's lymphomas, further improvement in the potency of the vaccines would require strategies to enhance T-cell responses, as rituximab depletes normal B cells and impairs the generation of antibody responses.

Anti-idiotype antibodies in cancer treatment

As a cancer immunotherapy tool, idiotypes (Ids) have been used in different ways over the last three decades, depending on the actual human tumor cell target. It all started with passive, monoclonal, anti-Id antibody treatment of B-cell lymphoma, a setting in which results were tantalizing, but logistics unsustainable. It then moved toward the development of anti-Id vaccines for the treatment of the same tumors, a setting in which we have recently provided the first formal proof of principle of clinical benefit associated with the use of a human cancer vaccine. Meanwhile, it also expanded in the direction of exploiting the antigenic mimicry of some Ids with Id-unrelated, tumor-associated antigens for the immunotherapy of a number of solid tumors, a setting in which clinical results are still far from being consolidated. All in all, over the years Id-based immunotherapy has paved the way for a number of seminal therapeutic improvements for cancer patients, including the development of most if not all Id-unrelated monoclonal antibodies that have recently revolutionized the field.

Antibodies, Fc receptors and cancer

Since the first report of the successful use of a monoclonal antibody for the treatment of human B cell lymphoma in 1982, several antibodies have become incorporated into standard treatment protocols for cancer. One of the most important factors that determine antibody activity in vivo is the efficient interaction with cellular Fc-receptors on innate immune effector cells. It has become clear that the outcome of this interaction is influenced by several factors, such as the antibody isotype-specific affinity to activating and inhibitory receptors, the level of inhibitory FcgammaRIIB expression, and the composition of the sugar side chain attached to the antibody Fc-portion. These novel insights into antibody FcR interactions might be useful to produce the next generation of improved immunotherapeutic molecules.

The antiinflammatory activity of IgG: the intravenous IgG paradox

How high doses of intravenous IgG (IVIG) suppress autoimmune diseases remains unresolved. We have recently shown that the antiinflammatory activity of IVIG can be attributed to a minor species of IgGs that is modified with terminal sialic acids on their Fc-linked glycans. Here we propose that these Fc-sialylated IgGs engage a unique receptor on macrophages that, in turn, leads to the upregulation of an inhibitory Fcgamma receptor (FcgammaR), thereby protecting against autoantibody-mediated pathology.

BiovaxID: a personalized therapeutic cancer vaccine for non-Hodgkin's lymphoma

The clonal immunoglobulin molecule, idiotype (ID), expressed on the surface of B-cell malignancies can function as a tumor-specific antigen. BiovaxID is a patient-specific therapeutic cancer vaccine composed of the tumor idiotype conjugated to a carrier protein, keyhole limpet hemocyanin (KLH). In a Phase II clinical trial, administration of ID-KLH vaccine together with granulocyte-macrophage colony-stimulating factor to follicular lymphoma patients in complete remission induced tumor-specific cellular and humoral immunity and molecular remissions, and was associated with prolonged disease-free survival. A randomized, double-blind, Phase III clinical trial is ongoing to definitively determine the clinical benefit of BiovaxID plus granulocyte-macrophage colony-stimulating factor vaccination in patients with follicular lymphoma.

Current management of follicular lymphomas

After decades of stagnation, the prognosis of patients with follicular lymphomas (FL) has changed substantially within the last few years due to new and effective therapeutic modalities. These include myeloablative therapy followed by autologous stem cell transplantation (ASCT) in younger patients in first remission, which showed a significant prolongation of remission duration in three prospective randomised trials while the impact on overall survival still needs to be determined. Adding the anti-CD 20 antibody Rituximab to conventional chemotherapy resulted in a significant increase in remission rate, remission duration and, in two of four currently available prospective randomised studies, even in a longer overall survival. A prolongation of remission duration was also seen when Rituximab was given as maintenance after cytoreductive therapy including Rituximab. Radio-immunotherapy (RIT) with radioisotopes coupled to monoclonal antibodies produced encouraging data in several phase II studies. New therapeutic perspectives have also emerged from increasing insights into the biology of the disease that unravel molecular targets for novel agents, some of which have entered clinical evaluation already.

Follicular NHL: from antibodies and vaccines to graft-versus-lymphoma effects

Monoclonal antibody therapy with rituximab in combination with standard chemotherapy has improved the survival of patients with advanced-stage follicular lymphoma (FL). A series of next-generation anti-CD20 antibodies may be less immunogenic and have even greater antitumor activity through augmented interactions with host effector mechanisms responsible for tumor cell kill. Additional approaches with patient-specific immunoglobulin idiotype vaccines; novel monoclonal antibodies binding to biologically active cell-surface antigen are also demonstrating early clinical activity. Antibodies targeting radioisotopes, toxins or drugs are also slowly entering clinical trials and practice. Last, allogeneic stem cell transplantation following reduced-intensity conditioning provides graft-versus-tumor immune responses that may be able to control FL and allow this risky but potentially curative treatment option to older patents or those with comorbidities.

Vaccine-based approaches to squamous cell carcinoma of the head and neck

Vaccine-based approaches for the treatment of advanced squamous cell carcinoma of the head and neck have achieved very limited success. Improvement in vaccine efficacy for both diseases control and survival is predicated on a careful analysis of the root causes for successes and failures to date. In this review, we analyse the utility and limitations of select protective and therapeutic vaccine strategies for tumour prevention and therapy. Based on this characterisation, we define potential directions which are meritorious of future study.

Monoclonal Antibodies for B-Cell Lymphomas: Rituximab and Beyond

The year 2007 marks the 10th anniversary of approval by the U.S. Food and Drug Adminstration of the first monoclonal antibody for the treatment of cancer. Rituximab, an anti-CD20 chimeric monoclonal antibody, was approved for the treatment of patients with relapsed/refractory low-grade B-cell non-Hodgkin lymphomas. From an immunologic perspective, this therapeutic indication provided the long-elusive validation of immunotherapy as the fourth modality of treatment for patients with cancer. From a clinical perspective, it was hard to imagine then that this nonchemotherapeutic approach would dramatically impact the management of patients with almost every type of B-cell malignancy and that it would even find a place as a therapeutic option for patients with non-malignant disorders. Although thousands of patients have been treated worldwide with rituximab, there is still debate regarding its mechanism(s) of action. The demonstration that a number of patients do not benefit with this treatment and that no cures have been achieved with single-agent rituximab prompted several investigators to identify those barriers limiting the efficacy of this monoclonal antibody. Here, we summarize what we have learned in the past 10 years about rituximab efficacy and its mechanisms of action and resistance. We also discuss the new generation of monoclonal antibodies, the development of which has been spurred by the widespread success of anti-CD20 MAb therapy.

Glycan optimization of a human monoclonal antibody in the aquatic plant Lemna minor

N-glycosylation is critical to the function of monoclonal antibodies (mAbs) and distinguishes various systems used for their production. We expressed human mAbs in the small aquatic plant Lemna minor, which offers several advantages for manufacturing therapeutic proteins free of zoonotic pathogens. Glycosylation of a mAb against human CD30 was optimized by co-expressing the heavy and light chains of the mAb with an RNA interference construct targeting expression of the endogenous alpha-1,3-fucosyltransferase and beta-1,2-xylosyltransferase genes. The resultant mAbs contained a single major N-glycan species without detectable plant-specific N-glycans and had better antibody-dependent cell-mediated cytotoxicity and effector cell receptor binding activities than mAbs expressed in cultured Chinese hamster ovary (CHO) cells.

Humoral immune response and immunoglobulin G Fc receptor genotype are associated with better clinical outcome following idiotype vaccination in follicular lymphoma patients regardless of their response to induction chemotherapy

We have reported that anti-idiotype antibody response and FcgammaRIIIa 158 valine/valine (V/V) genotype both correlate with better outcome in a group of 136 follicular lymphoma patients receiving idiotype vaccination after induction chemotherapy. Here, we examined whether this correlation is related in any way to the chemotherapy response. In patients with complete response (CR), the 5-year progression-free survival (PFS) was 69% for patients with antibody response and/or V/V genotype, while the PFS was only 40% for patients with neither; the median time to progression (TTP) was 10.47 versus 3.46 years (P=.012). In patients with partial response (PR), the 5-year PFS was 57% for patients with antibody response and/or V/V genotype, and 17% for patients with neither; the median TTP was not reached versus 1.31 years (P=.001). This study further confirms the strong association of clinical outcome with antibody response and with the functionally more active form of the Fc receptor in patients receiving idiotype vaccination regardless of their response to induction chemotherapy.

Activating and inhibitory FcγRs in autoimmune disorders

Autoimmune disorders are characterized by the destruction of self-tissues by the immune system. Multiple checkpoints are in place to prevent autoreactivity under normal circumstances. Coexpression of activating and inhibitory Fc receptors (FcR) represents such a checkpoint by establishing a threshold for immune cell activation. In many human autoimmune diseases, however, balanced FcR expression is disturbed. Analysis of murine model systems provides strong evidence that aberrant FcR expression can result in uncontrolled immune responses and the initiation of autoimmune disease. This review will summarize this data and explain how this information might be used to better understand human autoimmune diseases and to develop novel therapeutic strategies.

Clinical results of vaccine therapy for cancer: learning from history for improving the future

Active, specific immunotherapy for cancer holds the potential of providing an approach for treating cancers, which have not been controlled by conventional therapy, with very little or no associated toxicity. Despite advances in the understanding of the immunological basis of cancer vaccine therapy as well as technological progress, clinical effectiveness of this therapy has often been frustratingly unpredictable. Hundreds of preclinical and clinical studies have been performed addressing issues related to the generation of a therapeutic immune response against tumors and exploring a diverse array of antigens, immunological adjuvants, and delivery systems for vaccinating patients against cancer. In this chapter, we have summarized a number of clinical trials performed in various cancers with focus on the clinical outcome of vaccination therapy. We have also attempted to draw objective inferences from the published data that may influence the clinical effectiveness of vaccination approaches against cancer. Collectively the data indicate that vaccine therapy is safe, and no significant autoimmune reactions are observed even on long term follow-up. The design of clinical trials have not yet been optimized, but meaningful clinical effects have been seen in B-cell malignancies, lung, prostate, colorectal cancer, and melanoma. It is also obvious that patients with limited disease or in the adjuvant settings have benefited most from this targeted therapy approach. It is imperative that future studies focus on exploring the relationship between immune and clinical responses to establish whether immune monitoring could be a reliable surrogate marker for evaluating the clinical efficacy of cancer vaccines.

Clinical benefit associated with idiotypic vaccination in patients with follicular lymphoma

BACKGROUND

Follicular lymphoma is considered incurable, although cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy can induce sequential remissions. A patient's second complete response is typically shorter than that patient's first complete response. Idiotype vaccines can elicit specific immune responses and molecular remissions in patients with follicular lymphoma. However, a clinical benefit has never been formally proven.

METHODS

Thirty-three consecutive follicular lymphoma patients in first relapse received six monthly cycles of CHOP-like chemotherapy. Patients who achieved a second complete response were vaccinated periodically for more than 2 years with autologous lymphoma-derived idiotype protein vaccine. Specific humoral and cellular responses were assessed, and patients were followed for disease recurrence. Statistical tests were two-sided.

RESULTS

Idiotype vaccine could be produced for 25 patients who had a second complete response. In 20 patients (80%), a humoral (13/20) and/or a cellular (18/20) idiotype-specific response was detected. The median duration of the second complete response has not been reached, but it exceeds 33 months (range = 20+ to 51+ months). None of the 20 responders relapsed while undergoing active vaccination. All responders with enough follow-up for the comparison to be made experienced a second complete response that was statistically significantly (P<.0001) longer than both their first complete response (18 of 18 patients) and than the median duration of a CHOP-induced second complete response, i.e., 13 months (20 of 20 patients). The five nonresponders all had a second complete response that was shorter (median = 10 months; range = 8-13 months) than their first complete response (median = 17 months; range = 10-39 months).

CONCLUSIONS

Idiotypic vaccination induced a specific immune response in the majority of patients with follicular lymphoma. Specific immune response was associated with a dramatic and highly statistically significant increase in disease-free survival. This is the first formal demonstration of clinical benefit associated with the use of a human cancer vaccine.

Distribution of the FcgammaRIIIa 176 F/V polymorphism amongst healthy Chinese, Malays and Asian Indians in Singapore

AIMS

To determine and compare the distribution of the FcgammaRIIIa 176 F/V polymorphism across three ethnically distinct populations (Chinese, Asian Indians and Malays) in Singapore.

METHODS

The FcgammaRIIIa 176 F/V polymorphism was genotyped by direct sequencing from genomic DNA samples obtained from normal healthy Chinese, Asian Indians and Malays (n = 192 from each population).

RESULTS

The allelic frequencies of the high binding affinity FcgammaRIIIa 176 V allele for Chinese, Asian Indians and Malays were 35%, 33% and 46%, respectively (F allele frequencies were 65%, 67% and 54%, respectively). Genotype distributions were found to conform to the Hardy-Weinberg law (P > 0.05) in each group. chi(2) comparisons revealed significant differences in the genotype distributions of the FcgammaRIIIa 176 V/F polymorphism of Malays from the other two populations (Chinese and Asian Indians). However, no significant difference in the genotype distributions of the FcgammaRIIIa 176 V/F polymorphism was observed between Chinese and Asian Indian populations.

CONCLUSIONS

The genotype distributions of the FcgammaRIIIa 176 V/F polymorphism in healthy Malays are significantly different from both Chinese and Indians. These observations provide the fundamentals on which future disease associations may be built and also present important implications for the design of therapeutic regimens amongst various ethnic groups.

Vaccination of advanced prostate cancer patients with PSCA and PSA peptide-loaded dendritic cells induces DTH responses that correlate with superior overall survival

Prostate stem cell antigen (PSCA) and prostate-specific antigen (PSA) are overexpressed in most prostate cancers. PSCA- and PSA-derived, HLA-A2 binding peptides are specific targets for T-cell responses in vitro. A phase I/II trial was performed to demonstrate feasibility, safety and induction of antigen-specific immunity by vaccination with dendritic cells (DC) presenting PSCA and PSA peptides in patients with hormone- and chemotherapy-refractory prostate cancer. Patients received 4 vaccinations with a median of 2.7 x 10(7) peptide-loaded mature DC s.c. in biweekly intervals. Clinical responses were assessed 2 weeks after the 4th vaccination. Immune monitoring was performed by DTH and HLA multimer analysis. Twelve patients completed vaccination without relevant toxicities. Six patients had stable disease after 4 vaccinations. One patient had a complete disappearance of lymphadenopathy despite rising PSA. Four patients with SD and 1 progressor developed a positive DTH after the 4th vaccination. With a median survival of all patients of 13.4 months, DTH-positivity was associated with significantly superior survival (p = 0.003). HLA tetramer analysis detected high frequencies of peptide-specific T cells after 2 vaccinations in 1 patient who was also the sole responder to concomitant hepatitis B vaccination as an indicator of immune competence and survived 27 months after start of vaccination. Vaccination with PSA/PSCA peptide-loaded, autologous DCs may induce cellular responses primarily in immunocompetent patients, which appear to be associated with clinical benefit. Testing of DC-based vaccination is warranted for patients at earlier stages of prostate cancer.

Engineering of therapeutic antibodies to minimize immunogenicity and optimize function

One of the first difficulties in developing monoclonal antibody therapeutics was the recognition that human anti-mouse antibody (HAMA) response limited the administration of murine antibodies. Creative science has lead to a number of ways to counter the immunogenicity of non-human antibodies, primarily through chimeric, humanized, de-immunized, and most recently, human-sequence therapeutic antibodies. Once therapeutic antibodies of low or no immunogenicity were available, the creativity then turned to engineering both the antigen-binding domains (e.g., affinity maturation, stability) and altering the effector functions (e.g. antibody-dependent cellular cytotoxicity, complement-dependent cellular cytotoxicity, and clearance rate).

Anti-CD20 monoclonal antibody with enhanced affinity for CD16 activates NK cells at lower concentrations and more effectively than rituximab

Growing evidence indicates that the affinity of monoclonal antibodies (mAbs) for CD16 (FcgammaRIII) plays a central role in the ability of the mAb to mediate antitumor activity. We evaluated how CD16 polymorphisms, and mAb with modified affinity for target antigen and CD16, affect natural killer (NK) cell phenotype when CD20(+) malignant B cells were also present. The mAb consisted of rituximab (R), anti-CD20 with enhanced affinity for CD20 (AME-B), and anti-CD20 with enhanced affinity for both CD20 and CD16 (AME-D). Higher concentrations of mAb were needed to induce CD16 modulation, CD54 up-regulation, and antibody-dependent cellular cytotoxicity (ADCC) on NK cells from subjects with the lower affinity CD16 polymorphism. The dose of mAb needed to induce NK activation was lower with AME-D irrespective of CD16 polymorphism. At saturating mAb concentrations, peak NK activation was greater for AME-D. Similar results were found with measurement of CD16 modulation, CD54 up-regulation, and ADCC. These data demonstrate that cells coated with mAb with enhanced affinity for CD16 are more effective at activating NK cells at both low and saturating mAb concentrations irrespective of CD16 polymorphism, and they provide further evidence for the clinical development of such mAbs with the goal of improving clinical response to mAb.

Phase I trial of a novel intradermal idiotype vaccine in patients with advanced B-cell lymphoma: specific immune responses despite profound immunosuppression

The immunoglobulin receptor of B-cell lymphomas constitutes a specific tumor antigen (idiotype) and a target for active immunotherapy. Encouraging results have been reported in phase II trials after s.c. vaccination of follicular lymphoma patients during clinical remission with idiotype produced from eukaryotic cell lines and coupled to an immunogenic carrier macromolecule. We have developed a good manufacturing protocol for rapid expression of idiotype vaccines as recombinant Fab fragments in Escherichia coli. The objectives of this trial were to show safety and feasibility of intradermal immunization with this vaccine and to investigate whether immune responses were induced by this immunization route. Patients (n = 18) with advanced B-cell malignancies received repetitive intradermal vaccinations with 0.5 to 1.65 mg recombinant idiotype Fab fragment mixed with lipid-based adjuvant in combination with 150 mug granulocyte macrophage colony-stimulating factor s.c. at the same location. The patients' immune status was assessed by flow cytometry of peripheral blood lymphocytes and concomitant hepatitis B vaccination. Cellular and humoral immune responses to the vaccine were assessed by enzyme-linked immunospot and ELISA. Side effects of a total of 65 vaccinations were mild and did not affect the immunization schedule. No patient developed hepatitis B surface antibodies (anti-HBs) after two hepatitis B immunizations. Of 17 evaluable patients, five developed specific anti-vaccine antibodies, and eight developed anti-Fab T-cell responses. T-cell reactivity was independent of the cellular immune status and was idiotype specific as shown by statistical regression analysis (P = 0.0024) and epitope mapping studies. Intradermal administration of uncoupled recombinant idiotype with appropriate adjuvants may overcome profound clinical immunosuppression and induce specific immune responses.

Current status of therapeutic vaccines for non-Hodgkin's lymphoma

PURPOSE OF REVIEW

Therapeutic vaccines targeting B cell lymphoma idiotype have reached an advanced stage of clinical development, with three multicenter randomized clinical trials ongoing. This review describes the rationale and development of this immunotherapeutic approach, the design of current phase III trials, and other active vaccination approaches likely to move forward into clinical testing for lymphomas.

RECENT FINDINGS

Several groups have achieved promising results in phase II trials of patient-specific idiotype vaccines, with very few side effects noted. Anti-idiotype antibodies, in addition to cytotoxic T cells, are now believed to be important effectors of antitumor immunity after idiotype vaccination. The manufacturing of autologous tumor idiotype proteins is being rapidly refined by the use of molecular technologies. Two trials involving more than 1000 patients are now under way, which use idiotype vaccination after induction chemotherapy; one trial completed accrual in early 2004. A third trial opened in 2004, using rituximab followed by idiotype vaccine with maintenance booster vaccines continuing throughout the period of normal B cell recovery. In accordance with the United States Food and Drug Administration, progression-free survival serves as the accepted primary efficacy endpoint in these studies.

SUMMARY

Lymphoma idiotype vaccination represents a promising immunotherapeutic approach targeting a patient-specific tumor antigen. The results of pivotal phase III trials for three first-generation idiotype vaccines will become available in the next several years. Advanced manufacturing techniques should permit application of this tailor-made treatment to large numbers of non-Hodgkin's lymphoma patients.

The feasibility of gene expression profiling generated in fine-needle aspiration specimens from patients with follicular lymphoma and diffuse large B-cell lymphoma

Lymphoma of germinal center cell (GC) origin generally is an indolent malignancy that transforms progressively into a more aggressive disease. According to the World Health Organization classification, lymphomas of follicular center cell origin are classified as either large B-cell lymphoma (LBCL) or follicular lymphoma (FL). The authors tested the feasibility of performing gene expression profiling using amplified RNA from fine-needle aspirates (FNA) obtained from lymph nodes. Twenty-four samples from patients with a diagnosis of FL or LBCL were obtained after Institutional Review Board-approved informed consent was obtained. The diagnoses were confirmed by 2 pathologists and were classified into 2 groups (10 LBCL samples and 14 FL samples) by using conventional morphology and immunophenotyping. One hundred nanograms of total RNA were subjected to 2 cycles of standard, double-stranded complementary DNA synthesis and in vitro transcription for target amplification using a small-sample target-labeling protocol. The biotinylated cRNA from each sample was hybridized to gene chips. Gene expression profiling results were analyzed first by principal-component analysis (PCA) by using a list of 146 probe sets that represented 62 genes that are characteristic of an activated B-cell (ABC) signature or a GC signature. The analysis identified 5 LBCL samples with an ABC cell signature. Using a list of 207 probe sets that represented 113 genes involved in FL transformation, PCA analysis identified 2 overlapping clusters corresponding to FL and GC-diffuse LBCL. To improve this classification further, the authors generated a list of 72 genes that were expressed differentially between FL and GC-LBCL. Using this list of genes, PCA analysis demonstrated a clear separation between FL and GC-LBCL. However, five FL samples clustered as an intermediate group between FL and GC-DLBCL. These samples were characterized morphologically by a mixed cell pattern with relatively fewer large, noncleaved lymphocytes and more small, cleaved lymphocytes. The results support the feasibility of FNA-based transcription profiles in patients with FL or LBCL, which, in combination with morphology and immunophenotyping, can help in the subtyping of these entities.

Combined vaccination with idiotype-pulsed allogeneic dendritic cells and soluble protein idiotype for multiple myeloma patients relapsing after reduced-intensity conditioning allogeneic stem cell transplantation

BACKGROUND AND OBJECTIVE

To combine the use of idiotype-pulsed allogeneic dendritic cells (alloDC) and soluble protein Id conjugated with KLH (Id-KLH) in a vaccine strategy for multiple myeloma (MM).

DESIGN AND METHODS

Four MM patients received the combined vaccine after having experienced disease relapse/progression following reduced intensity conditioning (RIC) allogeneic stem cell transplantation (alloSCT) and failure to rescue therapy with donor lymphocyte infusion or chemotherapy (CHT).

RESULTS

Vaccination was well tolerated and induced an anti-KLH antibody response in all 4 patients as well as substantial cell proliferation. In contrast, no case showed similar effects against either tumor-specific Id or irrelevant isotype control immunoglobulins (Ig). In turn, vaccination was associated with modulation of biological responses linked to both inflammatory and T-cell activation, with secretion of effector Th1 cytokines. In particular, an important increase in the spontaneous ex vivo secretion of TNFalpha, IL-6 and IFNgamma as well as IL-2 and IL-10 was frequently observed prior to the fourth vaccination. Moreover, in vitro stimulation with Id-KLH and Id-KLH plus alloDC, but not with alloDC alone was associated with an enhanced number of TNF-alpha+ T-cells and an increased secretion of IFNgamma and IL-2 before the third and fourth vaccination. From a clinical standpoint, 2 patients had a transient response and 1 has stable disease after stopping vaccination, while 3 of them ultimately progressed.

INTERPRETATION AND CONCLUSIONS

The results show for the first time that the use of Id-pulsed alloDC following RIC alloSCT is safe and feasible. However, crucial strategy improvements are warranted to possibly achieve clinical benefit.

Fcgamma receptors: old friends and new family members

Although cellular receptors for immunoglobulins were first identified nearly 40 years ago, their central role in the immune response was discovered only in the last decade. They are key players in both the afferent and efferent phase of an immune response, setting thresholds for B cell activation, regulating the maturation of dendritic cells, and coupling the exquisite specificity of the antibody response to innate effector pathways, such as phagocytosis, antibody-dependent cellular cytotoxicity, and the recruitment and activation of inflammatory cells. Moreover, because of their general presence as receptor pairs consisting of activating and inhibitory molecules on the same cell, they have become a paradigm for studying the balance of positive and negative signals that ultimately determine the outcome of an immune response. This review will summarize recent results in Fc-receptor biology with an emphasis on data obtained in in vivo model systems.

Non-clinical development of cancer vaccines: regulatory considerations

This paper discusses regulatory requirements essential during the non-clinical development of cancer vaccines. DNA vaccines and vaccines containing monoclonal antibodies are specifically addressed. ICH, CHMP, FDA, and WHO guidance documents in addition to scientific literature are reviewed and the regulatory framework, including respective EMEA and the FDA divisions responsible for review and assessment of cancer vaccines, is described. Selection criteria for an appropriate animal model for efficacy and/or toxicity studies are discussed.

The High-Affinity IgG Receptor, FcγRI, Plays a Central Role in Antibody Therapy of Experimental Melanoma

We examined the role of FcgammaR in antibody therapy of metastatic melanoma in wild-type and different FcgammaR knock-out mice. Treatment of B16F10-challenged wild-type mice with TA99 antibody specific for the gp75 tumor antigen resulted in a marked decrease in numbers of lung metastases. Treatment of individual FcgammaR knock-out mice revealed the high-affinity IgG receptor, FcgammaRI (CD64), to represent the central FcgammaR for TA99-induced antitumor effects. The potential of immune-modulating agents to further enhance the protective effect induced by monoclonal antibody (mAb) TA99 was examined in combination treatments consisting of mAb TA99 and a TLR-4 agonist, monophosphoryl lipid A (MPL). MPL did potently boost TA99 antibody-induced effects, and combination therapy was, again, found to be dependent on the presence of FcgammaRI.

The Carbohydrate at FcγRIIIa Asn-162

FcgammaRIIIa plays a prominent role in the elimination of tumor cells by antibody-based cancer therapies. Non-fucosylated bisected IgGs bind this receptor with increased affinity and trigger FcgammaRIII-mediated effector functions more efficiently than native, fucosylated antibodies. In this study the contribution of the carbohydrates of both binding partners to the strength of the complex was analyzed. Glycoengineering of the antibody increased affinity for two polymorphic forms of soluble human FcgammaRIIIa (by up to 50-fold) but did not affect binding to the inhibitory FcgammaRIIb receptor. While the absence of carbohydrate at FcgammaRIIIa's Asn-162 increased affinity for native IgG, presumably due to the removal of steric hindrance caused by the bulky sugars, it unexpectedly reduced affinity for glycoengineered (GE) antibodies by over one order of magnitude, bringing the affinity down to the same level as for native IgG. We conclude that the high affinity between GE antibodies and FcgammaRIII is mediated by productive interactions formed between the receptor carbohydrate attached at Asn-162 and regions of the Fc that are only accessible when it is nonfucosylated. As FcgammaRIIIa and FcgammaRIIIb are the only human Fcgamma receptors glycosylated at this position, the proposed interactions explain the observed selective affinity increase of GE antibodies for only these receptors. Furthermore, we predict from our structural model that only one of the two Fc-fucose residues needs to be absent for increased binding affinity toward FcgammaRIII. This information can be exploited for the design of new antibodies with altered Fc receptor binding affinity and enhanced therapeutic potential.

Update on cancer vaccines

PURPOSE OF REVIEW

Vaccination against cancer has had a variable history, with claims of success often fading into disappointment. The reasons for this include poor vaccine design, inadequate understanding of the nature of the immune response, and a lack of objective measures to evaluate performance. The impact of genetic technology has changed everything. We now have multiple strategies to identify candidate tumor antigens, and we understand more about activation and regulation of immunity against cancer. There are novel vaccine strategies to activate specific attack on tumor cells. We also have modern assays using surrogate markers of performance to correlate with clinical effects. It is timely to select significant relevant papers to illustrate the growing potential for patients with cancer.

RECENT FINDINGS

Recent findings include tumor antigen discovery and vaccine formulation, relevant knowledge concerning mechanisms of induction of effective immunity from preclinical models, and translation into clinical trials with objective evaluation of performance.

SUMMARY

The ability of the immune response to dispose of cancer cells is clear. Passive transfer of antibody or immune cells is already clinically successful. We are now in a position to harness new gene-based information to design vaccines capable of inducing effective and long-lasting immunity. Safe vaccines could be used either in patients or in transplant donors. Pilot clinical trials are the means of testing performance, with continuing vaccine design modification to target specific antigens in different cancers.

Personalized immunotherapy for the treatment of non-Hodgkin's lymphoma: a promising approach

The efficacy of immunotherapeutic strategies for the treatment of lymphoid malignancies has been demonstrated in recent years. In patients with B-cell lymphomas, particularly indolent lymphoma, the use of passive immunotherapy, such as the anti-CD20 monoclonal antibody rituximab, has made an impressive impact on patient outcome. Personalized immunotherapy, a method that triggers the immune system to mount a response against tumor cells, has shown promising results in early clinical trials in hematologic malignancies. This therapeutic modality appears safe, with the most common adverse events being transient, local reactions at the site of injection. Furthermore, personalized immunotherapy has the potential to generate immunologic memory, which could provide prolonged remission. Currently, 3 large phase III studies are evaluating the efficacy and safety of personalized immunotherapy in patients with follicular lymphoma. It is hoped that the results of these studies will lead to the incorporation of this promising approach into the standard treatment of patients with lymphoma.

Direct targeting of genetically modified tumour cells to FcγRI triggers potent tumour cytotoxicity

Expression of the type I receptor for Fc domain of immunoglobulin (Ig)G (Fc gammaRI or CD64) is restricted to myeloid effector cells, such as monocytes, macrophages and a subset of dendritic cells. Previous work has indicated a role for Fc gammaRI in antibody-dependent phagocytosis and lysis of tumour cells. We hypothesised that tagging of tumour cells with an anti-Fc gammaRI single chain Fv (sFv) may facilitate targeting to this receptor on effector cells, thereby initiating tumour cytotoxicity. A vector encoding the sFv for an Fc gammaRI-specific antibody (H22), linked to the transmembrane domain of platelet-derived growth factor was constructed. Transfected tumour cells expressed high surface levels of functional H22-sFv, which greatly enhanced susceptibility for phagocytosis and lysis by monocytes and macrophages. The expression of H22-sFv evoked the ability of tumour cells to directly activate monocytes, as evidenced by phosphorylation of mitogen-activated protein kinase and secretion of the inflammatory cytokines interleukin (IL)-1beta, tumour necrosis factor-alpha and IL-6. Moreover, growth of tumour cells in mice expressing H22-sFv was profoundly delayed (or absent) in transgenic mice expressing human Fc gammaRI. These results demonstrated that tumour cells can be readily modified to activate cell effector mechanisms, a strategy that may be useful for in vivo targeting in patients.

Recombinant, tumour-derived idiotype vaccination for indolent B cell non-Hodgkin’s lymphomas: a focus on FavId™

FavId (Favrille, Inc., San Diego, CA, USA) is a personalized therapeutic vaccine product for B cell non-Hodgkin's lymphoma, custom-manufactured from individual patient's tumour cells. This investigational agent consists of recombinant tumour-specific immunoglobulin (idiotype [Id]) chemically conjugated to the highly immunogenic carrier protein keyhole limpet haemocyanin (Id-KLH). The vaccine product is administered by subcutaneous co-injection with the cytokine adjuvant granulocyte-macrophage colony-stimulating factor (GM-CSF) with the goal of stimulating tumour-specific T cell and humoral immunity. Therapeutic Id vaccines have shown promising results in early phase clinical trials in follicular lymphoma, and several Phase III trials are ongoing. FavId's advantages over other Id vaccine formulations include its rapid and efficient manufacturing technology utilising recombinant baculovirus, with a production time of only 8-12 weeks. In Phase II studies, FavId Id-KLH plus GM-CSF vaccines have been found to be safe, immunogenic and clinically active in follicular lymphoma. At present, FavId is being tested in a randomised, placebo-controlled Phase III trial in follicular lymphoma, aimed at improving the time to disease progression when administered following cytoreduction with rituximab. If found to be efficacious in this pivotal trial, FavId would represent a tumour-selective immunotherapy for lymphoma with little toxicity and a novel mechanism of action.

Skewed T-cell differentiation in patients with indolent non-Hodgkin lymphoma reversed by ex vivo T-cell culture with gammac cytokines

The unfavorable clinical evolution in indolent non-Hodgkin lymphomas suggests defective control of neoplastic growth by the immune system. To address this issue, we evaluated phenotype, function, and maturation profile of CD4(+) and CD8(+) T cells from peripheral-blood, lymph nodes, or bone marrow of patients with B-cell non-Hodgkin lymphoma (NHL) at diagnosis. T cells from these patients frequently showed an activated but apoptosis-prone phenotype with low frequency of tumor-reactive T cells showing a TH2/Tc2 functional profile in the response to autologous tumor. In peripheral blood or in lymph nodes and bone marrow, and, in comparison to healthy donors, patients' T cells showed a skewed differentiation toward Tnaive and Tcentral memory stages, with low expression of granzyme B and perforin. T-cell culture with autologous tumor in the presence of IL-2, IL-15, and autologous bone marrow-derived cells led to massive T-cell expansion and to differentiation of cytotoxic factor(+) CD8(+) T cells releasing IFN-gamma and killing autologous B-cell tumor in an HLA-class I-restricted fashion. These results suggest impaired T-cell differentiation to effector stage in patients with B-cell NHL, but indicate that T-cell responsiveness to gammac cytokines is retained, thus allowing to promote generation of antitumor T cells for immune intervention.

CD16 polymorphisms and NK activation induced by monoclonal antibody-coated target cells

CD16 and natural killer (NK) cells appear to play a central role in mediating the anti-tumor effects of monoclonal antibody (mAb) therapy, yet little is known about changes in NK cells that result from interaction of the NK cells with mAb-coated tumor cells under physiologic conditions. We developed a system using peripheral blood mononuclear cells (PBMCs) and either transformed B cells or breast cancer cells to assess how mAbs impact on NK cell phenotype. Rituximab, apolizumab and trastuzumab induced modulation of CD16 and upregulation of CD54 on NK cells when the appropriate target cells were present. Higher concentrations of mAb were needed to induce these changes on NK cells from subjects with the lower affinity CD16 polymorphism. Phenotypic changes were greater in NK cells from subjects with the higher affinity polymorphism even when saturating concentrations of mAb were used, demonstrating increased concentration of mAb can overcome some, but not all, of the influence CD16 polymorphisms have on NK activation. These studies provide a straightforward and easily reproducible technique to measure the ability of mAb-coated tumor cells to activate NK cells in vitro which should be particularly useful as mAbs with varying affinity for both target antigen and Fc receptor (FcR) are developed.

Modulation of Dendritic Cell Maturation and Function by B Lymphocytes

Investigating the signals that regulate the function of dendritic cells (DC), the sentinels of the immune system, is critical to understanding the role of DC in the regulation of immune responses. Accumulating lines of evidence indicate that in addition to innate stimuli and T cell-derived signals, B lymphocytes exert a profound regulatory effect in vitro and in vivo on the Ag-presenting function of DC. The identification of B cells as a cellular source of cytokines, chemokines, and autoantibodies that are critically involved in the process of maturation, migration, and function of DC provides a rationale for immunotherapeutic intervention of autoimmune and inflammatory conditions by targeting B cells. Conversely, efficient cross-presentation of Ags by DC pulsed with immune complexes provides an alternative approach in the immunotherapy of cancer and infectious diseases.

Progress and controversies in developing cancer vaccines

Immunotherapy has become a standard approach for cancer management, through the use of cytokines (eg: interleukin-2) and monoclonal antibodies. Cancer vaccines hold promise as another form of immunotherapy, and there has been substantial progress in identifying shared antigens recognized by T cells, in developing vaccine approaches that induce antigen-specific T cell responses in cancer patients, and in developing new technology for monitoring immune responses in various human tissue compartments. Dramatic clinical regressions of human solid tumors have occurred with some cancer vaccines, but the rate of those responses remains low. This article is part of a 2-part point:counterpoint series on peptide vaccines and adoptive therapy approaches for cancer. The current status of cancer vaccination, and associated challenges, are discussed. Emphasis is placed on the need to increase our knowledge of cancer immunobiology, as well as to improve monitoring of cellular immune function after vaccination. Progress in both areas will facilitate development of effective cancer vaccines, as well as of adoptive therapy. Effective cancer vaccines promise to be useful for treatment and prevention of cancer at low cost and with low morbidity.

Selective blockade of inhibitory Fcgamma receptor enables human dendritic cell maturation with IL-12p70 production and immunity to antibody-coated tumor cells

The final differentiation or maturation of dendritic cells (DCs) in response to environmental stimuli influences their ability to both initiate immunity and determine the quality of the response to antigens. Circulating immune complexes and cell-bound immunoglobulins present in normal human sera represent a potential stimulus for inadvertent DC activation in the steady state and during autoimmunity. Here, we show that selective blockade of the inhibitory Fcgamma receptor (FcgammaR) FcgammaRIIb with recently developed monoclonal antibodies leads to maturation of human monocyte-derived DCs, which depends on the presence of IgG in normal human plasma. Plasma, in the presence of an FcgammaRIIb blockade, caused the DCs to up-regulate the expression of costimulatory molecules and to produce the inflammatory mediator IL-12p70. FcgammaRIIb blockade of DCs loaded with tumor cells led to increased tumor-specific T cell immunity without the need for exogenous stimuli other than human plasma. Therefore, the activation status of DCs in the presence of normal human serum depends on the balance between activating and inhibitory FcgammaRs and can be enhanced by new antibodies that react selectively with FcgammaRIIb. These data suggest an approach for modifying this balance to enhance immunity to immune complexes and antibody-coated tumor cells and to silence DC activation by immune complexes in autoimmune states.