Correlation of anti-idiotype network with survival following anti-G(D2) monoclonal antibody 3F8 therapy of stage 4 neuroblastoma

Quantitation and Identification of Therapeutic Anti-CD22 Monoclonal Antibodies in a Cell-Based ELISA Method

Since they lack native soluble membrane antigens, the analysis and selection of antigen-specific antibodies are commonly performed on whole live cells. Here, we have developed a simple and convenient enzyme-linked immunosorbent assay (ELISA) based on cell membrane antigens. Soluble cell membrane proteins isolated from Raji cells were immobilized on the polystyrene microplate, which permitted the assessment of a therapeutic anti-CD22 monoclonal antibody. The experiments showed less variability in the intra-assay. Compared to the living cell ELISAs, the advantage of the assay is avoiding cell losses and high variation of optical density (OD) readings. We provide a quantitative and reproducible ELISA that can be potentially applied to the development of specific antibodies against cell surface antigens.

Anti-GD2 Directed Immunotherapy for High-Risk and Metastatic Neuroblastoma

Neuroblastoma is one of the few childhood cancers that carries a tumor-specific antigen in the form of a glycolipid antigen known as GD2. It has restricted expression in normal tissue, such as peripheral afferent nerves. Monoclonal antibodies targeting GD2 have been applied clinically to high-risk neuroblastoma with significant success. However, there are different anti-GD2 products and administration regimens. For example, anti-GD2 has been used in combination with chemotherapy during the induction phase or with retinoic acid during the maintenance stage. Regimens also vary in the choice of whether to add cytokines (i.e., IL-2, GMCSF, or both). Furthermore, the addition of an immune enhancer, such as β-glucan, or allogeneic natural killer cells also becomes a confounder in the interpretation. The question concerning which product or method of administration is superior remains to be determined. So far, most studies agree that adding anti-GD2 to the conventional treatment protocol can achieve better short- to intermediate-term event-free and overall survival, but the long-term efficacy remains to be verified. How to improve its efficacy is another challenge. Late relapse and central nervous system metastasis have emerged as new problems. The methods to overcome the mechanisms related to immune evasion or resistance to immunotherapy represent new challenges to be resolved. The newer anti-GD2 strategies, such as bispecific antibody linking of anti-GD2 with activated T cells or chimeric antigen receptor T cells, are currently under clinical trials, and they may become promising alternatives. The use of anti-GD2/GD3 tumor vaccine is a novel and potential approach to minimizing late relapse. How to induce GD2 expression from tumor cells using the epigenetic approach is a hot topic nowadays. We expect that anti-GD2 treatment can serve as a model for the use of monoclonal antibody immunotherapy against cancers in the future.

Phase I Trial of Oral Yeast-Derived β-Glucan to Enhance Anti-GD2 Immunotherapy of Resistant High-Risk Neuroblastoma

Beta glucans, complex polysaccharides, prime leukocyte dectin-1 and CR3-receptors and enhance anti-tumor cytotoxicity of complement-activating monoclonal antibodies. We conducted a phase I study (clinicaltrials.gov NCT00492167) to determine the safety of the combination of yeast-derived beta glucan (BG) and anti-GD2 murine monoclonal antibody 3F8 in patients with relapsed or refractory high-risk neuroblastoma. Patients received intravenous 3F8 (fixed dose of 10 mg/m²/day × 10 days) and oral BG (dose-escalated from 10-200 mg/kg/day × 17 days in cohorts of 3-6 patients each). Forty-four patients completed 141 cycles. One patient developed DLT: transient self-limiting hepatic transaminase elevation 5 days after starting BG (120 mg/kg/day). Overall, 1, 3, 12 and 24 evaluable patients had complete response, partial response, stable and progressive disease, respectively, at the end of treatment. Positive human anti-mouse antibody response and dectin-1 rs3901533 polymorphism were associated with better overall survival. BG dose level and serum BG levels did not correlate with response. Progression-free and overall survival at 2 years were 28% and 61%, respectively. BG lacked major toxicity. Treatment with 3F8 plus BG was associated with anti-neuroblastoma responses in patients with resistant disease. Although the maximal tolerated dose for yeast BG was not reached, considering the large volume of oral BG, we recommended 40 mg/kg/day as the phase II dose.

Romiplostim for Immune Thrombocytopenia in Neuroblastoma Patients Receiving Chemotherapy

Thrombocytopenia, a serious complication of myelosuppressive chemotherapy in cancer patients, is managed with platelet transfusions until recovery of platelet counts. However, children receiving chemotherapy can rarely develop immune thrombocytopenia (ITP) that is refractory to transfused platelets. This limits the ability to achieve adequate platelet counts and administer further myelosuppressive chemotherapy safely, especially if first-line ITP therapy is ineffective. We report 2 cases of intravenous immunoglobulin refractory ITP in children receiving chemotherapy for high-risk neuroblastoma. ITP was successfully treated with the thrombopoietin-receptor-agonist romiplostim, allowing safe and timely continuation of antineuroblastoma therapies in these high-risk patients.

Spotlight on dinutuximab in the treatment of high-risk neuroblastoma: development and place in therapy

Neuroblastoma (NB) is a pediatric cancer of the sympathetic nervous system which accounts for 8% of childhood cancers. Most NBs express high levels of the disialoganglioside GD2. Several antibodies have been developed to target GD2 on NB, including the human/mouse chimeric antibody ch14.18, known as dinutuximab. Dinutuximab used in combination with granulocyte-macrophage colony-stimulating factor, interleukin-2, and isotretinoin (13-cis-retinoic acid) has a US Food and Drug Administration (FDA)-registered indication for treating high-risk NB patients who achieved at least a partial response to prior first-line multi-agent, multimodality therapy. The FDA registration resulted from a prospective randomized trial assessing the benefit of adding dinutuximab + cytokines to post-myeloablative maintenance therapy for high-risk NB. Dinutuximab has also shown promising antitumor activity when combined with temozolomide and irinotecan in treating NB progressive disease. Clinical activity of dinutuximab and other GD2-targeted therapies relies on the presence of the GD2 antigen on NB cells. Some NBs have been reported as GD2 low or negative, and such tumor cells could be nonresponsive to anti-GD2 therapy. As dinutuximab relies on complement and effector cells to mediate NB killing, factors affecting those components of patient response may also decrease dinutuximab effectiveness. This review summarizes the development of GD2 antibody-targeted therapy, the use of dinutuximab in both up-front and salvage therapy for high-risk NB, and the potential mechanisms of resistance to dinutuximab.

Adoptive immunotherapy with haploidentical natural killer cells and Anti-GD2 monoclonal antibody m3F8 for resistant neuroblastoma: Results of a phase I study

Natural killer (NK) cell-mediated antibody-dependent toxicity is a potent mechanism of action of the anti-GD2 murine monoclonal antibody 3F8 (m3F8). Killer immunoglobulin-like receptor (KIR) and HLA genotypes modulate NK activity and are key prognostic markers in m3F8-treated patients with neuroblastoma. Endogenous NK-cells are suppressed in the setting of high tumor burden and chemotherapy. Allogeneic NK-cells however, demonstrate potent anti-neuroblastoma activity. We report on the results of a phase I clinical trial of haploidentical NK-cells plus m3F8 administered to patients with high-risk neuroblastoma after conditioning chemotherapy. The primary objective was to determine the maximum tolerated NK-cell dose (MTD). Secondary objectives included assessing anti-neuroblastoma activity and its relationship to donor-recipient KIR/HLA genotypes, NK function, and donor NK chimerism. Patients received a lymphodepleting regimen prior to infusion of haploidentical CD3-CD56+ NK-cells, followed by m3F8. Overall and progression free survival (PFS) were assessed from the time of first NK-cell dose. Univariate Cox regression assessed relationship between dose and outcomes. Thirty-five patients received NK-cells at one of five dose levels ranging from <1×10⁶ to 50×10⁶ CD3-CD56+cells/kg. One patient experienced grade 3 hypertension and grade 4 pneumonitis. MTD was not reached. Ten patients (29%) had complete or partial response; 17 (47%) had no response; and eight (23%) had progressive disease. No relationship was found between response and KIR/HLA genotype or between response and FcγRIII receptor polymorphisms. Patients receiving >10×10⁶ CD56+cells/kg had improved PFS (HR: 0.36, 95%CI: 0.15-0.87, p = 0.022). Patient NK-cells displayed high NKG2A expression, leading to inhibition by HLA-E-expressing neuroblastoma cells. Adoptive NK-cell therapy in combination with m3F8 is safe and has anti-neuroblastoma activity at higher cell doses.

Structural Basis of GD2 Ganglioside and Mimetic Peptide Recognition by 14G2a Antibody

Monoclonal antibodies targeting GD2 ganglioside (GD2) have recently been approved for the treatment of high risk neuroblastoma and are extensively evaluated in clinics in other indications. This study illustrates how a therapeutic antibody distinguishes between different types of gangliosides present on normal and cancer cells and informs how synthetic peptides can imitate ganglioside in its binding to the antibody. Using high resolution crystal structures we demonstrate that the ganglioside recognition by a model antibody (14G2a) is based primarily on an extended network of direct and water molecule mediated hydrogen bonds. Comparison of the GD2-Fab structure with that of a ligand free antibody reveals an induced fit mechanism of ligand binding. These conclusions are validated by directed mutagenesis and allowed structure guided generation of antibody variant with improved affinity toward GD2. Contrary to the carbohydrate, both evaluated mimetic peptides utilize a "key and lock" interaction mechanism complementing the surface of the antibody binding groove exactly as found in the empty structure. The interaction of both peptides with the Fab relies considerably on hydrophobic contacts however, the detailed connections differ significantly between the peptides. As such, the evaluated peptide carbohydrate mimicry is defined primarily in a functional and not in structural manner.

Survival benefit associated with human anti-mouse antibody (HAMA) in patients with B-cell malignancies

BACKGROUND

About one-third of patients with relapsed B-cell malignancies develop human anti-mouse antibody (HAMA) following mouse antibody treatment. The purpose of this study was to assess the relationship between HAMA and survival in patients given a mouse anti-lymphoma monoclonal antibody (mAb), Lym-1, directed against a unique epitope of HLA-DR antigen that is up-regulated on malignant B-cells.

METHODS

ELISA was used to quantify HAMA in 51 patients with B-cell malignancies treated with iodine-131 (131I) labeled Lym-1. Sera were collected prior to and following radioimmunotherapy (RIT) with 131I-Lym-1 until documented to be HAMA negative or throughout lifetime. Univariate, then multivariate analyses including other risk factors, were used to analyze the relationship of HAMA to survival. The relationships of HAMA to prior chemotherapies and to absolute lymphocyte counts prior to RIT were also assessed.

RESULTS

Eighteen of 51 patients (35%) developed HAMA following RIT (range of ultimate maximum titers, 6.6-1,802 microg/ml). Using the time dependent Cox proportional hazards model, maximum HAMA titers were associated with survival (P=0.02). HAMA continued to be significant for survival in multivariate analyses that included known risk factors. In Landmark analysis of 39 patients that survived at least 16 weeks, median survival of patients with HAMA less than 5 microg/ml was 61 versus 103 weeks for patients with HAMA equal or greater than 5 microg/ml at 16 weeks (P=0.02). The median survival of the five patients with highest maximum HAMA titers was 244 weeks. At 16 weeks, there was an inverse correlation between the maximum HAMA titer and the number of previous chemotherapies (P<0.003). Absolute lymphocyte counts prior to 131I-Lym-1 treatment for patients that seroconverted were higher than those for patients that did not seroconvert (P=0.01).

CONCLUSIONS

Patients with B-cell malignancies that developed high HAMA titers had longer survival that was not explained by risk factors or histologic grade, suggesting the importance of the immune system.

Molecular characterization of the anti-idiotypic immune response of a relapse-free neuroblastoma patient following antibody therapy: a possible vaccine against tumors of neuroectodermal origin?

Neuroblastoma treatment with chimeric antidisialoganglioside GD2 Ab ch14.18 showed objective antitumor responses. Production of anti-idiotypic Abs (Ab2) against ch14.18 (Ab1) in some cases was positively correlated with a more favorable prognosis. According to Jerne's network theory, a subset of anti-idiotypic Abs (Ab2beta) carries an "internal image" of the Ag and induces Abs (Ab3) against the original Ag. The molecular origin of an anti-idiotypic Ab response in tumor patients was not investigated previously. To clone anti-idiotypic Abs, B cells of a ch14.18-treated neuroblastoma patient with Ab2 serum reactivity were used to construct Ab phage display libraries. After repeated biopannings on ch14.18 and its murine relative, anti-GD2 mAb 14G2a, we selected 40 highly specific clones. Sequence analysis revealed at least 10 of 40 clones with different Ig genes. Identities to putative germline genes ranged between 94.90 and 100% for V(H) and between 93.90 and 99.60% for V(L). An overall high rate of replacement mutations suggested a strong Ag-driven maturation of the anti-idiotypic Abs. Two clones that were analyzed further, GK2 and GK8, inhibited binding of ch14.18 to GD2 just as the patient's serum did. GK8 alone inhibited >80% of the patient's anti-idiotypic serum Abs in binding to ch14.18. Rabbits vaccinated with GK8 or GK2 (weaker) produced Ab3 against the original target Ag GD2. GK8 may be useful as a tumor vaccine for GD2-positive [corrected] tumors.

Immunotherapy of neuroblastoma: present, past and future

Neuroblastoma is a neuroectodermal tumor of childhood with poor prognosis and low survival in patients with advanced-stage disease who respond to conventional therapies but unfortunately, often present relapse. Therefore, the search for novel therapeutic strategies is warranted and represents the objective of many investigators. Among the new, innovative approaches, immunotherapy has attracted much interest. However, until recently, little information was available about the immunogenicity of human neuroblastoma.

A comparison of current neuroblastoma chemotherapeutics

Neuroblastoma is the most common solid tumour in childhood. Modern management includes a biopsy to perform genetic studies. Based on clinical data and Myc-N amplification (MNA), patients are divided in three prognostic groups: the low-risk (Stage 1, 2, 4S without MNA) has an event-free survival (EFS) of > 90% with surgery alone; the intermediate-risk (Stage 3, > 1 year of age, without MNA and Stage 3 and 4 infants without MNA) has an EFS of approximately 80% with mild chemotherapy and surgery; the high-risk group includes Stage 4, > 1 year of age and any stage and age with MNA. These patients are treated with chemotherapy, surgery, megatherapy, irradiation and 13-cis-retinoic acid. With this complex therapy, a 5-year EFS of 30-50% can be obtained.

Biomimetic design in microparticulate vaccines

Current efforts to improve the effectiveness of microparticle vaccines include incorporating biomimetic features into the particles. Many pathogens use surface molecules to target specific cell types in the gut for host invasion. This observation has inspired efforts to chemically conjugate cell-type targeting ligands to the surfaces of microparticles in order to increase the efficiency of uptake, and therefore the effectiveness, of orally administered microparticles. Bio-mimicry is not limited to the exterior surface of the microparticles. Anti-idiotypic antibodies, cytokines or other biological modifiers can be encapsulated for delivery to sites of interest as vaccines or other therapeutics. Direct mucosal delivery of microparticle vaccines or immunomodulatory agents may profoundly enhance mucosal and systemic immune responses compared to other delivery routes.

Emerging cancer-targeted therapies

There is reason to believe that the unfolding revolution in molecular biology and translational research will allow selective targeting of tumor cells, and radically change the way general practitioners and pediatric oncologists treat and follow children with cancer. This article highlights some of the most promising approaches being tested in the field. By learning about the underlying biology, the remaining hurdles, the projected timeline, and the possible impact of new therapies on the practice of pediatric oncology, health care professionals and patients should be better prepared for the future of pediatric oncology.

Antibody-based vaccines for the treatment of melanoma

Malignant melanoma remains a difficult clinical problem. Chemotherapy is not effective and immunotherapy has long been contemplated as the preferred approach to this disease. Extensive passive and active immunotherapy trials have been conducted. Active vaccination with whole cells or defined antigens, administered with a panoply of techniques to increase immunogenicity, has yielded inconsistent results. The development of antibody-based vaccines has allowed vaccination without the need for tumor tissue material or purified antigens. The idiotype network theory originally proposed by Lindemann and by Jerne provided the basis for the development of anti-idiotype (anti-Id) antibody vaccines, which mimic the internal image of the epitope targeted for immunization. Preclinical and phase I clinical data are available for various malignancies. In melanoma, some of the anti-Id vaccines have targeted gangliosides. One of these vaccines, TriGem, has been successful in generating a robust and specific humoral immunity in melanoma patients. Phase II data suggest this anti-Id vaccine has clinical activity.

Effects on fertility of immunizing mice with anti-idiotypic antibodies to porcine zona pellucida antigen

OBJECTIVE

To evaluate the effects on fertility by immunization with anti-idiotypic antibodies to porcine zona pellucida (PZP) antigen.

METHOD

Anti-idiotypic antibodies (Ab(2)) were produced in New Zealand rabbits immunized with 17D3 monoclonal antibodies (mAbs) (IgG, Ab(1)) to PZP antigen. The antisera were first passed through immuno-affinity chromatography column linked to normal mouse IgG so as to remove the antibody bound to normal mouse IgG The passing elute was then purified by immuno-affinity chromatography using 17D3 mAbs to get the Ab(2). Female BALB/c mice, 5-week-old, were grouped and immunized with the Ab(2), PZP antigen, target antigen of the Ab(1) and normal rabbit IgG, respectively. The treated female mice were mated with male BALB/c mice and sacrificed at gestation day 10. Analyses included ELISA measurement of anti-ZP antibody titer, fetal number determination and evaluation of ovarian histomorphology.

RESULTS

The Ab(2) appeared as a single protein band by SDS-PAGE. Shown by a competitive inhibition ELISA, the Ab(2) specifically bound to the variable region of the 17D3 Ab(1). Compared with controls, the female mice immunized with Ab(2) showed a decreased pregnancy rate and a statistically significant reduction in fetal numbers. Histological examination of ovaries demonstrated that Ab(2) exposure interfered less with follicular development than did exposure to PZP.

CONCLUSION

Immunization of female mice with Ab(2) to PZP mAbs suppresses fertility and fetal numbers with minimal ovarian pathology.

Phase II trial of the anti-G(D2) monoclonal antibody 3F8 and granulocyte-macrophage colony-stimulating factor for neuroblastoma

PURPOSE

To describe oncolytic effects of treatment with anti-G(D2) monoclonal antibody 3F8 plus granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with neuroblastoma (NB).

PATIENTS AND METHODS

Patients were eligible for 3F8/GM-CSF if intensive therapy had not eradicated potentially lethal NB. One cycle consisted of GM-CSF (subcutaneous bolus) on days 1 through 5, 11, and 12, and GM-CSF (2-hour intravenous [IV] infusion) followed after a 1-hour interval by 3F8 (1.5-hour IV infusion) on days 6 through 10 and 13 through 17. GM-CSF was dosed at 250 microg/m(2)/d on days 1 through 7 and at 500 microg/m(2)/d on days 8 through 17. 3F8 was dosed at 10 mg/m(2)/d (100 mg/m(2)/cycle). 3F8 was given with an opiate and an antihistamine. Patients without progressive disease (PD) or elevated human antimouse antibody titers could be treated again beginning 3 weeks after completion of a cycle.

RESULTS

Among 19 patients treated for NB resistant to induction therapy, 12 of 15 had complete remission (CR) of bone marrow (BM) disease, and three others who had less than partial responses achieved prolonged progression-free survival (one remains on study at 21+ months, two had PD at 12 and 17 months). Among patients treated for recurrent NB resistant to retrieval therapy, five of 10 had CR in BM. The 15 patients treated for PD fared poorly, although two had scintigraphic findings suggestive of a short-term response. Side effects were limited to readily manageable pain and, less commonly, rash of short duration; hence, patients were treated as outpatients.

CONCLUSION

3F8/GM-CSF is well tolerated and shows promise for treatment of minimal residual NB in BM.

Monoclonal antibody-based therapy of neuroblastoma

The curative potential of mAbs in the treatment of patients with metastatic neuroblastoma is increasingly evident. The idiotype network appears to represent one component of a complex mechanism for success with mAb-based immunotherapy. Ongoing strategies to modify or reconstruct mAbs, to engage them with cytokines, or to unite them with T cells open new avenues for harnessing the unique forces of the immune system against some of the most deadly pediatric cancers.