Immunotherapies with anti-GD2 antibodies (Abs) have improved survival of high-risk neuroblastoma (NB) patients (pts). In a closed single-center program, 53 pts received 5 cycles of 6 × 106 IU/m2 subcutaneous IL-2 (d1 – 5; 8 – 12) combined with long-term infusion (LTI) of 100 mg/m2 of the anti-GD2 Ab ch14.18/CHO (d8 – 18). Cytotoxic NK-, regulatory T cells (Tregs) and neutrophils were analyzed by flow cytometry. IFN-γ, IL-6, IL-10, IL-18 and CCL2 serum concentrations were measured using bead-based immunoassays. All data were correlated with PFS. IL-2 administration increased cytotoxic NK- and Treg cell counts in cycle 1 followed by further increase in subsequent cycles, whereas neutrophil levels were elevated only after the Ab infusion. Levels of IFN-γ, IL-6, IL-10, IL-18 and CCL2 were increased after the combined therapy. Importantly, pts with low Treg levels had significantly improved PFS compared to pts with high levels. Notably, Treg counts negatively correlated with INF-γ concentrations. In conclusion, LTI of ch14.18/CHO in combination with IL-2 resulted in Treg induction that negatively correlated with IFN-γ release and PFS.

Neuroblastoma (NB) is a challenging pediatric cancer with a 5-year survival rate below 50% in high-risk patients. Improvements were achieved with anti-GD2 therapies, but many patients still relapse. CD11b+ immune suppressive cells of myeloid lineage represent a promising target, as their immunosuppressive role in tumorigenesis was shown. Here, we analyzed myeloid-derived suppressor cells (MDSC) and the expression of MDSC-associated genes in a syngeneic NB mouse model. To show tumor promoting effects of CD11b+ cells and MDSC, these two cell populations were blocked by anti-CD11b monoclonal antibody administration or selectively depleted by low dose 5-Fluorouracil (5-FU) treatment, respectively. High numbers of CD11b+ leukocytes and a strong tumor-dependent induction of MDSC-associated genes could be shown by flow cytometry, immunohistochemical and RT-PCR analyses. MDSC depletion by both anti-CD11b and 5-FU treatment (superior effect) reduced the expression of MDSC-associated genes, delayed tumor growth and improved survival, suggesting a negative role of MDSC in NB. In conclusion, the depletion of immune suppressive myeloid cells resembles a promising treatment strategy against NB.

Introduction: We recently showed that MYCN-DNA minigene vaccination is an effective immunotherapeutic approach to treat MYCN-amplified neuroblastoma (NB) in vivo. To further enhance the therapeutic efficacy, we designed dual function DNA-vaccines driving the expression of MYCN antigens and interleukins (ILs) such as IL-2, IL-15 and IL-21 in one vector.

Introduction: Ganglidiomab is a murine IgG1 anti-idiotype antibody of anti-GD2 Ab ch14.18. We previously demonstrated an active GD2-specific humoral immune response against neuroblastoma (NB) after immunization of mice with ganglidiomab. To tailor this response to the murine variable regions in humans and to minimize nonspecific response against murine constant regions, we exchanged murine with human constant regions by Ab-engineering techniques.

Introduction: A current approach to consolidate remissions in the treatment of neuroblastoma (NB) consists of an anti-GD2-directed immunotherapy plus cytokines in combination with 13-cis retinoic acid. Fenretinide (4-HPR) is a synthetic derivative of retinoic acid and it is in clinical development for the treatment of high-risk NB patients. Since 4-HPR induces apoptosis mainly via the accumulation of ceramides, which are degraded to GD2, we evaluated its effect on anti-GD2-directed immunotherapies.

Purpose: GD2 is highly expressed in neuroblastoma (NB) and specifically recognized by monoclonal antibody ch14.18/CHO (Ab). Immunotherapy with bolus infusion of ch14.18 effectively prolonged survival. We piloted a treatment with continuous infusion of ch14.18 in combination with IL2 aiming at a reduction of toxicity and maintaining immune modulation.