No abstract

Transfection with RNA is an attractive method of Ag delivery to dendritic cells (DCs), but has not yet been standardized. We describe in this study the methods to efficiently generate an optimized mature monocyte-derived DC vaccine at clinical scale based on the electroporation of several RNAs either into immature DC followed by maturation or, alternatively, directly into mature DCs, which has not been possible so far with such high efficiency. Electroporation of DCs resulted in high yield, high transfection efficiency (>90%), and high migration capacity. Intracellular staining allowed the study of the expression kinetics of Ags encoded by the transfected RNAs (MelanA, MAGE-3, and survivin) and a validation of the vaccine (≥90% transfection efficiency). Expression of all three Ags peaked 3–4 h after electroporation in DC transfected either before or after maturation, but decreased differently. The DC vaccine can also be cryopreserved and nevertheless retains its viability, stimulatory capacity as well as migratory activity. In addition, we uncover that DC transfected after rather than before maturation appear to be preferable vaccines not only from a production point of view but also because they appear to be immunologically superior for CTL induction in sharp contrast to common belief. DCs transfected after maturation not only more effectively generate and present the Mage-3.A1 and MelanA.A2.1 epitopes to T cell clones, but they even are superior in priming to the standard proteasome-dependent MelanA.A2.1 wild-type prototype tumor epitope, both in terms of T cell expansion and effector function on a per cell basis.

Dendritic cell (DC)-based immunotherapy has been shown to be a promising strategy for anti-cancer therapy. Nevertheless, only a low overall clinical response rate has been observed in vaccinated patients with advanced cancer and therefore methods to improve DC immuno-stimulatory functions are currently under intense investigation. In this respect, we exposed human monocyte-derived DCs to a physiological temperature stress of 40°C for up to 24 h followed by analysis for (i) expression of different heat shock proteins, (ii) survival, (iii) cell surface maturation markers, (iv) cytokine secretion, and (v) migratory capacity. Furthermore, we examined the ability of heat-shocked DCs to prime naïve CD8(+) T cells after loading with MelanA peptide, by transfection with MelanA RNA, or by transduction with MelanA by an adenovirus vector. The results clearly indicate that in comparison to control DCs, which remained at 37°C, heat-treated cells revealed no differences concerning the survival rate or their migratory capacity. However, DCs exposed to thermal stress showed a time-dependent enhanced expression of the immune-chaperone heat shock protein 70A and both an up-regulation of co-stimulatory molecules such as CD80, CD83, and CD86 and of the inflammatory cytokine TNF-α. Moreover, these cells had a markedly improved capacity to prime autologous naïve CD8(+) T cells in vitro in an antigen-specific manner, independent of the method of antigen-loading. Thus, our strategy of heat treatment of DCs offers a promising means to improve DC functions during immune activation which, as a physical method, facilitates straight-forward applications in clinical DC vaccination protocols.

Polymorphisms in Fc-gamma-receptor (FCGR) genes as well as killer cell immunoglobulin-like receptor (KIR) and KIR ligand (KIRL) repertoires may influence antitumor effects of monoclonal antibodies (mAb). Here, we systematically analyzed high-and low-affinity FCGR2A and -3A genotypes as well as stimulating and inhibitory KIR/KIRL combinations in 53 neuroblastoma (NB) patients treated by long-term infusion (LTI) of anti-GD 2 IgG1 Ab ch14.18/CHO using validated real-time PCR methods.Patients with high-affinity FCGR2A and -3A genotypes showed a higher level of Ab-dependent cellmediated cytotoxicity (ADCC) on day 8 after the start of ch14.18/CHO and superior event-free survival (EFS) compared to patients with low FCGR genotypes. Similar observations were made for patients with stimulatory KIR/KIRL haplotype B (combination of KIR genes including activating receptor genes) compared to inhibitory haplotype A (a fixed set of genes encoding for inhibitory receptors, except 2DS4) and stronger effects were found in patients when haplotype B and high-affinity FCGRs were combined. Surprisingly, independent analysis of KIRs showed a major role of activating KIR 2DS2 for high ADCC levels and prolongation of EFS. The greatest effect was observed in 2DS2-positive patients that also had highaffinity FCGR2A and -3A genotypes.In summary, the presence of the activating KIR 2DS2 has a major effect on ADCC levels and survival in NB patients treated by LTI of ch14.18/CHO and may therefore be a useful biomarker in combination with FCGR polymorphisms for Ab-based immunotherapies.

The purpose of this randomized trial was to evaluate the efficacy of combination chemoimmunotherapy compared with chemotherapy alone. A total of 124 patients were randomized to receive intravenous cisplatin (35 mg m 72 , days 1 -3), carmustine (150 mg m 72 , day 1, cycles 1 and 3 only), dacarbacine (220 mg m 72 , days 1 -3) and oral tamoxifen (20 mg m 72 , daily) in combination with (n=64) or without (n=60) sequential subcutaneous IL-2 and IFN-a. In those patients who received sequential immunotherapy, each cycle of chemotherapy was followed by outpatient s.c. IL-2 (10610 6 IU m 72 , days 3 -5, week 4; 5610 6 IU m 72 , days 1, 3, 5, week 5) and s.c. IFN-a (5610 6 IU m 72 , day 1, week 4; days 1, 3, 5, week 5). The overall response rate of patients treated with the combination of chemotherapy and IL-2/IFN-a was 34.3% with seven complete responses (10.9%) and 15 partial responses (23.4%). In patients treated with chemotherapy, only, the overall response rate was 29.9% with eight complete responses (13.3%) and 10 partial responses (16.6%). There was no significant difference in median progression free survival (0 months vs 4 months) and in median overall survival (12 months vs 13 months) for combined chemoimmunotherapy and for chemotherapy, respectively.