Characterization of antigen-presenting properties of tumour cells using virus-specific cytotoxic T lymphocytes

Targeting of MYCN by means of DNA vaccination is effective against neuroblastoma in mice

The MYCN oncogene is a strong genetic marker associated with poor prognosis in neuroblastoma (NB). Therefore, MYCN gene amplification and subsequent overexpression provide a possible target for new treatment approaches in NB. We first identified an inverse correlation of MYCN expression with CD45 mRNA in 101 NB tumor samples. KEGG mapping further revealed that MYCN expression was associated with immune-suppressive pathways characterized by a down-regulation of T cell activation and up-regulation of T cell inhibitory gene transcripts. We then aimed to investigate whether DNA vaccination against MYCN is effective to induce an antigen-specific and T cell-mediated immune response. For this purpose, we generated a MYCN-expressing syngeneic mouse model by MYCN gene transfer to NXS2 cells. MYCN-DNA vaccines were engineered based on the pCMV-F3Ub plasmid backbone to drive ubiquitinated full-length MYCN-cDNA and minigene expression. Vaccines were delivered orally with attenuated S. typhimurium strain SL7207 as a carrier. Immunization with both MYCN-DNA vaccines significantly reduced primary tumor growth of MYCN-expressing NB cells in contrast to negative controls. The immune response was mediated by tumor-infiltrating T cells in vivo, which revealed MYCN-specific and MHC class I-restricted lysis of inducible MYCN-expressing NB target cells in vitro. Finally, these antigen-specific T cells also killed MYCN-negative mammary carcinoma cells pulsed with MYCN peptides in contrast to controls. In summary, we demonstrate proof of concept that MYCN can be targeted by DNA vaccination, which may provide an approach to overcoming MYCN immune-suppressive activities in patients with MYCN-amplified disease.

[Cell therapy for cancer treatment in children]

The cure rate for cancer in children is currently almost 75%. This rate has remained fairly constant over the past few years, which suggests that the limits of today's curative treatment potential have been reached. The development of cell therapy techniques opens up new therapeutic possibilities in paediatric oncology. Here, we deal both with a number of cell therapy techniques, which have already proved their efficacy in children, and other more innovative approaches, which require validation. Examples of the use of autologous and allogeneic cells are described. Clinical studies and their results, while often preliminary, are reported. The importance of well run clinical research, a clear and progressive legal framework and the necessary substantial economic support for the development of cell therapy are underlined.

Complicated mechanisms of class II transactivator transcription deficiency in small cell lung cancer and neuroblastoma

Small cell lung cancer (SCLC) and neuroblastoma (NB), the most aggressive adult and infant neuroendocrine cancers, respectively, are immunologically characterized by a severe reduction in major histocompatibility complex (MHC) that is indispensable for anti-tumor immunity. We had reported that the severe reduction of MHC in SCLC was caused by a deficient interferon (IFN)-gamma-inducible expression of class II transactivator (CIITA) that is known as a very important transcription factor for IFN-gamma-inducible class II and class I MHC expression (Yazawa T, Kamma H, Fujiwara M, Matsui M, Horiguchi H, Satoh H, Fujimoto M, Yokohama K, Ogata T: Lack of class II transactivator causes severe deficiency of HLA-DR expression in small cell lung cancer. J Pathol 1999, 187:191-199). Here, we demonstrate that the reduction of MHC in NB was also caused by a deficient IFN-gamma-inducible expression of CIITA and that the deficiency in SCLC and NB was caused by similar mechanisms. Human achaete-scute complex homologue (HASH)-1, L-myc, and N-myc, which are specifically overexpressed in SCLC and NB, bound to the E-box in CIITA promoter IV and reduced the transcriptional activity. Anti-sense oligonucleotide experiments revealed that overexpressed L-myc and N-myc lie upstream in the regulatory pathway of HASH-1 expression. The expression of HASH-1 was also up-regulated by IFN-gamma. Our results suggest that SCLC and NB have complicated mechanisms of IFN-gamma-inducible CIITA transcription deficiency through the overexpressed HASH-1, L-myc, and N-myc. These complicated mechanisms may play an important role in the escape from anti-tumor immunity.

Nonmyeloablative transplantation in children. Current status and future prospects

Over the last few years a variety of conditioning regimens have been developed that allow allogeneic hematopoietic stem cell engraftment with significantly decreased transplant related-toxicity. While these reduced-intensity regimens have offered hope for patients with malignancies formerly not eligible for myeloablative transplantation due to excessive morbidity (older patients and patients with significant organ toxicity), the role of nonmyeloablative hematopoietic cell transplantation (NM-HCT) in children is unclear. A review of the available literature for pediatric and adult studies shows several malignancies in which approaches designed to limit long-term complications in children may be appropriate. In addition, NM-HCT may offer a safer approach for children with inherited disorders curable by marrow transplantation, such as immunodeficiencies, hemoglobinopathies, or storage diseases. Finally, use of this approach to establish partial donor chimerism may provide an immunologic platform that will allow specific cellular therapies, targeted gene therapy, or immunologic tolerance in solid organ transplantation.