No abstract

Although tumor progression involves processes such as tissue invasion that can activate inflammatory responses, the immune system largely ignores or tolerates disseminated cancers. The mechanisms that block initiation of immune responses during cancer development are poorly understood. We report here that constitutive activation of Stat-3, a common oncogenic signaling pathway, suppresses tumor expression of proinflammatory mediators. Blocking Stat-3 in tumor cells increases expression of proinflammatory cytokines and chemokines that activate innate immunity and dendritic cells, leading to tumor-specific T-cell responses. In addition, constitutive Stat-3 activity induces production of pleiotropic factors that inhibit dendritic cell functional maturation. Tumor-derived factors inhibit dendritic cell maturation through Stat-3 activation in progenitor cells. Thus, inhibition of antitumor immunity involves a cascade of Stat-3 activation propagating from tumor to dendritic cells. We propose that tumor Stat-3 activity can mediate immune evasion by blocking both the production and sensing of inflammatory signals by multiple components of the immune system.

Purpose Gene-based immunotherapy for cancer is limited by the lack of safe, efficient, reproducible, and titratable delivery methods. Direct injection of DNA into tissue, although safer than viral vectors, suffers from low gene transfer efficiency. In vivo electroporation, in preclinical models, significantly enhances gene transfer efficiency while retaining the safety advantages of plasmid DNA. Patients and Methods A phase I dose escalation trial of plasmid interleukin (IL)-12 electroporation was carried out in patients with metastatic melanoma. Patients received electroporation on days 1, 5, and 8 during a single 39-day cycle, into metastatic melanoma lesions with six 100-μs pulses at a 1,300-V/cm electric field through a penetrating six-electrode array immediately after DNA injection. Pre- and post-treatment biopsies were obtained at defined time points for detailed histologic evaluation and determination of IL-12 protein levels. Results Twenty-four patients were treated at seven dose levels, with minimal systemic toxicity. Transient pain after electroporation was the major adverse effect. Post-treatment biopsies showed plasmid dose proportional increases in IL-12 protein levels as well as marked tumor necrosis and lymphocytic infiltrate. Two (10%) of 19 patients with nonelectroporated distant lesions and no other systemic therapy showed complete regression of all metastases, whereas eight additional patients (42%) showed disease stabilization or partial response. Conclusion This report describes the first human trial, to our knowledge, of gene transfer utilizing in vivo DNA electroporation. The results indicated this modality to be safe, effective, reproducible, and titratable.

ObjectiveThe aim of this study was to determine the order of melanoma nodal metastases. Summary Background DataMost solid tumors are thought to demonstrate a random nodal metastatic pattern. The incidence of skip nodal metastases precluded the use of sampling procedures of first station nodal basins to achieve adequate pathological staging. Malignant melanoma may be different from other malignancies in that the cutaneous lymphatic flow is better defined and can be mapped accurately. The concept of an orderly progression of nodal metastases is radically different than what is thought to occur in the natural history of metastases from most other solid malignancies. MethodsThe investigators performed preoperative and intraoperative mapping of the cutaneous lymphatics from the primary melanoma in an attempt to identify the 'sentinel" lymph node in the regional basin. All patients had primary melanomas with tumor thicknesses >0.76 mm and were considered candidates for elective lymph node dissection. The sentinel lymph node was defined as the first node in the basin from which the primary site drained. The sentinel lymph node was harvested and submitted separately to pathology, followed by a complete node dissection. The null hypothesis tested was whether nodal metastases from malignant melanoma occurred in equal proportions among sentinel and nonsentinel nodes. ResultsForty-two patients met the criteria of the protocol based on prognostic factors of their primary melanoma. Thirty-four patients had histologically negative sentinel nodes, with the rest of the nodes in the basin also being negative. Thus, there were no skip metastases documented. Eight patients had positive sentinel nodes, with seven of the eight having the sentinel node as the only site of disease. In these seven patients, the frequency of sentinel nodal metastases was 92%, whereas none of the higher nodes had documented metastatic disease. Nodal involvement was compared between the sentinel and nonsentinel nodal groups, based on the binomial distribution.Under the null hypothesis of equality in distribution of nodal metastases, the probability that all seven unpaired observations would demonstrate that involvement of the sentinel node is 0.008. 759

Effective treatment of cutaneous and subcutaneous malignant tumours by electrochemotherapy LM Mir', LF Glass23, G Sersa4, J Teissi65, C Domenge6, D Miklavdid7, MJ Jaroszeski38, S Orlowski9, DS Reintgen38, Z Rudolf4, M Belehradek6, R Gilbertl0, M-P Rols5, J Belehradek Jr', JM Bachaud", R DeConti23, B Stabuc4, M Cemazar4, P Coninx'2 and R Heller38 The application of electric pulses to the patients was safe and well tolerated. An instantaneous contraction of the underlying muscles was noticed. Minimal adverse side-effects were observed. ECT was shown to be an effective local treatment. ECT was effective regardless of the histological type of the tumour. Therefore, ECT offers an approach to the treatment of cutaneous and subcutaneous tumours in patients with minimal adverse side-effects and with a high response rate.

In vivo targeted gene transfer by non-viral vectors is subjected to anatomical constraints depending on the route of administration. Transfection efficiency and gene expression in vivo using non-viral vectors is also relatively low. We report that in vivo electropermeabilization of the liver tissue of rats in the presence of genes encoding luciferase or ~-galactosidase resulted in the strong expression of these genetic markers in rat liver cells. About 31)-40% of the rat liver cells electroporated expressed the ~galactosidase genetic marker 48 h after electroporation. The marker expression was also detected at least 21 days after transfection at about 5% of the level 48 h after electroporation. The results indicate that gene transfer by electroporatinn in vivo may avoid anatomical constraints and low transfection efficiency.

Electrochemotherapy is a local treatment of cancer employing electric pulses to improve transmembrane transfer of cytotoxic drugs. In this paper we discuss electrochemotherapy from the perspective of biomedical engineering and review the steps needed to move such a treatment from initial prototypes into clinical practice. In the paper also basic theory of electrochemotherapy and preclinical studies in vitro and in vivo are briefly reviewed. Following this we present a short review of recent clinical publications and discuss implementation of electrochemotherapy into standard of care for treatment of skin tumors, and use of electrochemotherapy for other targets such as head and neck cancer, deep-seated tumors in the liver and intestinal tract, and brain metastases. Electrodes used in these specific cases are presented with their typical voltage amplitudes used in electrochemotherapy. Finally, key points on what should be investigated in the future are presented and discussed.

No abstract