No abstract

The objective of this study was to determine the safety and antitumor activity of an autologous GM-CSF-secreting melanoma cell vaccine that was engineered ex vivo with recombinant replication-incompetent adenovirus harboring a human GM-CSF gene (Adv/hGM-CSF). Melanoma samples were surgically obtained from 30 patients (15 female and 15 male, ages ranging from 23 to 87) and were processed for vaccine preparation. Due to stringent eligibility criteria, 9 out of 30 patients were enrolled in the phase 1 clinical trial (FDA IND7677). Melanoma cell lines established from surgical specimens of 9 patients were transduced with Adv/hGM-CSF (MOI of 100) and subsequently irradiated at 35 Gy. These cell lines secreted human GM-CSF in vitro at an average rate of 80-424 ng/10(6) cells/24 h. All patients were intradermally and subcutaneously injected at several sites with irradiated autologous melanoma cells (2x10(6)-1x10(7) in 300 microl saline), 2-10 times, at intervals of 4-8 weeks. None of the patients vaccinated showed any serious adverse systemic response. Three patients (nos.1, 6 and 7) demonstrated local reaction (erythema) to the vaccination. Tumor-specific CTL assays performed in the absence of K562 cells showed that the levels of CTLs in peripheral blood of 5 patients increased following vaccination, whereas those in one patient declined. Levels of CTLs assayed in the presence of K562 cells were considerably lower than those assayed in the absence of K562 cells, but were also found to increase following vaccination in the peripheral blood of 6 patients. A patient who had been vaccinated 10 times (patient 1) responded to the vaccination by apparent reduction in size of metastatic tumor in the lung. Immunohistochemical examination of the vaccination sites of patient 1, biopsied after the 3rd and 4th vaccination. showed that the vaccination sites responded with infiltration of inflammatory cells, such as T cells (CD3+, CD8+), macrophages and dendritic cells (CD83+), for a period up to about 8 days. These data suggest that repeated vaccinations with irradiated autologous GM-CSF-producing tumor cells were well tolerated by patients and led to the activation of an antitumor immune response in some patients.

No abstract

The specific aim of this study was to examine the prophylactic as well as the therapeutic efficacies of irradiated mouse CT26 colon cancer cells, infected with recombinant adenoviruses harboring cDNAs specific for granulocyte macrophage-colony-stimulating factor (GM-CSF), interferon (IFN-gamma) and monocyte chemotactic protein1 (MCP-1). Results showed that tumor cells secrete the respective cytokines for several days after infection and subsequent irradiation. Vaccination with irradiated GM-CSF-secreting CT26 cells protected 90% of syngeneic mice challenged with live parental cells. On the other hand, vaccination with irradiated IFNgamma or MCP-1-secreting CT26 cells totally failed to protect mice from tumor development after challenge with parental cells. None of the tumor-free mice initially vaccinated with irradiated GM-CSF-producing CT26 cells developed tumor upon repeated challenge with parental cells during the entire observation period. The establishment of specific and long-lasting antitumor immunity following vaccination with GM-CSF-producing tumor cells requires the simultaneous presence of GM-CSF and tumor antigen at the vaccine site. Depletion of CD8+ cells, but not CD4+ cells, blocked the vaccine efficacy of GM-CSF-producing tumor cells. Subcutaneous injection of irradiated GM-CSF-producing CT26 cells also effectively prevented the growth of a small load of parental tumor that was implanted 3 days earlier or the development of metastatic foci in the lung from intravenously injected parental cells either 7 days before or 3 days after vaccination. Our data thus show that, in these experimental tumor models, subcutaneous injection of irradiated tumor cells adenovirally, transduced with the GM-CSF gene leads not only to prevention of growth of subsequently implanted tumor but also to elimination of pre-existing and metastatic tumors.