Methods for generation of genetically modified fibroblasts for immunotherapy of cancer

Considerable evidence has accumulated indicating that cultured human or rodent tumor cells can be successfully transduced with cytokine genes and selected in the appropriate antibiotic-containing culture media. The selected transductants are generally able to secrete the cytokine coded for by the transduced gene, and in many cases, substantial levels (e.g., ng quantities) of the cytokine are produced. Using retroviral vectors, it has been possible to obtain stably transduced tumor cells with a variety of cytokine genes (1-4). These tumor cells have been used for immunotherapy of cancer in numerous animal models of tumor growth or metastasis, and more recently, in vaccination protocols in patients with cancer. One possible criticism that can be leveled at this type of vaccination approach is that cultured, genetically modified, and selected tumor cells might have phenotypic characteristics that are substantially different from those of unmodified tumor cells. Since retroviral vectors are often used for transduction, it is also possible that viral antigens expressed on transduced tumor cells contribute to the immune response generated as a result of vaccination. Also, primary cultures of human tumor cells are often difficult to establish and maintain.