1.0 
Objectives 
1. Evaluate the safety of subcutaneous immunizations with a mixture of irradiated autologous 
fibroblasts genetically modified to express the gene for IL-2 and irradiated autologous tumor cells. 
2. Examine the effects of these immunizations on tumor growth in vivo. 
3. Assess whether the immunizations induce cellular or humoral anti-tumor immune responses. 
2.0 Background/Rationale 
2.1 Interleukin-2 Cancer Immunotherapy in Human Subjects 
Recent advances in our understanding of the biology of the immune system have lead to the 
identification of important modulators of immune responses (1-3). These agents mediate many of the 
immune responses involved in anti-tumor immunity. Several of these cytokines have been produced 
by recombinant DNA methodology and evaluated for their anti-tumor effects. In experimental clinical 
trials, the administration of cytokines and related immunomodulators has resulted in objective tumor 
responses in patients with various types of neoplasms (4-7). 
Interleukin-2 (IL-2) is an important cytokine in the generation of anti-tumor immunity (4). In 
response to tumor antigens, a subset of lymphocytes termed helper T-cells secrete small quantities of 
IL-2. This IL-2 acts locally at the site of tumor antigen stimulation to activate cytotoxic T-cells and 
natural killer cells which mediate systemic tumor cell destruction. Intravenous, intralymphatic or 
intralesional administration of IL-2 has resulted in clinically significant responses in some cancer 
patients (4-6). However, severe toxicities (hypotension and edema) limit the dose and efficacy of 
intravenous and intralymphatic IL-2 administration (5,7). The toxicity of systemically administered 
cytokines is not surprising since these agents mediate local cellular interactions and they are normally 
secreted in only very small quantities. 
To circumvent the toxicity of systemic IL-2 administration, several investigators have examined 
intralesional injection of IL-2. This approach eliminates the toxicity associated with systemic IL-2 
administration (8,9). However, multiple intralesional injections are required to optimize therapeutic 
efficacy (8,9). These injections will be impractical for many patients, particularly when tumor sites 
are not accessible for direct injection without potential significant morbidity. 
The aim of this study is to demonstrate the safety of a novel and more practical method of IL-2 cancer 
immunotherapy. In this approach, a patient's tumor cells are genetically modified to express and 
secrete IL-2. The genetically modified cells are then employed in subcutaneous immunizations to 
induce systemic anti-tumor immunity. 
This approach provides the benefit of local IL-2 administration and obviates the need for multiple 
intralesional injections. The amount of IL-2 secreted by the genetically modified cells is sufficient to 
induce anti-tumor immunity but is too low to produce systemic toxicity. In addition, the continuous 
expression of functional amounts of IL-2 may also produce greater augmentation of anti-tumor 
immune responses compared to that obtained by intermittent cytolane injections. 
2.2 Cytokine Gene Therapy in Animal Tumor Models 
Cytokine gene transfer has resulted in significant anti-tumor immune responses in several animal 
tumor models (10-13). In these studies, the transfer of cytokine genes into tumor cells has reduced or 
abrogated the tumorigenicity of the cells after implantation into syngeneic hosts. The transfer of 
genes for IL-2 (10,11), gamma interferon (IFN) (12), or IL-4 (13) significantly reduced or 
eliminated the growth of several different histological types of murine tumors. In the studies 
Recombinant DNA Research, Volume 18 
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