Recombinant DMA Advisory Committee - 6/9-10/94 
GENE TRANSFER PROTOCOL ENTITLED: IL-12 GENE THERAPY USING DIRECT 
INJECTION OF TUMOR WITH GENETICALLY ENGINEERED AUTOLOGOUS 
FIBROBLASTS /DR. LOTZE 
Review— Dr. Miller 
Dr. Walters called on Dr. Miller to present his primary review of the protocol submitted 
by Dr. Michael Lotze of the University of Pittsburgh, Pittsburgh, Pennsylvania. Dr. 
Miller noted that the investigator did not meet the deadline for submission of data; 
therefore, the review process has been impeded. At the time of submission, the entire 
vector sequence was not included, the vector was misnamed, preclinical data on IL-12 
production by transduced cells was submitted late, and the Southern blot data was 
incomplete. Discussion ensued regarding the appropriateness of reviewing this protocol 
given the timely delay in submission of relevant data. A decision was made to review 
the protocol despite these delays. The RAC members noted their dissatisfaction with the 
manner in which the investigator handled the submission. 
Subjects will receive intratumoral injections of irradiated autologous fibroblasts that have 
been transduced with the gene for IL-12. The investigator hypothesized that local 
production of IL-12 may promote tumor destruction. The RAC has previously 
recommended approval of studies involving other cytokine genes with this strategy. Dr. 
Miller raised several issues: (1) Is the retroviral vector construct, TFG-IU12-neo, stable 
and suitable for use in humans? Since IL-12 has 2 subunits, the proposed vector 
expresses both subunits and neo^ which will be used as a selectable marker. Expression 
of these 3 genes is accomplished using 2 identical ribosome entry sites (IRES) that allow 
translation of all 3 gene products from a single mRNA species. The feasibility of this 
approach should be documented, i.e., adequate levels of IU12 production and lack of 
rearrangement during transduction. Southern blot analysis of vector DNA firom 
transduced cells should be provided to demonstrate the lack of rearrangement. (2) Why 
did the investigators propose a different vector for the human study than was used for 
the preclinical experiments. (3) What is the rationale for initiating the IL-12 trial when 
the results of the IL-4 trial have not been submitted? (4) The animal data indicates that 
only intermediate doses of IL-12 are effective in tumor reduction, high doses of 11^12 
have little antitumor effect. Does the IL-12 dose have to be carefully titrated in humans 
to obtain a response? (5) IU12 toxicity studies have not been submitted for human 
subjects or large primates; therefore, can possible adverse effects to humans be predicted 
for the proposed doses of 11^12? 
Review— Dr. Parkman 
Dr. Parkman stated that there are 3 critical issues that should be addressed for any 
protocol: (1) the vector, (2) the preclinical data, and (3) the toxicity data. 
In regard to preclinical studies, data was submitted only for a preimmunization animal 
model. Animals were preimmunized with IL-12 transduced cells. Data was not 
submitted from a preexisting tumor model until yesterday. These data demonstrated EL 
Recombinant DNA Research, Volume 19 
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