Recombinant DNA Advisory Committee - 09/14-15/92 
precautions outlined in the protocol are more than adequate. In fact, the detailed 
precautions are greater than those taken for other infectious diseases such as tuberculosis 
or HIV. Normal tissue, germ cells, peripheral blood lymphocytes, and bronchial mucosa 
will be assayed for neo R . 
Patients requiring an additional biopsy beyond the one that is routinely required prior to 
the protocol will provide informed consent prior to entering the protocol and prior to 
having the additional biopsies performed. Between 80 and 90% of eligible patients will 
have had previous biopsies that will be evaluable for determining whether the mutations 
exist. Mr. Capron asked how many biopsy specimens would probably have to be 
screened before identifying 14 eligible patients. Dr. Roth explained that the prevalence 
of p53 mutations in NCSLC is between 50 and 70%. The prevalence of K-ras mutations 
is approximately 20%. Since the two mutations do not necessarily occur together, it is 
estimated that 7 of every 10 patients screened would possess both mutations. 
Dr. Leventhal asked what experiments would be performed on any recurrent tumor 
tissue. Dr. Roth explained that patients will be bronchoscoped at frequent levels so the 
tumor can be biopsied at the time of recurrence. The tissues will be examined for 
retroviral integration by semiquantitative PCR analysis in addition to gene expression. 
Dr. Leventhal suggested that the investigators should screen for new mutations, such as 
p52 in addition to the original mutations. 
Dr. Geiduschek stated that the data presented with regard to the bystander effect did not 
address the critical issue. The key experiment that would confirm this effect would 
determine that the genotype is transferred while the growth curve is not affected. Cells 
were never removed between day seven and nine to analyze the genotype distribution. 
Dr. Roth explained that as a result of Dr. Hirano's initial review, these experiments were 
initiated. Data suggests that when a population of cells is mixed and then selected for 
neo R , 46% of the cells still express neo. Therefore, the ratio of the two cell types after 
nine days would be the same as it was at the beginning of the experiment. 
Dr. Geiduschek inquired if the in vivo experiments in which mice were preinnoculated 
with tumor three days prior to treatment accurately reflects the human situation. Some 
of these NSCLC patients have had established tumors for a long period of time. Dr. 
Roth explained that there is always the difficulty of extrapolating animal models to the 
human situations. This particular murine model was designed because is most closely 
resembles the clinical manifestation observed in humans. The life span of mice is too 
short to approximate the human condition. However, the tumor cells injected into the 
mice are rapidly growing human NSCLC cells. 
Dr. H. Miller stated that one might argue that at the time of bronchoscopy, a physician 
has an obligation to resect as much tumor as possible. However, if it is entirely resected, 
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