Recombinant DNA Advisory Committee - 3/3-4/94 
that suppression of tumor growth in a murine model will correlate with the human 
response. 
Dr. Motulsky stated that the RAC was previously concerned whether the constructs 
demonstrated biological activity and whether rearrangements in the vector structure are 
likely to occur during vector propagation. The Southern blot data submitted is 
uninterpretable. The principal investigator has adequately responded to previous 
concerns about the sensitivity of the assays for detecting the transforming potential of the 
proposed constructs. The data demonstrates that the assay system will provide adequate 
sensitivity. 
Dr. Motulsky recommended approval of this study based on biologic plausibility; 
however, other reviewers' concerns about vector rearrangements, etc., must be addressed 
before full RAC approval can be recommended. 
Review--Dr. Haselkom (presented by Dr. Motulsky) 
Dr. Motulsky summarized the written review submitted by Dr. Haselkom. Non-small 
cell lung carcinoma has a very poor prognosis. Molecular analysis has revealed that 
mutations in the p53 tumor suppressor gene and in the K-ras oncogene account for the 
majority of cases of this type of cancer. Therefore, therapy targeted to these genes 
seems justified. Patients will be eligible who have inoperable lung cancers, who are not 
responsive to radiation, and who demonstrate a high probability of dying from 
pneumonia caused by blockage of the lung by the tumor mass. Following surgical 
debulking of the tumor mass by bronchoscopy, the residual tumor will be injected with 
retroviral constructs that express either the wild-type p53 gene or an antisense RNA to 
prevent translation of the mutated K-roj oncogene. The previous review raised three 
major issues: (1) the ability to detect transforming vimses, (2) demonstration of 
adequate biological activity, and (3) demonstration of the "bystander" effect in in vitro 
cell mixing experiments. The "bystander" effect on tumor growth was observed in animal 
experiments. The first two concerns have been satisfactorily addressed by the 
investigator. The mechanism of the "bystander" effect remains unknown; however, 
absence of knowledge about the mechanism should not prevent the protocol from being 
approved. The investigators should explain why the p53 gene does not induce apoptosis 
in all cell lines. 
Review-Ms. Grossman 
Ms. Grossman raised several serious concerns regarding the vectors used in this protocol. 
How will quality assurance of the clinical grade retroviral constructs to be administered 
to patients be maintained? The Southern blot analysis of vector DNA which 
demonstrates the absence of vector rearrangement, is uninterpretable. The size of the 
DNA bands are inconsistent with the LNp55B construct. She asked the investigator to 
respond to Dr. Miller's written comments that the LNp55B construct has the propensity 
to undergo rearrangement in vector structure during viral propagation due to the 
bidirectional SV40 polyadenylation signal. 
Recombinant DNA Research, Volume 19 
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