need to explore additional options with the goal of infecting 
murine TIL cells with retrovirus vectors. Dr. Mulligan echoed 
Dr. Erickson’s desire to see the PCR data in order to assess 
their sensitivity. Looking at page 3, section b, of the Anderson 
material, he commented that N2 infection of bone marrow 
transplants was not analogous to infection of TIL cells as an 
assay for tumorigenicity of the retrovirus vector. 
Dr. Mulligan expressed some general reservations about data 
presented in Tables 2, 3, and 4 showing that marked TIL cells do 
not differ from unmarked cell populations. In particular, he 
felt that it might be useful to examine T cell receptor beta 
chain gene rearrangement patterns in patients 2, 3, and 4, which 
were not studied. Further, he was interested in knowing the 
specific region where rearrangements had occurred. Finally, 
Dr. Mulligan questioned the sensitivity of the assay for helper 
virus as no data had been provided. 
Dr. Neiman reiterated concerns expressed by Dr. Kelley at the 
earlier subcommittee meeting that a satisfactory animal model for 
TIL infection had not yet been demonstrated. The alternative 
model--examining survival, marker gene expression, and retrieval 
of soluble antigen-activated murine CD 4 T lymphocytes — satisfied 
some of the safety issues, but not the scientific issues, in 
Dr. Neiman’ s opinion. He did not feel that the original 
questions had been resolved in this material. For example, the 
presence of helper virus in culture supernate could not be 
totally discounted with the tests described. Other assays for 
viral replication were not definitive. He also remarked that the 
’’dry run” testing in human cells requested by the subcommittee 
had not been supplied. 
Commenting on information depicted in Table 4, Dr. Neiman pointed 
to insertion bands on a Southern blot analysis as possible 
indicators of clonal selection following marking procedures. If 
there had been selection for specific cell populations, one could 
not rule out the possibility that the therapeutic TIL cells may 
have been eliminated. However, the information provided does not 
compare TIL killing capability in vitro vs. in vivo following 
selection of cells. 
Dr. Mclvor echoed previous requests to see the PCR data as well 
as assays for detecting the replication of virus. He also 
wondered about the comparative ease of retrieval of TIL cells 
from tumor vs. blood, spleen, and bone marrow, where the 
procedure appears to be straightforward. He remarked that it was 
unfortunate that murine TIL could not be infected with the 
retrovirus vector. 
Dr. Parkman noted that it is not possible to look for 
tumorigenesis in T cells in nude mice and suggested that another 
model might be more revealing. He commented on the utility of 
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Recombinant DNA Research, Volume 13 
