Recombinant DNA Advisory Committee - 03/1-2/93 
regard to the vector titer, Dr. Bank stated that the titer is approximately 5 x 10 4 as 
assayed by colchicine resistance; however, this number may be an underestimate. 
Dr. Parkman noted that the eligibility criteria for patients who would receive Taxol 
treatment is not clearly stated in the informed consent document. Dr. Bank responded 
that he would clarify this section of the informed consent document. 
Dr. Leventhal noted that patients will have 3 x 10 8 ABM cells harvested; 1 x 10 8 of these 
cells will be transduced. What procedures will be followed if the proposed number of 
cells are not obtained in the original harvest? Dr. Hesdorffer answered that if 3 x 10 8 
ABM cells are not obtained then either a lower number of cells will be transduced or no 
cells at all. 
Dr. Bank presented additional data demonstrating an increase in gene expression 
following Taxol administration. PCR amplification showed that the signal changed from 
negative to positive after Taxol and a 10-fold increase in MDR expression was observed 
by FACS analysis 8 months post-transduction in the murine model. FACS analysis of 
human marrow demonstrated that MDR expression in untransduced early cells is 
negligible. However, 15-20% of the cells demonstrated a log increase in MDR 
expression following transduction and 5 days in culture. 
Dr. Bank introduced his co-investigator, Dr. Steve Goff, to respond to the committee's 
questions regarding the vector sequences. Dr. Goff explained that the additional 
sequences at the end of the vector are derived from the Harvey sarcoma virus genome 
which has part of VL30 and env before the LTR. None of this portion of the vector 
contains open reading frames. Dr. Post noted that during the review of Dr. 
O'Shaugnessy's protocol, there was some confusion about the frame shift at the end of 
the MDR cDNA. Can you assure the RAC that your vector does not contain the same 
frame shift? Dr. Bank stated that his vector does not contain a frame shift at the end of 
the MDR cDNA. 
Dr. Parkman stated that approval of this protocol should be deferred because it lacks 
necessary information. There are basic requirements that a protocol should meet prior 
to submission: (1) investigators should demonstrate the lack of replication competent 
virus with the proposed vector. The minimum standard for RCR testing is the S + L* 
assay. (2) transduction and expression should be demonstrated using the proposed 
vector and target cell. Transduction does not always have to be performed in an animal 
model; in vitro long-term cultures may also be acceptable. (3) the clinical protocol must 
include extensive detail regarding all proposed procedures and assays. This protocol 
does not meet any of the aforementioned criteria. 
Committee Motion 
[80] 
Recombinant DNA Research, Volume 17 
