Recombinant DNA Advisory Committee - 09/14-15/92 
one. Investigators who submit a protocol to the FDA today are not aware of the newly 
developed standards. There will have to be a transition period that has not been 
established yet to deal with the clinical lots that are already in existence. The producer 
cell from these lots are no longer in existence and the supernatants are cryopreserved 
and ready for use. Investigators cannot retrospectively go back and obtain a sample of 
the cells since they are no longer available. 
Dr. Post asked what the requirements were under the old system of safety standards. Dr. 
Aebersold responded that S + /L' testing and amplification on NIH 3T3 cells were 
required for all supernatant preparations. Dr. Parkman asked if investigators will be 
required to keep an aliquot of the producer cells in long-term culture to verify the lack 
of helper virus contamination. Dr. Aebersold answered that there will be a requirement 
to culture the producer cells. 
Ms. Buc stated that it is inconceivable that the RAC is deliberating on an issue that was 
not an issue for approving a protocol this morning. There needs to be a sense of 
consistency. Dr. Parkman said the important issue is whether Dr. Schuening has a vector 
preparation already in storage that has been approved by the FDA. If they do not have 
a lot with FDA approval, then this discussion is irrelevant because the FDA will employ 
the revised requirements for subsequent lots. 
As a point of clarification, Dr. Krogstad explained the potential differences for concern 
between Drs. Walker and Blaeses' protocol and Dr. Schuening's protocol. The 
discussion about Drs. Walker and Blaeses' protocol was predicated on economics and the 
wasting of a substantial investment of a lot. The issues encompassing Dr. Schuening's 
protocols focus more on the safety aspect. If the RAC decides that there is a significant 
difference in the level of safety between these two protocols, safety should take 
precedence over economics. Dr. Parkman stated that economics was not a consideration 
with regard to his earlier comments. The relevant issue is the same testing criteria for 
both protocols. 
Presentation— Dr. Schuening 
The objective of the marking protocol is to determine whether peripheral blood 
progenitor cells contain pluripotent hematopoietic stem cells. Insights will also be 
obtained regarding the best method for mobilizing these peripheral blood stem cells in 
order to achieve optimal results. Data obtained from this study will indicate if 
peripheral blood contains long-term repopulating cells which would establish their 
potential use for autologous and allogeneic transplants or as long-term carriers of 
therapeutically relevant genes. 
Patients eligible for the gene marking protocol are those who are participating in the 
Recombinant DNA Research, Volume 16 
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