Recombinant DNA Advisory Committee - 12/3-4/92 
Dr. Leventhal noted that the investigators propose to increase the dose of taxol 10-fold. 
Is this a procedure that is normally part of the standard clinical protocol, or is this 
increased dose unique to the gene transduction protocol? 
Ms. Meyers stated that the informed consent should be revised to include the following: 
(1) a statement that the patient is not pregnant or planning to become pregnant, (2) a 
statement that results of the study will be made known to the patient, and (3) a section 
describing how the media will be handled. 
Presentation-Dr. O'Shaughnessy 
Dr. O'Shaughnessy responded to Dr. Leventhal's questions regarding MDR-1 expression. 
Following transplantation, bone marrow sampling will be performed on days 14, 28, and 
42. If the MDR-1 gene is not expressed in the cells obtained at these time points then 
additional sampling will be performed at 3 month intervals. Patients receiving 
vinblastine or taxol due to relapse will receive sampling after cycles 1 and 3 to monitor 
augmentation in the number of MDR-1 expressing cells. In situ PCR will be performed 
to determine P-glycoprotein (Pgp) expression in ABM cells, and rhodamine efflux assays 
for the detection of antibody against Pgp. Cell cultures will be grown with and without 
the presence of taxol in order to determine any differential effect, and the resulting 
colonies will be assayed by PCR. 
Dr. O'Shaughnessy addressed the issue of tumor cell contamination in both bone marrow 
and peripheral blood cell populations. Initially, the patient's cells will be subjected to 
routine hematoxylin and eosin staining in addition to immunohistochemical staining with 
a panel of 4 antibodies. The specificity of the antibodies has been extensively 
documented by E. J. Shpall, et. al. Data demonstrates that CD34( + ) selection results in 
a 2-5 log reduction in the number of breast cancer cells. In the event of relapse, patients 
will receive biopsies at the sites of recurrence. It is unlikely that MDR-1 transduced 
breast cancer cells will contribute to relapse; however, if this result was observed, the 
quality and quantity of the patient's life should not be influenced. Due to prior drug 
treatments, the tumor cells tend to be MDR-1 positive and express Pgp. There is no 
evidence that insertion of the MDR-1 gene will make these breast cancer cells more 
biologically aggressive. In the worst case scenario, MDR-1 transduced cells could 
contribute to relapse and the patient may not respond to taxol or vinblastine. In this 
event, the patient would be treated with another chemotherapy agent to palliate 
symptoms. Since patient survival at the time of relapse is approximately 6 months, the 
objective is primarily to alleviate symptoms; prolongation of survival is not the critical 
issue. 
In response to Dr. Leventhal's question regarding the administration of taxol, Dr. 
O'Shaughnessy stated that the 10% increase in dosage is a standard procedure for the 
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Recombinant DNA Research, Volume 16 
