C. HESDORFFER 4/93 
TOXICITY : 
We are aware of recent experiments in which three of seven 
monkeys whose bone marrow was transduced with high-titer 
retrovirus developed lymphoma shown to be due to insertion of 
wild-type amphotropic virus components (109). This toxicity is 
most likely due to the presence of intact amphotropic retrovirus 
in the retroviral stocks used. Assays for intact non-defective 
retroviruses using naive 3T3 or HeLa cells should have detected 
the presence of these dangerous retroviruses. As indicated 
earlier, our amphotropic GP+envAM-12 packaging line has been used 
extensively to generate retrovirus with retroviral vectors 
containing many different genes, and no evidence for intact 
retrovirus has been obtained from these producer lines, as 
assessed by assay on naive 3T3 cells. The use of GP+envAM-12 has 
been approved by the RAC and the FDA for human use (85) . 
We have used several different assays to test for intact 
retroviruses in the supernatants of our MDR amphotropic producer 
cells (A12M1) to be used in the proposed protocol. A 3T3 
amplification assay with A12M1 supernatants has consistently been 
negative by reverse transcriptase. The supernatants of 
transduced human bone marrow cells is also negative. In 
addition, we are using the S+L assay and Mus dunni cells to assay 
for virus as well (110). To date, all our studies have been 
negative . 
5. THE PROTOCOL : 
A. Human Cancer Results : 
The goal of this protocol is to evaluate the transfer 
and expression of the MDR gene in the bone marrow cells of human 
subjects with advanced cancer. These studies require approval of 
the RAC and the FDA as well as our Institutional Review Board 
(IRB) . 
The first of these clinical protocols will involve the transfer 
of A12M1 supernatants into the bone marrow cells of patients with 
advanced cancer undergoing ABMT as part of protocols whose 
ultimate goal is to reverse the bone marrow toxicity of 
chemotherapy. ABMT accompanying high-dose anti-cancer 
chemotherapy is currently being used in these patients who have 
no bone marrow involvement at Columbia-Presbyterian Medical 
Center (CPMC) as well as elsewhere. After MDR transduction, some 
of these patients may be treated with MDR-responsive drugs, such 
as taxol (and adriamycin) . 
These cancer patients are selected because: 1) They often 
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Recombinant DNA Research, Volume 18 
