the risks of insertional mutagenesis or recombination to yield replication competent wild- 
type virus is low. Limited studies in non-human primates and man have suggested that these 
estimated are correct unless helper virus is present. The amphotropic MFG-GC vector has 
been tested and is helper virus free. Before the initiation of clinical trials, both the 
viral producer line and viral supernatants of the R-GC vector will be certified and approved 
by the FDA for use in human trials. Our own studies in many mice continuing for over a 
year, and a limited number of studies in dogs, indicate that the MFG-GC vector is safe. 
N. 2 Leukopheresis and G-CSF Priming 
N.3 Partial Mveloabl ation With Cyclophosphamide 
There are risks associated with the use of cyclophosphamide (Cytoxan) to partially 
ablate the bone marrow. These include cytopenia, bleeding, infection, stomatitis, gastritis 
and alopecia (see earlier discussion). 
N.4 Risks Associated With G-CSF Priming and Leukopheresi s 
No major adverse effects have been reported in published studies employing successive 
leukopheresi s procedures. Serial leukopheresis may cause cytopenia, which may require 
postponement of the procedure for one or more days. Minor decreases in the hemoglobin may 
also occur. It is possible that patients with pre-existing anemia or thrombocytopenia may 
require the administration of red blood cells or platelets to restore adequate levels. 
Patients undergoing leukopheresis may experience symptoms of citrate toxicity, including 
parathesis, chills, abdominal discomfort, and nausea/ vomiting. Symptoms are routinely 
managed by making technical adjustments on the cell separator, and/or using calcium 
replacement (Ca gluconate) during the procedure. Severe reactions, which are rare, include 
tetany and seizure activity. Transient hypotension may also occur during the procedure. 
Side effects associated with G-CSF therapy include bone pain (believed to be due to 
marrow expansion) and transient elevation of uric acid, lactate dehydrogenase, and alkaline 
phosphatase. Occasional mild hypotension has been observed. There have been no reports 
of allergic reactions, anaphylaxis, or antibody formation. The frequency of other adverse 
reactions, such as fever, nausea/vomiting, skin rash, dyspnea, and diarrhea, was not 
significantly different from placebo administration in clinical trials. 
Possible risks associated with the use of central intravenous catheters, if used, 
include pneumothorax, bleeding, hypotension, air embolism, and bacterial infection, 
including sepsis. 
The potential complications of reinfusion of cryopreserved PSC are comparable to those 
of cryopreserved bone marrow. These risks include nausea, vomiting, dimethyl sulfoxide 
(DMSO) odor, hypertension, hypotension, cardiac arrythmia (brady-or tachycardia), volume 
overload, allergic reactions, and nephrotoxicity. 
Recombinant DNA Research, Volume 17 
[771] 
