Injected Into monkeys (under P3 biocontainment conditions) is now underway (see 
bel ow) . 
(e) Has a protocol similar to the one proposed for a clinical 
trial been carried out in non-human primates and/or other 
animals? What were the results? Specifically, Is there 
any evidence that the retroviral vector has recombined 
with any endogenous or other viral sequences In the 
animal s? 
(f) Is there evidence from animal studies that vector DNA has 
entered untreated cells, particularly germ line cells? 
What Is the sensitivity of the analyses? 
No evidence to date. Now being investigated using the PCR (polymerase- 
catalyzed-reaction) technique which is sensitive to one gene copy per 10^-10^ 
cells. 
Investigation in both cynomolgus and rhesus monkeys have been ongoing for 
over two years. Our results are discussed above In Sections I.B.2.a and b as 
well as In Kantoff et al.. 1987 (copy provided in Appendix B). The effect of 
a large amount of replication-competent virus is currently being Investigated 
(see bel ow) . 
Review 
This section will address Issues concerned with the safety of gene 
transfer. The two main topics that will be discussed are the chance for 
persistent retroviral infection and the chance for malignant transformation of 
Infected cells. We will also discuss the rationale and Importance of a 
replication-defective helper-free system. The review by Howard Temin on safety 
considerations using retroviral vectors is attached in Appendix B. 
I) Vector Design 
A. Rationale for replication defective, helper virus free system 
The details of our vector design are covered in Section I.B.l.a of this 
document. The rationale for originally selecting Moloney MuLV was that its 
structure was fully known, it is not acutely transforming, and it has minimal 
Recombinant DNA Research, Volume 12 
