The generation of replication competent virus poses a theoretical risk. However, 
the viral supernatents will have been analyzed for this prior to use, and the presence of 
helper virus will be assayed after infection of the synovial cells and prior to transfer. 
So far as we know, this is the first proposal to conduct a clinical trial for the 
development of a gene therapy for a chronic non-lethal disease. This means that very 
strict safety measures have to be built into the study. We have done this in the following 
ways: 
1. Joints receiving the genetically altered cells will be surgically removed one 
week after introduction of the cells. Our rabbit studies (see next section) have 
failed to detect the escape of transplanted cells from the joint into which they 
were injected for as long as six weeks . Furthermore, no changes in 
haemotopoietic parameters or blood chemistries occur during this time. 
2. IRAP occurs naturally in human synovial fluids and elsewhere in the body. 
3. Extensive toxicological testing of IRAP protein in animals, as well as 
pharmacologic and clinical testing in humans, has failed to reveal any evidence of 
adverse reactions. 
4. We will incorporate a "suicide" gene, thymidine kinase, into the vector to 
render transduced cells sensitive to ganciclovir. 
Patient discomfort has also been minimized. Those eligible for the trial will have 
polyarticular disease requiring staged replacement of other joints, such as the wrist, prior 
to MCP replacement. Synovial tissue will be recovered at the time of these prior 
surgeries. Synoviocytes will be cultured, transduced and tested while the patient is 
recovering from the initial joint replacement surgery and preparing for MCP 
replacement. Testing of cells for replicaiton competent virus, and adventitious agents 
will be conducted by Microbilogical Associates. 
One week prior to scheduled MCP surgery, MCP joints will be lavaged and the 
cells injected. This is the only extra procedure that patients will undergo . It is relatively 
minor. MCP replacement surgery then proceeds as planned, with analysis of the 
retrieved tissue proceeding as described elsewhere in this protocol. 
F. PRE-CLINICAL STUDIES 
(i) Vector Construction 
MFG Vector: The MFG vector is derived from MoMLV and has been described 
previously. The nucleotide numbers given for retriction sites in MoMLV are based on a 
numbering system where nucleotide 1 is the first base in the R region of the 5' LTR and 
thus the first base in the transcribed RNA. The MFG vector contains gag sequences up 
Recombinant DNA Research, Volume 19 
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