Figure 5. 
In-Vivo Anti-Tumor Effect of the STK Vector 
Transduced-3T3 Cells Mixed with 205 Tumor 
Tumors in groups 1 and 2 grew well regardless of GCV treatment. 
However, in group 3, if the mice were treated with GCV there was complete tumor 
elimination. Non-GCV treated tumor cells grew unabated as tumors in groups 1 and 2. 
The major difference between groups 2 and 3 is the production of vector since the in 
vitro sensitivity of 3T3/STK and the PA317/STK Producer to GCV is not significantly 
different. In no experiment did GCV alone demonstrate any significant anti-tumor effect 
on non-HS-tk-transduced tumors. Injection of the LNL6 producer cells result in 
transient growth and then elimination by day 15 in 5/5 mice. Therefore, these findings 
suggest that the transfer of a herpes TK gene into tumor in vivo can result in more 
efficient eradication of MCA 205 tumor than HS-tk-transduced non-producer cells. 
[796] 
Recombinant DNA Research, Volume 15 
