Figure 4. 
Mean Weight of Brain Tumors 
H Control 
ES3 1 0mg/Kg 
^1 20mg/Kg 
□ 30mg/Kg 
Study Groups 
I 
E. In Vivo Transduction with HS-tk Vectors in Mice and Rats: 
1. Anti-tumor Effect of In Situ Injection with an HS-tk Vector Producer Cell 
Line on the In Vivo Growth of the MCA 205 Tumor in Mice 
Initially, in order to determine if this in vivo gene transfer technique can 
promote an increased anti-tumor effect, we used the STK producer cell line. STK 
contains a NeoR gene promoted by the 5’-LTR and an SV40 promoted HS-tk gene. 
Figure 5 depicts the effect of GCV on tumor growth in vivo in mice that were injected 
with 2x1 0 6 MCA 205 tumor cells alone (group 1 ), 1x1 0 6 MCA 205 tumor cells plus 
IxlO 6 control non-producer HS-tk transduced 3T3 cells (3T3/STK; group 2) or 1x10 s 
MCA 205 tumor cells plus 1 xl 0® PA31 7 HS-tk vector producer cells (PA31 7/STK; 
group 3). The mice were ear tagged, cages coded and the tumors were measured 
twice weekly with a calipers in 3 dimensions. Tumor size is expressed as a volume 
(length x width x height). GCV treatment was initiated 4 days after injection of the cells 
and continued twice daily for 12 doses of 150mg/kg/dose. 
Recombinant DNA Research, Volume 15 
[795] 
