nodules of human malignant mesothelioma within the peritoneal cavities of SCID mice and the 
established mesothelioma nodules in the pleural space of rats. These results indicate that the 
H5.01 ORSV TK/GCV system is a promising novel therapeutic approach for the treatment of 
mesothelioma in patients. 
V.B.4. Safety Studies in Rodents 
We are currently concluding our preclinical toxicity trials in rodents. The trials were designed to 
mimic the proposed clinical trials. Groups of male and female rats (16 per group) were given virus 
intrapleurally followed by ganciclovir (10 mg/kg) x 14 days given intraperitoneally (see Table I 
below). This dose of GCV is the same as will be used in the clinical trial and induces tumor 
regression in preinfected rat mesothelioma cells implanted subcutaneously. Virus was given at 2 
doses, 1 x 10 10 and 2 x 10 10 pfu. When corrected for relative size (the human is 250-300 times 
larger than the rat), the higher dose used in the toxicity trials would translate to 6 x 10 12 pfu of 
virus. This dose is six times higher than the highest dose to be tested in the clinical trial. These 
doses are near the maximal that can be given due to technical limitations that include 1) the 
maximum concentration of viral particles that can be produced is 3 xIO 13 particles/ml= 6 x 10 11 
plaque-forming units/ml, 2) the fact that we must dilute the stock virus by at least 1:5 to avoid 
toxicity due to the 10% glycerol in the viral stock solution, and 3) the relatively small volume (i.e. 
0.25 ml) that can be injected into the rat thoracic cavity. Thus, the maximal possible dose of virus 
that is technically feasible would be: 6 x 10 11 pfu/ml diluted 1:5 (= 1.2 xIO 11 pfu/ml) x 0.25 
mis = 3 x 10 1 0 pfu. 
After instillation of virus and injection of GCV, blood samples were collected and necropsies 
performed according to the following schedule. All studies were carried out using Good Laboratory 
Practices (GLP) procedures. 
Table I 
Time 
Rx 
Rats Remainina 
Blood Tests 
Necropsy 
Day 0 
H5.010RSV77< 
1 6 
4 
Day 2 
GO/ 
1 6 
Day 4 
GCV (cont) 
1 6 
4 
4 
Day 8 
GCV (cont) 
1 6 
4 
Day 11 
GCV (cont) 
1 2 
4 
Day 16 
Stop GCV 
Day 18 
1 2 
4 
4 
Day 24 
8 
4 
Day 28 
4 
4 
4 
Day 60 
4 
4 
This study is now over and analysis of the blood and necrospy results are being completed. All the 
animals appeared healthy. There was only one death, and this was secondary to complications of 
cardiac puncture performed to obtain blood for study. 
There were no abnormalities seen in the blood tests which included determinations of hemoglobin, 
WBC’s, albumin, globulin, LDH, AST, ALT, GGT, Bili, Aik Phos., electrolytes, Cr, Calcium, 
phosphate, urate, glucose, amylase and lipase. A summary of these lab tests is included as Appendix 
D. 
Preliminary necropsy results showed no treatment-related lesions grossly. All histologic findings, 
including hepatic subcapsular hemorrhage, peribronchial/perivascular lymphoid infiltrates, and 
cardiac inflammation were considered spontaneous in nature in this strain of rat or were incidental 
Recombinant DNA Research, Volume 20 
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