Enhanced Antitumor Effect of Tirapazamine Delivered Intraperitoneally to VX2 Liver Tumor-Bearing Rabbits Subjected to Transarterial Hepatic Embolization

Abstract

We evaluated the effects of the combination of Tirapazamine (TPZ), activated preferentially under hypoxic conditions, and gelatin microspheres (GMS) on the tumor growth ratio in rabbits. We assigned 20 liver tumor-bearing Japanese white rabbits to 4 equal groups. Group 1 received 1 ml of saline intra-arterially (i.a.) and 20 ml of saline intraperitoneally (i.p.; saline group). Group 2 was injected with GMS i.a. and 20 ml saline i.p. (GMS group). Group 3 received 1 ml of saline i.a. and 300 mg/m(2) of TPZ i.p. (TPZ group), and group 4 was treated with GMS i.a. and 300 mg/m(2) of TPZ i.p. (GMS + TPZ group). The infusion of GMS was stopped when the blood flow stagnated. Before and 7 days after treatment, the liver tumor volumes were measured as the total number of pixels on 0.3Tesla (T) magnetic resonance imaging (MRI) scans. The tumor growth ratio (mean ± standard deviation) of the saline, GMS, TPZ, and GMS + TPZ groups was 519.15 ± 93.78, 279.24 ± 91.83, 369.78 ± 95.73, and 119.87 ± 17.62, respectively. The difference between the GMS + TPZ group and the other groups was statistically significant (P < 0.05). Our results show that the combination of TPZ i.p. and GMS i.a. enhanced the antitumor effect of TPZ. This procedure may represent a new alternative treatment for patients with hepatic cell carcinoma.