Table 1.

Summary of the Effects of i.t. Injection on the Biodistribution and Therapeutic Potential of HPMA Copolymer-Based Drug Delivery Systems: Evaluation of the Tumor-to-Organ Ratios of Intravenously and Intratumorally Applied HPMA Copolymers.

	31-kDa poly(HPMA)		65-kDa poly(HPMA)		28-kDa poly(HPMA)-GFLG-Doxorubicin
	i.v.	i.t.	i.v.	i.t.	i.v.	i.t.
Tumor	1	1	1	1	1	1
Spleen	0.7	3.8	0.5	10.6	0.2	1.9
Lungs	1.0	5.5	0.8	13.8	1.2	8.5
Liver	2.0	9.4	1.1	18.0	1.3	8.1
Kidneys	1.6	6.3	1.3	18.1	0.1	0.5
Heart	3.2	14.1	1.5	24.6	3.2	15.6
Testes	2.8	13.7	1.7	32.0	2.8	14.8
Skin	5.0	19.7	3.5	49.0	1.6	9.4
Ileum	3.5	13.6	3.3	40.3	2.5	19.3
Muscle	12.0	36.6	6.2	120.7	7.6	45.7

Tumor-to-organ ratios were calculated 24 hours after i.v. and i.t. injection. Hereto, the tumor concentrations of 31-kDa poly(HPMA), 65-kDa poly(HPMA), and 28-kDa poly(HPMA)-GFLG-doxorubicin at 24 hours p.i. were divided by the respective organ concentrations at 24 hours p.i. A tumor-to-organ ratio of >1 indicates a preferred localization to tumor tissues; a ratio of <1 indicates a more selective localization to the corresponding healthy tissues. The tumor-to-organ ratios allow for a more direct evaluation of the impact of i.t. injection on the biodistribution of the copolymers.