Table 1.

Effect of Increasing ²¹²Pb-Panitumumab F(ab′)₂ Doses (i.p) on the Weights of Athymic Mice Bearing i.p. LS174T Tumor Xenografts

		Days post RIT
RIT	Dose (μCi)	0	3	6	11	16	19	24	31	34
None	—	23.5 ± 1.2	23.7 ± 1.7	23.0 ± 1.5	23.8 ± 1.4	24.8 ± 0.6
Panitumumab F(ab′)2	10	23.1 ± 1.4	21.8 ± 1.1	20.8 ± 1.7	20.8 ± 2.2	22.0 ± 2.3	22.2 ± 2.6	22.4 ± 1.8	23.0 ± 1.9	22.9 ± 1.5
	20	22.1 ± 0.8	20.9 ± 1.1	20.1 ± 1.3	20.8 ± 1.8	20.8 ± 2.0	21.2 ± 2.0	21.1 ± 1.9	21.5 ± 1.4	21.7 ± 1.0
	30	22.3 ± 1.2	20.6 ± 1.2	19.8 ± 1.0	19.5 ± 1.6	20.8 ± 1.4	20.9 ± 1.8	20.7 ± 1.7	20.4 ± 1.6	20.5 ± 1.6
	40	23.8 ± 1.2	20.4 ± 1.0	19.4 ± 0.6	19.6 ± 0.7	21.1 ± 1.9	20.8 ± 1.8	20.4 ± 1.6	19.7 ± 1.9	21.3 ± 1.7
	50	23.0 ± 1.0	19.8 ± 1.1	17.4 ± 1.6	19.4 ± 0.9	20.1 ± 1.1	20.1 ± 1.3	20.6 ± 1.3	19.2 ± 0.8	20.6 ± 1.3
	60	22.4 ± 1.3	18.1 ± 1.4	15.6 ± 1.8
	80	22.6 ± 1.7	18.8 ± 1.6	16.5 ± 2.1	19.5 ± 1.1	19.9 ± 0.5	19.3 ± 0.2	20.1 ± 0.8	19.6	20.5
	100	22.8 ± 1.5	18.2 ± 2.2	15.6 ± 1.5

		Days post RIT
		0	2	5	10	15	18
HuM195 F(ab′)2	20	23.3 ± 1.1	21.6 ± 1.1	20.2 ± 1.1	20.4 ± 1.2	21.3 ± 1.3	21.0 ± 1.9
	40	23.1 ± 1.0	20.8 ± 0.8	19.4 ± 1.0	20.0 ± 1.1	20.0 ± 1.1
	60	23.3 ± 0.8	21.5 ± 1.1	20.0 ± 1.2	19.8 ± 1.0	21.5
	80	22.7 ± 1.0	19.9 ± 0.8	17.8 ± 1.1	17.8 ± 1.4

Athymic mice (n = 10) bearing 3 d i.p. LS-174T tumor xenografts were injected i.p. with 10–100 μCi ²¹²Pb-panitumumab F(ab′)₂ to establish the effective, suboptimal, therapeutic dose for subsequent studies with chemotherapeutics. Animal weights were monitored one to two times per week for 5 weeks as an indicator of toxicity. Additional groups included those that received no treatment and those that were injected with 20–80 μCi of the nonspecific control, ²¹²Pb-HuM195 F(ab′)₂. The values are the average weight (g) with the standard deviation.

i.p., intraperitoneal; RIT, radioimmunotherapy.