Effect of carboplatin on therapeutic efficacy of 212Pb-trastuzumab. Athymic mice bearing i.p. LS-174T xenografts were injected i.p. with carboplatin 24 hours before the injection of 10 μCi (i.p.) 212Pb-labeled trastuzumab (▴). Another set of mice were injected with carboplatin, followed by 212Pb-HuIgG, a nonspecific control, 24 hours later (◯). Additional groups were untreated (●), carboplatin (◊), 213Bi-trastuzumab (▽), and 212Pb-HuIgG (■).