CD70 and renal carcinoma: In the biodistribution study performed in tumor bearing animals using the human renal cancer cell line 786-O, high levels of tumor uptake were measured with (122 ± 42) % of the injected dose per gram of the CD70-TTC retained in the tumor compared to only ∼ 3 % ID per gram for the isotype control-TTC, a 40 fold difference at day 7.