Additionally, they demonstrated the ABCG2 421A > C genotype as a significant covariate associated with lower oral clearance by generating a population pharmacokinetics model of sunitinib from 19 Japanese patients with RCC, in which the number of patients with ABCG2 421 CC, CA and AA genotypes were 10, 8, and 1, respectively. Here, ABCG2 is linked to renal cell carcinoma.