Among patients with gastrointestinal stromal tumors treated with imatinib, the time to progression period significantly improves in carriers of the C allele of the variant of OCTN1 rs1050152 (L503F, c.1507C>T) as well as in carriers of the minor alleles of the variants of OCTN2 rs2631367 (c.-207C>G) and rs2631372 (c.-2087G>C), both localized in the promoter, suggesting that the activities of OCTN1 and OCTN2 may be predictors of efficacy to chemotherapy with imatinib [147]. This evidence concerns the gene SLC22A4 and gastrointestinal stromal tumor.