Gefitinib-d6 is intended for use as an internal standard for the quantification of gefitinib by GC- or LC-MS. Gefitinib is an EGFR inhibitor (IC50s = 0.023-0.079 μM). It inhibits colony formation of GEO colon, ZR-75-1 and MCF-10A breast, and OVCAR-3 ovarian cancer cell lines in soft agar assays (IC50s = 0.2-0.4 μM). Gefitinib (0.1 to 1 μM) induces apoptosis and inhibits EGFR autophosphorylation in the same cells. In vivo, gefitinib (1.25, 2.5, and 5 mg/kg) reduces tumor volume and increases survival in a GEO mouse xenograft model. Formulations containing gefitinib have been used in the treatment of non-small cell lung cancer (NSCLC).
