Lapatinib (GW572016) is an inhibitor of ErbB2 and EGFR (IC50=9.2/10.8 nM) with oral activity. Lapatinib has antitumor activity and can be used to treat advanced or metastatic breast cancer with HER2 overexpression.

ErbB2:9.2 nM (cell free), EGFR:10.8 nM (cell free)

方法：14 株人胃癌和食管癌细胞系用 Lapatinib (0.3125-10 µmol/L) 处理 6 天，使用 particle counter 检测细胞数。
结果：N87、OE19、NUGC4、NUGC3、FU97、SNU16 细胞对 Lapatinib 敏感，IC50 分别为 0.01、0.09、0.35、2.24、4.86、8.58 μmol/L。[1]
方法：人乳腺癌细胞 MDA-MB-231 和 SK-BR-3 用 Lapatinib (0.5-2 µM) 处理 48 h，使用 Western Blot 方法检测靶点蛋白表达水平。
结果：与较低浓度相比，用 1.0 μM Lapatinib 处理的 MDA-MB-231 和 SK-BR-3 细胞系中 PKM2 的表达均显著降低。[2]

方法：为检测体内抗肿瘤活性，将 Lapatinib (100 mg/kg) 腹腔注射给携带人胃癌肿瘤 N87 的 CD-1 athymic nude 小鼠，每天一次，持续三周。
结果：Lapatinib 导致 N87 异种移植物的肿瘤消退。[1]
方法：为检测体内抗肿瘤活性，将 Lapatinib (30-100 mg/kg，灌胃给药，每天两次持续二十一天) 和 Topoteca (6-10 mg/kg，腹腔注射，每四天一次持续三次) 灌胃给药给携带人乳腺癌肿瘤 BT474 的 SCID 小鼠。
结果：Lapatinib 和 Topoteca 组合在 ER2+BT474 异种移植物中显示出增强的功效。[3]

The IC50 values for inhibition of enzyme activity are generated by measuring the inhibition of phosphorylation of a peptide substrate. The intracellular kinase domains of EGFR and ErbB2 are purified from a baculovirus expression system. EGFR and ErbB2 reactions are performed in 96-well polystyrene round-bottomed plates in a final volume of 45 μL. Reaction mixtures contain 50 mM 4-morpholinepropanesulfonic acid (pH 7.5), 2 mM MnCl2, 10 μM ATP, 1 μCi of [γ33P] ATP/reaction, 50 μM Peptide A [Biotin-(amino hexonoic acid)-EEEEYFELVAKKK-CONH2], 1 mM dithiothreitol, and 1 μL of DMSO containing serial dilutions of Lapatinib beginning at 10 μM. The reaction is initiated by adding the indicated purified type-1 receptor intracellular domain. The amount of enzyme added is 1 pmol/reaction (20 nM). Reactions are terminated after 10 minutes at 23°C by adding 45 μL of 0.5% phosphoric acid in water. The terminated reaction mix (75 μL) is transferred to phosphocellulose filter plates. The plates are filtered and washed three times with 200 μL of 0.5% phosphoric acid. Scintillation cocktail (50 μL) is added to each well, and the assay is quantified by counting in a Packard Topcount. IC50 values are generated from 10-point dose-response curves [1].

Cells are plated in 96-well plates, in the media, at the following densities: HFF and HN5, 1000 cells/well and BT474, 5000 cells/well. After 24 h, the cells are exposed to vehicle (0.3% DMSO) or Lapatinib (1 nM, 10 nM, 100 nM, 1μM, 10μM, and 100μM). Lapatinib is removed from the cells after 72 h and is replaced by either DMEM containing 10% FBS and 50 μg/mL Gentamicin (HFF and HN5) or RPMI containing 10% FBS and 50 μg/mL Gentamicin (BT474). Methylene blue staining is performed at the time points over a total period of 16 days. Relative cell number is estimated using methylene blue staining. The absorbance at 620 nm is read in a Spectra microplate reader. Cell death and cell cycle analysis are assessed by propidium iodide staining and antibody detection of incorporated BrdUrd and staining with propidium iodide [1].

CD-1 nude female mice are used for HN5 human tumor xenografts, which are initiated by injection of a cell suspension in PBS: Matrigel (1:1). C.B-17 SCID female mice are used for BT474 human tumor xenografts, which are initiated by implantation of tumor fragments (20-100 mg) from established tumors. Tumor cells and fragments are implanted by s.c. injection in the right flank. The s.c. tumors are measured with calipers, and mice are weighed twice weekly. Tumor weight is estimated from tumor volume using this formula: length×width2/2=tumor volume (mm3). Treatment begins when tumors are palpable, 3-5 mm in diameter. Lapatinib (30 and 100 mg/kg) is administered p.o. twice daily for 21 days in a vehicle of sulfo-butyl-ether-β-cyclodextrin 10% aqueous solution (CD10) [1].