Wang Xingwen, Wu Yunyan, Song Xueling, Sun Chengtao, Wu Changshun, Feng Hong
Cancer Center, Shandong Provincial Hospital Affiliated to Shandong University, Shandong University, Jinan, Shandong, China.
Department of Ophthalmology, Shandong Provincial Hospital Affiliated to Shandong University, Shandong University, Jinan, Shandong, China.
J Cancer Res Ther. 2017;13(4):730-734. doi: 10.4103/jcrt.JCRT_587_17.
Human epidermal growth factor receptor 2 (HER2) is an important biomarker for the precise individualized treatment including trastuzumab of HER2-positive breast and gastric cancer. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are the routine analyses for formalin-fixed paraffin-embedded (FFPE) samples. However, IHC is variable and depends on the evaluator, and FISH is a labor intensive and expensive method. We evaluated the feasibility of droplet digital polymerase chain reaction (ddPCR) as a precise and quantitative method for HER2 amplification test.
We used ddPCR to confirm HER2 amplification status in 24 breast cancer and 29 gastric cancer samples to validate the HER2 cutoff value in ddPCR. After setting cutoff value, all the above-mentioned samples were tested by IHC. Afterward, another 51 equivocal IHC 2+ gastric cancer samples were further determined by FISH and ddPCR, respectively, and the concordance between ddPCR and FISH was calculated.
We set the HER2 cutoff value at 1.8. The concordance rate of HER2 status between ddPCR and IHC was 94.4% (17 out of 18) in 24 breast cancer samples. In 29 gastric cancer specimens, the concordance rate of HER2 amplification between ddPCR and IHC was 100% (22 out of 22). At last, compared with FISH determined HER2 status, ddPCR HER2 scores correctly classified 44 of 51 cases with 86.3% concordance in 51 equivocal IHC 2+ gastric cancer samples.
ddPCR was able to identify HER2 amplification status in breast and gastric cancers with precise correlation with IHC and FISH results. This method might become a standard method for testing FFPE samples. However, the technology requires further research.
人表皮生长因子受体2（HER2）是HER2阳性乳腺癌和胃癌精准个体化治疗（包括曲妥珠单抗治疗）的重要生物标志物。免疫组织化学（IHC）和荧光原位杂交（FISH）是对福尔马林固定石蜡包埋（FFPE）样本的常规分析方法。然而，IHC结果存在差异且依赖评估者，FISH是一种劳动强度大且昂贵的方法。我们评估了液滴数字聚合酶链反应（ddPCR）作为HER2扩增检测的精确且定量方法的可行性。
我们使用ddPCR来确认24例乳腺癌和29例胃癌样本中的HER2扩增状态，以验证ddPCR中的HER2临界值。设定临界值后，对上述所有样本进行IHC检测。随后，分别用FISH和ddPCR对另外51例IHC 2+的可疑胃癌样本进行进一步检测，并计算ddPCR与FISH之间的一致性。
我们将HER2临界值设定为1.8。在24例乳腺癌样本中，ddPCR与IHC之间HER2状态的一致性率为94.4%（18例中的17例）。在29例胃癌标本中，ddPCR与IHC之间HER2扩增的一致性率为100%（22例中的22例）。最后，在51例IHC 2+的可疑胃癌样本中，与FISH确定的HER2状态相比，ddPCR的HER2评分正确分类了51例中的44例，一致性为86.3%。
ddPCR能够识别乳腺癌和胃癌中的HER2扩增状态，与IHC和FISH结果具有精确相关性。该方法可能成为检测FFPE样本的标准方法。然而，该技术需要进一步研究。
