黏液性上皮卵巢癌第十七號染色體多套畸形對 HER2 狀態的影響：一項採取組織晶片及2010 年全球胃癌第三期ToGA trial 對小切片檢體評分基準的研究

Assessing the influence of polysomy-17 on HER2 status in mucinous epithelial ovarian cancer: a tissue microarray study using 2010 ToGA trial biopsy specimen criteria

目的：評估黏液性上皮卵巢癌組織中，第十七號染色體多套畸形(polysomy-17)對HER2 狀態所造成的影響。研究設計：在49 例黏液性上皮卵巢癌組織晶片中，我們根據2010 年全球胃癌第三期臨床研究(ToGA trial)對小切片檢體的評分基準，以4B5 抗體免疫組織化學染色(immunohistochemistry; IHC)方法，分析HER2 受體蛋白表現強度；以Abbott/Vysis，PathVysion Her2 DNAProbe Kit 螢光原位雜交(fluorescence in situ hybridization; FISH)方法，分析Her2 基因數量擴增比例。橘色螢光訊號代表「Her2 基因」；綠色螢光訊號代表「第 17 號染色體著絲點(chromosome 17 centromere locus，CEP17)」；也間接作為「第17 號染色體」的計數標誌。結果：我們的數據顯示：「Her2 基因數量擴增比例(FISH)」與「HER2 受體蛋白表現強度(IHC)」二者的整體一致性非常好(34/35=97.14%; kappa=0.9224)。Her2 基因FISH 比例擴增個案百分比，隨者HER2 受體蛋白IHC 表現強度（陰性、不確定、陽性）三個等級，呈現漸增趨勢(0%，14.29%，88.89%，P<0.001)。第17 號染色體著絲點「校正前」之Her2 基因數目中位數，也隨者HER2 受體蛋白IHC 表現強度三個等級，呈現漸增趨勢(1.80，1.90，9.90；P<0.001)；而「校正後」之Her2 基因數量比例（又稱為FISH）中位數，同樣隨者HER2受體蛋白IHC 表現強度三個等級，呈現漸增趨勢 (1.13，1.09，5.73; P<0.001)。此外；在「第十七號染色體多套畸形」亞群體中，其「校正前」Her2 基因中位數，顯著高於「非第十七號染色體多套畸形」亞群體中者(2.50 vs. 1.85，P=0.009)；但在前述二亞群體中，其個別「校正後」Her2 基因比例(FISH)中位數相比較，則無顯著差異(1.14 vs. 1.19，P=1.000)。結論：第十七號染色體多套畸形本身並不會顯著影響HER2 受體蛋白IHC 表現及Her2 基因數目擴增。理由是：第十七號染色體多套畸形經第17 號染色體著絲點校正後，伴隨增加具功能性的Her2 基因數目，僅呈現簡單算數級數增加，實際擴增之Her2 基因數目有限，因此，HER2 受體蛋白表現強度增加，也相對很有限。然而，「Her2 基因數量比例(FISH)擴增」與「HER2 受體蛋白表現強度(IHC)增加」兩個現象，是現今預測HER2單株抗體藥物對乳房、胃、胃食道交界處等癌症患者療效預後與藥物敏感評估的重要因子。目前，我們對黏液性上皮卵巢癌病患腫瘤組織中，「第十七號染色體多套畸形」所扮演角色的認知，仍舊十分有限。開發其它擷抗HER2 標靶藥物的潛力無窮，針對晚期或復發黏液性上皮卵巢癌病患，有機會被納入開發擷抗HER2 新藥臨床試驗。未來，一旦HER2標靶抗癌新藥研發成功後，對於此類病患的治療，將有很大的助益。

Objective: Her2 gene amplification and protein over-expression are important factors in predicting clinical sensitivity to anti-HER2 monoclonal antibody therapy in breast, gastric or gastroesophageal junction (GEJ) cancer patients. However, little information addresses chromosome 17 centromere CEP17 in mucinous epithelial ovarian cancer (EOC). The purpose of this study was to assess the influence of CEP17 polysomy on HER2 status in patients with mucinous EOC. Study Design: Of the 49 tissue microarray (TMA) samples of mucinous EOC, we applied 2010 ToGA trial biopsy scoring criteria to analyze the HER2 protein expression by an immunohistochemistry (IHC) test with 4B5 antibody, and the Her2 gene amplification by the fluorescence in situ hybridization (FISH) test with an Abbott/Vyzsis, PathVysion Her2 DNA Probe Kit. Results: Our data revealed a favorable overall concordance (34/35=97.14%) between Her2 FISH and HER2 IHC assays (kappa=0.9224). The percentage of Her2 FISH amplified cases showed a significant increasing trend through their corresponding HER2 IHC ordinals (0%,14.29%,88.89%,P<0.001). The medians of Her2 gene copies (before CEP17 correction) increased significantly through 3 HER2 IHC orders (1.80, 1.90, 9.90; P<0.001); and the medians of the FISH ratios (after CEP17 correction) also did so (1.13, 1.09, 5.73; P<0.001). Additionally, the median of Her2 gene copies was significantly higher in the CEP17 polysomy subgroup than that in the CEP17 nonpolysomy subgroup (2.50 vs. 1.85, P=0.009), but the medians of FISH ratios were not (1.14 vs. 1.19, P=1.000). Conclusion: The CEP17 polysomy did not significantly influence the HER2 IHC and Her2 FISH results in mucinous EOC. The arithmetic raise of CEP17 per se did not reflect a substantial increase in functional Her2 gene copies and HER2 protein overexpression. Verifying HER2 status in mucinous EOC is indispensable to select potentially candidates for novel anti-HER2 drug therapies in the future.