評估循環腫瘤HPV16 E2與E7基因於HPV+口咽癌病人之臨床效用

Abstract

隨著HPV-associated OPSCC的發生率逐年提升與其獨特的臨床特徵，人們對於HPV-associated OPSCC的專注度也日漸上升，目前主要診斷及預測疾病復發的方法為組織切片檢查，然而此方法是侵入性且耗費人力的，進而導致樣品數量不足及耗費時間等等問題。 此篇研究想透過液態檢體發展一套非侵入式且減省時間的系統來補充組織切片的不足，採用的方法為萃取病人血漿中的循環DNA並用PCR技術偵測其中的循環腫瘤HPV E2 及E7 DNA再與病歷做連結，檢體方面從10位HPV-associated OPSCC的患者採集術中與術後的血漿與組織檢體，另外從台大醫院耳鼻喉科生物資料庫取37個來至HPV-associated OPSCC患者的術中血漿。 在癌症診斷方面，利用ddPCR偵測循環腫瘤HPV16 E7 DNA具有最好的敏感度及特異性，而與TNM臨床分期做連結後發現循環腫瘤 HPV16 E2 DNA與淋巴結分期有較強的關聯性，進一步的結果顯示淋巴結檢體中HPV16 E2的表現量較HPV16 E7高且HPV16 E2過度表現在HPV相關癌細胞會促進細胞遷移與侵犯的能力，最後評估循環腫瘤HPV16 DNA與疾病進程的關係，結果發現8位病人在治療完均無偵測到循環腫瘤HPV16 DNA或是已歸零且在臨床檢查上也沒有觀察到復發的現象，而在另外兩位病人的術後檢體中偵測到了循環腫瘤HPV16 E2 DNA，但由於追蹤時間過短而無法透過臨床檢查評估疾病的狀況。 總結來說，循環腫瘤HPV E7 DNA診斷能力較強而HPV E2 DNA有潛力預測疾病進程及淋巴結分期且有過表現於淋巴結腫瘤的現象並會促進癌細胞遷移、侵犯，未來希望透過更充足的樣品數量及搭配其他臨床因子來證明循環腫瘤HPV DNA在臨床癌症管理上的能力。

With the incidence rate of HPV-associated OPSCC increasing and its unique characteristics, the importance of HPV-associated OPSCC management is gradually rising. The current method includes tissue biopsy or certain clinical factors. However, those methods are invasive and laborious. Hence, this study focuses on evaluating the clinical impact of different circulating tumor HPV DNA to develop a non-invasive and cost-effective method. A total of 46 patients, including 40 with HPV-associated OPSCC and 6 with HPV-negative OPSCC were recruited. 69 plasma specimens including 24 follow-up samples were collected. cfDNA was extracted from plasma, and multiplex ddPCR and qPCR were used to detect ctHPV16 DNA by targeting HPV16 E2 and HPV16 E7. In cancer diagnosis, detecting ctHPV16 E7 DNA by multiplex ddPCR exhibited the highest ability, with a sensitivity of 76.3% and specificity of 85.7%. When correlating ctHPV16 DNA with the TNM stage, the significance of ctHPV16 E2 DNA was stronger than ctHPV16 E7 DNA in the N stage. Further findings demonstrated that HPV16 E2 may be enriched in nodal tumors and induced HPV-associated cancer cell migration and invasion. For surveillance of disease progression, ctHPV E2 DNA can be detected before ctHPV16 E7 DNA, but the capacity to predict disease progression cannot be evaluated due to the short surveillance period. In summary, circulating tumor HPV16 E7 DNA had the highest diagnostic capacity and it was comparable with p16 IHC, while circulating tumor HPV16 E2 DNA has the potential to predict disease progression and lymph node staging. The expression of HPV16 E2 is higher than HPV16 E7 in lymph node tumors and HPV16 E2 overexpression in HPV-associated cancer cells will promote cancer cell migration and invasion. In the future, it is hoped that the clinical ability of circulating tumor HPV16 DNA in cancer management can be demonstrated through a larger number of samples and in conjunction with other clinical factors.