Xin Wang1, Yiying Guo2, Li Liu1, Jiacong Wei1, Jinyao Zhang2, Tongji Xie2, Jiyan Dong1, Junling Li2, Puyuan Xing3, Lin Yang4. 1. Department of Pathology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China. 2. Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China. 3. Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China. Electronic address: xingpuyuan@cicams.ac.cn. 4. Department of Pathology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China. Electronic address: linyang0616@126.com.
Abstract
BACKGROUND: Recently, expression of YAP1, a nuclear effector of an inactivated HIPPO pathway, has been identified as one of four molecular subtypes of SCLC. However, the clinicopathological relevance and prognostic significance of YAP1 expression in SCLC stratified by histological subtypes has not been systematically reported to date. METHODS: Tumor sections and corresponding formalin-fixed paraffin-embedded (FFPE) samples of 297 SCLC patients were retrieved from the pathological specimen repository and were subsequently reviewed by pathologists. Forty-six C-SCLCs (combined SCLCs) (15.5%) and 251P-SCLCs (pure SCLCs) (84.5%) were identified respectively. YAP1 expression was examined by immunohistochemistry (IHC) and assessed semi-quantitatively on tumor tissue array (TMA). Propensity score was used to match C-SCLCs and P-SCLCs in a ratio of 1 to 2 to balance age, gender, tumor stage and treatment methods. Finally, 46C-SCLCs and 92P-SCLCs were included for prognostic analysis. RESULTS: The positive rate of YAP1 expression was significantly higher in C-SCLCs than P-SCLCs before matching (52.2% vs 29.1%, P = 0.004). After matching by propensity score, the prescribed clinical parameters were well balanced between P-SCLCs and C-SCLCs. Expression of YAP1 was associated worse overall survival (OS) (5- year OS%, 39.0% vs. 74.9%, P = 0.013) and was an independent risk factor for OS (HR = 2.93, 95% CI: 1.01-8.51; P = 0.048) exclusively in C-SCLC. Univariate survival analysis in subgroups of different clinical variables also confirmed the prognostic impact of YAP1 was most significant in C-SCLC. But for P-SCLCs, expression of YAP1 showed no prognostic impact. CONCLUSIONS: Expression of YAP1 in small cell components of C-SCLC was significantly higher than that in P-SCLC. Besides, it served as an unfavorable predictor for OS in C-SCLC but not in P-SCLC, which suggested different entities of small cell components with variant YAP1 expression and potential different targetable oncogenic pathway between C-SCLC and P-SCLC.
BACKGROUND: Recently, expression of YAP1, a nuclear effector of an inactivated HIPPO pathway, has been identified as one of four molecular subtypes of SCLC. However, the clinicopathological relevance and prognostic significance of YAP1 expression in SCLC stratified by histological subtypes has not been systematically reported to date. METHODS:Tumor sections and corresponding formalin-fixed paraffin-embedded (FFPE) samples of 297 SCLCpatients were retrieved from the pathological specimen repository and were subsequently reviewed by pathologists. Forty-six C-SCLCs (combined SCLCs) (15.5%) and 251P-SCLCs (pure SCLCs) (84.5%) were identified respectively. YAP1 expression was examined by immunohistochemistry (IHC) and assessed semi-quantitatively on tumor tissue array (TMA). Propensity score was used to match C-SCLCs and P-SCLCs in a ratio of 1 to 2 to balance age, gender, tumor stage and treatment methods. Finally, 46C-SCLCs and 92P-SCLCs were included for prognostic analysis. RESULTS: The positive rate of YAP1 expression was significantly higher in C-SCLCs than P-SCLCs before matching (52.2% vs 29.1%, P = 0.004). After matching by propensity score, the prescribed clinical parameters were well balanced between P-SCLCs and C-SCLCs. Expression of YAP1 was associated worse overall survival (OS) (5- year OS%, 39.0% vs. 74.9%, P = 0.013) and was an independent risk factor for OS (HR = 2.93, 95% CI: 1.01-8.51; P = 0.048) exclusively in C-SCLC. Univariate survival analysis in subgroups of different clinical variables also confirmed the prognostic impact of YAP1 was most significant in C-SCLC. But for P-SCLCs, expression of YAP1 showed no prognostic impact. CONCLUSIONS: Expression of YAP1 in small cell components of C-SCLC was significantly higher than that in P-SCLC. Besides, it served as an unfavorable predictor for OS in C-SCLC but not in P-SCLC, which suggested different entities of small cell components with variant YAP1 expression and potential different targetable oncogenic pathway between C-SCLC and P-SCLC.