GASC1 Expression to Predict Response to Paclitaxel Plus Cisplatin in Oesophageal Squamous Cell Carcinoma.

e15065 Background: GASC1 is a novel driver oncogene involved in the development of multiple cancers. Our preliminary study reported GASC1 contributed to the occurrence and progression of esophageal squamous cell carcinoma (ESCC). However, it remains unclear if GASC1 contributes to chemoresistance of ESCC. Methods: We evaluated GASC1 expression immunohistochemically in biopsy specimens from 60 patients with ESCC (clinical stag II-‡W ), who received adjuvant chemotherapy with TP regiment, and compared clinical response rate (cRR, including clinical complete response (cCR) and partial response (cPR)), pathological complete response rate (pCRR) and over survival (OS) between the GASC1-positive and GASC1-negative groups. We also studied susceptibility of GASC1-suppressed ESCC cells to TP. Fisher’s exact test was performed for data analyses. P < 0.05 was considered to be significant. Results: GASC1 positive expression rate is 50% in ESCC before chemotherapy. The cRR and pCRR in GASC1- negative group were all significantly better than GASC1-positive group respectively (66.7% (20/24) vs. 40% (12/36), p = 0.035; 25% (6/24) vs. 0, p = 0.003). The rate of GASC1 positive expression correlate positively to the advanced clinical stage (II, III, ‡W respectively: 16.7%, 50%, 33.3% vs. 62.5%, 29.2%, 8.3%, p = 0.001), lymph node metastasis (69.4% vs. 37.5%, p = 0.014), and the higher pathologic grade (G1, G2, G3-4 respectively: 36.1%, 27.8 %, 36.1% vs. 75%, 16.7%, 8.3%, p= 0.009). After 2 years follow-up, the mean survival was 34.875 months in GASC1-negative and 24.159 months in GASC1-positive group, the median survival was 28.453 months in GASC1-negative and 18.992 months in GASC1- positive group. We also found GASC1 inhibition could improve the susceptibility of ECSS cells KYSE30, KYSE70 and KYSE150 to TP. Conclusions: Expression of GASC1 may be a useful predictive marker for response to paclitaxel- basic adjuvant chemotherapy and prognosis in ESCC. GASC1 inhibitor is hopeful to benefit reversing chemotherapy resistance on ESCC. (Registered with observational trials, ChiCRT, registration number ChiCTR-OCH-14004541) Clinical trial information: ChiCTR-OCH-14004541.