Expression molecular subtype as a predictor of outcomes of chemoradiotherapy for esophageal cancer.

Abstract

4030 Background: The standard treatment for advanced esophageal cancer is preoperative chemoradiotherapy (CRT) followed by surgery or definitive CRT (NCCN Guideline 2022 ver5). CRT has the advantage of preserving organs and functions and the prognosis for patients achieved complete response by CRT is good. However, it is currently impossible to predict the outcomes of CRT before treatment. We have performed RNA expression analysis of pre-treatment biopsy specimens of esophageal cancer and identified several intrinsic molecular subtypes, as well as E-type (high expression of squamous markers) with good prognosis for CRT and M2-type (high expression of stromal markers) with poor prognosis for CRT (US patent No 10,969,390 B2). Herein, we performed an integrated analysis to confirm the relationship between intrinsic expression molecular subtype classification and prognosis in the pooled population from two prospective cohort studies (UMIN000043637). Methods: Two cohort studies were as follows; 1) single institute prospective cohort study conducted at National Cancer Center Hospital East (n=157, UMIN-C000000459), 2) multicenter prospective cohort study conducted at 10 institutions (n=226, UMIN000016141). A total 383 cases met inclusion criteria and the Affymetrix U331Plus 2 panel (47,104 transcripts, 38,572 genes) was used to identify E-type and M2-type. The clinical course and outcome were blinded for subtype classification. Treatment was performed as usual at each institution, and treatment details and outcomes were examined by subtype. Results: Among 383 patients, 181 and 164 patients were treated by CRT and surgery, respectively. Ninety-nine percent (n=342) were squamous cell carcinoma. Stage I/II/III/IV were 13/61/86/21 and 17/63/81/3 in CRT group and surgery group, respectively. Among them, 76 (22%), 100 (29%), 169 (49%) patients were classified as E, M2 and others, respectively. Among the patients treated by CRT, CR rate of E-type and M2-type were 62.8% (95% CI, 47.8-75.7) and 33.3% (95% CI, 21.9-47.1) (p=0.006). The 5-year progression free survival (PFS) and overall survival (OS) rates of CRT group was 50.5% (95% CI, 34.7-64.4) and 59.8% (95% CI, 42.6-73.3) for E-type vs. 23.0% (95% CI, 12.0-36.2) and 29.0% (95%CI, 16.8-42.4) for M2-type, with statistically significant difference (p=0.011, p=0.003). Cox regression analysis showed that crude HR for PFS and OS of E vs M2 were 0.50 (95% CI, 0.296-0.859, p=0.012) and 0.41 (95% CI, 0.226-0750, p=0.004), respectively. In contrast, E and M2-type did not show the survival difference in surgery group. Conclusions: For the first time in the world, we confirmed that expression molecular subtype of esophageal cancer has the potential to predict the outcomes of CRT. The results may provide precision medicine in the selection of treatment for esophageal cancer.