Correlation of MECA-79-positive high endothelial venule density with clinical outcomes in upper tract urothelial carcinoma patients treated with radical nephroureterectomy.

417 Background: High endothelial venules (HEVs) are present in lymph nodes and tertiary lymphoid organs. It has been reported that low HEV density is associated with the poor prognosis of several carcinomas. MECA-79 antibody recognizes L-selectin ligand (6-sulfosialyl Lewis X glycan) expressed in HEV. In the present study, we examined whether MECA-79 positive HEV density was associated with clinical outcomes of patients with upper tract urothelial carcinoma (UTUC) treated with radical nephroureterectomy (RNU). Methods: Eighty-eight patients with UTUC who underwent RNU at the Hirosaki University hospital between January 2008 and December 2016 were enrolled. Tissue microarray for MECA-79 was performed, and HEV densities were calculated. HEV density < 1.5/mm2 was defined as HEV (−); HEV density ≥1.5/mm2 was defined as HEV(+). Results: Of 88 patients, 64 (72.7%) were male and 24 (27.2%) were female. The average age was 68.5 years (range, 36–84 years). Fifty-three patients (60.2%) had previously undergone neoadjuvant chemotherapy. The mean observation period was 39.0 months. Twenty-one (23.8%) patients developed recurrence, whereas 16 (33.3%) patients died during follow-up. Five-year cause-specific survival (CSS) rate was 66.1%, and five-year disease-free survival (DFS) rate was 70.7%. In our cohort, 25 (28.4%) patients were found to be HEV(−), whereas 63 (71.5%) were found to be HEV(+). The mean HEV density was 6.3/mm2(0-41.6). The 5-year DFS rates for HEV (+) and HEV (−) patients were 78.0% and 53.9%, respectively, with a statistically significant difference between the groups. (log-rank, p = 0.042). Moreover, the 5-year CSS rates for HEV (+) and HEV (−) patients were 72.5% and 53.4%, respectively, with a statistically significant difference between the groups. (log-rank, p = 0.0036). Conclusions: Low MECA-79-positive HEV density may be associated with poor prognosis of patients with UTUC treated with RNU. Despite the small sample size and preliminary nature of our study, our study provides valuable insights to guide future research.