Ribophorin II (RPN2) Expression is Associated with Advanced Esophageal Tumor Response to Docetaxel
No biomarkers have previously been identified that predict ESCC response to docetaxel, reported Hideo Baba, MD, PhD, of the Department of Gastroenterological Surgery at Kumamoto University in Japan, and coauthors. But RPN2 silencing previously has been shown to improve docetaxel-dependent apoptosis.
The authors immunohistochemically assessed RPN2 expression in tumor biopsy specimens from 79 patients diagnosed with node-positive ESCC, who had received docetaxel-based adjuvant chemotherapy. RPN2-negative tumors were associated with superior clinical responses to docetaxel. Patients with RPN2-negative tumors were more likely to have complete responses (CR) to docetaxel therapy (RECIST v1.0 criteria, 4/28 patients), than patients with RPN2-positive tumors (0/51; P<0.001). (When WHO response criteria were employed, CR was seen in 8/28 patients with RPN2-negative tumors, versus 1/51 patients with RPN2-positive tumors [P<0.001].)
The authors also found that in vitro suppression of RPN2 expression, increased ESCC tumor susceptibility to docetaxel.
Survival outcomes were not assessed because of the short follow-up period, the authors reported.
The study suggests “the clinical usefulness of RPN2 expression in endoscopic biopsy samples for predicting sensitivity to docetaxel-based chemotherapy,” the authors concluded. “We evaluated responses to neoadjuvant chemotherapy using various methods, including clinical and pathological responses and decrease in SUV by FDG-PET. All the response evaluators demonstrated the efficacy of RPN2 as a response marker.”
The study's sample size was relatively small, and replication in larger patient populations is needed to validate these results, the authors cautioned.
“Although a larger validation study is needed, the findings in this study have important clinical implications for patients receiving neoadjuvant chemotherapy for ESCC,” they wrote.