Ribonucleotide reductase M1 expression in intrahepatic cholangiocarcinoma.

Background/aims: Ribonucleotide reductase M1 (RRM1) is a key molecule for gemcitabine resistance. This study evaluated the immunohistochemical expression of RRM1 in resected specimens of intrahepatic cholangiocarcinoma (ICC) and investigated the efficacy of gemcitabine-based neoadjuvant chemotherapy in relation to RRM1 expression in tumors.
Methodology: A retrospective analysis was conducted on 34 consecutive Japanese patients who underwent resection of ICC. Of the 34 patients, 2 were treated with neoadjuvant chemotherapy consisting of gemcitabine 800mg/m2 every 2 weeks to address extrahepatic tumor extension. Expression of RRM1 in tumor specimens was assessed using immunohistochemistry and was classified as either positive or negative.
Results: RRM1-positive expression was detected in 19/34 (56%) tumor specimens. Two patients were treated with gemcitabine-based neoadjuvant chemotherapy; one had a tumor specimen showing RRM1-positive expression and showed a 14% tumor reduction rate (stable disease); another patient had a tumor showing RRM1-negative expression and showed a 68% tumor reduction rate (partial response). Surgical procedures planned before administration of neoadjuvant chemotherapy were performed in both patients.
Conclusions: Neoadjuvant chemotherapy with gemcitabine for locally advanced ICC was well tolerated and did not impair planned surgical resections. Tumor expression of RRM1 may determine the efficacy of gemcitabine-based chemotherapy for patients with ICC.