Expression of RRM1 and its association with resistancy to gemcitabine-based chemotherapy in advanced nasopharyngeal carcinoma

Gemcitabine has high activity against nasopharyngeal carcinoma (NPC). The level of ribonucleotide reductase subunit M1 (RRM1) expression is closely related to the efficacy of gemcitabine on non-small cell lung cancer and pancreatic cancer. However, the expression of RRM1 and its association with sensitivity to gemcitabine-based chemotherapy in advanced NPC is not known. In this study, we retrospectively collected 48 formalin-fixed, paraffin-embedded NPC tissues to evaluate the expression of RRM1 using immunohistochemistry. All patients were diagnosed and treated with gemcitabine-based chemotherapy at Sun Yat-sen University Cancer Center. RRM1 expression was positive in 17(35%) patients. RRM1 expression was not associated with sex, age, performance status, WHO histological type, number of distant metastases, previous treatment, or cycles of gemcitabine-based chemotherapy(P> 0.05). The progression-free survival of the RRM1-positive group was shorter than that of the RRM1-negative group (5 months vs. 7 months, P = 0.036), and the response rate of the RRM1-positive group was somewhat lower than that of the RRM1-negative group (51.6% vs. 35.3%, P = 0.278). There was no significant difference in median survival between the RRM1-positive and RRM1-negative groups (22 months vs. 19 months, P = 0.540). Our results show that RRM1-negative expression is related with longer progression-free survival in advanced NPC patients treated with gemcitabine-based regimens.