High RRM1 Expression Is Associated with Adverse Outcome in Patients with Cisplatin/Vinorelbine-treated Malignant Pleural Mesothelioma.

A possible predictive impact of ribonucleotide-reductase subunit-1 (RRM1) on vinorelbine efficacy in non-small cell lung cancer (NSCLC) has been previously reported. The present study aimed to further explore this finding in malignant pleural mesothelioma (MPM). Seventy-one patients with MPM receiving first-line chemotherapy with cisplatin-vinorelbine (CiV group, n=54) or carboplatin-pemetrexed (CaP group, n=17) were included. Formalin-fixed paraffin-embedded tumor specimens were analyzed by immunohistochemistry (IHC) for RRM1 expression using an H-score. In 66 patients eligible for IHC, the H-score was ≥upper quartile in 21 (RRM1-positive) and <upper quartile (RRM1-negative) in 45 cases. The long-term (2-year) survival rate for patients with RRM1-negative MPM in the CiV-treated group was significantly superior to that for patients with RRM1-positive MPM (47% versus 13%, p=0.002). No difference occurred in the CaP-treated group. Our findings suggest a possible role of RRM1 in predicting efficacy of cisplatin-vinorelbine in MPM, supporting previous findings in NSCLC.