Efficacy of gemcitabine in patients with non-small cell lung cancer according to promoter polymorphisms of the ribonucleotide reductase M1 gene

Purpose: High ribonucleotide reductase M1 (RRM1) expression in resected lung cancers has been associated with better clinical outcomes. However, gemcitabine-treated patients with high tumoral RRM1 expression generally evidence poor prognoses due to the decreased efficacy of gemcitabine therapy. This study was designed in accordance with the hypothesis that polymorphisms (-37 and -524) of the RRM1 promoter gene sequence, which regulate RRM1 expression, could influence the efficacy and prognosis of lung cancer patients treated with gemcitabine-based chemotherapy. Experimental Design: A retrospective dataset of 97 patients with advanced non-small cell lung cancer treated with gemcitabine regimens as a first-line treatment was studied in this work. The allelotyping of RRM1 promoter polymorphisms was conducted via real-time PCR using genomic DNA obtained from peripheral WBC. Results: The RRM1 promoter allelotype was RR37CC-R524TT in 58 patients, RR37AC-RR524CT in 29 patients, and other allelotypes in 10 patients. The response rate forgemcitabine-containing chemotherapy was 49.5%. The response rate was significantly higher in the RR37AC-RR524CT group (65.5%) compared with the group containing other allelotypes (42.6%; P = 0.039). Overall survival and progression-free survival did not differ significantly by allelotype. Conclusions: We detected significant differences in response rates to gemcitabine-based chemotherapy according to the allelotypes of the RRM1 promoter sequence, which could be determined using the germline DNA. Further functional and clinical studies will be required before this can be used as a predictive marker.