Abstract B03: Cisplatin-resistant cells possess collateral sensitivity to folate antimetabolites

Abstract

Abstract Cisplatin is widely used as a first-line chemotherapeutic agent for lung cancers. Although effective initially, lung cancer cells eventually acquire resistance to cisplatin, causing tumor recurrence. Understanding mechanisms that govern cisplatin resistance is expected to improve therapeutic efficacy in lung cancer patients. Although various studies using cisplatin-resistant cell lines have revealed possible mechanisms of resistance, the applicability of these mechanisms in a clinical setting are debatable. One possible reason for this discrepancy may be the use of cell line models which are exposed to unnaturally high doses of cisplatin to yield cells with a resistant phenotype. These cell lines may not be representative of naturally arising cisplatin-resistant cells in tumors that are treated according to a clinically established dose and schedule. Therefore, to improve the experimental model, we have established two new cisplatin-resistant lung cancer cell lines through intermittent low dose challenges that mimic a clinical treatment schedule (one pulse/month for up to six cycles). The resistant cell lines resulting from this procedure demonstrate improved clonogenic potential and sphere-forming properties, suggesting an increase in the population of tumor-initiating cells. Interestingly, via testing with several different anti-cancer drugs, we found that these resistant cells are more sensitive to the antifolate Pemetrexed, in comparison to their parental cells. To conclude, our study suggests that sequential administration of antifolates might be useful in the treatment of lung cancers that have acquired cisplatin resistance. Citation Format: Shih-Shin Chang, Hirohito Yamaguchi, Mien-Chie Hung. Cisplatin-resistant cells possess collateral sensitivity to folate antimetabolites. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B03.