PURPOSE: It is well known that the level of circulating cell free RNA (cRNA) rises in patients with many kinds of malignancy. Recent several studies suggested that cRNA level might correlate with tumor burden. Furthermore, experimental study using cancer cell line showed that the changes of cRNA were predictive for the response to the chemotherapy. The objective of this study was to find out whether cRNA could be used as a biomarker for clinical response to chemotherapy in patients with thoracic malignancy.
METHODS: Thirty-three patients with thoracic malignancy (non small cell lung cancer n=24, small cell lung cancer n=8, mesothelioma n=1) were divided into two groups according to the response of chemotherapy (Partial response group n=19, group I vs. non response group n=14, group II). Blood samples were collected 2 times before and 2 cycles after chemotherapy. The RNA was isolated from 1mL serum with the RNA spin Mini RNA Isolation Kit (GE Healthcare, USA). A real-time quantitative RT-PCR assay (QRT-PCR, TaqMan format) was used for transcript quantification of the glyceride 3-phosphate dehydrogenase (GAPDH) gene.
RESULTS: Post chemotherapy cRNA concentration expressed as Ct GAPDH level tended to decrease in group I (decrease 78.9%, increase 21.1%) as compared with group II (decrease 50%, increase 50%) (p=0.086). Pre chemotherapy cRNA concentration was not different between two groups. (41.22 vs. 41.36, p=0.823). Post chemotherapy cRNA concentration was significantly lower as compared with pre chemotherapy cRNA concentration in group I (39.92 vs. 41.36, p=0.003). However, post and pre chemotherapy cRNA concentration was not significantly different in group II (40.47 vs. 41.22, p=0.241).
CONCLUSION: We could find some correlation between cRNA and clinical response to chemotherapy in patients with thoracic malignancy.
CLINICAL IMPLICATIONS: This finding suggests that serum cRNA level may correlate with thoracic malignancy burden and changes of cRNA were predictive for the response to the chemotherapy in patients with thoracic malignancy.
DISCLOSURE: Soo-Jung Um, No Financial Disclosure Information; No Product/Research Disclosure Information