asco@alo33:161786
|
Background: Precision medicine and prediction of therapeutic response requires monitoring potential biomarkers before and after treatment. Liquid biopsies provide noninvasive prognostic markers such as circulating tumor DNA and RNA. Circulating tumor RNA ctRNA in blood is also used to identify mutations in genes of interest, but additionally, provides information about relative expression levels of important genes. In this study, e analyzed PD-L1 expression in ctRNA isolated from various cancer types. Tumors inhibit antitumor response by modulating the immune checkpoint proteins programmed death ligand 1 PD-L1 and its cognate receptor PD1. The expression of these genes has been implicated in evasion of immune response and resistance to targeted therapies. Methods: Blood samples ere collected from gastric GC , colorectal CRC , lung NSCLC , breast BC , prostate cancer PC patients, and a healthy control group. ctRNA as purified from fractionated plasma, and folloing reverse transcription, levels of PD-L1 expression ere analyzed using qPCR. Results: PD-L1 expression as detected in the ctRNA of 33.3 percent 39 plasma samples of GC patients, 23.4 percent 2294 of CRC patients, 39 percent 1641 of NSCLC patients, 54.5 percent 611 of BC patients and 35.3 percent 617 of PC patients. PD-L1 mRNA as not detected in the cancer-free group 09 , but this as not significantly different from the cumulative cancer patients p = 0.0602, Fishers Exact Test . The frequency of PD-L1 expression as significantly different among the cancer types e studied plt 0.0001, Fishers Exact . Hoever, median relative PD-L1 expression as not statistically significantly different 7.0 in GC, 5.6 in CRC, 10 in NSCLC, 7.8 in BC, and 9.1 in PC p = 0.258, Median Test . Conclusions: PD-L1 mRNA can be detected and quantitated in ctRNA of cancer patients. The frequency of PD-L1 expression varies by cancer type, hoever, hen detected in ctRNA, levels of PD-L1 expression do not significantly differ across these cancers. These results pave the ay for further studies aimed at determining hether monitoring the levels of PD-L1 mRNA in blood can identify patients ho are most likely to benefit from the conventional treatment.,J Clin Oncol 34, 2016 suppl; abstr e23101 ,Publication Only Tumor Biology
|