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Poster lunch

1811 - Frequencies and expression levels of programmed death ligand 1 (PD-L1) in circulating tumor RNA (ctRNA) in various cancer types. (45P)

Date

18 Nov 2017

Session

Poster lunch

Presenters

Toshiyuki Ishiba

Citation

Annals of Oncology (2017) 28 (suppl_10): x7-x15. 10.1093/annonc/mdx653

Authors

T. Ishiba1, K. Danenberg2, J. Usher2, T. Nakagawa3, G. Oda3, H. Uetake4, N. Hoshino1, Y. Nishioka1, T. Kawano1

Author affiliations

  • 1 Department Of Surgery, Soka Municipal hospital, 3400043 - Soka city, Saitama/JP
  • 2 Liquid Genomics, Inc., Liquid Genomics, Inc., Torrance/US
  • 3 Surgical Specialities, Tokyo Medilal and Dental University, tokyo/JP
  • 4 Specialized Surgeries, Medical and Dental University, Tokyo/JP
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Resources

Abstract 1811

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, we 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 were collected from gastric (GC), colorectal (CRC), lung (NSCLC), breast (BC), prostate cancer (PC) patients, and a healthy control group. ctRNA was purified from fractionated plasma, and following reverse transcription, levels of PD-L1 expression were analyzed using qPCR.

Results

PD-L1 expression was detected in the ctRNA of 33.3% (3/9 plasma samples) of GC patients, 23.4% (22/94) of CRC patients, 39% (16/41) of NSCLC patients, 54.5% (6/11) of BC patients and 35.3% (6/17) of PC patients. PD-L1 mRNA was not detected in the cancer-free group (0/9), but this was not significantly different from the cumulative cancer patients (p = 0.0602, Fisher’s Exact Test). The frequency of PD-L1 expression was significantly different among the cancer types we studied (p 

Conclusions

PD-L1 mRNA can be detected and quantitated in ctRNA of cancer patients. The frequency of PD-L1 expression varies by cancer type, however, when detected in ctRNA, levels of PD-L1 expression do not significantly differ across these cancers. These results pave the way for further studies aimed at determining whether monitoring the levels of PD-L1 mRNA in blood can identify patients who are most likely to benefit from the conventional treatment.

Clinical trial identification

Legal entity responsible for the study

Liquid Genomics, Inc.

Funding

None

Disclosure

All authors have declared no conflicts of interest.

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