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Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

3600 - Evaluation of the sensitivity of RAS mutation detection of the Idylla platform in comparison to the OncoBEAM RAS CRC assay

Date

21 Oct 2018

Session

Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

Topics

Targeted Therapy;  Pathology/Molecular Biology

Tumour Site

Colon and Rectal Cancer

Presenters

Ana Vivancos

Citation

Annals of Oncology (2018) 29 (suppl_8): viii150-viii204. 10.1093/annonc/mdy281

Authors

A. Vivancos1, E. Aranda Aguilar2, M. Benavides3, E. Elez Fernandez4, M. Toledano2, M. Alvarez5, E. Diaz Rubio6, A. Gómez-España2, V. Garcia-Barberan6, M.R. Chica-Parrao7

Author affiliations

  • 1 Genomics, Vall d'Hebron University Hospital, 08035 - Barcelona/ES
  • 2 Oncology, University Hospital Reina Sofia, 14004 - Cordoba/ES
  • 3 Oncology, Hospital Regional Universitario Carlos Haya, 29010 - Malaga/ES
  • 4 Oncology, Vall d'Hebron University Hospital, 08035 - Barcelona/ES
  • 5 Pathology, Hospital Regional Universitario Carlos Haya, 29010 - Malaga/ES
  • 6 Oncology, Hospital Clinico Universitario San Carlos, 28040 - Madrid/ES
  • 7 Oncology, Hospital Universitario Virgen de la Victoria, 29010 - Malaga/ES
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Resources

Abstract 3600

Background

Accurate detection of RAS mutations in metastatic colorectal cancer (mCRC) patients is of high clinical importance for therapy selection as RAS detection methods lacking sensitivity may lead to poor patient outcomes. Liquid biopsy has emerged as a viable alternative to individualize the management and treatment of mCRC patients. The objective of this study was to provide a head-to-head comparison of the sensitivity of two tests for KRAS mutation detection in plasma from mCRC patients: dPCR-based OncoBEAM and qPCR Idylla.

Methods

Plasma samples from mCRC patients determined to be KRAS-positive using OncoBEAM were re-tested using Idylla. 116 samples with mutant allelic fractions (MAF) below 5% were selected for analysis. The positive percent agreement (PPA) of KRAS mutation results was compared for replicate samples analyzed by OncoBEAM and Idylla.

Results

Idylla detected KRAS mutations in 81 out of 116 (69.8%, p < 0.0001) OncoBEAM KRAS-positive plasma samples. Categorization of results based on MAF% revealed distinct differences in sensitivity between the two technologies.Table: 550P

MAF% RangePPA Idylla vs OncoBEAM
1-5%89.1% (33/37) (p = 0.1336)
0.1-1%65.1% (41/63) (p < 0.0001)
0.02%-0.1%43.8% (7/16) (p = 0.0077)

Significant differences have been observed in patients with liver and other metastases, except lung, 41/51 (80.4%, p = 0.0044) and patients with lung and other metastases, except liver, 16/24 (66.7%, p = 0.0133).

Conclusions

OncoBEAM demonstrated significantly greater sensitivity for plasma detection of RAS mutations than Idylla. Moreover, these data identify a “gray zone” below 1% MAF where Idylla fails to identify RAS-positivity in patient plasma samples. These findings show that liquid biopsy assays with diminished sensitivity may lack the dynamic range to provide accurate and timely RAS mutational status information to properly guide highly individualized anti-EGFR therapy and chemotherapy treatment decisions that may benefit patient outcomes.

Clinical trial identification

Legal entity responsible for the study

Ana Vivancos.

Funding

Sysmex Inostics.

Editorial Acknowledgement

Disclosure

A. Vivancos: Consultant: Sysmex Inostics. All other authors have declared no conflicts of interest.

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