Abstract 2405: A method for comprehensive genomic analysis of cell free DNA
Authors: Parpart-Li Sonya T. , Angiuoli Samuel V. , Chesnick Bryan , Galens Kevin , Jones Siân , Kadan Maura , Kann Lisa , Lytle Karli , Murphy Derek , Nesselbush Monica , Phallen Jillian , Riley David , Shukla Manish , Zhang Theresa , Husain Hatim , Velculescu Victor E. , Diaz Luis A. , Sausen Mark 
Published: August 2015

Circulating tumor DNA (ctDNA) is released from tumor tissue into the blood, carries tumor specific genetic alterations, and can be analyzed through noninvasive “liquid biopsy” approaches to identify genetic alterations in cancer patients. Liquid biopsies offer a considerable advantage as they may eliminate the need for invasive tissue biopsies and allow for the detection of alterations in multiple metastatic lesions throughout the course of therapy. However, the fraction of ctDNA obtained from a blood sample is often very low (&lt;1.0%) and can be difficult to detect. Additionally, most methods to evaluate circulating tumor DNA (ctDNA) interrogate single hot spot mutations or a few genetic alterations. The next generation of ctDNA assays must interrogate multiple gene regions from a single sample with high precision and accuracy and need to evaluate all forms of actionable genomic alterations including point mutations and structural alterations. To address these issues, we have developed a ctDNA approach called PlasmaSelect to detect somatic sequence mutations and translocations at low allele frequencies in the circulation of cancer patients. Utilizing digital genomic approaches, PlasmaSelect achieves high sensitivity and specificity while interrogating &gt;80,000 nucleotides spanning 63 well-established cancer genes. In addition to evaluation of exons in genes that are frequently mutated in cancer, PlasmaSelect also performs a comprehensive genomic analysis of translocations in 10 genes and the full coding regions of 18 tumor suppressor genes significant in cancer tumorigenesis. To evaluate the PlasmaSelect approach, we performed dilution series using tumor-derived DNA, containing well-characterized somatic mutations, in the presence with wild-type DNA. PlasmaSelect was able to detect genetic alterations with a lower level of detection of &gt;0.1% with high specificity. We evaluated the utility of PlasmaSelect for detection of genetic alterations in the plasma and matched tissue biopsy specimens from late stage cancer patients. These analyses demonstrated high concordance between the somatic sequence mutations and translocations identified in the tumor sample and those identified directly in the plasma, including alterations in both driver genes as well as those related to acquired resistance to targeted therapies. PlasmaSelect provides a non-invasive platform to enable liquid biopsy detection of clinically relevant genetic alterations across a large number of genomic loci.

Citation Format: Sonya T. Parpart-Li, Samuel V. Angiuoli, Bryan Chesnick, Kevin Galens, Siân Jones, Maura Kadan, Lisa Kann, Karli Lytle, Derek Murphy, Monica Nesselbush, Jillian Phallen, David Riley, Manish Shukla, Theresa Zhang, Hatim Husain, Victor E. Velculescu, Luis A. Diaz, Mark Sausen. A method for comprehensive genomic analysis of cell free DNA. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2405. doi:10.1158/1538-7445.AM2015-2405