Abstract LB059: Dual methylation and mutation analysis from a single input of plasma cfDNA without sample splitting

Abstract

Genomic and epigenetic changes are known to be the underlying mechanism of cancer development. Assessing the genomic (mutation) and epigenetic (methylation) changes has become increasingly important for cancer detection and treatment selection, especially in the field of cfDNA-based liquid biopsy. Targeted Next-Generation Sequencing (NGS) enables in-depth analysis of specific genomic regions that is essential for the clinical application of liquid biopsy. However, current targeted NGS assays are complicated, lengthy, and inefficient. Two major hurdles of existing targeted NGS methods make them impractical for the clinical setting. First, there is no comprehensive, end to end, kit solution available for targeted methylation sequencing (TMS) from sample to sequencing ready library. Second, the low yield of cfDNA from clinical blood samples presents a major challenge for multi-modal analyses on one sample. Thus, an assay that is capable of both methylation and mutation analysis would be optimal for clinical research and future diagnostic assays.Here, we report the performance of Point-n-Seq, a kit solution that can provide in-depth DNA analysis with highly flexible and customizable focused panels to enable both methylation and mutation analysis without sample splitting. Custom panels of 10 to 1000s of markers can be designed with >99% first-pass success rate. We conducted both performance validation and multi-center, multi-operator, reproducibility studies. With spike-in titration of cancer cell-line gDNA with known mutation and methylation profile, we achieved a reliable detection level down to 0.003% of tumor DNA with a linear relationship between the measured and expected fractions.In a pilot study, we designed a colorectal cancer (CRC) TMS panel covering 560 methylation markers and a mutation panel with >350 hotspot mutations in 22 genes. From only 1ml of plasma from late stage CRC patients, we detected cancer-specific methylation signals in all samples tested, and hotspot mutations with clinical implications. Next, a tumor-informed mutation panel covering approximately 100 personalized mutations for each patient was compared to the tumor-independent CRC methylation panel to analyze 23 stage I and II CRC patient plasma samples. The initial results showed that tumor-independent TMS assay achieved a comparable or superior limit of detection compared to the personalized tumor-informed approach. Moreover, to further improve assay sensitivity, metrics for cfDNA size can be integrated into the analysis of the same workflow without sample splitting. The Point-n-Seq kit, with a highly streamlined workflow and dual methylation and mutation analysis, provides a highly sensitive and robust non-invasive method for cancer detection, monitoring and treatment guidance. Citation Format: Grace Q. Zhao, Yun Bao, Heng Wang, Vanita S. Natu, Jayashree Joshi, Yingmin Wang, Elena Arzumanyan, Wanping Wang, Jianmin Wang, John Coller, Shengrong Lin. Dual methylation and mutation analysis from a single input of plasma cfDNA without sample splitting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB059.