Abstract 5217: Cancer target enrichment panels using advanced molecular inversion probes (MIPs) with ability to reduce amplification bias and detect low frequency variants
Authors: Bannen Ryan , Brockman Michael , D’Ascenzo Mark , Jefferson Keynttisha , Green Dawn , Halvensleben Heather , Heilman Kurt , Richmond Todd , Burgess Daniel 
Published: July 2016

Next generation sequencing (NGS) of enriched targets is increasingly being used to discover and track mutations in genes implicated in cancer. Amplicon-based target enrichment approaches are frequently used with cancer samples because there is no sample library preparation needed and primer-based approaches are typically efficient with sequencing reads. However, traditional amplicon approaches don't scale up well and may have PCR and coverage uniformity bias. As the number of samples is increased, a fast, reliable, and cost-effective target enrichment method is a critical tool for mutation discovery and tracking.

Existing target enrichment approaches based on molecular inversion probes (MIPs) have presented challenges with probe design and dependability. We have developed HEAT-Seq (High Efficiency Amplification of Targets for Sequencing) using advanced versions of MIPs which enable library-free enrichment, improved scalability, and the ability to remove PCR duplicates. We have also developed companion command line software which trims primer sequences and removes PCR duplicates. This software uses community standard file formats (FASTQ, SAM/BAM) and is intended to be compatible with common “best practice” NGS analysis pipelines.

Here we describe two HEAT-Seq cancer panels which have been optimized to improve coverage uniformity and probe reliability.

The HEAT-Seq Oncology Panel targets both strands for all protein coding bases in 60 cancer-related genes where possible. The target for this design is 245 kb. With 2 million 2×76bp reads for each of 8 replicates, we observe an on-target read rate of &gt;95%. After duplicate removal, the% of target bases with at least 20x coverage is &gt;90%. We observe uniformity (percent of probes &gt; = 20% of the target mean) of ∼90%.

The HEAT-Seq Ultra Hot-Spot Panel is a mutation-focused design that provides ultra-deep sequencing coverage capability for sequencing of mutation hot-spots in 53 cancer-related genes to detect low frequency variants in heterogeneous samples. The target for this design is 30.5 kb. With 500,000 2×76bp reads for each of 24 replicates, we observe an on-target read rate of ∼80%. After duplicate removal, the% of target bases with at least 20x coverage is &gt;95%. We observe uniformity (percent of probes &gt; = 20% of the target mean) of ∼95%. We also observed detection of validated low frequency variants down to 1%.

In summary, both panels have been shown to capture cancer-related genes and target regions at depths sufficient to identify and track genomic variants.

Citation Format: Ryan Bannen, Michael Brockman, Mark D’Ascenzo, Keynttisha Jefferson, Dawn Green, Heather Halvensleben, Kurt Heilman, Todd Richmond, Daniel Burgess. Cancer target enrichment panels using advanced molecular inversion probes (MIPs) with ability to reduce amplification bias and detect low frequency variants. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5217.