Technology

Sequencing by expansion (SBX) technology

Overcoming limitations of today’s next-generation sequencing (NGS) technologies

As Roche Sequencing Solutions looks forward to meeting tomorrow’s biggest needs in genomics, it’s clear that today’s sequencing technologies face several limitations that impact growing needs for faster speed, improved accuracy, greater scalability, and increased flexibility.

Some traditional sequencing technologies leverage a cycle-based approach for measuring the bases of the DNA, which delays access to usable data. While on-market single-molecule nanopore technology addresses this challenge, it can be limited by fundamental signal-to-noise limitations—a result of poor spatial resolution and molecular distinction of nucleobases.

The SBX technology is in development and not commercially available. The content of this material reflects current study results or design goals.

Find out how SBX is paving the way for new opportunities in multi-omics research

Learn how Mark Korkoris and his team are transforming what’s possible with expanded applications and improved performance using sequencing by expansion.

Read the article

A new GUINNESS WORLD RECORDS™ title has been set

for the fastest DNA sequencing technique, in collaboration with Broad Clinical Labs and Boston Children’s Hospital. Find out how we did it in a brand-new publication in the NEJM.

A new approach to NGS

Roche has responded to the demand for improved performance by developing a new category of NGS technology, called sequencing by expansion (SBX). This powerful approach to NGS has been designed for flexibility and performance, with headroom to scale into the future. Specifically, SBX boasts several advantages, including:

  • Flexible operation that is tunable to sample needs
  • High accuracy with demonstrated F1 scores of >99.80% (SNV) and >99.7% (InDel) for HG001 whole genome samples
  • Very high throughput capable of 7 genomes in 1 hour at >30x; >5B duplex reads in 1 hour of sequencing
  • Flexible read lengths spanning 50bp to >1000bp
  • Ultra-fast workflow options for urgent samples, including sample to variant call format (VCF) in <5 hours
  • Cost efficiency enabled by a scalable and reusable sensor module

Fundamentally, SBX technology converts DNA information into a longer, “expanded” molecule, overcoming the spatial challenges of current nanopore technology and enabling higher signal-to-noise for improved accuracy. This expanded molecule, or Xpandomer, is then fed through Roche’s proprietary nanopore, driving single-molecule sequencing at incredibly high rates of speed and facilitating rapid access to usable sequencing data.

X-NTPs

SBX technology utilizes a proprietary biochemical conversion process to expand and encode the sequence of a DNA template into an Xpandomer molecule.

The building blocks of the Xpandomer are expandable nucleotide triphosphates, or X-NTPs. These high signal-to-noise reporters are the result of sophisticated molecular engineering and include an easily differentiated reporter code, a translocation control element for highly controlled transit through the pore, enhancers for robust Xpandomer synthesis, and an acid-cleavable bond for post-replication expansion. 

Xpandomer Synthesis

Each of the four, easily differentiated X-NTPs (one for each base), act as substrates for template-dependent, polymerase-based replication.

The polymerase, XP synthase, has been carefully engineered to incorporate large X-NTP monomers, enabling >99.3% mean raw read accuracy, uniform GC coverage, and longer read lengths. Polymerase enhancing moieties, or PEMs, are also added to the synthesis reaction to assist the polymerase in properly incorporating X-NTPs into the growing polymer. 

By stabilizing the extending molecule, PEMs play an important role in increasing read length beyond traditional short-read sequencing technologies. Following synthesis of the surrogate molecule, acid-cleavable bonds are broken, allowing the newly synthesized Xpandomer to extend 50X longer than the original DNA molecule. 

Single-molecule measurement

The Xpandomer molecule is then routed through a biological nanopore in a highly efficient and accurate manner.

Movement of the Xpandomer through the pore is guided by voltage pulses that advance the Xpandomer through the pore one reporter code at a time. 

The highly differentiated reporter codes are easily measured during this translocation process via a scalable complementary metal oxide semiconductor (CMOS)-based array, which combines electrodes, detection circuits, and analog-to-digital conversion. Because the CMOS array contains roughly eight million microwells (each containing a nanopore), measurement occurs in a massively parallel, highly controlled manner without the convolution issues of traditional nanopore sequencing. The result is the cost-effective measurement of hundreds of millions of bases per second, bypassing the traditional approach of cyclical incorporation and measurement of a single base at a time. 

The SBX technology is in development and not commercially available. The content of this material reflects current study results or design goals.

  • ASHG materials
  • ESHG materials
  • AGBT materials

ASHG 2025 Workshop Videos

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Event posters

Demonstrating the versatility, accuracy and throughput of Sequencing By Expansion (SBX)

Enhanced Detection of Structural Variants, VNTRs, and Haplotype Phasing with SBX Simplex Longer Sequencing (SBX-SL)

Whole Genome Precision at Scale: Sequencing by Expansion for Cancer Genomics Research

Whole Genome Sequencing Minimum Residual Disease Detection using Sequencing By Expansion (SBX)

ESHG workshop resources

Engineered for both quality and efficiency, SBX offers high-accuracy whole-genome sequencing (WGS) through its duplex sequencing method, SBX-D. This innovative approach links both strands of the target DNA within a single read. 

Utilizing SBX-D, seven genome in a bottle (GIAB) reference samples can be sequenced at over 30X coverage in less than one hour, achieving impressive F1 scores of greater than 99.8% for single nucleotide variants (SNVs) and greater than 99.7% for insertions and deletions (Indels). This presentation further details the high-sensitivity variant calling performance of SBX-D using paired tumor/normal formalin-fixed paraffin-embedded (FFPE) samples. Additionally, data was presented from a 15-sample, tissue-aware Minimal Residual Disease (MRD) study, demonstrating the detection of MRD at levels as low as 1x10⁻⁶ tumor fraction. Furthermore, the utility of longer (~1000mer) SBX-simplex reads, which offer a throughput of 1 Tb per sequencing hour, is also discussed. Watch this presentation to discover more about Roche’s novel SBX technology and its remarkable potential.

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Sequencing by Expansion (SBX): A versatile, high throughput single molecule sequencing technology

Mark Kokoris

Head, SBX Technology
Roche Diagnostics Solutions

Sean Hofherr, PhD @ESHG25

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Refining the SBX Fast workflow for reproducible speed and performance

Sean Hofherr, PhD, FACMG

Chief of Clinical Strategy and Product Development
Broad Clinical Labs

Redefining nanopore sequencing with Duplex Sequencing by Expansion (SBX-D)

A high-accuracy, high-throughput sequencing technology

SBX sequencing as a flexible RNA-seq toolkit

Enabling high throughput single cell transcriptomic profiling at scale

AGBT workshop presentations

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SBX Technology

Mark Kokoris
Head, SBX Technology
Roche Diagnostics Solutions

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Cancer Whole Genome Sequencing using SBX technology

Edwin Cuppen
Scientific director
Hartwig Medical Foundation

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Enabling Rapid WGS for Trios by Roche SBX Technology

Sean Hofherr, PhD, FACMG
Chief of Clinical Strategy and Product Development
Broad Clinical Labs

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Multiomic drug response profiling in highly multiplexed cancer cell lines

Aziz Al'Khafaji, PhD
Director, Molecular R&D
PI, Methods Development Lab
Broad Clinical Labs

The SBX technology is in development and not commercially available. The content of this material reflects current study results or design goals.

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