Liquid biopsy & ctDNA diagnostics

Liquid biopsy and ctDNA diagnostics detect and sequence circulating tumor DNA (ctDNA) — tumor-derived DNA fragments shed into the bloodstream — from a blood draw instead of a surgical tissue sample, using next-generation sequencing (NGS) or digital PCR to identify actionable mutations, guide companion-diagnostic drug matching, and track molecular residual disease (MRD) after treatment. Guardant Health’s Guardant360 CDx received FDA approval as a companion diagnostic for Boehringer Ingelheim’s HERNEXEOS in 2026, and the company’s newly expanded Guardant360 Liquid CDx panel is the largest FDA-approved liquid biopsy panel to date, with a 100x expanded genomic footprint. Natera’s Signatera MRD test has IVDR certification across multiple cancers, is FDA-approved as a companion diagnostic in muscle-invasive bladder cancer, and is now recommended by NCCN guidelines for bladder-cancer ctDNA-MRD testing. Foundation Medicine (Roche) has stacked FDA companion-diagnostic approvals for FoundationOne CDx and FoundationOne Liquid CDx across NSCLC, prostate and other indications, and launched FoundationOneMRD, combining structural-variant detection with digital PCR. Sysmex Inostics supplies PlasmaSeqSensei NGS kits and targeted oncology panels, with published clinical evidence that its circulating-tumor-HPV-DNA assay predicts survival. MedGenome contributes ctDNA biomarker research and oncology genomics services from India, and Burning Rock Biotech is a Nasdaq-listed Chinese liquid-biopsy company running NGS-based ctDNA panels for solid-tumor profiling.

The key directions of liquid biopsy and ctDNA diagnostics are:

1. Companion diagnostics (Companion Diagnostics): ctDNA panels approved alongside a specific targeted therapy to select eligible patients — Guardant360 CDx, FoundationOne CDx/Liquid CDx, Signatera CDx.
2. Molecular residual disease monitoring (Minimal Residual Disease MRD): post-treatment blood tests that detect trace ctDNA to flag recurrence before imaging can — Signatera, FoundationOneMRD.
3. Broad genomic profiling (Circulating Tumor DNA): pan-cancer NGS panels sequencing hundreds of genes from a single blood draw for treatment selection — Guardant360, Sysmex Inostics targeted panels.
4. Ultra-sensitive detection chemistry (Digital PCR): digital PCR and tumor-informed sequencing methods pushing detection sensitivity into the parts-per-million range needed for MRD.

Sectoral value chain#

[blood draw & cfDNA/ctDNA extraction] ──> [library prep & NGS / digital PCR] ──> [bioinformatics variant calling]
                                                        │
                                          (companion-diagnostic / MRD algorithm)
                                                        │
                                                        ▼
[longitudinal MRD monitoring] <─── [regulatory approval & reimbursement] <─────┘

Value chain levels#

Cross-cutting technologies of the sector:

• Circulating tumor DNA sequencing (Circulating Tumor DNA): NGS panels sequencing cfDNA to detect tumor-derived mutations at low allele fractions without a surgical biopsy.
• Digital PCR (Digital PCR): partition-based PCR quantification reaching the ultra-low-frequency sensitivity MRD detection requires, complementing broader NGS panels.
• Tumor-informed MRD algorithms (Minimal Residual Disease MRD): patient-specific variant panels (built from the resected tumor) tracked in serial blood draws to detect molecular recurrence months before imaging.

The stack pairs cell-free DNA extraction with ultra-sensitive NGS and digital-PCR detection chemistries, then layers tumor-informed bioinformatics to separate true low-frequency tumor signal from background sequencing noise.

1. Broad NGS genomic profiling (Circulating Tumor DNA):
   • Guardant360’s expanded panel and FoundationOne Liquid CDx sequence hundreds of cancer genes directly from plasma cfDNA, matching patients to targeted therapies without a tissue biopsy.
2. Tumor-informed MRD detection (Minimal Residual Disease MRD):
   • Natera’s Signatera and Foundation Medicine’s FoundationOneMRD build a patient-specific variant panel from the resected tumor, then track those exact variants in serial blood draws at sensitivity sufficient to flag recurrence before imaging.
3. Digital PCR and targeted panels (Digital PCR):
   • Sysmex Inostics’ PlasmaSeqSensei kits and targeted panel assays (including circulating-tumor-HPV-DNA) use partition-based digital PCR alongside NGS for ultra-low-frequency variant detection.
4. Companion-diagnostic regulatory linkage (Companion Diagnostics):
   • US CDx approvals (Guardant360 CDx, FoundationOne CDx/Liquid CDx, Signatera CDx) and EU IVDR certification tie the assay directly to an approved drug label, the commercial core of the sector’s reimbursement model.