Cell-Free DNA Variant Classification Without White Blood Cell Sequencing

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Solution Overview

Problem

Current liquid biopsy tests face challenges in differentiating cell-free tumor DNA (ctDNA) from other cell-free DNA (cfDNA) due to the presence of clonal hematopoiesis variants and biological noise, necessitating costly and complex workflows involving genotyping the white blood cell fraction.

Innovation Solution

A bioinformatic model that utilizes a computer to generate datasets and ratios of genetic variant frequencies between plasma and white blood cells, applying machine learning models to classify nucleic acid variants as tumor or non-tumor origin, improving sensitivity and specificity without requiring WBC sequencing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If WBC sequencing is performed to filter non-tumor variants, then the specificity of cancer detection is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvespecificity of cancer detectionVSAvoidworkflow complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes non-tumor variants from the cfDNA sample by identifying and filtering out variants originating from clonal hematopoiesis or other non-cancerous sources, retaining only tumor-derived variants for analysis. This extraction approach improves specificity without requiring full WBC sequencing by focusing on distinguishing tumor-specific molecular signatures.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary computational layer that uses machine learning models and bioinformatic algorithms to differentiate tumor variants from non-tumor variants. This intermediary system processes the cfDNA data to identify patterns characteristic of tumor origin versus hematopoietic origin, resolving the contradiction by providing specificity enhancement through software rather than additional wet-lab sequencing steps.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If WBC sequencing is performed to filter non-tumor variants, then the specificity of cancer detection is improved, but the cost increases

Engineering Contradiction:
Improvespecificity of cancer detectionVSAvoidtesting cost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent employs cost-effective computational methods and publicly available machine learning models to achieve variant differentiation. Instead of investing in expensive WBC sequencing infrastructure, the approach uses affordable bioinformatic pipelines that process cfDNA data to filter non-tumor variants, significantly reducing the quantity of financial resources required while maintaining high specificity.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses computational copies and simulations of WBC sequencing results by training machine learning models on reference datasets. Rather than performing actual WBC sequencing on each patient sample, the system creates virtual representations of expected non-tumor variant patterns from training data, enabling cost-effective filtering that replicates the benefits of WBC sequencing without the associated costs.

Inventive Principle:
Principle #26Copying

3Ease of operation

If plasma-only analysis is used without WBC sequencing, then the ease of operation is improved, but the measurement precision deteriorates due to inability to differentiate tumor and non-tumor variants

Engineering Contradiction:
Improvesimplicity of workflowVSAvoidaccuracy of variant classification
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical/biological system of WBC sequencing with a computational/informatic system. Instead of physically separating and sequencing white blood cells, the invention uses machine learning algorithms and bioinformatic analysis to virtually differentiate tumor variants from non-tumor variants in plasma-only samples. This substitution maintains ease of operation while achieving measurement precision through advanced computational methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the analytical parameters by applying machine learning models that evaluate multiple features of detected variants simultaneously (frequency, distribution patterns, molecular signatures) rather than relying on simple presence/absence thresholds. This parameter transformation enables accurate tumor versus non-tumor classification in plasma-only samples, maintaining both operational simplicity and measurement precision.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS20250336472A1Validation of a bioinformatic model for classifying non-tumor variants in a cell-free DNA liquid biopsy assay
Publication Date: 2025.10.30 GUARDANT HEALTH INC
  • US20250336472A1 patent drawing
  • US20250336472A1 patent drawing
  • US20250336472A1 patent drawing

AI summary

Provided herein are methods of differentiating tumor and non-tumor origin nucleic acid variants in cell-free nucleic acid (cfNA) samples. Certain of these methods include generating a tumor variant dataset comprising a population of reference tumor-related genetic variants in which the tumor variant dataset comprises frequency of observance data among reference samples that comprises reference plasma only samples and reference white blood samples for tumor-related genetic variants in the population of reference tumor-related genetic variants and determining ratios of the frequency of observance data between the reference samples for tumor-related genetic variants in the population of reference tumor-related genetic variants to produce a relative prevalence dataset. Additional methods and related systems and computer readable media are also provided.