ctDNA Dynamics MRD Agent
The ctDNA Dynamics MRD Agent provides comprehensive analysis of circulating tumor DNA dynamics for molecular residual disease (MRD) detection, treatment response monitoring, and early relapse prediction. It integrates tumor-informed and tumor-naive approaches with temporal modeling for longitudinal ctDNA analysis.
When to Use This Skill
- When monitoring minimal/molecular residual disease post-treatment.
- For tracking treatment response through ctDNA kinetics.
- To predict relapse before clinical/radiological detection.
- When assessing tumor burden dynamics during therapy.
- For early detection of acquired resistance mutations.
Core Capabilities
MRD Detection: Ultra-sensitive detection of residual disease (LOD 0.001% VAF).
Kinetic Modeling: Model ctDNA clearance and doubling time.
Response Prediction: Predict treatment response from early ctDNA dynamics.
Relapse Prediction: Identify molecular relapse months before imaging.
Resistance Monitoring: Track emergence of resistance mutations.
Multi-Timepoint Integration: Analyze longitudinal ctDNA trajectories.
Detection Approaches
| Approach |
Method |
LOD |
Best Use Case |
| Tumor-Informed |
Track known mutations |
0.001% |
Post-surgical MRD |
| Tumor-Naive |
Panel-based detection |
0.1% |
Screening, unknown primary |
| WGS-Based |
Fragmentomics + mutations |
0.01% |
Comprehensive profiling |
| Methylation |
cfDNA methylation |
0.1% |
Tissue of origin, early detection |
Kinetic Parameters
| Parameter |
Definition |
Clinical Meaning |
| ctDNA Half-Life |
Time to 50% reduction |
Treatment sensitivity |
| Doubling Time |
Time to 2x increase |
Tumor growth rate |
| Nadir |
Lowest ctDNA level |
Depth of response |
| Time to Nadir |
Days to reach nadir |
Response kinetics |
| Clearance Rate |
Exponential decay constant |
Treatment efficacy |
| Lead Time |
MRD+ to clinical relapse |
Early detection window |
Workflow
Input: Serial ctDNA measurements (VAF or copies/mL), timepoints, treatment dates.
QC: Assess sequencing quality, coverage, tumor fraction.
Mutation Tracking: Quantify tracked variants across timepoints.
Kinetic Modeling: Fit exponential/sigmoidal models to dynamics.
MRD Calling: Determine MRD status with confidence intervals.
Resistance Detection: Identify emerging resistant clones.
Output: MRD status, kinetic parameters, predictions, visualizations.
Example Usage
User: "Analyze this patient's serial ctDNA data to assess MRD status and predict relapse risk."
Agent Action:
python3 Skills/Oncology/ctDNA_Dynamics_MRD_Agent/ctdna_mrd_analysis.py \
--ctdna_data serial_ctdna.tsv \
--tracked_mutations tumor_mutations.vcf \
--sample_times 0,14,42,90,180 \
--treatment_start 0 \
--surgery_date 7 \
--cancer_type colorectal \
--output mrd_analysis/
Input Data Format
Sample_ID Timepoint_Days Mutation VAF Copies_per_mL Coverage
PT001_T0 0 TP53_R248Q 5.2 1500 15000
PT001_T1 14 TP53_R248Q 2.1 620 18000
PT001_T2 42 TP53_R248Q 0.05 15 20000
PT001_T3 90 TP53_R248Q 0.002 0.6 22000
Output Components
| Output |
Description |
Format |
| MRD Status |
Positive/Negative at each timepoint |
.csv |
| Kinetic Parameters |
Half-life, doubling time, nadir |
.json |
| Response Classification |
Major/Minor/No response |
.csv |
| Relapse Risk |
Probability and predicted time |
.json |
| Dynamics Plot |
ctDNA trajectory visualization |
.png, .pdf |
| Resistance Variants |
Emerging mutations |
.vcf |
| Clonal Evolution |
Clone frequency over time |
.csv |
Response Definitions
| Response Category |
ctDNA Change |
Clinical Correlation |
| Major Molecular Response |
>2 log reduction |
Excellent prognosis |
| Molecular Response |
1-2 log reduction |
Good prognosis |
| Stable Molecular Disease |
<1 log change |
Intermediate |
| Molecular Progression |
>0.5 log increase |
Poor prognosis |
Cancer-Specific Parameters
| Cancer Type |
Typical Half-Life |
MRD Lead Time |
ctDNA Shedding |
| Colorectal |
1-2 days |
6-12 months |
High |
| Lung (NSCLC) |
1-3 days |
3-6 months |
High |
| Breast |
2-5 days |
6-18 months |
Moderate |
| Pancreatic |
1-2 days |
3-6 months |
High |
| Melanoma |
2-4 days |
3-9 months |
Variable |
AI/ML Components
Kinetic Modeling:
- Non-linear mixed effects models
- Bayesian hierarchical models
- Gaussian process regression
MRD Detection:
- Error-suppressed variant calling
- Machine learning noise filtering
- Duplex UMI deduplication
Relapse Prediction:
- Time-series forecasting (LSTM, Transformers)
- Survival analysis (Cox, Random Survival Forests)
- Multi-mutation integration
Clinical Trial Support
| Application |
Endpoint |
ctDNA Metric |
| Neoadjuvant |
pathCR surrogate |
Pre-surgery clearance |
| Adjuvant |
DFS surrogate |
Post-surgery MRD |
| Metastatic |
PFS/OS surrogate |
ctDNA dynamics |
| Maintenance |
Duration decision |
MRD negativity |
Prerequisites
- Python 3.10+
- Variant callers (Mutect2, Strelka)
- UMI-aware pipelines
- scipy, lifelines, survival analysis tools
- PyTorch for deep learning models
Related Skills
- MRD_EDGE_Detection_Agent - Ultra-sensitive MRD detection
- Liquid_Biopsy_Analytics_Agent - Comprehensive liquid biopsy
- Tumor_Heterogeneity_Agent - Clonal evolution tracking
- HRD_Analysis_Agent - Genomic biomarkers
Special Considerations
- Tumor Fraction: Low tumor fraction limits sensitivity
- Pre-Analytical: Plasma processing affects cfDNA quality
- Clonal Hematopoiesis: CHIP variants can confound results
- Panel Design: Ensure sufficient mutation coverage
- Timing: Sample timing relative to treatment critical
FDA-Cleared ctDNA Tests
| Test |
Cancer Types |
Application |
| Guardant360 CDx |
Pan-cancer |
Treatment selection |
| FoundationOne Liquid CDx |
Pan-cancer |
Treatment selection |
| Signatera |
Solid tumors |
MRD monitoring |
| Guardant Reveal |
CRC |
MRD detection |
Author
AI Group - Biomedical AI Platform
1---2name: ctdna-dynamics-mrd-agent3description: AI-powered circulating tumor DNA dynamics analysis for molecular residual disease detection, treatment response monitoring, and early relapse prediction using liquid biopsy.4---56<!--7# COPYRIGHT NOTICE8# This file is part of the "Universal Biomedical Skills" project.9# Copyright (c) 2026 MD BABU MIA, PhD <md.babu.mia@mssm.edu>10# All Rights Reserved.11#12# This code is proprietary and confidential.13# Unauthorized copying of this file, via any medium is strictly prohibited.14#15# Provenance: Authenticated by MD BABU MIA1617-->18192021# ctDNA Dynamics MRD Agent2223The **ctDNA Dynamics MRD Agent** provides comprehensive analysis of circulating tumor DNA dynamics for molecular residual disease (MRD) detection, treatment response monitoring, and early relapse prediction. It integrates tumor-informed and tumor-naive approaches with temporal modeling for longitudinal ctDNA analysis.2425## When to Use This Skill2627* When monitoring minimal/molecular residual disease post-treatment.28* For tracking treatment response through ctDNA kinetics.29* To predict relapse before clinical/radiological detection.30* When assessing tumor burden dynamics during therapy.31* For early detection of acquired resistance mutations.3233## Core Capabilities34351. **MRD Detection**: Ultra-sensitive detection of residual disease (LOD 0.001% VAF).36372. **Kinetic Modeling**: Model ctDNA clearance and doubling time.38393. **Response Prediction**: Predict treatment response from early ctDNA dynamics.40414. **Relapse Prediction**: Identify molecular relapse months before imaging.42435. **Resistance Monitoring**: Track emergence of resistance mutations.44456. **Multi-Timepoint Integration**: Analyze longitudinal ctDNA trajectories.4647## Detection Approaches4849| Approach | Method | LOD | Best Use Case |50|----------|--------|-----|---------------|51| Tumor-Informed | Track known mutations | 0.001% | Post-surgical MRD |52| Tumor-Naive | Panel-based detection | 0.1% | Screening, unknown primary |53| WGS-Based | Fragmentomics + mutations | 0.01% | Comprehensive profiling |54| Methylation | cfDNA methylation | 0.1% | Tissue of origin, early detection |5556## Kinetic Parameters5758| Parameter | Definition | Clinical Meaning |59|-----------|------------|------------------|60| ctDNA Half-Life | Time to 50% reduction | Treatment sensitivity |61| Doubling Time | Time to 2x increase | Tumor growth rate |62| Nadir | Lowest ctDNA level | Depth of response |63| Time to Nadir | Days to reach nadir | Response kinetics |64| Clearance Rate | Exponential decay constant | Treatment efficacy |65| Lead Time | MRD+ to clinical relapse | Early detection window |6667## Workflow68691. **Input**: Serial ctDNA measurements (VAF or copies/mL), timepoints, treatment dates.70712. **QC**: Assess sequencing quality, coverage, tumor fraction.72733. **Mutation Tracking**: Quantify tracked variants across timepoints.74754. **Kinetic Modeling**: Fit exponential/sigmoidal models to dynamics.76775. **MRD Calling**: Determine MRD status with confidence intervals.78796. **Resistance Detection**: Identify emerging resistant clones.80817. **Output**: MRD status, kinetic parameters, predictions, visualizations.8283## Example Usage8485**User**: "Analyze this patient's serial ctDNA data to assess MRD status and predict relapse risk."8687**Agent Action**:88```bash89python3 Skills/Oncology/ctDNA_Dynamics_MRD_Agent/ctdna_mrd_analysis.py \90 --ctdna_data serial_ctdna.tsv \91 --tracked_mutations tumor_mutations.vcf \92 --sample_times 0,14,42,90,180 \93 --treatment_start 0 \94 --surgery_date 7 \95 --cancer_type colorectal \96 --output mrd_analysis/97```9899## Input Data Format100101```tsv102Sample_ID Timepoint_Days Mutation VAF Copies_per_mL Coverage103PT001_T0 0 TP53_R248Q 5.2 1500 15000104PT001_T1 14 TP53_R248Q 2.1 620 18000105PT001_T2 42 TP53_R248Q 0.05 15 20000106PT001_T3 90 TP53_R248Q 0.002 0.6 22000107```108109## Output Components110111| Output | Description | Format |112|--------|-------------|--------|113| MRD Status | Positive/Negative at each timepoint | .csv |114| Kinetic Parameters | Half-life, doubling time, nadir | .json |115| Response Classification | Major/Minor/No response | .csv |116| Relapse Risk | Probability and predicted time | .json |117| Dynamics Plot | ctDNA trajectory visualization | .png, .pdf |118| Resistance Variants | Emerging mutations | .vcf |119| Clonal Evolution | Clone frequency over time | .csv |120121## Response Definitions122123| Response Category | ctDNA Change | Clinical Correlation |124|-------------------|--------------|---------------------|125| Major Molecular Response | >2 log reduction | Excellent prognosis |126| Molecular Response | 1-2 log reduction | Good prognosis |127| Stable Molecular Disease | <1 log change | Intermediate |128| Molecular Progression | >0.5 log increase | Poor prognosis |129130## Cancer-Specific Parameters131132| Cancer Type | Typical Half-Life | MRD Lead Time | ctDNA Shedding |133|-------------|-------------------|---------------|----------------|134| Colorectal | 1-2 days | 6-12 months | High |135| Lung (NSCLC) | 1-3 days | 3-6 months | High |136| Breast | 2-5 days | 6-18 months | Moderate |137| Pancreatic | 1-2 days | 3-6 months | High |138| Melanoma | 2-4 days | 3-9 months | Variable |139140## AI/ML Components141142**Kinetic Modeling**:143- Non-linear mixed effects models144- Bayesian hierarchical models145- Gaussian process regression146147**MRD Detection**:148- Error-suppressed variant calling149- Machine learning noise filtering150- Duplex UMI deduplication151152**Relapse Prediction**:153- Time-series forecasting (LSTM, Transformers)154- Survival analysis (Cox, Random Survival Forests)155- Multi-mutation integration156157## Clinical Trial Support158159| Application | Endpoint | ctDNA Metric |160|-------------|----------|--------------|161| Neoadjuvant | pathCR surrogate | Pre-surgery clearance |162| Adjuvant | DFS surrogate | Post-surgery MRD |163| Metastatic | PFS/OS surrogate | ctDNA dynamics |164| Maintenance | Duration decision | MRD negativity |165166## Prerequisites167168* Python 3.10+169* Variant callers (Mutect2, Strelka)170* UMI-aware pipelines171* scipy, lifelines, survival analysis tools172* PyTorch for deep learning models173174## Related Skills175176* MRD_EDGE_Detection_Agent - Ultra-sensitive MRD detection177* Liquid_Biopsy_Analytics_Agent - Comprehensive liquid biopsy178* Tumor_Heterogeneity_Agent - Clonal evolution tracking179* HRD_Analysis_Agent - Genomic biomarkers180181## Special Considerations1821831. **Tumor Fraction**: Low tumor fraction limits sensitivity1842. **Pre-Analytical**: Plasma processing affects cfDNA quality1853. **Clonal Hematopoiesis**: CHIP variants can confound results1864. **Panel Design**: Ensure sufficient mutation coverage1875. **Timing**: Sample timing relative to treatment critical188189## FDA-Cleared ctDNA Tests190191| Test | Cancer Types | Application |192|------|--------------|-------------|193| Guardant360 CDx | Pan-cancer | Treatment selection |194| FoundationOne Liquid CDx | Pan-cancer | Treatment selection |195| Signatera | Solid tumors | MRD monitoring |196| Guardant Reveal | CRC | MRD detection |197198## Author199200AI Group - Biomedical AI Platform201202203<!-- AUTHOR_SIGNATURE: 9a7f3c2e-MD-BABU-MIA-2026-MSSM-SECURE -->