Review of SIMMA utility for paediatric tumour monitoring via cfDNA profiling and ecDNA detection

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medRxiv Published April 18, 2026 Medically reviewed April 25, 2026 Study authors: Sauer, C. M.; Tovey, N.; Ptasinska, A.; Hughes, D.; Stockton, J.; Zumalave, S.; Rust, A. G.; Lynn, C… DOI ↗ By Dr. Julia Lee, PhD · Oncology, Genomics & Drug Development

Key Takeaway

Consider SIMMA cfDNA profiling for paediatric tumour monitoring, noting ecDNA detection months before relapse.

This publication is a review examining the application of the SIMMA single-molecule sequencing approach for liquid biopsy in paediatric oncology. The scope encompasses the analysis of 792 plasma and cerebrospinal fluid cfDNA samples collected from 277 paediatric patients diagnosed with diverse brain and extracranial tumours. The authors focus on the utility of this multimodal cfDNA profiling method for individual patient management across aggressive malignancies.

The key synthesized findings highlight the method's ability to reconstruct extrachromosomal DNA (ecDNA) and predict disease burden. The review indicates that ecDNA reconstruction can occur months before clinical relapse, offering a potential early warning signal. Additionally, the limit of detection for the assay is reported as approximately 100 ppm. These results aim to unlock the potential of ecDNA as a biomarker for disease detection and monitoring.

The authors establish the clinical utility of this approach for individual patients, emphasizing its capacity to provide uncertainty estimates alongside diagnostic data. However, the review does not report specific adverse events, discontinuations, or detailed study design elements such as randomization. Consequently, the practice relevance is framed around the potential of the technology rather than definitive clinical guidelines derived from a randomized trial.

In conclusion, this review supports the exploration of SIMMA for monitoring paediatric tumours but cautions against inferring causality or overstating certainty given the narrative nature of the source. The findings suggest that ecDNA profiling may complement existing monitoring strategies, though further validation is implied by the lack of reported safety data and statistical confidence intervals in this synthesis.

Study Details

EvidenceLevel 5

PublishedApr 2026

View Original Abstract ↓

Cell-free DNA (cfDNA) profiling enables minimally invasive cancer detection and monitoring. We present SIMMA, a low-input single-molecule sequencing approach that enables multimodal whole-genome and high-depth targeted sequencing of the same cfDNA sample for both tumour-agnostic and tumour-informed liquid biopsy analysis. Across 792 plasma and cerebrospinal fluid cfDNA samples from 277 paediatric patients with diverse brain and extracranial tumours, SIMMA enabled tumour diagnosis, detection of driver mutations, and reconstruction of extrachromosomal DNA (ecDNA) months before clinical relapse. Using conformal prediction trained on genome-wide fragmentomics, genomic and epigenomic data, SIMMA predicts disease burden as a continuous variable and provides well-calibrated uncertainty estimates for each sample, achieving a limit of detection of [~]100 ppm from low-pass whole-genome sequencing data. In summary, SIMMA establishes the clinical utility of multimodal cfDNA profiling with uncertainty quantification for individual patients and unlocks the potential of ecDNA as a liquid biopsy biomarker for disease detection and monitoring across diverse aggressive malignancies.