# Analytical validation of NeXT Personal®, an ultra-sensitive personalized circulating tumor DNA assay

Source: https://onco.cc/key-papers/paper-northcott-next-personal-validation-oncotarget-2024/  
OnCo record `paper-northcott-next-personal-validation-oncotarget-2024` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The laboratory validation of Personalis' whole-genome blood test for leftover cancer, which detected tumour DNA at a few parts per million.

## Summary

NeXT Personal uses whole-genome sequencing of tumour and matched normal to identify up to about 1,800 patient-specific somatic variants for a personalised panel, sequenced in plasma cell-free DNA. Validation used panels from two cell lines and 123 patients across nine cancer types. The detection threshold was 1.67 parts per million and the 95 per cent limit of detection 3.45 parts per million; the assay was linear from 0.8 to 300,000 parts per million (Pearson 0.9998), precision ranged from a coefficient of variation of 12.8 to 3.6 per cent across 25 to 25,000 parts per million, and specificity measured 100 per cent against a 99.9 per cent target.

## Fields

- Kind: Key paper
- Last checked: 2026-11-04
- Journal: Oncotarget
- Year: 2024
- DOI: 10.18632/oncotarget.28565
- Authors: Northcott J, Bartha G, Harris J, et al.
- Findings: Detection threshold 1.67 ppm; LOD95 3.45 ppm.; Linear from 0.8 to 300,000 ppm.; Up to about 1,800 tracked variants per patient.
- What it means: Personalised whole-genome designs can detect tumour DNA at a few parts per million. The panel favours variants present at high fraction in the tumour, so it is built to detect the trunk, not to tell branches apart.
- Caveats: Company-authored analytical validation.; Personalis' product page gives a limit of quantification of 10 parts per million, so detections below that are not quantitative by the company's own definition.; Validated cell-free DNA input was 2 to 30 ng.

## Sources

- Northcott et al., Oncotarget 2024: https://doi.org/10.18632/oncotarget.28565
- PubMed: https://pubmed.ncbi.nlm.nih.gov/38484152/

## Connected records

- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/)
- technologies: [MRD / molecular residual disease testing](https://onco.cc/technologies/mrd-testing/), [Whole-exome & whole-genome sequencing](https://onco.cc/technologies/wes-wgs/)
- drugs: [NeXT Personal Dx](https://onco.cc/drugs/next-personal/)
- companies: [Personalis (Tempus)](https://onco.cc/companies/personalis/)
- terms: [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [Minimal / molecular residual disease (MRD)](https://onco.cc/terms/mrd/), [Tumour-informed versus tumour-naive ctDNA assays](https://onco.cc/terms/tumour-informed-assay/)
- bottlenecks: [Naming which clone or phenotype is left after treatment](https://onco.cc/bottlenecks/b-subclone-attribution-residual-disease/)
- journals: [Oncotarget](https://onco.cc/journals/oncotarget/)
- biomarkers: [ctDNA MRD positivity (molecular residual disease after curative treatment)](https://onco.cc/biomarkers/ctdna-mrd-positive/)

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