Study Confirms High Concordance for Northstar Response ctDNA Test

BillionToOne, Inc. has announced the publication of a peer-reviewed study in The Journal of Liquid Biopsy that assesses the performance of Northstar Response®, a non-invasive liquid biopsy assay, in comparison to a commercially available tumor-informed ctDNA assay for patients with advanced cancer.

This study, the first of its kind, evaluates 169 paired samples from 61 patients, of which 71 samples from 36 patients had sequential draws for both assays within a week. The results indicate that Northstar Response effectively tracked changes in tumor burden, achieving a 94% concordance rate with the tumor-informed ctDNA results across evaluable sequential pairs (67 of 71). The quantitative results across repeated measurements demonstrated a strong correlation (conditional R² = 0.97).

Crucially, all discordant results from the Northstar Response assay were validated against clinical imaging and/or biopsy data, suggesting that the tumor-informed assay results were false-positive or false-negative. Examples include instances where Northstar Response detected disease progression due to tumor evolution, such as a case of hormone receptor conversion in advanced breast cancer. These findings highlight the significance of tumor-agnostic monitoring methods for tracking tumor dynamics.

Dr. Vaia Florou, Associate Professor of Oncology at the University of Utah's Huntsman Cancer Institute, commented on the implications of the findings: "The ability to combine cancer-associated methylation with single-molecule precision to track changing tumor signals directly from blood is game-changing, as so many patients in the clinic will benefit."

Northstar Response allows for monitoring of treatment response without the need for tissue sequencing, making it particularly beneficial when such samples are unavailable or inadequate. The simplified workflow promises faster initiation of molecular monitoring, potentially reducing wait times by weeks.

Dr. Allen Chen, Vice President of Oncology Clinical Development and Medical Affairs at BillionToOne, stated, "Northstar Response not only provides high accuracy in assessing disease evolution during treatment but also improves accessibility to molecular testing for a broader patient population."

Northstar Response is specifically designed for treatment response monitoring in cancer patients, utilizing BillionToOne's patented QCT™ molecular counting platform to quantify ctDNA in sequential blood samples, independent of earlier tissue samples.

It is important to note that Northstar Response may yield false-positive or false-negative results and should not be the sole basis for medical decision-making. It is a laboratory-developed test performed in a CLIA-certified and CAP-accredited laboratory and has not been approved by the U.S. Food and Drug Administration (FDA).

Reference: Choksi A, Varga MG, Farmer T, et al. Concordance of tumor-informed and tumor-agnostic ctDNA assays for treatment response monitoring in advanced solid tumors. The Journal of Liquid Biopsy. Volume 14, 2026, 100669.