BillionToOne's Northstar Response Assay Shows Strong Concordance with Tumor-Informed ctDNA Assay

MENLO PARK, Calif., Oct. 07, 2026 /CourierPR/ -- BillionToOne, a next-generation molecular diagnostics company, has announced the publication of a peer-reviewed study comparing its tissue-free Northstar Response® assay with a commercially available tumor-informed ctDNA assay. The study, published in The Journal of Liquid Biopsy, evaluated 169 paired samples from 61 patients, with 71 samples from 36 patients that had sequential concurrent draws for the two assays collected within seven days of each other.

Northstar Response, a methylation-based liquid biopsy assay utilizing patented single-molecule counting technology, tracked disease dynamics on par with or better than the tumor-informed comparator, without requiring tissue sequencing. The retrospective real-world study found that quantitative results, after patient-specific baseline normalization, across repeated measurements were closely aligned (conditional R² = 0.97). Across evaluable sequential pairs, the two approaches reached the same conclusion of the change in tumor burden direction in 94% of cases (67 of 71).

Importantly, in all of the divergent cases, Northstar Response results were concordant with the ground truth substantiated by imaging and/or biopsy, indicating that the tumor-informed results were either false-positives or false-negatives. For instance, Northstar Response detected progression in cases where the tumor had evolved since the original biopsy, including a case of hormone receptor conversion in advanced breast cancer. Together, the cases illustrate the particular value of tumor-agnostic monitoring to track tumor burden and evolution.

Since Northstar Response is not limited to alterations selected from an earlier tissue sample at a fixed point in time, it can capture clinically meaningful changes in disease biology that emerge under treatment pressure. Northstar Response’s simplified workflow can also significantly accelerate the start of molecular monitoring of treatment, potentially by weeks, and enable testing when tissue is unavailable, inadequate, or difficult to biopsy.

Northstar Response is BillionToOne's tissue-free, methylation-based ctDNA assay purpose-built for treatment response monitoring in patients with cancer. Powered by the company's patented QCT™ molecular counting platform, Northstar Response quantifies tumor burden through serial blood draws with no dependence on tumor tissue at any stage of the patient journey.

BillionToOne, headquartered in Menlo Park, California, is a next-generation molecular diagnostics company with a mission to create powerful and accurate tests that are accessible to all. The company's proprietary single-molecule next-generation sequencing (smNGS) platform is the only multiplex technology that can detect and precisely quantify genetic targets at the physical limit of detection, down to the single DNA molecule. Enabled by Quantitative Counting Templates™ (QCTs™), the platform quantifies disease-related DNA fragments with single base-pair resolution, providing absolute quantification.

Volume 14, 2026, 100669.