At the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, Abbott presented new prospective sub-study findings demonstrating the potential of minimal residual disease (MRD) testing to predict distant recurrence in patients with triple-negative breast cancer (TNBC), one of the most aggressive forms of breast cancer.

The data stem from a sub-study of the PARTNER trial (NCT03150576), conducted by Cambridge University Hospitals NHS Foundation Trust, in which Abbott evaluated circulating tumour DNA (ctDNA) in blood samples collected from TNBC patients undergoing neoadjuvant chemotherapy (NAC).

The analysis explored whether tumour-informed MRD assays could identify patients at higher risk of disease recurrence following treatment.

Patients enrolled in the PARTNER trial underwent serial blood collections at multiple time points, including before treatment, during chemotherapy, after chemotherapy, following surgery, and during post-operative follow-up. Abbott’s primary objective was to determine the relationship between post-operative ctDNA positivity and distant recurrence-free interval (DRFI).

For the study, Abbott used OncoDetect, an MRD testing platform originally developed by Exact Sciences and acquired by Abbott as part of its $21 billion acquisition of the company in March 2026.

The platform enabled the development of two tumour-informed MRD assays based on whole-exome sequencing (WES) and whole-genome sequencing (WGS), respectively.

The WES-based assay, which used a median panel size of 159 variants, detected ctDNA in 91% of patients at baseline. Following neoadjuvant chemotherapy, detectable ctDNA remained in only four of 63 patients. Over a median follow-up period of five years, distant recurrences were observed in eight patients, representing 13.1% of the study population.

The WGS-based assay employed a substantially larger median panel size of 2,962 variants and demonstrated enhanced sensitivity, detecting ctDNA in 98% of patients at baseline.

 According to Abbott, post-operative ctDNA detection using the WES MRD assay proved highly prognostic for distant recurrence among TNBC patients treated with neoadjuvant chemotherapy, while the WGS approach improved ctDNA detection rates at diagnosis.

Dr. Rick Baehner, Chief Medical Officer, Precision Oncology, Abbott’s cancer diagnostics business, said that the study underscores the growing role of next-generation MRD technologies in personalising cancer care.

“Through our PARTNER study specifically, we’re seeing the potential for next-generation MRD testing to help identify recurrence risk earlier and provide more personalised insight after treatment,” said Baehner.