New prospective sub-study analysis data presented by Abbott at the 2026 American Society of Clinical Oncology (ASCO) meeting has highlighted the value of minimal residual disease (MRD) testing in charting distant recurrences in triple-negative breast cancer (TNBC) patients.
In a sub-study of Cambridge University Hospitals NHS Foundation Trust’s PARTNER trial (NCT03150576), Abbott evaluated blood samples for ctDNA analysis during and post-neoadjuvant chemotherapy (NAC) with two tumour-informed MRD assays using primary tumour and germline sequencing.
TNBC patients enrolled within PARTNER underwent serial blood collections at baseline (prior to NAC), mid-NAC, post-NAC, two to four weeks post-op, three months post-op, and 12 months post-op. Germline and somatic DNA were provided to Abbott via the Personalised Breast Cancer Programme. The primary objective of Abbott’s analyses was to determine the association of circulating tumour DNA (ctDNA) positivity post-op with the distant recurrence-free interval (DRFI).
Abbott used two versions of the Oncodetect test, developed by Exact Sciences, which it inherited following a $21bn acquisition of the company in March 2026. Oncodetect used whole-exome sequencing (WES) to select ≤200 variants or whole-genome sequencing (WGS) to select 400-5000 variants to prepare the two MRD assay versions, respectively.
For the WES MRD assay, median panel size was 159 variants. At baseline, ctDNA was detected in 51 of 56 patients (91%). Following surgery, five of 62 patients (8%) had detectable ctDNA. Distant recurrences developed in nine patients (15%), three of whom were ctDNA-positive following surgery, within a median follow-up of five years.
For the WGS MRD assay, median panel size was 3,429 variants. At baseline, ctDNA was detected in 59 of 60 patients (98%).
Abbott concluded that post-operative detection of ctDNA using a WES MRD assay was ‘highly prognostic’ for distant recurrence in TNBC patients following NAC, while WGS MRD improved ctDNA detection at all timepoints.
In written comments to Medical Device Network, Dr Rick Baehner, CMO, Precision Oncology, Abbott’s cancer diagnostics business, said: “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. At the same time, advances in multi-cancer early detection are helping move cancer diagnosis further upstream, with the goal of finding cancer before symptoms appear.
“As these technologies continue to mature and gain adoption, we believe they have the potential to fundamentally shift cancer care toward earlier detection, earlier intervention, and more personalised management throughout a patient's journey.”
Large players within the diagnostics space are building out their MRD testing provision. Roche subsidiary Foundation Medicine acquired Saga Diagnostics in a $595m buyout in April 2026, with the company’s CEO, Dan Malarek, touting MRD tests as “one of the fastest-growing areas within diagnostics”.
