Liquid biopsy has emerged as a promising tool in the clinical care of patients living with breast cancer. In recent years, these tests have shown potential in identifying actionable alterations, monitoring treatment response and genomic evolution, and detecting minimal residual disease (MRD). Recent data have sparked discussion among researchers, clinicians, and patient advocates about circulating tumor DNA (ctDNA) assays as a guide in adaptive clinical trials. Other new and exciting opportunities are on the horizon.

Sessions at the 48th annual San Antonio Breast Cancer Symposium^®, December 9-12, will explore this dynamic landscape of liquid biopsy in breast cancer and address questions about the current and future applications of the technology.

“Multiple potential assays are available for oncologists in routine clinical practice. Which one has to be used in what setting, when or when not we should use them, or how? Clinicians may not have the technical expertise, but patients ask for it, so a lot of these practical questions come up,” said SABCS^® Program Planning Committee Member Pedram Razavi, MD, PhD, Breast Medical Oncologist at Memorial Sloan Kettering Cancer Center.

“And then what is on the horizon for ctDNA?” he added. “How can we use it, what different types of clinical trials can be designed?”

Experts will begin by discussing innovations in liquid biopsy on Tuesday, December 9, from 12:45 to 2:15 p.m., during Translational Workshop 2: Liquid Biopsy in Breast Cancer, Bridging Technology and Clinical Practice. The workshop will review emerging technologies, including cell-free RNA sequencing, novel ctDNA analyses, and more. The session will also feature a neurologist’s insights about the diagnostic potential of ctDNA in central nervous system metastases. And Dr. Razavi, who will moderate the session, will highlight ctDNA’s potential to monitor disease and the design of adaptive clinical trials to guide escalation or de-escalation of patient care.

The recent SERENA-6 trial showed a benefit to modifying therapy based on early detection of ESR1 mutations via serial ctDNA monitoring. While the biological and clinical implications of these findings are important and support the idea that early eradication of resistant clones can improve outcomes, the results have also sparked debate among experts regarding the optimal implementation of such strategies, Dr. Razavi said. As ultrasensitive ctDNA MRD assays continue to advance and push the limits of ctDNA detection forward a hundred- or thousandfold, similar adaptive strategies have the potential to revolutionize clinical trials and make a big difference for patients in both early- and late-stage settings, he said.

“There is significant amount of both over- and under-treatment in breast cancer. We are not only trying to improve the outcomes for our patients, but also trying to move toward more precise, individualized care that spares patients unnecessary toxicity while maximizing their chances of long-term control and cure,” Dr. Razavi said.

State of the Art 1 – Refining Risk and Tailoring Treatment: Liquid Biopsy for Adaptive Therapy in Breast Cancer, on Wednesday, December 10, from 1 to 2:15 p.m., will further explore the possibilities for liquid biopsy to detect MRD, stratify patients by risk, and guide personalized management strategies during or after curative intent therapy.

As SABCS 2025 nears, don’t be surprised to hear about additional poster abstracts and oral presentations detailing developments in ctDNA liquid biopsy, Dr. Razavi said. The topic should continue to be of great interest to clinicians, translational researchers, basic scientists, and patient advocates for years to come.

“ctDNA is here to stay and transform our practice, and we haven’t even tapped into most of the potential,” Dr. Razavi said.