Liquid Biopsy Test May Offer Faster Feedback On Breast Cancer Therapy

Not all therapies work for every person — treatment success can be dependent upon a variety of factors, including the type of breast cancer a person has, their breast cancer stage, and their overall health. This makes it difficult for doctors to predict how well a treatment will work for each patient.

Now, a new study published in the journal Clinical Cancer Research showcases a new liquid biopsy that can help predict how well patients with advanced breast cancer will respond to targeted therapies.

For this study, researchers analyzed blood samples from 167 people with advanced breast cancer taking part in the plasmaMATCH trial to look for circulating tumor DNA (ctDNA) — extremely small pieces of DNA from cancerous cells and tumors that can be found in the bloodstream.

Scientists measured the amount of ctDNA both before the start of breast cancer treatment and 4 weeks after treatment began.

In the first group, researchers found that participants with undetectable ctDNA in their bloodstream had good outcomes after 4 weeks of treatment — their cancer remained dormant for 10.6 months, compared with 3.5 months for those with detectable ctDNA.

In this same group, 46.2% of participants with low levels of ctDNA after 4 weeks responded to treatment, while only 7.9% responded to treatment among participants whose ctDNA levels remained high.

In the second group, having low ctDNA levels before treatment began was linked with 10.2 months of breast cancer progression-free survival, compared to 4.4 months for those with higher ctDNA amounts.

In this same group, 40% of participants with low ctDNA levels responded to treatment, compared to 9.7% for those with high levels.

Additionally, in the second participant group, researchers found a correlation between ctDNA levels and patient outcomes.

For example, participants with no longer detectable ctDNA levels averted their breast cancer for 12 months and 85.7% responded to therapy, compared to 4.3 months and 11.4% among participants with detectable ctDNA amounts.

“By analysing circulating tumor DNA in blood samples from patients with advanced breast cancer, we identified a clear link between these levels, both at the start and after one cycle of treatment, and how well patients responded to therapy,” Iseult Browne, MD, clinical research fellow at The Institute of Cancer Research, London, in the U.K., and first author of the study, said in a press release.

“Patients with low or undetectable ctDNA consistently had better outcomes, including longer progression-free survival and higher response rates. These findings support the use of ctDNA as a non-invasive biomarker for predicting outcomes and monitoring treatment response.”

– Iseult Browne, MD

Medical News Today had the opportunity to speak with Richard Reitherman, MD, PhD, a board-certified radiologist and medical director of breast imaging at MemorialCare Breast Center at Orange Coast Medical Center in Fountain Valley, CA, about this study.

Reitherman, who was not involved in the research, explained that this study had a participant population of breast cancer patients whose cancer has spread to other organs outside of the breast and axilla, which is stage 4 or metastatic.

“Detecting and treating breast cancer when it has spread to other organs — commonly bone, liver, and lungs — is more difficult,” he continued.

“The importance of the current article relates to not only earlier detection of metastatic disease, more precise ability to monitor response to treatment, but also to how ctDNA levels can be prognostic in terms of predicting which patients will respond to treatment and who will not.”

“Treatment of metastatic disease usually involves a succession of alternative drugs over time as the cancer develops resistance to a specific drug,” Reitherman added.

According to him, “this study demonstrates how liquid biopsy monitoring of ctDNA allows earlier identification of responders and non-responders so that treatments can be adjusted.”

Reitherman commented that this study documents the amazing scientific advances that are not limited to basic research, but are translational and have actual benefit to breast cancer patients facing metastatic breast cancer today.

“Hope is essential to breast cancer patients — they need something to believe in that is not just for today, but for their future,” he added.

MNT also spoke with Richard Zelkowitz, MD, medical director of breast oncology at Hartford HealthCare Cancer Institute, about this research who commented he found the results to be extremely exciting.

“Being able to identify patients who might not be responding well to a specific treatment and making that change in the patient’s treatment plan as soon as possible, is a game-changer for metastatic breast cancer care,” Zelkowitz explained.

“As standard of care in patients with hormone sensitive advanced breast cancer, we continuously monitor circulating DNA to help us focus specific types of treatment for those with advanced disease. This ensures we can provide more personalized care,” he added.

“The importance of early predictions is so vital when it comes to treating advanced stages of breast cancer,” Zelkowitz continued.

“Knowing whether a treatment is working through a simple blood test can make all the difference in providing patients with the best possible treatment plan and outcomes. If you can assess response, you know how to continue therapy,” he told us.

“We need to be able to correlate these results with patient survival,” Zelkowitz added. “If we can show that early detection resulted in change improving a patient’s quality of life and better outcomes, that will be the key.”