Studies show prognostic value for circulating tumor cells in advanced prostate and breast cancer

Menarini Silicon Biosystems, the pioneer of liquid biopsy and single cell technologies, announced today that results from a new study presented at the virtual 2020 meeting of the American Society of Clinical Oncology (ASCO) suggest that circulating tumor cell (CTC) counts may be useful in determining long-term prognosis and guiding treatment selection in patients with metastatic castrate sensitive prostate cancer (mCSPC). A second study showed predictive value of CTC counts in metastatic breast cancer. Researchers used Menarini's CELLSEARCH^® Circulating Tumor Cell test, considered the gold standard in liquid biopsy technology, to detect and count CTCs.

A current challenge in treating mCSPC is the lack of accurate biomarkers that indicate which patients will do well with particular therapies, or how long patients will live, according to lead researcher, Amir Goldkorn, M.D., Associate Professor of Medicine at the University of Southern California's Keck School of Medicine. With this study, researchers determined CTC counts are a non-invasive way to obtain valuable prognostic information at the start of treatment.

These findings have important clinical implications, suggesting that patients with high initial CTC counts are less likely to respond and more likely to progress on hormonal therapy. Though additional analysis is required, these results indicate that CTCs could become a valuable biomarker that can tell us about a patient's long-term prognosis and help guide therapy."

Amir Goldkorn, M.D., Associate Professor of Medicine at the University of Southern California's Keck School of Medicine

The study (Abstract #5506) investigated mCSPC patients early in the disease, when participants were first being treated with hormone therapy. Researchers enumerated CTCs in 1200 men at the start of the study, and then looked at two endpoints: the level of prostate-specific antigen (PSA) after seven months, and progression-free survival (PFS) after two years.

The results showed clear prognostic value for the CTC count. The 63% of men who had no circulating tumor cells when the study began were more than six times more likely at seven months to have PSA values below 0.2, which has been shown to be highly correlated with longer survival times than higher PSA values. The men also were 3.7 times more likely to survive, with no cancer progression, after two years.

In addition to Dr. Goldkorn's oral presentation on the study, the research was included in a live discussion among a panel of experts on the ASCO meeting site on Sunday, May 31.

The second study, presented as a poster at ASCO (Abstract #1028), examined the role of CTC counts and mutations in circulating tumor DNA (ctDNA) in predicting prognosis, treatment response and disease spread in metastatic breast cancer (MBC). Led by Massimo Cristofanilli, M.D., F.A.C.P., Associate Director for Translational Research at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University, the researchers looked at  36 Stage III and 203 Stage IV breast cancer patients.

They found that CTC counts were much higher in the Stage IV patients—an average of 62.2 cells per 7.5 mL of blood compared to 14.5 cells in Stage III patients -- and that within each group, high CTC counts predict worse outcomes. In addition, they discovered that mutations in one particular gene in ctDNA --  known as PI3KCA -- dramatically increased in Stage IV patients compared to Stage III patients, and were also highly predictive of worse prognosis and treatment outcomes.

These new studies demonstrate the important role our rare cell technologies play in advancing precision medicine research, which could one day translate to better, more personalized treatment options for patients with prostate and breast cancer."

Fabio Piazzalunga, President and CEO of Menarini Silicon Biosystems, Inc.

CELLSEARCH is the first and only clinically validated blood test cleared by the FDA for detecting and counting CTCs to aid physicians in managing patients with metastatic breast, prostate, and colorectal cancers when used in conjunction with other clinical methods of monitoring. The test is also approved by the China Food & Drug Administration for use in monitoring patients with MBC. The CELLSEARCH System is the most extensively studied CTC technology, with research published in more than 650 peer-reviewed publications.