Menarini Silicon Biosystems has published data from a Phase III STIC CTC study that supported the reliability of using circulating tumour cell (CTC) count to guide frontline therapy choice for patients with estrogen receptor-positive (ER+), HER2-negative (HER2) metastatic breast cancer.

For detecting and counting CTCs, Menarini Silicon Biosystems’ CELLSEARCH CTC System, a clinically validated blood test approved by the Food and Drug Administration (FDA) was used.

The test helps physicians to manage patients with metastatic breast, prostate, and colorectal cancers when used along with other clinical methods of monitoring.

The randomised trial was conducted on 778 women with Stage 4 ER+, HER2- breast cancer and the outcomes of treatment decisions were compared based on physician assessment versus CTC count.

In the trial, patients in the clinically driven treatment group received treatment selected by a physician based on clinical factors.

In the CTC-driven treatment group, patients with five or more CTCs in 7.5ml of blood received chemotherapy and those with less than five CTCs in 7.5ml received hormone therapy.

CELLSEARCH system was used to capture and isolate tumour cells, circulating in the blood in all patients.

The results supported the reliability and clinical utility of using the CTC count to guide front line therapy choice.

The CTC count for most patients in the clinically driven group correlated with the physician’s treatment choice.

In the CTC-driven group, progressing treatment to frontline chemotherapy for patients with high CTC count significantly improved progression-free survival (PFS).

Moreover, for patients with low CTC count, de-escalation to hormone therapy did not have a detrimental impact on PFS or overall survival (OS).

Menarini Silicon Biosystems president and CEO Fabio Piazzalunga said: “The results of the STIC CTC study provide evidence that the CTC count can support physicians when making effective treatment decisions.”