Circulating Tumor Cell Count Reliable in Determining Best Treatment Approach for Metastatic Breast Cancer

In Clinical Trials by Barbara Jacoby

From: journalofclinicalpathways.com

Circulating tumor cell count is a reliable biomarker for choosing between chemotherapy or endocrine therapy for patients with HER2-negative metastatic breast cancer, according to a recent study published in JAMA Oncology (2020 Nov 5. doi:10.1001/jamaoncol.2020.5660).

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“The choice between chemotherapy and endocrine therapy as first-line treatment for [HER2-negative] metastatic breast cancer is usually based on the presence of clinical features associated with a poor prognosis,” wrote François-Clément Bidard, MD, PhD, Department of Medical Oncology, Institut Curie, Saint-Cloud, France, and colleagues.

“In this setting, a high circulating tumor cell count is a strong adverse prognostic factor for overall survival and progression-free survival (PFS),” they continued.

This randomized, open-label noninferiority phase 3 trial aimed to compare the efficacy of clinical driven treatment choice versus circulating tumor cell-driven treatment choice for the first-line treatment of metastatic breast cancer.

The primary end point was investigator-assessed PFS in the per-protocol population.

A total of 755 patients were included in the per-protocol population and randomized to clinician-driven first-line treatment choice (n = 377) or circulating tumor cell count–driven first-line treatment choice (n = 378). Chemotherapy was the treatment choice for 138 (37%) and 103 (27%) patients in each arm, respectively.

The median PFS was 15.5 months in the circulating tumor cell count-driven arm versus 13.9 months in the clinician-driven arm.

“This randomized clinical trial found that the [circulating tumor cell] count may be a reliable biomarker method for guiding the choice between chemotherapy and endocrine therapy as the first-line treatment in [HER2]-negative metastatic breast cancer,” concluded Dr Bidard and colleagues.—Marta Rybczynski