Natera (NTRA) said Thursday it enrolled the first patients in a study evaluating its Signatera molecular residual disease test to guide treatment decisions in early-stage breast cancer.

The company said the study will enroll about 725 patients at 50 US sites and use Signatera to identify patients who may be able to defer standard of care.

Natera said the test aims to reduce over-treatment with certain standard therapy despite limited benefit and significant side effects.

Shares of Natera were down 2% in premarket activity Thursday.