Guardant Health’s Guardant360 CDx received Japanese regulatory approval as a companion diagnostic to identify ESR1 mutations and help select patients eligible for Eli Lilly’s Inluriyo. The approval allows Guardant360 to be used in Japan to guide therapy selection for breast cancer patients with ESR1 alterations. The decision expands Guardant’s geographic CDx footprint and reflects growing regulatory acceptance of plasma‑based tests for treatment selection. Japanese approval could prompt further submissions by other liquid biopsy developers seeking companion‑diagnostic status abroad.