Japan’s regulator cleared Guardant Health’s Guardant360 CDx as a companion diagnostic to identify ESR1 mutations and guide eligibility for Eli Lilly’s breast cancer drug Inluriyo. The approval positions Guardant’s liquid biopsy as a clinically actionable test in a major Asian market. The decision expands Guardant’s geographic footprint for tumor‑agnostic and biomarker‑directed testing and signals continued uptake of cfDNA‑based companion diagnostics alongside targeted oncology launches. Hospitals and molecular labs in Japan will integrate the test into treatment pathways for metastatic breast cancer, potentially streamlining patient selection and shortening time to targeted therapy.