FDA clears Guardant360 CDx
The FDA cleared Guardant360 CDx as a companion diagnostic to detect ESR1 mutations for imlunestrant in breast cancer—officially expanding blood-based, non‑invasive testing into treatment selection. This signals a bigger shift toward ctDNA assays being used as companion diagnostics in clinical workflows. (onclive.com)
U.S. approval of imlunestrant (Inluriyo) occurred on September 25, 2025 for adults with ER‑positive, HER2‑negative, ESR1‑mutated advanced or metastatic breast cancer after progression on at least one line of endocrine therapy. (fda.gov) (fda.gov) Guardant Health issued its press release on September 29, 2025 announcing the Guardant360 CDx claim tied to Inluriyo and noting the assay was used to identify ESR1‑mutant patients in the Phase 3 EMBER‑3 trial. (guardanthealth.com; fda.gov) (investors.guardanthealth.com) In EMBER‑3 the ESR1‑mutated analysis cohort comprised 256 patients, with median investigator‑assessed PFS of 5.5 months on imlunestrant versus 3.8 months on investigator‑choice endocrine therapy (hazard ratio 0.62; p=0.0008). (fda.gov) (fda.gov) Guardant’s release lists the specific ESR1 variants flagged by the assay for Inluriyo eligibility, including E380, V422del, S463, L469, L536, Y537, and D538. (guardanthealth.com) (investors.guardanthealth.com) FDA device documentation specifies the cfDNA test’s ESR1 detection is limited to missense mutations between codons 310 and 547 in the ligand‑binding domain. (fda.gov) (fda.gov) Guardant360 CDx’s new Inluriyo claim brings its total to multiple FDA‑cleared companion diagnostic indications, with the press release calling this the sixth CDx claim and noting a prior breast cancer CDx linkage to Menarini’s ORSERDU (elacestrant) in 2023. (guardanthealth.com; fda.gov) (investors.guardanthealth.com) Guardant states Guardant360 CDx is broadly covered by Medicare and commercial payors representing over 300 million lives, signaling payer reach for blood‑based comprehensive genomic profiling in the U.S. market. (guardanthealth.com) (investors.guardanthealth.com)
