Guardant Health won FDA approval for its Guardant360 CDx liquid biopsy as a companion diagnostic to identify BRAF V600E-mutant metastatic colorectal cancer patients eligible for Pfizer's encorafenib (Braftovi) plus cetuximab and chemotherapy. The decision rests on data from Pfizer’s Phase 3 BREAKWATER trial showing improved response rates, progression-free survival and overall survival with the Braftovi regimen. Guardant360 CDx is now an FDA-cleared ctDNA test for this indication and joins FoundationOne Liquid CDx as an approved liquid CDx for the combination. Guardant framed the approval as a validation of circulating tumor DNA (ctDNA) for treatment selection and resistance monitoring, while experts continue debating the optimal clinical use of ctDNA to guide colorectal cancer therapy. Guardant360 CDx now counts 25 companion diagnostic indications across multiple tumor types.