Companion diagnostics
The test that decides whether a specific drug is right for you, approved together with the drug.
PD-L1 IHC (22C3, SP142), HER2 IHC/ISH, FoundationOne CDx, Guardant360 CDx, myChoice CDx (HRD), Oncomine Dx. The 'HER2-low' and 'HER2-ultralow' labels for T-DXd showed that an existing test can acquire a new decision threshold overnight.
How it works
Analytically and clinically validated assay linked to a drug label.
- Enriches responders
- Regulatory clarity
- Threshold effects
- Different assays for the same biomarker are not interchangeable
The FDA-approved tissue (324 genes) and blood genomic tests that serve as companion diagnostics for dozens of drugs.
A 70-gene test that tells whether an early breast cancer is genomically low or high risk, used to decide who can skip chemotherapy.
A 21-gene test that tells most women with early hormone-positive breast cancer whether they can safely skip chemotherapy.
Zolbetuximab is the first drug against Claudin 18.2, a protein exposed on stomach cancer cells. Added to chemotherapy it extends survival by two to three months; nausea is the price.
Patients with newly diagnosed advanced stomach cancer should now have Claudin 18.2 tested alongside HER2, PD-L1 and mismatch repair, because roughly a third will be eligible for zolbetuximab, which adds about three months of median survival. The main practical problem is nausea and vomiting during infusions, which needs aggressive prophylaxis. How to sequence or combine it with immunotherapy in PD-L1-positive tumours is unresolved.
Patients whose breast cancer was previously called HER2-negative may now be eligible for an effective HER2-directed drug if their tumour has even low-level HER2 staining, so pathology reports must now distinguish HER2-low (1+ or 2+/ISH-negative) from HER2-zero. This applies to metastatic disease after at least one line of chemotherapy; it does not mean these patients benefit from trastuzumab or other older HER2 drugs.
Latest papers
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Pages like this
not linked directly; found by shared links- TechnologyHistopathology & immunohistochemistry
Shares Agilent Technologies (Dako), Publish each laboratory's biomarker proficiency results, Histology automation and IHC autostainers, PD-L1 expression testing (22C3, SP142, SP263).
- IdeaStanding reflex biomarker panels per tumour type, run without an oncologist's order
Shares Pathologists order genomic profiling automatically at diagnosis of advanced cancer, Combined positive score (CPS), Fragmented care and guideline gaps, Biomarkers are not validated or standardised.
- CompanyFoundation Medicine (Roche)
Shares Regulators recognise each other's companion diagnostic approvals, FoundationOne CDx / Liquid CDx, Every tumour sequencing report lists open, nearby, matched trials pulled live, Fragmented care and guideline gaps.
- IdeaLock the biomarker cut-off before phase 3, and publish it
Shares Test the drug in biomarker-negative patients too, so the biomarker can be validated, Companion diagnostic, Biomarkers are not validated or standardised.
- TechnologyComprehensive genomic profiling
Shares Labcorp, Funda Meric-Bernstam, FoundationOne CDx / Liquid CDx, Pathologists order genomic profiling automatically at diagnosis of advanced cancer.
- TechnologyPre-analytics: blood-collection tubes and tissue fixation
Shares QIAGEN, Reference laboratories and companion-diagnostic testing.
- IdeaRandomised trials to test whether biomarker-negative patients really do not benefit
Shares Test the drug in biomarker-negative patients too, so the biomarker can be validated, HER2-low and HER2-ultralow, Biomarkers are not validated or standardised.
- TermGenomic profiling
Shares FoundationOne CDx / Liquid CDx, Biomarker, Companion diagnostic.