Guardant's liquid biopsy works in Keytruda's favor

Cancer diagnostics company Guardant Health has incorporated a pan-cancer microsatellite instability test into its liquid biopsy product, Guardant360 — and, according to a 1,000-patient study, it’s proving to be accurate, the company said this morning.

The test could be particularly important for Merck: So-called MSI status can flag whether a patient would benefit from taking pembrolizumab, or Keytruda. 

To date, it’s been tricky to determine whether a particular cancer might have microsatellite instability. The process currently requires a traditional biopsy, which isn’t always possible for cancer patients. But considering the fact that pembrolizumab is now an approved option for all cancers that are linked to microsatellite instability, a simple blood test could improve patients' odds of receiving the drug when they need it. 

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