Tuesday, August 2, 2022

Guardant Receives Coverage for Colorectal Cancer, Minimal Residual Disease Testing

In a press release on August 2, 2022, Guardant announces it has received Medicare coverage for its REVEAL test, which is a direct measurement of residual disease  in plasma of stage 2 and 3 colorectal cancer patients.

See the press release here.  See early coverage at Genomeweb here.

The coverage comes under a "foundational" or "umbrella" LCD that allows MolDx to cover liquid biopsy tests for 

  • Either solid cancers, or, hematopoietic cancers, and
  • Either for detection of relapse, or, response to therapy

Under that umbrella, MolDx makes test by test and context by context decisions.   For example, Test A might be approved for detection of relapse in colorectal cancer, and test B might be approved for detection of response to therapy in liver cancer.   See LCD L38816.

Two weeks earlier, Natera announced coverage by MolDx for MRD testing in bladder cancer, notably, on cited 2019 and June 2021 publications. (Powles, Nature, 2021; Christensen, J Clin Oncol, 2019).  This suggests the case-by-case MolDx review process is not real fast.


On ctDNA in bladder cancer, see also a short review by Fenner . Friends of Cancer Research published a white paper last winter on ctDNA as a regulatory endpoint in cancer drug trials, here.  On the other hand, the June 2022 ESMO guidelines Pascual et al. on ctDNA focus on CDx applications for drug selction, not yet ready for a full recommendation for MRD applications for treatment path management.

Natera's test is a per-patient bespoke test based on exome analysis of the tumor.  Guardant's test is a pre-designed test which is the same for all patients.  Multiple companies are looking at either approach to MRD.  Positive reports appear regularly (breast cancer here, colon cancer here,) while negative reports (here) appear from time to time also.