Thoughts and experiences with Guardant 360 somatic testing

[SeosamhM]

Happy summer, folks. This is a posting inspired by smurtaw's recent post on Guardant 360 testing (see: healthunlocked.com/advanced.... Apparently tested folks are not only getting cancer biomarker indications from this test, but also a "Tumor Mutational Burden (TMB)" score.

I really only know Guardant 360 by rumor and research. It is (per the manufacturer literature) a test that is "...FDA-approved for complete genomic testing across all solid cancers, providing doctors guideline-complete genomic results in 7 days from a simple blood draw to inform treatment decisions." So...

Does anyone have any thoughts or experiences with Guardant 360 (or its competitors, if they exist) that they'd like to share? While I categorically discard the hype of "complete genomic testing" (a moving target, for certain!), it does seem like this test fits into standard of care...somehow, somewhen...

Thanks! - Joe M.

[Tall_Allen]

If one has lots of big metastases shedding , it's great. Uneven results from smaller metastases.

[SeosamhM in reply to Tall_Allen]

Thanks. It makes sense that free-floating tumor "trash" density is critical to detection. See smurtaw's reply about his MO use as a screening tool - it seems to be an interesting application, but certainly not one currently use in our SOC.

[Tall_Allen in reply to SeosamhM]

That would be a very expensive screening tool.

[SeosamhM in reply to Tall_Allen]

Yah - just found that out doing some Medicare research for another poster..... the test retails $5K...

[tango65]

The problem is to get enough genetic material from the tumor in the blood sample. It may work in people with multiple metastases and a PSA greater than 5 or according to other studies greater than 10. The larger the tumor load and the PSA the higher the chances of getting a good study.

pubmed.ncbi.nlm.nih.gov/352...

[SeosamhM in reply to tango65]

Thanks, Tango - great resource.

[Herman_PSA_OK]

I just got my results back for my Guardant-360 blood test and it detected an alteration biomakers PIK3CA V448_L452del (1.1% of cfDNA). My appt. with my medical oncologist is next week. What the heck does that mean and how does it relate to my PCa? The report indicated Alpelisib as an associated FDA-approved in other indication. In other words, not FDA approved for prostate cancer. It also provided information for a local near me clinical trial availability for this biomarker defect. Any comments or suggestions would be appreciated.

[Sleepyeye1911]

The Gardant 360 test can help considerably.Because of this, I was put on Keytruda. Wonder

Drug for some patients.

[noahware]

I was also wondering, after looking at the Guardant website, when the second of these two panels might be indicated or beneficial:

"A Guardant360 CDx report contains both professional services, which includes 74 genes, in addition to the FDA-approved report, which includes 55 genes."

"Guardant360 TissueNext is an analytically validated tissue comprehensive genomic profiling panel that includes TMB, MSI status, and PD-L1 IHC, if ordered. A Guardant360 TissueNext report includes 84 genes."

Even though both list a total of 84 genes for Point Mutations and Deletion Variants, for example, the TissueNext report lists CHEK2 while the CDx report does not.

[SeosamhM]

Hmmm. Why not, right? Another tool in the chest, yah?

[SeosamhM]

Well, if insurance isn't balking - I'm also a sucker for data. I will look into it. You would think the Guardant manufacturer would be pushing for this if only to move it into routine screening status and more $.

[dhccpa]

Does Medicare pay for the test? If so, under what conditions?

[SeosamhM in reply to dhccpa]

Yes, it looks like some "liquid biopsy" tests were approved in 2020, including Guardant. The key language is here:

cms.gov/medicare-coverage-d...

The conditions seem straight forward: Patient has been diagnosed with a recurrent, relapsed, refractory, metastatic, or advanced solid tumor that did not originate from the central nervous system.

While I am still on private health insurance, I always ask my LPN case manager and office staff about these things!

[dhccpa in reply to SeosamhM]

Thanks! I'll follow up on that.

[SeosamhM in reply to dhccpa]

Dunno if link appeared correctly: cms.gov/medicare-coverage-d...

[dhccpa in reply to SeosamhM]

Thanks

[noahware]

I frankly don't know a thing about any genetic testing costs, or how insurance might or might not cover different tests. I plan to bring it up at my next MO appt... but sounds like a good topic for a new thread!