What experience has anyone had with the Signatera blood test?

Checkmate 274 showed this efficacy. Very encouraging!

My oncologist said that was definitely true.

That is very interesting. Your case implies nivo can keep working after completing therapy.

Natera is a fairly new blood test that measures molecules/milliliter of tumor DNA from a person's own tumor. My results in two-month intervals are 0.25, 4.73, 0.13, 0.15, 0.17, 0.24, 0.17, and 0.00. 4.73 was two weeks after surgery and was expected. My oncologist hoped for 0.00 sooner because of 12 months of immunotherapy but better late than never. This test is used to alert doctors to a problem before it shows up on scans. Anyone have experience with this test?

A silver lining is that 2025-04-11 bloodwork, showed 5.8% on eosinophils. Research has shown this increase often correlates with immunotherapy efficacy. https://pubmed.ncbi.nlm.nih.gov/38776583 https://pmc.ncbi.nlm.nih.gov/articles/PMC9078345

Unfortunately, Northstar came back at 130 today. A 4.4X increase. Hopefully, Opdivo will eradicate the MRD.

Normal stool movement this morning. So it appears it is not Opdivo colitis. That is a relief. The stool sample is no longer required as per the Mayo RN.

The CT scan came back clean. The diarrhea ended Thursday. Friday I only had two stools. Yesterday I had only one stool. So far today I have not had a stool. The PA suspects viral involvement. I never did the stool. Typically Mayo style they schedule an IV hydration session at the same time as the CT in different buildings. So I had to rush over to the main building for a CT that was delayed by 90 minutes anyway because I had to drink oral contrast. But I left the stool sample kit with the IV nurse in the other building. And by the time they did the CT that building had closed for the day. I may do the stool tomorrow if still suggested by the PA. The bloodwork came back clean except for two white blood cell types that were elevated. The PA however noted no concern with that. So it is unlikely it is colitis. I have some abdominal discomfort today similar to how it felt with chemo constipation. Hopefully, I do not have constipation now.

I now have it in writing from Billion to One that they do not charge patients when insurance does not cover Northstar Response. Just like Natera for Signatera.

Back @ Mayo today for stool test, blood work, IV hydration and maybe a CT (depends on authorization) due to diarrhea and abdominal pain the past few days. Hopefully a stomach bug (my wife and sons had this through early this week) and not colitis.

Morthstar billed my insurance $7K+. It was denied. Northstar informed me they will not bill me.

Commercial insurance typically does not cover ctdna testing. Medicare does when the cancer is advanced. Fortunately, the DNA companies usually do not charge (Natera) or very little (Billion to One).

Signatera is the standard currently and has been used in many clinical trials for years. Northstar Response is fairly new and unknown to most oncologists. Both companies also provide DNA analysis to detect mutations to target treatments and assess risk of the cancer tissue.

Some oncologists use ctdna to commence further treatments. Others do not (like my oncologist). However, it does influence their decision. Based on my signatera (repeat negative) my oncologist was holding off on opdivo. With northstar coming back very low (close to the detectable limit of 25 at 31) , he agreed with my request to start opdivo. Hopefully, DDMVAC 4 resolved the remaining MRD as the first Northstar was pulled before this cycle. Although my kidneys recovered 100% interestingly my oncologist did not agree with two additional DDMVAC cycles despite my request. The oncology RN also noted that Northstar may have picked up necrotic ctdna from DDMVAC 3 as the first Northstar was pulled a couple of weeks after that cycle. I will know more next week with Northstar 2.

I still have opdivo side effects today. Bad stomach pain that comes and goes. Some back pain that comes and goes. And I was extremely fatigued around noon and had to nap for 90 minutes.