KRAS Wild To A KRAS Mutation After 3 Years!

[camicom]

Hello,

I am 3 years into my Stage 4 diagnosis, and have been doing Folfox with Cetuximab, due to me being KRAS wild. The results have been really positive other than the rash. My CEA is back into normal range, and tumors are calcifying. Just stopped Folfox and have been doing Cetuximab and Xeloda. Just took my 3rd Myguardant liquid DNA test for mutations and markers, my tumor burden started at 6% ln the first, went to .6% on the 2nd and now is at 1.6% on the 3rd. My doctor called me to give me the results and also let me know that the test is showing 3 new KRAS mutations with low %, but nonetheless they are there. If this is the case, then the cetuximab is useless and it the FOLFOX that is causing the good results again. He was shocked that my tumors mutated 3 years into treatment.

Have any of you had the same thing happen? I would appreciate any infomation.

Thanks again:)

[Bpaint]

My husband’s oncologist told us it is common for the cancer to mutate like that. My husband’s been using Vectibix off and on, and his oncologist has said it is likely his cancer will develop a kras mutation to resist the medication eventually.

[GrouseMan]

Not a surprise at all about the mutations. Mets often have different set of mutations than the Primary and even among themselves. I read a paper more than 16 years go on this subject I think it was. Hence the reason for multiple drug cocktails. I would stick with the Cetuximab (a monoclonal Antibody to EGFR) until there is no benefit from it as far as can be determined. I suspect it's still effective on that larger percent of cancer cells that are still KRAS wild. Do they know specifically what KRAS mutation you have? There are KRAS mutations that activate and a few that are still susceptible to an EGFr inhibitor I believe. Cetuximab is acting on the cells further down the signaling pathway from KRAS. You could be lucky and have the one Kras mutation that has a drug available to inhibit it.

My wife was KRAS wild but they didn't add Erbitux until after exhausting the standard FolFox, FolFiri, with added Avastin added to both. She tolerated chemo well. Erbitux seemed to work for several months as far as we could tell keeping her CEA in the normal range that is until it started to creep up. Using imaging to monitor cancer status was difficult as it hard to see the tumors developing in her Peri cavity and these typically are not as sensitive to chemotherapy (or for that matter surgery). Her liver Mets were well calcified, and her oncologist thought for all intents and purposes were dead. Spleen mets completely disappeared. It was in the final couple of months that these became large enough to visualize on scans and they more or less took over and ended up causing blockage of her colon from the outside and ureter from her kidney to her bladder. Up until the last month she had a good quality of life despite nearly 4 years of chemo. I personally think had they added Erbitux early on, she might have avoided the Peri Mets. YMMV.

Good luck in your journey

GrouseMan