i wanted to give you all an update on my off-label use of Keytruda (since I am MSS it is not approved for use by me....since it doesn’t generally work for colon cancer patients which microsatellite stable tumors.)
HOWEVER, it looks like it is working for me....and here is the reason why (according to my doctor and the Foundation One reps): it is not whether the tumor is ZmSS or MSI that is determinative as to whether the immunotherapy will work....it is the THE TUMOR’S MUTATION BURDEN THAT DETERMINES WHETHER KEYTRUDA WILL WORK.
Foundation One is seeing evidence that people whose tumors have a high (or moderately high) mutation burden tend to respond to the immunotherapy treatments. Generally MSI tumors have a high mutation burden and MSS tumors have just one or two mutations if any. In my case (probably dilute to the fact that I’ve had many different courses of treatments over the kart 7 years) my ZmSS tumor has a moderate mutation burden (11 mutations.). So my local oncologist (who has been doing tons of work with immunotherapy over the last 6 years) got permission to treat me with Keytruda off-label.
My CEA (which is super sensitive and very accurate over the last 7 years) was 39.6 before my first Keytruda treatment. Three weeks later, before my second treatment, my CEA had risen to 66.4. Before my third treatment, my CEA was back down to 39.2, and three weeks later before my 4th treatment it was down to 13.0. On Friday, before my 5th treatment my CEA was down to 3.5 and my CT scan showed shrinkage of the only slightly enlarged lymph nodes in my hilar lung area to normal size.
This is an amazing breakthrough for MSS patients. If you are MSS, please get Foundation One Testing to see if you have a moderate or high mutation burden. If you do, immunotherapy couldvwork for you.
Please feel free to contact me if you have questions.
Mommy to Jack (8) now (15) and Katie (4) now (11)
(My Most Precious Things)
Dx 8/11 Stage IV CRC (liver mets) CEA 2,600+
9/11 Folfiri 2/12: Failed Liver Resection
5/12 HAI pump/removed primary
4/13 Liver Resection!
8/13; 10/13; 12/13; 3/14; 8/14; 11/14; 2/15; 7/15; 12/15 RFA lungs
5/17: Upper Left Lobe of lung resected.
02/18: 3 new mets lymph nodes in hilar/lung:
05/18: Started Keytruda (MSS but moderate mutation burden): CEA: 66.4, 39.2, 23.8, 13, 3.5
Lymph nodes all normal via CT scan