Just inject the cancer's antigen into your dendritic cells, Duh!

If it really was that easy to do genetic engineering, and not just replicating what others have done, I am sure there would be many home brew diseases spreading far more rapidly than Covid-19.

"This is the plague with which the LORD will strike all the nations that fought against Jerusalem: Their flesh will rot while they are still standing on their feet, their eyes will rot in their sockets, and their tongues will rot in their mouths."
-https://biblehub.com/zechariah/14-12.htm

Just create a virus that delivers the antigen of a healthy cell to the dendritic cell or macrophages, and the body will attack itself.