How long can remission from stage 4 lymphoma last after clinical trial treatment...

Hello. I was diagnosed with stage 4 non Hodgkin's lymphoma is 2017. I did 6 months of chemo and went into remission just after Christmas. In two months it was already back stage 4 and had spread into my lungs. Ice chemo didn't kill enough of the cancer to allow me to get the stem cell transplant so they told me to get my affairs in order and figure out who was going to take care of my kids there was nothing else they could do. I had already done chemo 4 different times and had most lymph nodes on left side of my body removed. About 2 or 3 months before I was supposed to die Dana farber came out with a trail, I was one of the first of a handful of people to have it tested on. They were hoping it would slow the cancer down if anything but it put me in full remission and I have been for five years now