Somehow this week—Brad’s seventh in the hospital—slipped by without me updating at all. There really hasn’t been much news to report. Brad’s vision has continued about the same, with maybe a very slight improvement. His gut GVHD has improved a little bit, but he’s had nausea and remains unable to think about eating. The predictions that his recovery will be long and very, very slow seem to be holding true. He is, however, more alert during visits and more able to walk a bit in the hospital room, though he doesn’t have much energy, to say the least.

As I write this, Brad is having his third photopheresis treatment, with the machine I wrote about last time. He has slept through it (thanks, I think, to Ativan; also, his days and nights are a bit switched so he’s been sleeping much later in the mornings). They will do another one tomorrow morning, and will continue twice-weekly photopheresis for at least a month. It may end up being a long-term maintenance treatment to manage his graft vs host if the GVHD becomes a long-term issue, which is a real possibility.

I’ve heard from a few people that the whole concept of graft vs. host disease is deeply confusing. It sure is. Everything about Brad’s disease seems to me counterintuitive, starting with the fact that he has really only seemed sick when he is getting treated. (But make no mistake, his cancer is very aggressive even though it mostly didn’t make him feel particularly ill.) I’ll try to explain a bit more about what is happening with the GVHD to make Brad so sick.

Most people, I think, are familiar with the idea of rejection in organ transplant—if you were to need and get a kidney donated from someone, for instance, there is a good chance your own immune system would recognize it as a foreign body and would attack it. Thus, organ transplant recipients are given immune suppressants. In a stem cell (or bone marrow) transplant, rejection works the other way around. Brad’s immune system is no more; instead, the immune system (in the form of stem cells) is what he got transplanted.

As the new immune system settles in and starts to grow in the process called engraftment, the new immune system looks around, sees that everything around it is a foreign body, and in many cases just freaks the hell out (forgive the not-very-technical terminology) and attacks at random. That is why GVHD can pop up in so many places and seems so weird and stubborn. In the case of Brad’s GI GVHD, the new immune system has stripped away the epithelial lining of the entire gut. On his skin it gave him rashes, and it especially made his hands’ skin swell and peel. And there are several other possible manifestations, like Brad’s rare acute ocular GVHD. Brad gets immune suppressants to keep the new immune system somewhat in check (currently he gets two forms of these drugs), but obviously in his case they have not fully tamed the immune response; he will remain on immune suppressants for many months, even after he comes home from the hospital.

The reasons why Brad got GVHD and others with sibling-matched donors don’t are really just unknown and probably unknowable. But it may have something to do with the fact that this whole complicated, counterintuitive treatment of stem cell transplant is still relatively new and not completely understood. When James and Brad were tested to see if James was a match to be a donor, they checked a number of proteins or markers, called HLA (human leukocyte antigen) markers, to see if they were a match. They look at ten specific ones; thirty years ago, when bone marrow transplants were brand new, they only had four markers they could check for. It’s now known that there are many, many other markers that medical science just doesn’t have the technology to test for yet. What that all means is that there’s no such thing as a guarantee of a perfect match, even though all ten of the markers they tested in Brad and James were a match. With a matched sibling-donor transplant, we’ve been told, the chance of severe GVHD is somewhere around ten percent, so—just as with Brad’s initial cancer diagnosis of an extremely rare form of lymphoma—he has been just damned unlucky. (By the way, for anyone new to the blog or wondering about the backstory, I recapped the pre-transplant phase in our very first post.)

The tiny bit of silver lining in all this nasty GVHD is that  it does serve as an indicator that the new immune system is functioning well (if with a certain amount of confusion about its ultimate goals.) And in the big picture, that immune system has a very important job: fighting Brad’s cancer when it returns. If it can do that, all this GVHD, however awful, will be worth it.