[long note, some recapping of stuff we've shared before, lots of new detail about the specific processes that Sam's going through now. a couple of funny jokes about rabbits if you read closely.]

Sam finished his 6th session of radiation today, and is doing about as well as expected. He's asleep beside me now -- he was really tired before the session, and just completely zonked now -- he's been asleep for 3 or 4 hours.

Last night wasn't great -- fitful sleep, lots of tossing & turning, not a lot of rest -- and today has been mostly getting wheeled from our room over to radiology, back to the room & then all of that over again. 

He's in reasonable spirits, making good jokes, surprising people with his insights. (They were surprised when the doc asked the nurse for the ID number on his admission bracelet and he rattled it off from the top of his head this afternoon. That kind of stuff happens all day long with him here.)

He's currently getting the last dose of ATG for a couple more hours yet. So during the quiet time I figured I would learn more about what's happening to him now, and share it here. 

As you'll know from following along, Sam's spent the last couple of months on an immunotherapy called blinatumomab. Blina is a Bispecific Monoclonal Antibody (BITE) that binds to the patient's own T cells and the leukemic cells themselves in a way that lets the patient's T cells kill the cancer. Here's a run down on how it works. That article is about using it for relapsed leukemia -- Sam's is in remission, but we used it in his case because his mutation, KMT2A, is prone to relapse, and blina has been shown to be more effective than chemotherapy. And it certainly has been in Sam's case, chasing all the cancer we can find away.

And as we've talked about here, to ensure durability of cure, we've embarked upon the significantly more challenging path of a stem cell transplant. For that to work optimally over the short & long term, you've got 3 things you want to accomplish: (1) you want to kill as many of Sam's remaining cancer cells as possible at the outset (being cytotoxic to the leukemia), (2) you want to suppress Sam's immune system in the right ways to reduce the negative reaction (graft versus host disease GvHD) to the donated cells (immunosuppression), and (3) you want to build his immune system back in a way that it can go hunt and kill any residual cancer cells over time.

Each of the processes we're going through now addresses one or more of those three goals.

The ATG (anti-thomucyte globulin) he's on now has been doing immunosuppression by killing off his T cells -- labs this morning (and yesterday) showed zero in his body. Fun fact: he's getting ATG-T, which consists of polyclonal immunoglobulin obtained from the hyperimmune sera of rabbits immunized with human thymocytes (immature T cells) recovered from patients undergoing cardiac surgery.

WHAT?? I mean, my (admittedly casual) reading of that sentence says that we're developing rabbits with hyperimmune blood that they got from human heart surgery patients. I'd like to know who figured that one out and how.

(The other option would have been to get the horse-derived ATG -- I guess you can collect more of it from each horse, but seems easier to round up a bunch of rabbits. I don't really know how the lab collection works, but I'm pretty sure what I'm imagining in my head is definitely not right.)

Anyhoo. Sam's on his third night of ATG. First night was rough with flu symptoms. Last night a little easier. Tonight we're anticipating pretty smooth sailing since he doesn't really have any T cells to object to the leporine invasion (also, just fwiw, I learned about that movie from my 11th grade Latin teacher, so all of you who have been feeling smug these past 35 years about how you think Latin is useless can think on that for awhile).

So the ATG is making progress on the immunosuppression. (The linked article above is actually pretty interesting, although maybe a little more topical to me & Kathy than most of you.)

The TBI (total body irradiation) is different, with a dual purpose of both immunosuppression and killing any remaining cancer, especially acting on cells that tend to hide out in difficult to treat "sanctuary sites" like the CNS (central nervous system) and testes. 

It is a lot harder to write funny things about radiation therapy than it is to write about the blood of super soldier rabbits.

He's gotten two doses of radiation each day on Monday, Tuesday & Wednesday. It's caused increasing fatigue; some nausea, although I think we're managing that much better than we have in the past. (Pro tip: always get ahead of it. Once you're vomiting, the game is kind of over for awhile.) They fitted him for a mold last week that he lies down in for an hour at a time, and then the big machine works on him. The writeup I linked to here is also really good & interesting -- it goes through how we took what appeared to be wholly negative (radiation kills cells/humans/life) into a positive around using it to "make space" inside a sick person's bone marrow to allow healthy bone marrow to engraft and thrive. 

Plenty of things to worry about as parents, but for Kathy & me, the long term effects of radiation are probably the ones that are on our mind the most (other than pure relapse). The machines that Stanford has are state of the art, though, designed to maximize effectiveness and minimize unwanted toxicity. So hopefully it will be alright. Only way through is through.

I think that's all I have to say about that for now, other than that despite the obvious toll it took on him, Sam didn't complain a single time that I know of. He's focused and strong, resolute.

I complained just now about the burrito I ate not being spicy enough. Not joking. Wasn't an A+ burrito.

Actually, the thing I'll say is that I am optimistic and hopeful that that's the last time in his long life that Sam will go through radiation like that. And I'm looking forward to the day with precision medicine where nobody will have to.

Tomorrow, we are in a new regime -- this one is cancer-killing, rather than immunosuppressing, and is a drug called Thiotepa -- its mechanism of action is to attack the cancer cells' DNA directly, preventing the double helix DNA strands from uncoiling and separating -- so they can't reproduce. Thiotepa is pretty odd, though, in that it is excreted through the skin, in sweat -- it's toxic & will cause burns. So starting at 9a tomorrow, Sam will have to take showers at least every 6 hours, and we won't be able to touch him without gloves, etc. That'll take us through Day -6.

Tomorrow Kathy will also start to take GCSF to induce lots of stem cell production -- she'll start that about the same time that Sam starts his new meds. 

Next play.