chimerism

I am not the type of person who flips to the end of a book before I decide whether or not I am willing to settle into the narrative and yet when it comes to this story, I find myself desperate to know the ultimate conclusion.  As I lay sleepless at night contemplating and refining my role in service to the main character of this tale, I wonder what it will take for me to get my hands on a copy of the divine author's outline? If only the author will tell me how these characters fare this challenge, I promise I will read, no savor, each moment of every scene and chapter no matter how mundane or harrowing.  

One of my favorite writing teachers once shared that you should always leave the reader high up on a pedestal where they cannot get down without you.  Whomever is crafting this story of ours has this particular technique down perfectly.  The scenes unfold day by day and I am always left wondering what next.  We have mini-resolutions at the end of sections: completing two chemotherapeutic regimens; hospital admission for conditioning; the stem cell collection and transfer; release to the hotel to fend off skin driven insanity; finding our way home in search of comfort and answers; and finally better management of the itching and laryngitis, nausea, sinus infection and fatigue.

But while symptoms improve, they do not entirely disappear and new issues continue to appear to keep the story rolling: discomfort from the tumor vaccines; painful legs and feet; and consistent diarrhea which may be the first sign of GVHD.  And still the greater story has so much further to develop before we are released from its pages.  Sometimes I wonder if we will ever be released from these pages, but I have to believe that as much as this transplant will be forever intertwined in our life story, there will be many novellas for us where the content exists outside of these days or the back story references are few.

For now we are tightly in the grip of this unfolding drama and one of the chapters these past weeks revolves around the chimera and bone marrow biopsy results.  Dr. Soiffer told us a few weeks ago that they would love to see Aaron cancer free and engrafted at 100% but that anything over 90% would be acceptable and would not warrant any changes to his immunosuppressant regimen.  As of August 23rd, (Day 32), Aaron is 90% engrafted by peripheral blood analysis and 93% by bone marrow.  By H&E histology, his bone marrow biopsy taken that day showed a single lymphoid aggregate that is suspicious for minimal involvement of CLL.

When I first heard the news I was disappointed because I so much wanted to just hear that we had attained full engraftment and that we were done with CLL once and for all.  But even if this had been the news delivered to us, a transplant is a dynamic process and people who are fully engrafted can lose their graft just as people who are not fully engrafted can increase their donor percentages.  The fact that Aaron's own immune system is still functioning should not be a surprise.  Aaron had what is called a non-myeloablative stem cell transplant (NMT). Essentially this means that a conditioning regimen was selected to weaken but not destroy Aaron's bone marrow and immune system before they infused Sarah's cells.  Sarah's transplanted cells are engrafting alongside Aaron's own immune system.  

Chimerism is a topic I discussed in an early post.  It is the condition where cells in an organism come from two different individuals.  In the best case scenario, the end result of a bone marrow transplant is that the blood and marrow cells come from the donor while all other types of cells come from the patient. Complete chimerism means that all of the blood and marrow cells come from the donor.  Mixed chimerism means that some cells come from the donor and some the patient.  Complete and mixed chimerism induced by a stem cell transplant can be determined by cytogenetics, molecular genetic and immunological techniques so that transplant physicians no longer have to rely simply on graft versus host disease to indicate that the donor cells are settling in.   

After a transplant, the change from the patient's blood and marrow cells does not occur all at once and is slower after a non-myeloablative than a myeloablative.  Chimerism analysis is important for monitoring post transplant outcome and for determining appropriate therapy after transplantation.  Early patterns of chimerism may predict either graft versus host disease or graft loss.  Dr. Soiffer will perform chimerism analyses frequently over the next six months to ensure that Aaron's donor percentage continues to increase.  We want to see him move from a state of mixed to complete chimerism with no evidence of his DNA in the peripheral blood or marrow as this indicates a much better prognosis for a cure. Hopefully this will happen in a few months.

As much as I would like to be delivered without mystery, there are no immediate denouements to this story.  Dr. Soiffer refuses to speculate on what Aaron's status looks like in terms of patients he has transplanted other than to say that the numbers usually do increase to 100% over time and that Aaron looks good.  While Aaron is used to tight measured language from his doctors, I am always in search of the wise crone on our path, the one with the magical incantations and crystal ball that can reveal our future.  Beyond waiting for her, I can pursue my answers in medical journals. What I have learned is that "mini" transplants are essentially synonymous with mixed chimerism in the early months post transplant.  It is natural that the recipient and donor cells coexist in the marrow space as Aaron's bone marrow was not completely destroyed.  

Though the presence of any potential CLL may frighten us, it should not discourage us.  CLL is not curative with chemotherapy alone which is why Aaron's cancer returned after our first attempt several years ago.  The cure for CLL is the infusion of Sarah's cells which are meant not only to replace Aaron's bone marrow but also to seek out and destroy any CLL that may have been left behind.  This is called graft versus tumor effect or graft versus leukemia and this is our salvation against a relapse of the cancer.  GVL is usually a by-product of GVHD and this can be very dangerous, even fatal, so the management of Aaron week after week is critical.  So while Dr. Soiffer is guarded with his knowledge as if it is a secret we are too young to know, he is the magician in this story who will yield his powers as needed.  We are told that he is exceptionally gifted with manipulating GVL and GVHD, bringing patients back from the brink of death and into a cure.  And so we must put our trust in him and in our faith, as we continue on without a map.

A few years ago, Aaron and I were looking at treadmills and we considered ones that have the vision panel where the runner is placed on a particular course and you can see them as they make progress down the roads and over the hills.  The imagery is meant to motivate you to keep going.  We are in the early stages post transplant, now Day 51, and we have so much more of this quest to full health.   Marking our story in words affords me a glimpse of our movement through this process even on the days when I feel like we have been on the same page for weeks.  Because no matter how wound up I am in a particular struggle or feel that I can bear no more, eventually the moment arrives, the page is turned, and we are given a distant view of where we are heading before we are propelled into the next scene.  
We must make our way on this journey one day at a time and I know that we can go higher or lower just like Sarah's cells.  Let's hope we all rise and enjoy ourselves along the way as much as possible.  And even if a package arrives with all of the main points neatly laid out, I will continue to remind myself that stealing ahead to the final sentence will only diminish this story.