Transplantation

A major reason for creating this blog was to share my journey as I undergo a bone marrow transplant. As many readers might not be entirely aware of the process involved, here is a brief summary of what lies ahead of me.

Finding the Seed

Bone marrow transplantation is more accurately referred to as hematopoietic stem cell transplantation (HSCT). That basic premise of HSCT is that the existing hematopoietic system (i.e. all blood cells including red blood cells, white blood cells, platelets, granulocytes, etc) are heavily suppressed or killed off and replaced by a new hematopoietic system from harvested stem cells. Hematopoietic stem cells can be harvested from your own body prior to chemotherapy (known as an autologous transplant), or from a related or unrelated donor (an allogeneic transplant).

In my case, I will be receiving an allogeneic transplant from a compatible unrelated donor. My older sister, my only sibling, was found not to be a match and therefore, a comprehensive search of potentially compatible unrelated donors was made on my behalf. The search was conducted by the staff at the Royal Melbourne Hospital on an international database of registered and volunteering bone marrow donors (Australian donors can be registered through www.abmdr.org.au). Luckily, I’m a generic run-of-the-mill Caucasian male and there was little trouble finding a compatible donor. However, many other people who require bone marrow transplants (sometimes much more urgently than I do) can struggle to find an appropriate donor. It’s a numbers game - the more volunteers who are registered to be donors, the more likely these people will find the match they need. It only takes a quick blood test to become registered, so please track down your local registry and get yourself on the database. You could save a life.

Digging the Hole

For the harvested donor stem cells to engraft (i.e. ‘take hold’) and regenerate a new hematopoietic system, they need room to grow. They also need to avoid being rejected by my existing immune system. To do this much of the original, cancerous bone marrow will be killed off and any remaining immunity will be heavily suppressed. For me, this will be achieved by eight consecutive days of high-intensity chemotherapy and immunosuppression.

The amount of chemotherapy I am given will be a balancing act. Too little chemo will increase the risk that the donor cells won’t engraft and that the transplant fails. Even if they do engraft, an insufficient amount of chemo could also mean that too many cancer cells are left alive and the disease may grow back over time (i.e. relapse). Conversely, if too much chemo is given, then the risk of toxicity and organ failure becomes very real. My liver has developed a small degree of fibrosis from years of living with the disease and consequently, its function is already partly compromised. As a result, the intensity of my chemotherapy regime will be reduced slightly to allow my liver to cope (hopefully).

Growing the Plant

The stem cells from my donor will be infused into my bloodstream at the end of the eight day chemotherapy regime. They will quickly find their way to my bone marrow and start reconstituting a new hematopoietic system. It generally takes about 10-20 days for the new system to regrow. In the meantime, I am left with little blood and virtually no immunity. The time between the stem cells going in and the new system growing back is apparently when I’ll experience the most severe effects of the chemotherapy. In addition to a high risk of infection, I have been told to expect mouth ulcers, nausea, vomiting, diarrhoea, hair loss, and tiredness. Put simply, I will be very, very sick.

My symptoms will start to become progressively better as the donor’s cells start to reconstitute and become established in my bloodstream. If everything goes well, I will be able to return home 2-7 days after my blood counts return to ‘normal’.

Controlling Overgrowth

One of the most common, and potentially most severe side-effects of allogeneic transplants is graft-versus-host disease (GVHD). GVHD develops when the newly developed immune system from the donor (graft) begin to recognise the cells from my body (host) as foreign and start attacking them. As bad as that sounds, a small to intermediate amount of GVHD is actually a good thing since the donor’s cells will eventually kill of any remaining cancerous cells. This is why allogeneic HSCT has the potential to be curative.

However, there is a significant risk that the GVHD will be too severe and may permanently damage organs such as the skin, gut and liver. Immunosuppressants are always given to try and reign in the severity of GVHD, but a large number of patients (~20-25%) will ultimately die or become permanently disabled from the disease. Unfortunately, the risk does not end as soon as I leave hospital either. Acute GVHD generally happens within the first 100 days after the transplant, while chronic GVHD can happen at any time over a period of a year or two. At present, there is no technology beyond tissue-typing that helps the doctors predict how severe GVHD will be prior to transplantation. It’s simply a risk I have to accept.

If it all goes well, it will take 1-2 years for me to make a full recovery from the transplant - we have a long journey ahead of us.

Timeline

My transplant was delayed by a week to allow some follow up checks on my liver. Now that these are complete, the process will now commence on Wednesday the 1st of March, meaning that I will receive the donor cells on the 9th of March.

More to come soon.