Becoming a Chimera

Today marks 7 weeks since I was last an in-patient in hospital and my last chemotherapy treatment. I was told to expect a week or two break before starting the maintenance phase of treatment whilst we were waiting for any developments with the stem cell transplant. As I mentioned in a previous post, my neutrophils showed a delayed suppression a week after the Methotrexate chemo, falling from 1.8 to 1.0, and continued to drop each week since then until I was neutropenic at 0.4.

Due to the significant drop in levels, another bone marrow biopsy was performed to ensure the drop was nothing to worry about and to check if I remained in remission. Fortunately, my bone marrow came back clear (phew) and so we continued to check my levels each week, and if high enough we would start the maintenance chemo. Two weeks ago my neutrophils had increased to 0.5, though this was not high enough for treatment, it showed that my bone marrow was trying to recover, albeit minimal!

On the 12th of April, I had a meeting at Southampton hospital regarding the allogeneic (another person) stem cell transplant. We were told there was news of a willing matched donor. After hearing Harriet was unfortunately not a match for me, we had turned to the national and European bone marrow/stem cell donor registers. After approximately two months of looking, it was such a relief to hear they had been successful in the search, and I already feel indebted to this kind stranger!! The donor is a 9/10 unrelated genetic match to me. I tried to explain this within a previous post, but let’s have a little refresh, even if just for my sake, as my memory is not what it was pre-chemo! Matching is done based on our Human Leukocyte Antigen (HLA), what makes you ‘you’, with identical twins having identical HLAs. Our HLA is made up of genes, with five key sites targeted for matching. Each site has two alleles (types of genes), equating to 10 in total, obviously the higher the match the better, so 9/10 is pretty darn good! Alongside this genetic match, our medical backgrounds needed to match too, in order to avoid complications with infections later down the line. Interestingly, our blood types do not have to match and therefore my blood type will change post-transplant to that of my donors.

This got me thinking. My blood type would change, and the DNA in my blood would be different from that in other cells in my body. Will I therefore have two sources of DNA and could this be a genuine issue for the guys down at CSI (bare with me, I’m not planning anything illegal, this is all hypothetical)? When I looked into this, it appears that recipients of a stem cell transplant will have two types of DNA, and thought to have undergone Chimerism; a Chimera is an organism composed of cells from different sources (not just a mythical creature). For example, the DNA from my hair and skin would be mine, but the DNA from my blood would match that of the donors. Though very rare, this has actually been documented in a real crime investigation in Alaska, and also aired in an episode of Law and Order. Who knew… well apart from all the haematology doctors and any keen biologists!

I digress. Leading up to my admission date I have had multiple hospital appointments to check my vital organs (lungs, heart and kidneys) and had an appointment with the radiography department to become accustomed to the total body irradiation (TBI) aspect of the treatment. This included a CT scan which obtained images of my lungs. Your lungs are the densest part of the body and will therefore absorb a substantial amount of the radiation if they aren’t protected. From the CT scan the radiographers will be able to build a protective shield which is placed in front of my lungs during the TBI, to reduce the radiation beams and risk of damage to my lungs.

All being well I will be admitted to Southampton hospital on the 10th May, and receive my new cells 9 days later on the 19th of May, apparently referred to as a RE-BIRTH! Before I receive the new stem cells my bone marrow and immune system needs to be treated with conditioning therapy (a combination of high dose chemotherapy and TBI). The chemotherapy drug I will be having is called Cyclophosphamide. I had been introduced to this chemo during my second induction phase of treatment, having it twice in a 4 week phase of treatment. Both times it was administered I had excruciating upper abdominal pains, fortunately alleviated by pain meds. However, the dose I will receive this time round is 10 times the previous dose and I will be having it back to back for 2 days, followed with TBI twice a day, best of luck to me!!

The combined short term side effects that one should expect due to TBI and the Cyclophosphamide are as follows;

• Nausea and vomiting
• Disruption to your bowel (diarrhoea)
• Changes to sense of smell and taste
• Mucositis (mouth and gut, which may result in the insertion of a feeding tube)
• Lethargy and Fatigue
• Fluid gain
• Erythema (reddening of skin)
• Parotitis (inflammation of salivary glands)
• Weight loss/gain
• Infections (due to the significantly suppressed immune system, i.e. lack of one, making them potentially fatal)
• Hair loss (just as mine was an acceptable length to go out without a scarf)
• Acute GvHD (Graft vs. Host disease – new cells recognising the host cells (your body) as foreign and attacking them)

The potential long term side effects of the conditioning treatment are somewhat daunting;

• Infertility (hoping my ovary is OK in the freezer)
• Cataracts
• Long term lethargy and fatigue
• Lung and heart damage
• Chronic GvHD
• Second malignancies (slightly higher risk of developing a second cancer)
• Premature menopause

These all sound pretty scary, and when I first heard this in one go, I was not feeling too positive about this phase of treatment. It was pretty overwhelming, especially with mortality and chances of remaining in remission statistics thrown at you!! This treatment has much higher risks associated with it than the traditional standard care (further chemotherapy). However, the transplant will hopefully give me the best chance at remaining in remission. Though it is important to remember that experiencing all of the side effects listed above is a worst case scenario, the doctors and nurses and information booklets have used the terminology ‘this is what you SHOULD expect’ rather than ‘you MAY experience’, specifically for the short term effects, more often than not. Yes it will be rough and yes it will probably not be my finest hour (visually), but as I said at the start of all this, I’m all in, so let’s get cracking!

On transplant day, known as ‘day zero’, the new cells will be passed as a fluid through my Hickman line, just like a blood transfusion, and will take between 30 mins to several hours depending on the amount I am given. After the transplant the stem cells will make their way to my bone marrow and start to grow into normal blood cells, this is known as engraftment, and usually takes two to three weeks to occur. Usually the first sign of engraftment is a rise in white blood cells. For my donor; they would have received growth factor hormones as injections, to stimulate the production of stem cells, as we do not have enough cells naturally to harvest for a stem cell donation. The cells will be harvested by passing  the blood through a cell separator which contains a centrifuge that spins the blood, separating the cells in the blood into different layers. The layer of stem cells are collected and the donors remaining blood cells returned to them. This takes a approximately 4 hrs and I’ve heard it does not hurt one bit, and you get the added bonus of being a hero life saver!! Always time for a stem cell donor register plug; you can register at either Anthony Nolan or Delete Blood Cancer.

Most patients spend around 6 weeks in hospital, this includes the conditioning treatment prior to the transplant. The first +30 days are crucial for engraftment and I will remain in hospital during this time. The first +100 days post transplant, I will be monitored closely, with multiple hospital appointments, as during this time my new immune system will be recovering. I have been told and often read that it can take a while to regain strength and feel ‘normal’ after a stem cell transplant, and I shouldn’t expect to be back at work full time for around 6-12 months post-transplant. Again these are average statistics, and one where I hope to sit to the left of the bell curve… we’ll see. I have just over a week until I go in, and so I am currently under ‘house arrest’ to reduce the risk of catching an infection, especially with my neutropenic status. Next week I intend on enjoying the good weather forecast, with my factor 50 on, getting my last few runs in, some last minute shopping, and packing my hospital bag/s.

“We could never learn to be brave and patient, if there were only joy in the world” – Helen Keller