Monday 27 August 2012

What is the antibody treatment?

Today marks three weeks since I was informed my Hodgkin's Lymphoma is refractory (no longer responding to chemotherapy) and that my last chance for a cure is an antibody treatment that is not yet approved for general use on the NHS, i.e. requires special approval due to the costs etc involved.  As you can probably imagine, the idea of whether I receive the antibody treatment potentially coming down to NHS budgets is not the most comfortable one, and when it was explained it could take up to three weeks for a decision to be made, it did cross my mind that they might seem like long weeks.

As luck (or not) would have it, today is actually a bank holiday Monday, so although three weeks have passed now I'm still waiting to find out the decision; A nurse I spoke to on Friday afternoon told me that the panel were scheduled to make their decision on a conference call later that day, and that in all likelihood I would find out on Tuesday.  The doctor that had been fielding questions for the panel over the last couple of weeks or so seemed quietly optimistic that the antibody treatment would be approved though, but obviously couldn't make any promises, so I'm kind of assuming all will be well.

To be honest, the three weeks of waiting have passed pretty quickly really, and it's not even been on my mind that much.  I did spend a few hours reading about the antibody treatment in the first few days (a nurse looking after my case provided some materials, and I did some further research online), but after that I pretty much forgot about it.  Although I've been signed-off work since starting the treatment for my latest cancer relapse, I've not really ever struggled with filling my time, so have rarely found myself contemplating (let alone worrying about) what the future may hold; Granted I've spent a fair bit of that time in hospital, and/or feeling naff, but it is funny how quickly you can get used to not working, not to mention find yourself thinking how/why did I ever fit in a full-time job!

So, what is the antibody treatment, I hear you say?  Well, the one that I will hopefully be starting soon is called Brentuximab Vedotin.  There are a few different categories of antibody treatments, each of which work in different ways, but this one essentially locks-on to cells that it recognises as cancer, and then delivers those cells some chemotherapy right to their door!  I suppose in that sense such antibody treatments are a bit like a courier service for chemotherapy, which continuing the analogy makes traditional chemotherapy a bit like the leaflets we all get posted through our doors, i.e. for some those leaflets are useful, but for others they are just an annoyance we could do without!

In case you are curious, some antibody treatments use radiation instead of chemotherapy to kill the cancer, i.e. they lock-on in the same way, but have radioactive isotopes attached to them, and hence are really an especially targeted form of radiotherapy.  The other two categories of antibody treatments take slightly different approaches though: The first essentially paints a target on the cancer cells, by simply locking-on to them, so that the patient's own immune system can then recognise them as cancerous and kill them off, and the second locks-on to the cancer cells in such a way as to prevent them from receiving their normal signal to divide/grow, thereby kind of starving the cancer.

As you might imagine, one of the tricky parts of developing the various antibody treatments is that ideally such drugs need to lock-on to only the cancerous cells.  However, whilst the ideal solution involves finding something unique about the cancerous cells that is not found in normal cells, settling for something that is nearly unique can work too.  The key to the nearly unique scenario is finding something that is much more targeted than traditional chemotherapy, as it just attacks fast dividing cells, and from which the body can easily recover, i.e. repair any damage caused by friendly-fire.

Perhaps not surprisingly, the various types of cancer tend to have different characteristics, and consequently that means when developing antibody treatments it can be necessary to design drugs on an almost type of cancer specific basis.  Due to the complexity of some of these drugs, it can take a long time to develop them, hence that combined with their potential specificity has implications in terms of cost, as well as for what types of cancer there are currently antibody treatments available.

In the case of Brentuximab Vedotin, it works by targeting a protein/receptor known as CD30, which is found on most of the cells in Hodgkin's Lymphoma (as well as Anaplastic Large Cell Lymphoma).  In a clinical trial of this antibody treatment, conducted in 2010, a third of the patients suffering from relapsed and/or refractory Hodgkin's Lymphoma achieved complete remission (no signs of the disease), another forty percent achieved partial remission (at least a fifty percent reduction in the disease), and a further twenty percent achieved at least some measurable reduction in the disease.  It would seem that it was these results that led to the drug quickly being approved for use in the U.S. and Europe, and it currently being available on a compassionate use/named patient basis in the NHS.

For myself, the Brentuximab Vedotin is just intended to reduce the Hodgkin's Lymphoma by enough to enable me to have an Allogeneic (from a donor) Stem Cell Transplant, in the hope that the two types of treatment combined will finally form the cure for my disease.  Consequently, that means I don't need to achieve complete remission from the antibody treatment, but I do need to have a significant response to it, so that the stem cell transplant stands a chance of working.  In other words, the idea is that what the antibody treatment doesn't get itself, and is still around after the chemotherapy (and perhaps total body irradiation) given as part of the stem cell transplant, will be mopped-up by the new immune system I have afterwards; the new immune system being thanks to the generous gift provided by my (yet to be identified) compatible stem cell (or bone marrow) donor!

When the antibody treatment was first suggested to me, given the failed attempt with chemotherapy, and I asked about the percentage cure rates, the doctor seemed to kind of give mixed impressions about the prognosis, as whilst the treatment plan itself sounded better there were clear suggestions that the reality may not be so positive.  However, after reading about the results of the clinical trials of Brentuximab Vedotin, I felt much more positive about it all really (justified or not!).  It may be an odd thing to say, but at this point odds roughly equivalent to flipping a coin don't seem so bad to me!

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