Posted 10/4/2010 8:05 AM (GMT -6)
Hey, welcome to the forum.
Right, biologics all work in similar ways to bind to TNF Alpha molecules, which are produced by our immune system and are integral to producing inflammatory responses in response to bacterial invasion (&c). The exact mechanisms between the different biologic Anti-TNF therapies differ slightly, and to be honest they are not well understood.
Different biologics do seem to have different levels of effectiveness for different autoimmune disorders, but I'm not really clued up on this, your Rheumatologist is in the best position to advise on this. I'm surprised Etanercept (Enbrel) isn't in your list of options, it's my biologic of choice and I've found it to be very effective, and with a very tolerable side effect profile. In fact, I injected it last night and today I've not really noticed anything apart from being a little tired.
All the therapies potentially increase the risk of infection, and there appears to be a casual link with certain types of cancer. This is because TNF supression reduces the effectiveness of the Immune System, and TNF Alpha is partially responsible for killing cancerous cells. This is not to say that Anti-TNF therapy causes cancer, because TNFs role in cancer prevention is largely not understood, and the link may be due to the illness itself, or other treatments. (i.e. Psoriatic Arthritis patients having concurrent light therapy will skew the statistics due to the increased risk of skin cancer.)
I'm not going to bother describing how the individual biologics work, but they're all the result of cloning from human or animal antibodies, except for Abatacept, which what is known as a "Fusion Protein" (Enbrel is also a fusion protein). A fusion protein means that the DNA 'blueprints' of two seperate genes, which code two serperate proteins, are combined in order to create one resultant protein, using genetic modification by adding extra DNA information into existing cells. You needn't concern yourself with the details of this though - basically, they all have similar side effect profiles and levels of effifacy, and if one doesn't work, that is not to say another won't - different people respond differently to the different biologic treatments. I've discussed the different biologics/mode of action in other threads on here in the past, so feel free to search for those on here.
Side effects tend to be tiredness, increased infections, general malaise. There is also an increased risk of TB with biologics, so it is important that a chest X-ray is performed prior to treatment, and perhaps a TB scratch test.
Hope that helps, but it does seem that there isn't much to help choose between them. For what it's worth, I think Humira and Remicade are more common than Cimzia, Simponi and Orencia, or at least, I hear about more discussion of these. Preferences for different biologic agents tends to vary between different countries, where are you from?
I think you need to discuss with your Rheumatologist to see if any of them have shown to be more effective in their experience, in treating JRA. I don't really know much about JRA - what's the prognosis? Is it something which can be 'grown out of', or does it tend to become RA as the child gets older?
21, Male, England.
Dx: Psoriatic Arthritis, Fibromyalgia, Dyspraxia
Rx: 50mg Etanercept (Enbrel) Sub-Cut Injection, 7.5mg MTX, 25mg Amitriptyline
Oh, and plenty of Tramadol, Dihydrocodeine, Domperidone, Hydroxyzine, and Scotch
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