1. < Polymyalgia Rheumatica (PMR)

Genetic testing to determine drug suitability

Posted by mtr2601 @mtr2601, Mar 12 2:41pm

Pharmacogenetics is a rapidly advancing tool for Doctors to help tailor drugs to an individual. A simple blood test (wait a few weeks for result) can tell your treating physician if you have genes that will make particular drugs unsuitable for you.
Is there anyone here who has had this type of test for Auto immune drug therapies?

Interested in more discussions like this? Go to the Polymyalgia Rheumatica (PMR) Support Group.

emo | @emo | Mar 14 9:00pm
In reply to @mtr2601 "Thanks for that info, i didnt want to front up to my Doctor to request testing..." + (show)
@mtr2601

Thanks for that info, i didnt want to front up to my Doctor to request testing if there was no scientific basis for doing it. Just finding out if you are a slow or fast metaboliser is valuable when it comes to the drugs we are being asked to take. If you are a slow metaboliser, drugs are probably going to affect you for much longer and be more potent at lower than standard doses than if you are a fast metaboliser.

Jump to this post

That’s very true. I guess my testing found I’m a slow metabolizer because most of the recommendations they gave me were to start at a lower dose first if possible.

It would be great if the testing was more widely applicable to other drugs though.

REPLY
teddyz | @teddyz | Mar 15 10:37am
In reply to @emo "I have had pharmacogenomics testing, at Mayo actually. Afterward, there’s a consultation with one of the..." + (show)
@emo

I have had pharmacogenomics testing, at Mayo actually. Afterward, there’s a consultation with one of the pharmacists to explain it.

It was pretty complex, and I don’t exactly have a science brain, but it was my understanding that while the science is evolving, there’s still many limitations around what they can recommend based on the data they currently have. If I remember correctly, most of the existing data is based on genes that affect how your liver metabolizes medications.

But please don’t quote me on that because I’m not 100% on it, but the main idea was that because the majority of the research is focused on how one specific part of the body processes medications, it limits which medications they can advise on. And there’s also more data regarding some genes more than others.

The pharmacist specifically told me there isn’t supporting data for most of the kinds of medications used for autoimmune conditions. Drugs we discussed that I can recall were gabapentin, some antidepressants including amitryptaline, blood thinners, and there’s some cancer medications.

It was fascinating though and felt affirming because I learned I have a genetic variant that’s associated with metabolizing drugs more quickly, and the specific variant is involved in metabolizing around 30% of prescription drugs on the market. She said that might explain why I have trouble with so many medications.

Jump to this post

This helps explain why I've heard different doctors have varying confidence levels in these tests. My niece had it done and it was 100% on target with the meds we already knew didn't work for her (non-autoimmune related). Like so many, it's an evolving field and we can hope they get more accurate.

REPLY
nyxygirl | @nyxygirl | Mar 16 3:14pm
In reply to @emo "I don’t have PMR; I’m actually a caregiver for my father who has PMR, so not..." + (show)
@emo

I don’t have PMR; I’m actually a caregiver for my father who has PMR, so not sure if my experience is transferable.

But I’m on Humira; it’s a TNF blocker (a type of cytokine that causes inflammation). Before, I took Enbrel, also a TNF blocker. I have seronegative spondyloarthropathy (it affects the insertion points where tendon goes into bone, i.e. where the Achilles inserts into the base of the heel).

We had to do the usual trial and error approach. If pharmacogenomics were to advance enough, how great would it be to just be able to know which medications are must likely to work without having to go through potentially months to see which class and type of medications would work best?

Jump to this post

hello @emo -- and all - my friend works at Foundation Medicine so the term "companion Diagnostics" came to mind -- a quick Google search and I found this : https://www.thermofisher.com/blog/proteomics/rheumatoid-arthritis-treatment-biologics-and-companion-diagnostics/
https://www.foundationmedicine.com/blog/companion-diagnostics-explained-their-critical-role-cancer-care-and-our-latest-approvals

REPLY
1 reply
DadCue | @dadcue | Mar 16 3:45pm
In reply to @nyxygirl "hello @emo -- and all - my friend works at Foundation Medicine so the term "companion..." + (show)

The term "inflammation pathway" is misleading because there aren't single pathways or multiple single pathways. For example, there isn't a separate TNF inflammation pathway that is distinct from the IL-6 inflammation pathway.

These cytokines fuction in a network with other cytokines. There is "crosstalk" along with "upsteam" and "downstream" regulation and feedback mechanisms in this complex network of cytokines. This makes it nearly impossible to determine which biologic will work the "best" for any particular diagnosis.
https://www.sciencedirect.com/science/article/pii/S0167488911001844
It is a complex network to say the very least. I'm just happy IL-6 inhibition worked well for me. My rheumatologist said he made a "lucky guess" but I think he was just being humble. He explained to me why he guessed the way he did and I didn't understand a word of it.

In summary, "Disturbances in information flow may cause chronic inflammatory disease." as the link above points out. I think we are stuck with "trial and error" for the time being. Doctors can't even diagnose what inflammatory disease we have with any degree of certainty.

Just my opinion!

REPLY
View MoreView Less
Please sign in or register to post a reply.