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generic Imatinib may not be the best choice... plus, we can't get a third TKI drug under ODB. What???

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#1 lisalisa


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Posted 28 October 2013 - 12:40 PM

Hi everyone!

I run patient group in Toronto for people living with CML. Recently, the CML community has been dealt two significant blows.

The first was in June when the patent for Gleevec expired, opening the door to two generic drugs. At about 20% of the cost of Gleevec, it all sounds good - if only the generics were the same. How is it that these generics received Health Canada approval, despite the fact that they are based on a different formulation of the brand?

And in case you are wondering what the big deal is about a different formulation... From the patients I have spoken to who have been switched to the generic, it is all about awful side effects. Side effects today, loss of response tomorrow?

The second blow I just learned about last week. The other big disappointment happened this week when I learned that people living with CML are only allowed 2 TKI's in a lifetime. What?? And here I was resting (fairly) easily, reassured by the fact that if Gleevec stops working tomorrow, I still have two more get-out-of-jail cards in my pocket, plus countless others in the pipeline. Well, that bubble has burst. Turns out if you are on your second TKI, and you develop adverse effects outside of three months, you have pretty much reached the end of the TKI line. Again, I have to ask, What??

We have started campaigning the government about these two issues - I am hoping the media picks it up. Isn't it bad enough to have to deal with a cancer diagnosis? Unfortunately, if these two situations are allowed to exist, we will see a highly treatable disease become one that people may start dying from. At the very least, our quality of life will be significantly compromised.

Please visit our Facebook page at https://www.facebook.com/cmlsupport

I'd love to hear from you,

Lisa Machado

CML Support


#2 GerryL


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Posted 29 October 2013 - 06:52 PM

Generic Tyrosine Kinase Inhibitors (TKIs) Arrive In Canada


Hi Lisa,

The two TKIs in a lifetime must be a Canadian thing. We have subsidised prescription medication in Australia and would be allowed all three drugs, I'm not sure if the third generation TKIs are available here yet.

#3 Trey


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Posted 29 October 2013 - 08:29 PM

The imatinib mesylate (the actual therapeutic agent) in the generic drugs would be exactly the same as Gleevec.  The difference is that Gleevec uses a beta crystalline pill structure and the generics use an alpha crystalline pill structure of delivering the imatinib.  Novartis claims their beta crystalline form has better shelf life due to enhanced thermal stability (does not break down as quickly in heat) and less hygroscopicity (does not absorb as much moisture from the air).  Also, Novartis says their beta crystalline form is more soluble than the alpha crystalline form, which could possibly enable better absorption in the body than the generics, depending on the difference in solubility.  That part is unknown, so whether this affects generic drug effectiveness is also unknown.  It is also possible that the alpha form is taken up differently from the alimentary canal, either greater or lesser uptake.  And there could also be some impact on cellular uptake.  Recall that imatinib has two required uptakes, first from the alimentary canal, and secondly through the cell wall into the leukemic white blood cells, which is the only place it does any good for CML patients.  Who knows, but maybe the alpha form is taken up more easily into off-target cells, which would account for the enhanced side effects (if actually true -- just saying there is not enough data yet on that issue).

Generics are assumed to be bio-equivalent, and therefore do not require clinical trials to prove efficacy, but a lower level of bio-equivalence testing can sometimes be required such as drug blood level tests (not nearly as useful).  So the generics do not have clinical trial data to show if there are any differences.  However, patients in India and elsewhere have used the alpha crystalline imatinib, and those drugs do work, but I do not know of any head-to-head comparisons among large groups of patients (i.e., a clinical trial).  So maybe they work better or worse, or maybe the same.  But it is interesting to note that Indian drug manufacturers fought to have the right to manufacture the beta crystalline form, and won that battle last year.  So they now manufacture the beta crystalline form in India. 

Overall, the generics should work well enough, but whether they work just as well as Gleevec is unknown at this time.  I would be interested to hear about patients who start out on them at diagnosis to see how they respond, and their side effects profiles.

#4 lisalisa


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Posted 30 October 2013 - 09:01 AM

Hey Trey,

Thanks for all your info. Here in Ontario, we are starting to see a number of patients who have experienced new side effects on the generic that were significant enough to require changing back to the brand, or switching to another drug. We are campaigning the government to make some changes so that patients who take Gleevec (this also includes GIST patients) can continue to take the brand and save themselves the pain of having to go through these side effects. In the interim, Novartis has started a patient assistance program through which all CML patients can continue to get access to Gleevec.

#5 chriskuo


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Posted 30 October 2013 - 01:39 PM

How much do patients in Ontario pay for the drugs (generic imatinib vs Gleevec)?

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