Tarceva Dosage - 1259816

Hi Tom,

That's a good question. When drugs are tested in clinical trials, the dosage eventually chosen is the "maximum tolerated" dose. It's the point at which most trial participants were able to tolerate treatment without unacceptable side effects. Once that dosage is set, further trials determine whether the drug is effective. Usually no large-scale attempt is made to see if a lower dosage will be just as effective. Some patients are just more sensitive to Tarceva, both in side effects and efficacy. But at the start, you don't know if you're one of those patients. So do you want to start with a lower dosage that may not be effective, or start at the standard dose and reduce if side effects warrant? If the lower dose is not effective, it could be the dose or it could be that the drug simply doesn't work for you, and you would waste further time (and the cancer could possibly progress further) treating with the higher dose, only to find it ineffective as well.

JimC
Forum moderator

It's certainly a more open question for patients with an EGFR mutation, who may do just as well on a lower dose, but it may well be that many patients with EGFR wild type (no mutation) require a higher dose for any beneficial effect. This isn't to say that it's wrong to drop the dose, where a higher level of side effects may represent crossing a certain threshold biological activity, but the survival benefit for a broad population that includes primarily EGFR wild type patients used 150 mg daily, and I would not presume that the results in this broad population would be the same with 100 mg. I would say that it's very likely that starting at 100 mg would lead to many patients not having their dose raised, which could mean that far more patients end up with their dosing being below a threshold they actually need to exert a survival benefit.

-Dr. West

Not to hijack tvoltagg's thread, but these questions always confuse me when I think of myself. I started on 150 mg and am now down to 25 mg. I have been on this dosage since July 2013. I realize that I am a little unusual in that I am stage IV and have shown NED since July of 2012. However, how do I know - other than not showing progression - that 25 mg is good enough? In a setting like this, would it be beneficial to slowly raise the dosage? Or is this a situation where if there is progression, raising the dosage could help at that time?

Of course you're not hijacking the thread. I think your question fits appropriately here.

I'll ask a doctor to give some input here.

I hope you and your family are doing alright,
Janine

Hi sherry - dosing of oral drugs really does take a lot of factors into account. For tarceva factors could include the EGFR mutation status, the tolerability of the drug in the past for that patient, bloodwork/lab values, and the current disease state. I think it is challenging to know in this forum what the optimal dose is for your situation but certainly being NED for over a year is an amazing accomplishment - congrats!!! I can say that when resistance occurs, raising the dosage is occasionally heplful - especially if dose is very low and/or progression is very slow, but usually a better strategy at that time is adding another treatment to erlotinib or switching to another type of treatment. Hope this helps!

Thank you Dr. Sequist. Yes, your answer does help, and thank you. I have been very fortunate in that I went from a single lesion to a single met in 3 years, with nothing in between. I'm hoping to break my record this time around. :) I was asking more in general and using myself as an example. In my case, it is due to intolerable side affects. I am more curious in general if, in the face of progression, more is better, but it sounds like with everything else, it is on a case by case basis.