PIK3CA mutations contribute to fulvestrant resistance in ER-positive breast cancer

[Jac-genova]

I recently came across a study that basically stated that women with PIK3CA gene mutations may actually have fulvestrant resistance. I wanted to ask if any other women had that gene mutation and if so which medications/treatments are you pursuing?

ncbi.nlm.nih.gov/pmc/articl...

[Hidden]

I have that mutation and indeed, Faslodex failed me.Currently on Capecitabine and that, so far after 3 cycles, seems to be effective. Keeping my fingers crossed it'll remain effective.

Anja

[blms in reply to Hidden]

How long were you on faslodex before you knew it did not work?

[Hidden in reply to blms]

After the initial loading shots of two... Truth be told, i failed Ibrance before when it was determined i had minimal progression, so onc put me on Faslodex after which my tumor markers went up significantly and scan showed increased progression.

[blms in reply to Hidden]

Also is this other drug IV?

[Hidden in reply to blms]

Capecitabine (Xeloda) is available as an IV, but i take the oral version. It took some trying to get to a tolerable cycle, which I believe we have achieved. I feel very good on it right now, with few side effects

[Aquatan in reply to Hidden]

Would you let me know what your tolerable dosing regime is? I have just finished piqray a few weeks ago and just started xeloda, testing things out and believe it or not, still got massive constipation

[Samsontheodore]

I have the PIKC3A gene mutation identified from the Foundation One test. Interesting you should say this because after a year on Ibrance and Fulvestrant, they quit working for me. Wonder if that is the reason why!

I was switched to Tamoxifen combined with Afinitor (Everlimus), and have been on this combo 17 days. Praying it works as my second line of treatment, but miss the almost normal year I had on Ibrance and Faslodex. Have read here some ladies are on that combo successfully for five years or longer!

I assumed I would change to the drug, Piqray. However, it is possibly harder to maintain that drug with stronger side effects, so went on Tamoxifen (was on in 2007 and easy to take for me) and Afinitor (Everlimus) route at 7.5 mg (couldn’t handle 10 mg dosage). So far, other than getting through some diarrhea, I pray it is working (only on 17 days so far)! Let me know what doctor put you on! Good luck! 🙏🏻

[kduck in reply to Samsontheodore]

What other side effects do you have on afinitor? Do you take every day?

[jersey-jazz]

Wow! Thank you! I too have the PIK3CA gene mutation. My oncologist is about to put me on fulvestrant. I'll be sending her this reference from NCBI.

[Jac-genova in reply to jersey-jazz]

I showed that to my mom's oncologist and he basically said that at some point the tumor will become resistant to all aromatase inhibitors so it's just a matter of mixing and trying them. Curious to hear what your oncologist says. Thanks!

[MaryCos]

Thanks for sharing this. I found out about a month ago that I have the PIK3 gene mutation. Have been on Ibrance and Letrozole since late September (and Zometa since July... when I wrongly began chemo as a first line for my de novo MBC), and there has been no evidence of progression in my two scan cycles since starting hormonal treatment (1/8 and, most recently, over this past week). Had never heard this about Fulvestrant, so I hope I get a good long run on my current meds!

I did speak with my oncologist about the PIK3 thing, and asked if this is actually a good thing. It is for the fact that Piqray is an option for me now.

[mariootsi]

I have PIK3CA and presently on Ibrance and Fulvestrant! Interesting.

[Adele_Julia in reply to mariootsi]

So am I ... Interesting

[Photo-Bug]

I, too, have the mutation. I was on each of the Ibrance doses along with Fulvestrat. There was no improvement. That's when I was switched to Xeloda.

With the side effects of Piqray I don't want to go there.

[Pbsoup]

Interesting. I just had a stable-ish scan since starting Faslodex a few months ago, but my markers shot up this week. (scan showed nothing new, but there were a few areas of increased hyper-metabolism) My Onc was convinced they would go down by now, and that Faslo + Ibrance would do the trick after a small amount of progression in December...

I have been asking and asking for genomic testing, just so we have more data to factor in, but he keeps prevaricating. I think I will show him this and get pushier. He says I am on a ten year plan, and I am hardly about to die, but so far nothing seems to be going quite the way he says it will. Am I just being neurotic?

I feel great, and want to stay on Ibrance as long as possible...but not sure if things are brewing that I should be more proactive about... (I know I have dithered on here before re a second opinion... why am I afraid to suggest it to him?)

This study also suggests combining Piquray with a CDK 4/6 inhibitor might work--but the study was based on observing only 4 women I believe, then the rest was done in a petri dish so more research is necessary.

[Hidden]

Hi All....(for those of you who may remember that I was previously active on this board, "Hello! I'm doing well! ".

I scanned the study and am left wondering how valid it is. It seems they looked at MBC patients who had developed fulvestrant resistance and determined that 3 out of 4 had the PI3K mutation. If I remember correctly, roughtly 2/3's of ER+ patients have this mutation. So is the 3/4 meaningful? I'll take a closer look *soon*, but in the meantime will mention that I've been on Fulvestrant/faslo + Ibrance for more than 2.5 years, and I have that mutation. Anecdotal, I know, but adding one person to a study of four sort of counts?

In my time off from the board, I've developed several no doubt wacky hypotheses re: how these studies are populated/potentially mis-populated. If I end up with any confidence re: my ideas, I'll be sure to share...

But, the short of it is that I'm not bought into the study, for what that's worth...

Take care, everyone, be well...

Lynn

[Pbsoup in reply to Hidden]

You’re back!!! Yay!!!! We’ve missed you

[Pbsoup in reply to Pbsoup]

And to add I had the exact same thought about this study. ...

[Teddielottie in reply to Hidden]

Lovely to see you back on here Lynn ... have missed you and your ‘wacky hypotheses’. ( your terms ! !) and your great sense of humour . Hope you are good ! Are you still sticking with Ibrance 125 mg ? 😀x

[Hidden in reply to Teddielottie]

I am, indeed, still on the 125! My doc and I have a handshake agreement to ignore my labs! So far, so good, i.e. still haven't been sick with anything, not even a cold, but I isolated for....oh, a year!?! Fully vaxxed up now, so not worried about any illnesses! Thanks for thinking of me!

[Staysha in reply to Hidden]

I’ve missed you Lynn. Glad all is well with you.

Stacy