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

[hopehope67]

After 26 months my onc reduced the dose of ibranca from 125 to 100. I had low neutrophils, felt very tired with breathing problems especially in recent months . Therefore, instead of one week off, I used to be up to 2 weeks, so that the neutrophils would increase from 0.6-0.9 to 1.00. After the first cycle with dosa 100, I feel better, there are no breathing problems, and my neutrophils are 1.16. The marker is stable, I have the next CT scan in 3 months. I am also on fulvestrant every month and Zometi every 3 months. My onc is now asking for a PIK3CA mutation test. I found this study in your discussions from a year ago ncbi.nlm.nih.gov/pmc/articl... . I am interested in your latest experiences in this. Thanks in advance.

[Fiercefighter13]

Hi there!! I had low neutrophil counts, platelet counts and RBC counts on Ibrance. I was on 100mg. for almost three years. I asked to be switched to Verzenio and my counts went up quite a bit, they are at normal levels now. I am taking Verzenio 150 mg twice a day, every day. I know that a lot of people get diarrhea and stomach upset on Verzenio, but honestly, I have done great on it. No hint of any stomach problems and I have been on it now for three months. For me, Verzenio has been a lot easier to tolerate than Ibrance. I just hope its working. Its almost time for my next scan, but luckily I feel great. As far as Fulvestrant causing resistance, I think most breast cancer will become resistant to all therapies given enough time. I have the PIK3 mutation as well as the CDH1 mutation (Lobular carcinoma). I hope you do better on your lowered dose, from what I have read from many people on this site, Ibrance does not seem to be dose dependent. It seems to work, if it works, at any dose. I don't know if that's really true, but it seems to be what many are saying. Take care!

[hopehope67 in reply to Fiercefighter13]

Thank you. I agree with you that most breast cancer will become resistant to all therapies given enough time. That's why I am extremely grateful that I found this group of brave women who share their experiences and new knowledge, giving us hope that our story will last a long time.