HER is a receptor that can be expressed by breast cancer cells and helps them to grow. There are medicines that can target and block this receptor, slowing or stopping the cancer from growing.
No HER receptors found is called HER negative, and these medicines wouldn't work for this type of cancer.
HER 1+ and 2+ were previously considered HER negative, but are now considered HER "low" and some medicines which target the HER receptor are approved for its treatment.
HER 3+ is when there are enough receptors to call the cancer HER positive. And all the medicines which target the HER receptor can/should be used to slow or stop its growth.
It's important to note that cancers can lose/gain different receptors over time.
I was HER2+ and being treated with Phesgo which now appears to be ineffective. Now I am HER3+ and going to start on Kadcyla. Does this mean my prognosis is worse?
I'm sorry to hear that Phesgo didn't work for you. I should probably state that I'm not medically qualified in any way.
The change from HER2+ you HER3+ shouldn't affect you prognosis. If anything, it gives the treatments more receptors to bind to.
Phesgo is a medicine to block the HER receptor, which should slow the growth. It seems your cancer has just produced more receptors to try and counter the medicine.
Kadcyla is an "antibody drug conjugate". It binds to the HER receptor, then releases a toxic drug that kills the cells.
I hope that you have more luck with this new treatment!
I was on Phesgo for nearly two years and am sad to have to move on to a intravenous treatment from the easy injection and am terrified the side effects are going to be cumulative.
I can't comment on Kadcyla as my wife has never been on it, but she's currently on Enhertu for HER2low disease, and the only real side effects are fatigue and low neutophil counts.
If you click on my name it'll take you to my profile where you can see all the treatments she's been on, and she's still doing OK!
Interesting I was offered Enhertu but my oncologist advised me against it as the side effects are too severe. I was surprised as I had read such good reports of it.
