AI or targeted therapy failure?
Hi there,
Just wondering how one knows which medication failed if you are taking a targeted therapy and an AI?
My sister is on Ibrance and Letrazole and MRI was clear on spine in November and now a 19 mm spot on T2. Her tumour markers have also been slowly rising.
Her cancer is lobular, estrogen positive, progesterone negative and Her2 negative
Previously (6 yrs ago) it was progesterone positive.
She was on Kisqali for a short time but could not tolerate side effects.
Thanks for any insights you may have.
R.
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Hi @barnswallow25, and welcome to our Community!
We're so sorry to hear of your sister's diagnosis, but we're really glad you've found us. You're sure to get a wealth of advice, information, encouragement, and support here — we're all here for you both!
We do hear that sometimes medications that once worked on MBC stopped having an effect on the cancer and a new medication then becomes an option. You can read more about What Happens If Metastatic Breast Cancer Treatment Stops Working? for more. But, in a nutshell, typically there is another CDK4/6 Inhibitor and/or hormonal therapy combination one could try if the previous treatment fails the patient.
Please let us know how else we can help support you and your sister. Others will surely be by soon to weigh in!
—The Mods
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They don't know. That's why they typically change both the AI and the CDK4/6.
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Barnswallow25, I am sorry your sister is experiencing some progression. There are some oncologists that will radiate a new "cancer" spot if there is progression and stay on the same treatment. However, if tumor markers are rising and she has a new spot, it might be time to have a new biopsy and look for any acquired mutations?
I have read about the importance of FES Petscans for Lobular breast cancer stage IV patients as the regular scans don't always show lobular breast cancer well. You can do a search on the topics for FES Petscan or stage IV ILC and see if you can find more info.
Hope this helps!
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barnswallow, It is more common just a failure of the endocrine therapy- early study found around a third of women remained sensitive to the same CDK4,6i, and nowadays I think many MOs just switch to a different ET and different CDK4,6i, and see if it works. Lobular especialy is sensitive to anti-estrogens.
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