Keytruda for High TMB in ER+ Metastatic Breast Cancer — Anyone With Experience?

punam

My wife has ER-positive, HER2-low (IHC 1+) metastatic breast cancer and has been living with metastatic disease for about 10 years.
Unfortunately, her latest PET scan has shown progression after approximately three months on Xeloda. Her oncologist is now considering Keytruda (pembrolizumab) because of high tumor mutational burden.
Her molecular results include:
• Tissue TMB: approximately 16 mut/Mb
• More recent blood TMB: approximately 65 mut/Mb
• MSS
• PD-L1 CPS 1
I understand that Keytruda is not routinely used for most ER-positive breast cancers, but high TMB provides a potential rationale for immunotherapy. We are discussing this carefully with her oncologists and are also seeking second opinions.
I would really appreciate hearing from anyone with ER-positive metastatic breast cancer who received Keytruda because of high TMB.
If you are comfortable sharing, what was your TMB? Did you have tumor shrinkage or stable disease? How soon was the first scan, and how long did the response or disease control last? I would also be interested in how well you tolerated the treatment.
Enhertu remains another option for my wife because she is HER2-low, but at present I am particularly trying to learn about real-world experiences with Keytruda in high-TMB ER-positive breast cancer.
Thank you very much to anyone willing to share their experience.

moderators

Hi @punam! Just bumping your post so it gets a little more attention. We know you’re hoping to hear from others who have used Keytruda for high TMB in ER-positive metastatic breast cancer. Hopefully some members with a similar experience will come across your post and be able to share what their treatment was like and how it worked for them.

Have you had a chance to talk with your doctors about Keytruda and whether they feel it’s a good option for your wife?

The Mods

punam

Thank you very much for bumping the post.
Yes, we have now discussed Keytruda with her treating oncologist. Following the recent PET-confirmed progression on Xeloda, he is considering Keytruda as the next treatment, particularly because of her high TMB.
We are currently seeking a couple of additional expert opinions before making the final decision, mainly regarding whether Keytruda should be used now and how it should be sequenced with Enhertu, which remains another option because she is HER2-low.
I am especially hoping to hear from anyone with ER-positive metastatic breast cancer who received Keytruda because of high TMB, as there seems to be relatively little real-world experience in this particular setting.
Thank you again for helping the post get more visibility.

shanagirl

hi punum ,

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My Husband, My Life, My Love, My Family, My Cancer

As I go through this forced path I have been thrown down, I have come to realize the love I have always had for my husband was strong. He is amazing and I love him with my very soul and entire heart. …552726 views40608 commentsStarted by micmelMost recent by seeq12:13 amStage IV/Metastatic Breast Cancer, Open to All To Contribute

shanagirl

punum

Try the below link below for TNBC MBC Stage IV. They are all familiar with the diagnosis and Ketruda questions you have

Take care🙏🩵

https://community.breastcancer.org/en/discussion/887281/tnbc-mbc-stage-4#latest