You should be eligible to take Enhertu. This is an antibody-drug conjugate that targets cancers that express HER2. It is approved for all solid tumors that are 3+ for HER2. I expect your oncologist will recommend this tomorrow.

People on this forum who have taken it have found it to work (at least for a while) and for it to be quite tolerable.

Good luck!

@jchantler Welcome to Mayo Clinic Connect and to our Support Group. I see you have already received a recommendation from @val64. The results of your second CT scan must have been a shock for you and not the results you'd hoped for.

My cancer journey is and was different than yours as I did not have chemotherapy. In your place here is what I would do. You have some questions in your post that I would ask my oncologist. Directly. And write these questions down on a card or paper so you can refer to them during your appointment.

1. Since you have new tumors that have shown up in your lungs are these tumors a new cancer? Does this mean I have lung cancer or is the lung tumor also clear cell carcinoma?

2. the current treatment does not seem to be working for me. What's next? What other clinical trials am I eligible to enter?

3. My insurance won't pay for Trastumzab. If you think this would be a next step for me will you be willing to appeal the decision of my insurance?

In a medical environment it can be difficult to advocate for yourself. Do you have someone who goes to your appointments with you who can take notes and provide you with support? You will do the talking but your support (your spouse, relative, good friend) will jump in as needed. In addition, with your support in the appointment tomorrow you will two sets of ears - yours and your support person. I know that when I am very anxious during appointments I miss information and so my husband is present with me and takes notes.

Do you have other questions to ask your oncologist?

I also have clear cell carcinoma of the endometrium and had your same chemo juice. A CT scan before my last infusion showed metastasis to lymph nodes so my CCC is considered chemo resistant. Thus, I expect that it was the surgeries and radiation that enable me to sit here and reply.
I don’t have HER, P53 or other markers that direct me towards any treatment proven to help. Technically, my metastasis puts me into Stage 4, but my doctor won’t say it. So I understand where you are at.
I always have a list of questions when I see my oncologist and when first diagnosed my husband even recorded our conversations. Doctors don’t like that, but it really helped, as such discussions move quickly and we can misunderstand or forget.
I hope that you get the information you need and some answers that relay hope. The emotional journey can be more challenging than the medical one.

i'm on medicare for 4b serous endometrial. i was on trastumzab with the first infusion and medicare covered it with no problem. are you sure about your insurance or did you just talk to some idiot? i just finished 6 (carbo, platin, trastumzab (actually i'm getting Keytruda but same thing). when i get the EOB's from insurance, the herceptin is about $10K (medicare gives them about $1K i think).

from the keytruda website:
a kind of uterine cancer called advanced endometrial carcinoma in adults:
when a laboratory test shows that your tumor is mismatch repair proficient (pMMR) or not microsatellite instability-high (MSI-H), and
you have received anti-cancer treatment, and it is no longer working, and
your cancer cannot be cured by surgery or radiation.

sounds like it should be approved. maybe you need a second opinion (they take a LONG time to get, however, at least in the SF bay area). I'm pMMR (there is something called Jemperli for dMMR).