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Switching from Ibrance to Verzenio - Tips?


Daughter/caregiver here to a mom (70yo) with MBC. I'd love to know if anyone has experience switching from Ibrance directly to Verzenio.

Context: My mom has been on Ibrance for 14 months, with an excellent response. She quickly had to reduce her dose to 75mg due to immediate neutropenia, but was able to get a handle on significant bone, liver and lung mets (there's nothing left in her lungs or liver) with this dose. She went from being very sick to getting back to all her normal activities like singing, exercise, hanging out with friends. However, her TMs had been going up the last 6 months or so, and a recent PET scan finally showed some progression in her hip, and a couple other tiny spots in her spine. Her doctor is recommending a switch from Ibrance + Anastrozole to Verzenio + Fulvesant because: 1) Less neutropenia issues with Verzenio, so her MO thinks she might be able to tolerate a higher does which will control the disease better, and since she so well did well on this class of drugs her doctor would prefer her to stick with it as long as possible; 2) Fulvesant is a stronger estrogen-blocker.


  1. Anyone have experience switching from Ibrance immediately to Verzenio? How was your experience?
  2. I'm currently combing through the Verzenio thread for info on what to expect in terms of SEs, and how to manage those, but if anyone has any top tips, I'd love to hear them! I'm particularly concerned about the diarrhea, as we are going on a bucket list trip to New Zealand in 5 weeks. My mom is starting Verzenio immediately, so we'll have a couple of weeks to see how the drug treats her, but I want to do what we can now to prepare since I know the first weeks/months can be the worst in terms of SEs. (Important to note that her doctor is fully supportive of this trip!)

Thank you in advance for any and all insights!


  • weninwi
    weninwi Member Posts: 762
    edited October 2022


    I've posted on the Abemaciclib Verzenio Stage 4 board, but here are some of my main thoughts:

    Based on my reading I think you mother's MO is advising a good treatment path with the switch to Verzenio and Fulvestrant.

    What I learned while on Verzenio (I'm 73):

    I was told to follow a low fiber diet by the oncology pharmacist who did my medication teaching, to help control the diarrhea. This was terrible advice. It might help some at the start, like for one or two weeks, but never long term as it causes nutrient deficiencies.

    I suggest reading and following the diarrhea management advice by researcher Constatine Kaniklidis that is posted at the start of the Abemeciclib Verzenio Stage 4 discussion board. At least as a good start.

    I was overly timid in using imodium at first. My GI doctor finally told me I could use up to 6 a day if needed. The down side of too much imodium is of course constipation. I ended up needing 1 every other day or daily if I had something special planned.

    Many women on the Verzenio Stage 4 board talk of using a fiber product like metamucil to add volume to the stool. I used such a product, but without the added sugar. I think it helped somewhat.

    Like many of the other women on Verzenio, I used a daily probiotic. This is so very important. Verzenio's primary side effects are on the GI tract, so the gut microbiome needs to be fed daily and kept healthy. I drank a non-sweetened Kefir that I could buy locally - at least 1/2 cup twice daily. There are other fermented foods to choose that also feed the microbiome. Some women order liquid probiotics that are shipped on ice, but this is expensive. The advice I got re probiotics in capsule or tablet form is that they are probably a waste of money. Not sure.

    Stay well hydrated. This is especially important as a person gets older. I keep a glass pitcher of water on my counter as a way to keep tract of how much I'm drinking every day.

    I developed nutrient deficiencies while on Verzenio - low Vit D3, low B12, low albumin, and low protein. I don't think these are commonly reported side effects of Verzenio, but nutrient absorption can lessen simply due to aging. I suggest asking for a baseline Vit D3 and B12 levels. In my opinion Vit D3 should be around 50 (I think 30 is too low and at my clinic 80 is considered the safe high, but higher is probably still safe). Repeat the levels maybe in 6 months?? Taking these supplements sublingually circumvents any malabsorption that may occur due to Verzenio's affects on the GI tract. Pay attention to your mother's albumin and protein levels when the blood work is done. The only thing to do for this is to make sure she is getting enough good quality protein daily. I aimed for at least 90 grams per day, or more.

    Finally, don't hesitate to request a dose reduction if diarrhea or other side effects affect quality of life. There was a recent article that Verzenio is therapeutic at reduced doses. I'll post the link if I can find it again. I did find this somewhat related article:


  • kristifromsandiego
    kristifromsandiego Member Posts: 15
    edited October 2022

    Wish I could help. I started Verzenio today. Along with anastrozole. I can tolerate the anastrozole pretty well now we wait to see how the Verzenio reacts. Good luck

  • booksnbikes
    booksnbikes Member Posts: 2
    edited October 2022

    Thanks @kristi! I hope Verzenio treats you well. My mom was on anastrozole too and tolerated it as well. I did get some DMs with some information on managing Vernezio side effects. I can send those to you via message if you'd like?