Does Anyone Know Why Ibrance Gets a Week Off Every Month and Verzenio Does Not?

[Fiercefighter13]

Hi all! I'm being switched from Ibrance/Letrozole to Verzenio/Letrozole and have been researching (or trying to research), the reason Ibrance is taken 3 weeks with 1 week off.....and Verzenio is taken every day. I can't seem to find the reasoning behind the dosage protocol. I know that the week off on Ibrance is to allow our bodies to rebound, and raise neutrophils, red blood cells, platelets, and sometimes other metabolic responses that get suppressed. Does that translate to no rebound while on Verzenio? I've looked at the chemistry profiles of each medication, and I understand how they work, but what I'm missing is the "why" one gets a rebound week and not the other. Has anyone tried both medications, and if so, how did your blood work look differently month to month comparatively with each medication? I'm having a hard time understanding why one needs a week off and the other does not. I can certainly ask my doctor and I plan on doing that when I see her in two weeks, but in the meantime, I'd like to get some real life experience information so that I can ask her better questions. Thanks for listening, and thanks in advance to anyone who might have some answers! Take care!

[kpgirl]

Ibrance and Verzenio have the same objective but work differently, thus causing different side effects. (You'd have to Google on their chemical processes) Ibrance's main side effect is neutropenia, which is why a pause is needed. Verzenio's main side effect is diarrhea. I was first on Ibrance. Over the course of about 21 months I was switched from 125 mg to 100 mg and then to 75 mg, but had to pause longer and longer each time due to neutropenia. I was then switched to Verzenio and have been on it continuously for 3 months, albeit on the lowest dose of 50 mg twice a day. My white blood cell count is much, much better, and it is true that diarrhea is a side effect, although that is slowly getting better. In 4 weeks they will do blood work again and if my wbc count is OK, I will go up to 100 mg twice a day.I really like the feeling of continuity on Verzenio and fewer blood tests. On Ibrance, I was getting blood test every week. The fewer doctor's appointments I need to go to, the better!

[Fiercefighter13 in reply to kpgirl]

I can whole heartedly agree, the fewer doctor's appointments, the better! I have seen a few people change from Verzenio to Ibrance because of severe neutropenia, which is what prompted part of my question. We are all different and react differently to these medications so I have to guess that some people have higher neutrophil counts on one or the other. If going to Verzenio raises my neutrophil count, that will be a welcome change. I'm hoping the diarrhea is manageable for me. I hope you continue to do well with Verzenio! Take care!

[luckysmom13]

Verzenio is supposed to be less likely to cause neutropenia than Ibrance. The week off Ibrance allows the WBC counts to rebound.

I'm on Verzenio and my WBC is consistently on the low end of normal. Of course everyone is different in how they respond!

[Fiercefighter13 in reply to luckysmom13]

Thank you for the information, it’s good to know what I’m heading into!

[Hidden]

I searched on "Verzenio" on this site so am catching up on the topic. I switched to this med several weeks ago.

Just wanted to add one tidbit to this discussion in case others also search in the future...

My doc at Duke said that Verzenio is a bit more effective than Ibrance (I haven't fact checked this, but believe him) likely *because* there's no break. I told him that I often felt...vulnerable...during my Ibrance break (which is why I would sometimes take an extra dose or two during break), so am glad to be taking the meds continuously now.

And my blood counts look better than they have in many years. I asked my doc if they would decrease in the future and she said "No, this is probably as bad as they'll get". BTW, I was in Ibrance 150 for seven years and am now on Verzenio 150, 2/day.

So far, I'm a fan...

Lynn

[Fiercefighter13 in reply to Hidden]

Your doctor's information seems to be the gist of what I'm reading a lot lately. My doctor was hesitant to switch me because of the diarrhea associated with Verzenio. I've been on it now for almost two months, and I feel great. No diarrhea or stomach issues for me on Verzenio, and it's strange, but I feel much better than I did on Ibrance. I don't know if that's psychological, or physical, but I feel better. I just had my doctor's appointment, and my neutropenia is gone and my white blood cell count is in the normal range, my platelets are normal now and my red blood cell count is normal as well, for the first time in almost 3 years. At least for me, it's easier to tolerate than Ibrance. As far as how it's doing with the cancer, that remains to be seen, but I'm staying hopeful!