Ribociclib 400 mg – has anyone reduced to 200 mg because of side effects?

Hello everyone,

I joined this forum when I started taking Ribociclib in December last year. Because of brain fog and very low energy, I haven’t been back since and have found it difficult to navigate the forum. I’m hoping to reconnect and hear about other people’s experiences.

I’ve been reading some of your posts today, and it’s reassuring to know I’m not alone in dealing with some of these side effects.

I’m now 66, and I was diagnosed with breast cancer in April 2024, just few months before I was 65. I had a right breast invasive ductal carcinoma (IDC), which was Grade 2, oestrogen receptor-positive (ER 8), progesterone receptor-positive (PR 7) and HER2-negative. The cancer had spread to one of my lymph nodes. I had two operations to remove the lump (the second was to achieve clear margins), followed by five weeks of radiotherapy.

The pathology showed a 13.5 mm invasive tumour, with a composite tumour size of 19 mm including DCIS. There was also lymphovascular invasion (LVI), and 1 of the 6 lymph nodes removed was positive, with a 3.5 mm deposit. My second operation achieved a clear margin.

I also had an Oncotype DX test carried out on my tumour tissue. My recurrence score was 16, with a reported 5-year distant recurrence risk of 4%. My understanding is that, because the score was relatively low, my oncologist felt that chemotherapy was unlikely to provide enough additional benefit, so I didn’t have chemotherapy. My staging CT also showed no evidence of distant metastatic disease.

Although I had a full hysterectomy around 14 years ago and had already been through the menopause, my cancer was still hormone-positive, which came as a surprise to me.

Alongside the cancer, I have a long history of other health problems, including unexplained infertility, more than 35 years of chronic fatigue, over 20 years of insomnia, memory problems (especially short term memory), a chronic dry cough, and lower back pain caused by a degenerated facet joint. The back pain is particularly debilitating, as I struggle to sit for more than 15 minutes or lie down for more than a few hours. Unfortunately, I’ve tried almost every available treatment without much success.

After radiotherapy, I started taking Anastrozole. I also had a bone density scan, which showed that I already had osteoporosis in my lower back, so I was started on a weekly Alendronic acid tablet.

Last September, my oncologist contacted me to say that Ribociclib had been approved as an additional preventative treatment for my type of breast cancer. I was advised that it could have significant side effects, but that I needed to start it by December if I wanted the opportunity to take it. I decided it was worth trying, knowing that I could stop if I couldn’t tolerate it.

So far, my blood tests, including my liver and kidney function, have all been fine. However, the fatigue has become overwhelming. I also have a persistently high heart rate, my chronic dry cough seems worse, and for the past three months I’ve had very watery eyes.

My breast cancer nurse said that if the side effects become too difficult, my Ribociclib dose could be reduced from 400 mg to 200 mg.

My biggest concern is whether the lower dose would still be effective at reducing the risk of my cancer returning. I also wonder whether changing from Anastrozole to another hormone therapy might help, or whether the Ribociclib is more likely to be causing these symptoms.

I’d really appreciate hearing from anyone who has reduced their Ribociclib dose, changed hormone therapy, or experienced similar side effects.

Did reducing the dose help with the fatigue? What did your oncologist tell you about the effectiveness of the lower dose? Has anyone changed from Anastrozole to another hormone therapy and found that their side effects improved?

I’d also be very interested to hear from anyone with a similar diagnosis and treatment plan, particularly those who have had one positive lymph node and a relatively low Oncotype DX score.

I hope I’ve posted this in the right section. Apologies if there is already a similar thread elsewhere—I found a few discussions about Ribociclib, but I wasn’t sure where best to post my questions.

Thank you for taking the time to read my post. Any advice or shared experiences would be greatly appreciated.

Best wishes,

Newby

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If you drop medicine amount

The effect will be less too

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@newby2025

Just a quick post before work, so excuse brevity but there is a lot of ribociclib info in this thread and this is my post relating to dropping the dose.

Essentially you can drop the dose, it is likely to be as beneficial but should reduce side effects. It all relates to how you metabolise the drug.

Good luck

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I dropped down to 200mg due to repeated chest infections and problems with dry skin on my hands and feet. I’ve had an improvement in fatigue levels and also my eyebrows and hair are growing better. I think losing weight has helped too and find my energy levels are ready for more exercise.

I feel more like me :blush:

As for swapping AI, I’m not sure. I’m on Letrozole and find the side effects pretty dire. Some days it feels like every single joint is aching. Exercise is helping.

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Hi Newby,

Melanie again!

I had a 12mm tumour, plus a naughty 3m aggressive one behind it, which hadn’t been picked up previously.

Eleven lymph nodes were removed, three of which were cancerous.

My oncotype was low like yours at 14, as a consequence of which, I didn’t need chemo.

My DEXA scan was good.

A liver investigation in 2024 showed I had no liver damage and no fatty liver.

My kidney function is good.

I had to go from 400mg Ribociclib to 200mg as my neutrophils went down to 0.5 (they are currently 1.1 which is still low, but in the tolerance range) . The ribo gives me sore gums and pains in my neck as if my glands are up.

I moved from Anastrozole to Exemestane and have found very little difference in the existing side effects… ergo every joint and muscle seems to hurt, my eyes water relentlessly, I am tired all the time but also have insomnia. (Very common it seems).

I have little energy, or inclination for exercising, but know that I must keep myself strong. I am 63 and have a BMI of 22, good cholesterol, I don’t smoke, but I enjoy a glass of wine.

My hair has become horribly course, despite my cutting it short at the beginning of the cancer journey, which is making growing it out a total pain, as it looks awful. A wonderful girl came on this forum to respond to my hair problem and gave me lots of products to try, am very grateful.

I have just started having rib pain from under the breast, round to the back, which hurts more when I breathe and also my breast is very tender. No idea what that is, but am putting it down to being another side effect.

I am lucky to have a full body cryotherapy chamber and a hydroxy hyperbaric pod in my home (although I haven’t felt like going in the Pod in this weather) so I’m hoping using these will also help with any inflammation and clear free radicals. If any of you are in the Fareham Hampshire area, please let me know and we can organise ‘wellness days’ here.

Much love and strength to all of you and remember

Cancer is NOT always a death sentence.

Melanie x

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I took Ribociclib for Secondary Breast Cancer and had to drop the dosage because of the side effects. I was like a zombie and my feet peeled (something called PPE?) I worried it wouldn’t work on the lowered dose - but the oncologist reassured me. It did work and held everything in check till last year. Good luck, hope the lower dose helps you cope.

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Hi,

Are you saying that you have a new breast cancer tumour whilst being on Ribociclib …? How many cycles/years have you been on it? Did you have another lumpectomy last year to remove the tumour and are you still on Ribociclib…?

Questions questions sorry :cry:! My belief was that Ribociclib interferes with any cancer cells which are starting to metastasise, therefore preventing a new tumour forming. But you appear to be saying you have a new tumour despite being on it..? I feel devastated for you! And worried that all these side effects might be for nought :cry:

How do you feel about this and do you believe the lower dose was the reason you were not fully covered against new tumours?

All my heartfelt prayers to you :folded_hands:t2: how dare our own bodies try and kill us! Melanie xxx

No, no, you’ve misunderstood! Please don’t worry - I didn’t get a tumour after starting Ribociclib. Since they’ve now started giving it to patients after Primary treatment, you can be confident it’s effective.

I started Ribociclib (with Letrozole) when the secondary breast cancer was discovered. The tumour and the bone mets were under control taking the full dose but my body wasn’t tolerating the side effects - so the oncologist lowered the dose by one third. He explained that the lower dose would control the tumour and bone mets just as well as the higher dose. You can bet it was the first question I asked! Indeed it did work well, keeping my cancer markers down and preventing both the tumour and the bone mets from growing for over two and a half years. Then I moved to other endocrine treatments when two of the bone mets showed signs of growing.

Remember, this is secondary breast cancer and it progresses differently from the treatment of primary, being incurable. I originally had primary breast cancer in 2003, only needing a lumpectomy and radiotherapy, followed by five years of Tamoxifen. So I’d gone 19 years clear before this secondary breast cancer was discovered by chance. I’m now three years eight months down this journey and just at present I’ve reached a tricky spot and am waiting to learn about the next stage. Yes, I’m nervous but I know my oncologist will set me on the best way forward.

And I constantly remind myself that there’s no point worrying about what I can’t change - even though I do, of course! Press on - I hope all works out well for you.

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*oh I seeeeee! Yes I totally misunderstood :woman_facepalming:t3:!

I’m so sorry you are once again burdened with cancer and you’ve been told it’s incurable …:folded_hands:t2:? So I’m guessing they are just trying to control it… Are you in pain? What age are you? More questions !! I am 63 and would, therefore, be quite happy if I lasted 19 years before a secondary tumour, because I probably won’t be here! :face_with_hand_over_mouth:

The whole thing is so scary and out of our control to alter, apart from taking the meds.

Have you altered your life now that you know you have limited time…? I don’t know what I would do in that situation… probably just drink champagne :clinking_glasses: until it came out of my ears!

You sound so positive and you’re right, we can’t alter what has happened, so best to smile and greet each day :pink_heart:

Sending you love and strength

Melanie xxx*

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Hi Bordercat,

Thank you so much for your detailed reply. This is exactly the sort of experience I was hoping to hear about, as I’ve been quite worried about reducing the dose and whether 200mg would still give me enough protection.

It’s really reassuring to hear that you had the same concerns, discussed it with your oncologist, and that the clinical trial data supported the lower dose. Your explanation about fast and slow metabolisers also helped me understand why 200mg can still be an effective dose for some people.

It’s interesting that your liver results took a while to settle even after reducing the dose. Thankfully my liver and kidney blood tests have been fine so far, but the fatigue is becoming very difficult, which is why I’m considering the reduction.

Thank you again for taking the time to explain everything. Your reply has definitely made me feel less worried about the possibility of going down to 200mg.

Newby

Hi Liteleft,

Thank you for replying. It’s really encouraging to hear that reducing to 200mg improved your fatigue and that you’re feeling more like yourself again. That’s exactly what I’m hoping might happen if I have to reduce my dose.

It’s also interesting that you’re on Letrozole. I’ve been wondering whether changing from Anastrozole to another AI might help with some of my side effects, although I can see from your experience that Letrozole isn’t necessarily easier!

Thank you again for sharing your experience. It’s really helpful.

Newby

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Hi Hilary,

Thank you so much for replying and sharing your experience. I’m sorry you had such difficult side effects, but it’s really reassuring to hear that you had to reduce the dose and that your oncologist reassured you that it would still work.

The fact that you were on the lower dose and it kept everything under control for so long is particularly encouraging for me, as my biggest worry has been that reducing from 400mg to 200mg might mean losing some of the benefit.

I’m struggling quite badly with fatigue at the moment, so hearing from people who have reduced the dose and found they could cope better is really helpful.

Thank you again for taking the time to reply, and I hope you’re doing well.

Newby

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Hi Melanie,

I’m so sorry for taking so long to reply again! I really do appreciate you taking the time to give me so much information. I’ve been struggling with the fatigue and brain fog and haven’t had the energy to keep up with the forum, even though I really do want to.

It was particularly interesting to read about your experience because there are quite a few similarities between us. Your Oncotype was low like mine, you had positive lymph nodes, and you’ve also gone from 400mg to 200mg Ribociclib. It’s really reassuring to hear that you have been on 200mg and that your oncologist was happy with the change.

I should have mentioned that my oncologist had actually suggested changing me from Anastrozole to Exemestane when she first offered me Ribociclib, as I was already having side effects from Anastrozole. The nurse also discussed it with me and prescribed a month’s supply to try. Unfortunately, I was about to go to India for two months and needed enough Anastrozole for the trip, and there wasn’t really enough time to sort out the new prescription and hospital/GP correspondence. With everything else going on, including getting my COVID and flu jabs and preparing for the trip, I decided to stay with Anastrozole.

Once I started Ribociclib, I felt it probably wasn’t sensible to change both treatments at the same time, so I’ve still never actually tried the Exemestane. It’s interesting to hear that changing made very little difference for you, although I suppose everyone’s experience is different.

I’m sorry you’re still having such a difficult time with the joint and muscle pain, watery eyes, tiredness and insomnia. I hope the rib pain and breast tenderness settle down, but I think I’d get those checked rather than just assuming they’re another side effect.

Thank you again for such a detailed reply. It has been really helpful and has made me feel much more reassured about the possibility of reducing the Ribociclib dose.

I’ve also discovered the longer thread specifically about reducing Ribociclib, so I’m going to follow that one from now on, as I think it will be easier for me to keep up with. I find the forum quite confusing to navigate sometimes, and with my energy and brain fog I struggle to keep track of all the different threads!

Much love and strength to you too.

Newby x

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Hi Olivie,

Thank you for replying. I was worried about that too, which is why I wanted to hear from people who have actually reduced their dose. I’ve since had a few replies from people who have gone down to 200mg and found it was still beneficial, which has been reassuring.

Thank you for taking the time to reply.

Newby

Hi Newby,

Thank you for your informative response and I am now going to search for the Ribociclib thread you tell of, sounds an obvious one to follow.

Much love and luck

Melanie x

Hi all, did anybody drop ribociclib all together due to due to sideffects?

I’ve started two months ago, and i’m suffering with all if the below. They already reduced my dose from 400 to 200 but by second week of the cycle I’m on the floor with fatigue…