Do CDK4/6 inhibitors have any side effects in breast cancer?

Question

Hello doctor,

I am 54 years old and just started treatment for metastatic HR (hormone receptor) positive, HER2 (human epidermal growth factor receptor 2) negative breast cancer with liver metastases. I am being given a CDK4/6 (cyclin-dependent kinases 4 and 6) inhibitor and Letrozole.

What should I expect in terms of side effects, like fatigue or low blood counts?
Will this regimen shrink liver tumors?
How long does it typically keep the disease stable?
Can I still work part-time?
How is my response monitored?
Do I need frequent scans or blood tests?

Please suggest.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I have read your query and can understand your concern. CDK4/6 (cyclin-dependent kinases 4 and 6) inhibitors and Letrozole, when used in combination with breast cancer treatment, can cause a range of side effects.

The common side effects include

Neutropenia (low white blood cell count).
Anemia (low red blood cell count).
Fatigue.
Diarrhea.
Nausea.
Hot flashes.
Other potential side effects include hair thinning, rash, and in rare cases, interstitial lung disease. The combination of CDK4/6 inhibitors and Letrozole can effectively shrink liver metastases from breast cancer.

This combination has become a standard first-line treatment for hormone receptor-positive, HER2 (human epidermal growth factor 2) negative advanced breast cancer, demonstrating significant improvement in progression-free survival.

Clinical trials show that this combination can extend progression-free survival (PFS) by a median of 10 to 15 months compared to Letrozole alone.

When taking a combination of CDK4/6 (cyclin-dependent kinases 4 and 6) inhibitors and Letrozole, regular blood tests and scans are generally required to monitor potential side effects and disease progression. Initial monitoring may be more frequent, potentially every two weeks, to assess how the body responds and make necessary dose adjustments. After the first two months, monitoring can often be less frequent. The probable cause and diagnosis are metastatic breast cancer.

I hope this answers your query.

Let me know if I need to assist you further.

Thank you.