CDK4/6 Inhibitor Drugs: A Patient Guide

CDK4/6 inhibitor drugs are targeted medicines that slow signals cancer cells use to divide.

They work on proteins involved in the cell cycle, the process by which cells prepare to make new cells. They are systemic treatments, meaning the medicine circulates through the body rather than acting only at one local site.

These medicines are usually taken by mouth according to a prescribed schedule. Treatment plans may include blood tests and clinical reviews because the medicine can affect blood cells and other body functions. Your oncology team may adjust the dose, pause treatment, or change the schedule if side effects need attention.

CDK4/6 inhibitors are commonly considered in treatment plans for certain hormone receptor-positive breast cancers, often alongside endocrine therapy. Whether one is suitable depends on the cancer's characteristics, its extent, treatments already received, other health conditions, and the goals of care.

Your oncologist will explain the intended role of the medicine in your individual plan and how it fits with scans, appointments, and other treatments.

Endocrine therapy on its own, another targeted medicine, chemotherapy, surgery, radiation therapy, or supportive care may be discussed in different circumstances. A treatment recommendation is based on the cancer biology and your overall situation, not on a single medicine category.

Take the medicine exactly as prescribed and do not double a dose after a missed dose unless your oncology team specifically tells you to. Keep an up-to-date list of all medicines, vitamins, herbal products, and supplements, because some can change how treatment works.

Contact the oncology team promptly for fever, chills, signs of infection, severe diarrhoea, shortness of breath, chest symptoms, or side effects that make eating, drinking, or daily activities difficult.

Monitoring continues throughout treatment because your needs can change. Attend planned blood tests and appointments even when you feel well. Before starting a new medicine or supplement, check with your oncology pharmacist or treating team so potential interactions can be reviewed.