Palbociclib can cause adverse reactions that range from laboratory abnormalities to clinically serious complications. The likelihood and severity vary according to treatment combination, patient characteristics and other factors.
Common adverse effects
Commonly reported effects include:
- Neutropenia
- Leukopenia
- Infections
- Fatigue
- Nausea
- Stomatitis
- Anemia
- Diarrhea
- Thrombocytopenia
- Alopecia
- Decreased appetite
- Increased liver enzymes
The EMA identifies neutropenia, infections, leukopenia, fatigue, nausea, stomatitis, anemia, diarrhea, alopecia and thrombocytopenia among the common adverse effects of Ibrance.
Neutropenia
Neutropenia is the most prominent hematologic adverse reaction associated with palbociclib.
In PALOMA-2, neutropenia occurred in 80% of patients receiving IBRANCE plus letrozole, with Grade 3 or 4 neutropenia reported in 66%. PALOMA-3 showed a similar pattern.
Neutropenia can increase susceptibility to infection.
Serious adverse reactions
Important serious risks include:
| Risk | Why it matters |
|---|---|
| Severe neutropenia | Can lead to serious infection |
| Febrile neutropenia | Fever with severe neutropenia can require urgent assessment |
| ILD/pneumonitis | Can be serious, life-threatening or fatal |
| Embryo-fetal toxicity | Can harm a developing fetus |
| Infection | Risk may increase when white blood cells are suppressed |
ILD and pneumonitis
Severe, life-threatening or fatal interstitial lung disease/pneumonitis has been reported with CDK4/6 inhibitors including IBRANCE. New or worsening cough, shortness of breath or low oxygen levels require prompt clinical assessment.
Important warning signs
Patients should promptly report symptoms such as:
- Fever
- Chills
- Signs of infection
- New or worsening cough
- Shortness of breath
- Unusual bleeding
- Severe weakness
- Other concerning symptoms
Monitoring
CBC monitoring is central to safe palbociclib treatment, particularly because neutropenia is common.