Must-read for patients: Overview of basic information in the Chinese instructions for palbociclib/palbociclib

1. Generic names: Palbociclib, Palbociclib

Product name:IBRANCE, Aibexin

Other names: palbociclib, palbociclib

2. Who can take palbociclib? Indications?

Palbociclib is indicated for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer (BC) in combination with:

1. Aromatase inhibitor as initial endocrine-based therapy; or

2. Fulvestrant (Fulvestrant) is used for patients with disease progression after endocrine therapy.

3. What are the side effects of palbociclib?

The most common side effects of palbociclib are neutropenia, infection, leukopenia, fatigue, feeling sick, oral mucosal inflammation, anemia, diarrhea, alopecia, and thrombocytopenia. Adverse events such as interstitial lung disease (ILD)/non-infectious pneumonia and palmar-plantar dysesthesia syndrome (PPES) have also occurred after marketing.

4. How to take palbociclib?

1. Recommended dose: The recommended dose of palbociclib is 125 mg capsule, taken orally once a day for 21 days, followed by a 7-day break, including a complete cycle of 28 days. Palbociclib should be taken with food. If the patient vomits or misses a dose, additional doses should not be taken. The next prescribed dose should be taken at your normal time. Palbociclib capsules should be swallowed whole (do not chew, crush, or open before swallowing). They should not be ingested if the capsule is cracked, broken, or incomplete.

2. Combined medication: Palbociclib can be used in combination with other drugs. When giving palbociclib, the recommended dose of fulvestrant is 500 mg, administered on days 1, 15, and 29, and once a month thereafter. Refer to the instructions for dosing of aromatase inhibitors.

3. According to current clinical practice standards, premenopausal/perimenopausal women who receive palbociclib plus aromatase inhibitors or fulvestrant should also receive luteinizing hormone-releasing hormone (LHRH) agonist treatment; for men who receive palbociclib plus aromatase inhibitors, consider using LHRH agonists for treatment according to current clinical practice standards.

5. How to store palbociclib?

PalbociclibStorage temperature20°C to 25°C (68°F to 77°F); excursions allowed between 15°C and 30°C (59°F to 86°F).

6. How does palbociclib work?

Pabociclib is an inhibitor of cyclin-dependent kinase (CDK) 4 and 6. In vitro, palbociclib reduces cell proliferation in estrogen receptor (ER)-positive breast cancer cell lines by blocking cells from entering the S phase from the G1 phase of the cell cycle. Combined treatment of cancer cell lines with palibociclib and antiestrogen resulted in reduced retinoblastoma (Rb) protein phosphorylation, resulting in reduced E2F expression and signaling, and increased growth arrest compared to treatment with each drug alone. In vitro treatment of ER-positive breast cancer cell lines with palbociclib and antiestrogen in combination resulted in increased cellular senescence compared with each drug alone. Cell senescence persisted for up to 6 days after palbociclib clearance and was more severe if antiestrogen treatment was continued.

In vivo studies using patient-derived ER-positive breast cancer xenograft models demonstrated that the combination of palbociclib and letrozole increased inhibition of Rb phosphorylation, downstream signaling, and tumor growth compared with each drug alone. Human bone marrow mononuclear cells treated with palbociclib in the presence or absence of antiestrogens in vitro did not senescence and resumed proliferation after drug withdrawal.

7. What will happen if you take too much palbociclib?

The reported oral LD50 is 100 mg/kg. In vitro and in vivo tests have shown that palbociclib has clastogenic activity. Additionally, it has been reported to cause harm to the fetus due to its mechanism of action. Finally, at high doses, it also increases the incidence of microglial tumors in the central nervous system. Treatment of palbociclib overdose should include general supportive measures.

8. Who cannot use palbociclib?

1. Women: Pregnant women taking palbociclib may be harmful to the fetus. Advise women of childbearing potential to use effective contraception during treatment and for at least 3 weeks after the last dose; women who are breastfeeding should not breastfeed for at least 3 weeks.

2. Males: Due to potential genotoxicity, male patients with reproductive female partners are advised to use effective contraception during palbociclib treatment and for 3 months after the last dose.