Palbocent(Palbociclib)

Therapeutic Group: Oncology

Presentation

Palbocent 125: Each capsule contains Palbociclib INN 125 mg.

Description

Palbociclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 are

downstream of signaling pathways which lead to cellular proliferation. In vitro, Palbociclib reduced

cellular proliferation of estrogen receptor (ER)-positive breast cancer cell lines by blocking progression

of the cell from G1 into S phase of the cell cycle. Treatment of breast cancer cell lines with the

combination of Palbociclib and antiestrogens leads to decreased 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 the combination of Palbociclib and antiestrogens led to increased cell senescence compared to

each drug alone, which was sustained for up to 6 days following Palbociclib removal and was greater if

antiestrogen treatment was continued. In vivo studies using a patient-derived ER-positive breast cancer

xenograft model demonstrated that the combination of Palbociclib and letrozole increased the inhibition

of Rb phosphorylation, downstream signaling, and tumor growth compared to each drug alone.

Human bone marrow mononuclear cells treated with Palbociclib in the presence or absence of an

anti-estrogen in vitro did not become senescent and resumed proliferation following Palbociclib

withdrawal.

Indications

Palbociclib is indicated for the treatment of HR-positive, HER2-negative advanced or metastatic breast

cancer in combination with:

• an aromatase inhibitor as initial endocrine based therapy in postmenopausal women; or

• fulvestrant in women with disease progression following endocrine therapy.

Dosage & Administration

The recommended dose of Palbociclib is a 125 mg capsule taken orally once daily for 21 consecutive
days followed by 7 days off treatment to comprise a complete cycle of 28 days. Palbociclib should be
taken with food.
Administer the recommended dose of an aromatase inhibitor when given with Palbociclib. Please refer
to the Full Prescribing Information for the aromatase inhibitor being used.
When given with Palbociclib, the recommended dose of fulvestrant is 500 mg administered on Days 1,
15, 29, and once monthly thereafter. Please refer to the Full Prescribing Information of fulvestrant.
Pre/perimenopausal women treated with the combination Palbociclib plus fulvestrant therapy should be
treated with luteinizing hormone-releasing hormone (LHRH) agonists according to current clinical
practice standards.

Side Effects

Most common adverse reactions (incidence ≥10%) were neutropenia, infections, leukopenia, fatigue,
nausea, stomatitis, anemia, alopecia, diarrhea, thrombocytopenia, rash, vomiting, decreased appetite,
asthenia, and pyrexia.

Precautions

• Neutropenia: Complete blood count should be monitored prior to start of Palbociclib therapy and
at the beginning of each cycle, as well as on Day 15 of the first 2 cycles, and as clinically indicated.
• Embryo-Fetal Toxicity: Palbociclib can cause fetal harm. Patients should be advised about
potential risk to the fetus and to use effective contraception.

Use in Pregnancy & Lactation

Based on findings from animal studies and its mechanism of action, Palbociclib can cause fetal harm
when administered to a pregnant woman. There are no available data in pregnant women to inform the
drug-associated risk. In animal reproduction studies, administration of Palbociclib to pregnant rats and
rabbits during organogenesis resulted in embryo fetal toxicity at maternal exposures that were ≥4 times
the human clinical exposure based on AUC. Pregnant women should be advised about the potential risk
to a fetus.
The estimated background risk of major birth defects and miscarriage for the indicated population is
unknown. In the U.S. general population, the estimated background risk of major birth defects and
miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively.
There is no information regarding the presence of Palbociclib in human milk, its effects on milk
production, or the breastfed infant. Because of the potential for serious adverse reactions in breastfed
infants from Palbociclib, advise a lactating woman not to breastfeed during treatment with Palbociclib
and for 3 weeks after the last dose.
Pediatric Use
The safety and effectiveness of Palbociclib in pediatric patients have not been established.
Geriatric Use
No overall differences in safety or effectiveness of Palbociclib were observed between these patients
and younger patients.
Hepatic Impairment
Mild hepatic impairment had no effect on the exposure of Palbociclib. The pharmacokinetics of
Palbociclib has not been studied in patients with moderate or severe hepatic impairment.
Renal Impairment
Mild and moderate renal impairment had no effect on the exposure of Palbociclib. The pharmacokinetics
of Palbociclib has not been studied in patients with severe renal impairment.