Palbociclib

Indications

Palbociclib is used for: Indicated for hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, advanced breast cancer, in combination with an aromatase inhibitor as initial endocrine based therapy in postmenopausal women, or with fulvestrant in women with disease progression endocrine therapy

Adult Dose

Oral Hormone receptor positive, HER2-negative locally advanced carcinoma of breast, Hormone receptor positive, HER2-negative metastatic carcinoma of breast Adult: In combination with aromatase inhibitor, or in combination with fulvestrant in women who have received prior endocrine therapy: 125 mg once daily for 21 days, followed by 7 days off, repeat every 28 days until disease progression or unacceptable toxicity. Dosage Modifications Dose reduction, dosing interruption, or discontinuation may be required according to individual safety or tolerability (refer to detailed product guideline). Recommended dose reduction: 1st reduction: 100 mg once daily; 2nd reduction: 75 mg once daily; discontinue if dose reduction below 75 mg once daily is required. Hepatic impairment Mild or moderate (Child-Pugh A or B): No dose adjustment required Severe (Child-Pugh C): Reduce dose to 75 mg/day for Days 1-21 of each 28-day cycle

Child Dose

Renal Dose

Renal impairment Mild, moderate, or severe (CrCl >15 mL/min): No dose adjustment required Hemodialysis: Not studied

Administration

Hard Capsule: Should be taken with food. Take at the same time each day. Swallow whole, do not chew/crush/open. Avoid grapefruit products.

Contra Indications

Pregnancy and lactation.

Precautions

Neutropenia observed in clinical trials; febrile neutropenia also reported; monitor CBC count prior to starting drug and at the beginning of each cycle, as well as on Day 14 of the first 2 cycles, and as clinically indicated; dose interruption, dose reduction, or delay in starting treatment cycles is recommended for patients who develop grade 3 or 4 neutropenia

Pregnancy-Lactation

Pregnancy Based on findings in animals and mechanism of action, palbociclib can cause fetal harm when administered to a pregnant woman In animal studies, palbociclib was teratogenic and fetotoxic at maternal exposures that were ?4 times the human clinical exposure based on AUC at the recommended human dose Females of reproductive potential should have a pregnancy test before starting treatment Based on findings in animals, male fertility may be compromised by treatment Contraception Females of reproductive potential: Use effective contraception during treatment and for at least 3 weeks after the last dose Male patients with female partners of reproductive potential: Because of potential for genotoxicity, use effective contraception during treatment and for 3 months after the last dose Infertility Males: Based on animal studies, may impair fertility in males of reproductive potential Lactation Unknown if distributed in human breast milk; because many drugs are excreted in human milk Owing to the potential for serious adverse reactions in breastfed infants, advise lactating women not to breastfeed while taking palbociclib and for at least 3 weeks after the last dose

Interactions

Increased plasma concentration and systemic exposure with strong CYP3A inhibitors (e.g. clarithromycin, telithromycin, itraconazole, ketoconazole, posaconazole, voriconazole, indinavir, ritonavir, ritonavir-boosted lopinavir, nelfinavir, saquinavir, telaprevir, nefazodone, verapamil). Decreased plasma concentration with moderate CYP3A inducers (e.g. bosentan, efavirenz, etravirine, modafinil, nafcillin) or strong CYP3A inducers (e.g. carbamazepine, phenytoin, enzalutamide, rifampicin). May increase the plasma concentration of CYP3A substrates (e.g. ciclosporin, everolimus, sirolimus, tacrolimus, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine).

Adverse Effects

Side effects of Palbociclib : >10% Neutropenia, all grades (75%) Neutropenia, grade 3 (48%) Leukopenia, all grades (43%) Fatigue, all grades (41%) Anemia, all grades (35%) Upper respiratory tract infection, all grades (31%) Stomatitis, all grades (25%) Nausea, all grades (25%) Alopecia, grade 1 (22%) Diarrhea, all grades (21%) Leukopenia, grade 3 (19%) Thrombocytopenia, all grades (17%) Decreased appetite, all grades (16%) Vomiting, all grades (15%) Peripheral neuropathy, all grades (13%) Asthenia, all grades (13%) Epistaxis, all grades (11%) 1-10% Neutropenia, grade 4 (6%) Anemia, grade 3 (5%) Diarrhea, grade 3 (4%) Thrombocytopenia, grade 3 (2%) Nausea, grade 3 (2%) Fatigue, grades 3/4 (2%) Asthenia, grade 3 (2%) Upper respiratory treact infection, grade 3 (1%) Decreased appetite, grade 3 (1%)

Mechanism of Action

Palbociclib is a reversible, selective inhibitor of cyclin-dependent kinase (CDK) 4 and 6. Cyclin D1, CDK 4 and 6 are downstream of multiple signalling pathways which lead to cellular proliferation. Inhibition of CDK4/6 reduces proliferation of breast cancer cell lines by blocking progression from G1 into S phase of the cell cycle.