PALBOCICLIB Drug Interactions: What You Need to Know

INTERACTIONS Palbociclib is primarily metabolized by CYP3A and sulfotransferase (SULT) enzyme SULT2A1. In vivo, palbociclib is a time-dependent inhibitor of CYP3A.

• CYP3A Inhibitors: Avoid concurrent use of IBRANCE with strong CYP3A inhibitors. If the strong inhibitor cannot be avoided, reduce the IBRANCE dose. ( 2.2 , 7.1 )
• CYP3A Inducers: Avoid concurrent use of IBRANCE with strong CYP3A inducers. ( 7.2 )
• CYP3A Substrates: The dose of sensitive CYP3A4 substrates with narrow therapeutic indices may need to be reduced when given concurrently with IBRANCE. ( 7.3 )

7.1 Agents That May Increase Palbociclib Plasma Concentrations Effect of CYP3A Inhibitors Coadministration of a strong CYP3A inhibitor (itraconazole) increased the plasma exposure of palbociclib in healthy subjects by 87%. Avoid concomitant use of strong CYP3A inhibitors (e.g., clarithromycin, indinavir, itraconazole, ketoconazole, lopinavir/ritonavir, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telaprevir, telithromycin, and voriconazole). Avoid grapefruit or grapefruit juice during IBRANCE treatment. If coadministration of IBRANCE with a strong CYP3A inhibitor cannot be avoided, reduce the dose of IBRANCE <span class="opacity-50 text-xs">[see Dosage and Administration (2.2) and Clinical Pharmacology (12.3) ]</span> .

7.2 Agents That May Decrease Palbociclib Plasma Concentrations Effect of CYP3A Inducers Coadministration of a strong CYP3A inducer (rifampin) decreased the plasma exposure of palbociclib in healthy subjects by 85%. Avoid concomitant use of strong CYP3A inducers (e.g., phenytoin, rifampin, carbamazepine, enzalutamide, and St John&apos;s Wort) <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> .

7.3 Drugs That May Have Their Plasma Concentrations Altered by Palbociclib Coadministration of midazolam with multiple doses of IBRANCE increased the midazolam plasma exposure by 61%, in healthy subjects, compared to administration of midazolam alone. The dose of the sensitive CYP3A substrate with a narrow therapeutic index (e.g., alfentanil, cyclosporine, dihydroergotamine, ergotamine, everolimus, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus) may need to be reduced, as IBRANCE may increase its exposure <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> .

None. None. ( 4 )

AND PRECAUTIONS

• Neutropenia: Monitor complete blood count prior to start of IBRANCE therapy and at the beginning of each cycle, as well as on Day 15 of the first 2 cycles, and as clinically indicated. ( 2.2 , 5.1 )
• Interstitial Lung Disease (ILD)/Pneumonitis: Severe and fatal cases of ILD/pneumonitis have been reported. Monitor for pulmonary symptoms of ILD/pneumonitis. Interrupt IBRANCE immediately in patients with suspected ILD/pneumonitis. Permanently discontinue IBRANCE if severe ILD/pneumonitis occurs. ( 5.2 )
• Embryo-Fetal Toxicity: IBRANCE can cause fetal harm. Advise patients of potential risk to a fetus and to use effective contraception. ( 5.3 , 8.1 , 8.3 )

5.1 Neutropenia Neutropenia was the most frequently reported adverse reaction in PALOMA-2 with an incidence of 80% and PALOMA-3 with an incidence of 83%. A Grade ≥3 decrease in neutrophil counts was reported in 66% of patients receiving IBRANCE plus letrozole in PALOMA-2 and 66% of patients receiving IBRANCE plus fulvestrant in PALOMA-3. In PALOMA-2 and PALOMA-3, the median time to first episode of any grade neutropenia was 15 days and the median duration of Grade ≥3 neutropenia was 7 days <span class="opacity-50 text-xs">[see Adverse Reactions (6.1) ]</span> . Monitor complete blood counts prior to starting IBRANCE therapy and at the beginning of each cycle, as well as on Day 15 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 <span class="opacity-50 text-xs">[see Dosage and Administration (2.2) ]</span> . Febrile neutropenia has been reported in 1.8% of patients exposed to IBRANCE across PALOMA-2 and PALOMA-3. One death due to neutropenic sepsis was observed in PALOMA-3. Physicians should inform patients to promptly report any episodes of fever <span class="opacity-50 text-xs">[see Patient Counseling Information (17) ]</span> .

5.2 Interstitial Lung Disease (ILD)/Pneumonitis Severe, life-threatening, or fatal interstitial lung disease (ILD) and/or pneumonitis can occur in patients treated with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, including IBRANCE when taken in combination with endocrine therapy. Across clinical trials (PALOMA-1, PALOMA-2, PALOMA-3), 1% of IBRANCE-treated patients had ILD/pneumonitis of any grade, 0.1% had Grade 3 or 4 and no fatal cases were reported. Additional cases of ILD/pneumonitis have been observed in the postmarketing setting, with fatalities reported <span class="opacity-50 text-xs">[see Adverse Reactions (6.2) ]</span> . Monitor patients for pulmonary symptoms indicative of ILD/pneumonitis (e.g. hypoxia, cough, dyspnea). In patients who have new or worsening respiratory symptoms and are suspected to have developed pneumonitis, interrupt IBRANCE immediately and evaluate the patient. Permanently discontinue IBRANCE in patients with severe ILD or pneumonitis <span class="opacity-50 text-xs">[see Dosage and Administration (2.2) ]</span> .

5.3 Embryo-Fetal Toxicity Based on findings from animal studies and its mechanism of action, IBRANCE can cause fetal harm when administered to a pregnant woman. 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 area under the curve (AUC). Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with IBRANCE and for at least 3 weeks after the last dose <span class="opacity-50 text-xs">[see Use in Specific Populations (8.1 and 8.3) and Clinical Pharmacology (12.1) ]</span> .