LIBTAYO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LIBTAYO (LIBTAYO).
Cemiplimab is a human monoclonal antibody that binds to programmed death-1 (PD-1) receptor and blocks its interaction with PD-L1 and PD-L2, releasing PD-1 pathway-mediated inhibition of the anti-tumor immune response.
| Metabolism | Cemiplimab is a monoclonal antibody that is degraded into small peptides and amino acids via catabolic pathways; metabolism is not mediated by cytochrome P450 enzymes. |
| Excretion | Cemipilmab is catabolized by general protein degradation; no specific elimination pathway quantified. Biliary/fecal excretion not reported; renal excretion of intact drug minimal. |
| Half-life | Terminal elimination half-life approximately 19 days (range 11–26 days), supporting every-3-week dosing regimen. |
| Protein binding | No formal protein binding studies; as a monoclonal antibody, expected to be minimally bound to serum proteins. |
| Volume of Distribution | Steady-state volume of distribution (Vd) approximately 5.7 L (0.08 L/kg for a 70 kg adult), indicating limited extravascular distribution. |
| Bioavailability | Intravenous only; bioavailability is 100% by IV route. |
| Onset of Action | Clinical response may be observed within 6–12 weeks after first dose; pharmacokinetic steady state achieved by ~12 weeks. |
| Duration of Action | Pharmacodynamic effects persist for weeks after last dose; dosing continues until disease progression or unacceptable toxicity. |
350 mg intravenously every 3 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh A). Not studied in moderate or severe hepatic impairment (Child-Pugh B or C). |
| Pediatric use | Safety and efficacy not established in pediatric patients. |
| Geriatric use | No specific dose adjustment recommended for elderly patients. Clinical studies included patients ≥65 years with no overall differences in safety or efficacy. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LIBTAYO (LIBTAYO).
| Breastfeeding | There are no data on the presence of cemiplimab in human milk, effects on the breastfed infant, or effects on milk production. Human IgG is known to be excreted in breast milk, but the extent of transfer of cemiplimab, a monoclonal antibody, is unknown. The M/P ratio has not been determined. Because of the potential for serious adverse reactions in the breastfed infant, advise women not to breastfeed during treatment with LIBTAYO and for at least 4 months after the last dose. |
| Teratogenic Risk | Based on its mechanism of action as a PD-1 inhibitor, LIBTAYO (cemiplimab) is expected to cause fetal harm when administered to a pregnant woman. There are no adequate and well-controlled studies in pregnant women. In animal models, blockade of PD-1/PD-L1 signaling has been shown to disrupt maternal-fetal immune tolerance and lead to increased fetal loss, stillbirth, and neonatal death. The risk is present throughout pregnancy; however, the greatest risk is likely during the second and third trimesters when the fetal immune system is more developed. Human IgG4 (immunoglobulin G4) antibodies are known to cross the placental barrier, and cemiplimab is a human monoclonal antibody of the IgG4 subclass, so fetal exposure is expected. |
■ FDA Black Box Warning
Immune-mediated adverse reactions: severe and fatal immune-mediated adverse reactions including pneumonitis, colitis, hepatitis, endocrinopathies, nephritis and renal dysfunction, skin adverse reactions, and solid organ transplant rejection.
| Serious Effects |
None
| Precautions | Immune-mediated adverse reactions requiring management (e.g., corticosteroids, hormone replacement); infusion-related reactions; complications of allogeneic hematopoietic stem cell transplantation; embryo-fetal toxicity. |
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| Fetal Monitoring | Monitor pregnant women for potential adverse effects of immune checkpoint inhibition, including immune-mediated adverse reactions that could affect the mother and fetus. Fetal monitoring should include assessment of fetal growth and well-being with ultrasound, as well as monitoring for signs of immune-related fetal harm such as hydrops or growth restriction. There is no specific biomarker for fetal PD-1 inhibition. Additionally, monitor maternal thyroid function, liver function, and for signs of immune-related endocrinopathies that could affect pregnancy outcomes. |
| Fertility Effects | Based on animal studies, cemiplimab may impair female fertility. In a 13-week repeat-dose toxicology study in cynomolgus monkeys, cemiplimab caused menstrual cycle irregularities and decreased corpora lutea and ovarian weights. The effects on male fertility have not been fully evaluated. The long-term effects on human fertility are unknown, but given the mechanism, there is a potential for immune-mediated damage to reproductive tissues. |