FDA recently approved changes to the Trogarzo (ibalizumab-uiyk) product labeling to update:
WARNINGS AND PRECAUTIONS with a new subsection, Embryo-Fetal Toxicity to provide information based on animal data regarding the potential risk of reversible immunosuppression in infants with in utero exposure to Trogarzo.
USE IN SPECIFIC POPULATIONS, Pregnancy, with data from an enhanced pre- and post-natal development study in cynomolgus monkeys.
A summary of the major changes is as follows:
5.3 Embryo-Fetal Toxicity
Based on animal data, TROGARZO may cause reversible immunosuppression (CD4+ T cell and B cell lymphocytopenia) in infants born to mothers exposed to TROGARZO during pregnancy. Immune phenotyping of the peripheral blood and expert consultation are recommended to provide guidance regarding monitoring and management of exposed infants based on the degree of immunosuppression observed. The safety of administering live or live-attenuated vaccines in exposed infants is unknown
Based on animal data, ibalizumab-uiyk use during pregnancy may cause reversible immunosuppression (CD4+ T cell and B cell lymphocytopenia) in infants exposed to ibalizumab-uiyk in utero. Immunoglobulin G (IgG) antibodies, such as ibalizumab-uiyk, are transported across the placenta in significant amounts, especially near term; therefore, ibalizumab-uiyk has the potential to be transferred from the mother to the developing fetus (see Clinical Considerations). There are no available data on ibalizumab-uiyk use in pregnant women to evaluate for a drug- associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. 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.
In a reproductive study in monkeys, reversible decreases in CD4+ T cells and B cells and increases in CD8+ T cells were observed within the first 4 weeks after birth in infants born to pregnant monkeys receiving ibalizumab-uiyk intravenously (see Data). Lymphocyte counts returned to near normal levels by 3 months of age. One infant monkey died from a systemic viral infection that may be related to ibalizumab-uiyk-induced immunosuppression. No malformations or premature births were observed in this study.
Fetal/Neonatal Adverse Reactions
Immunoglobulin G (IgG) antibodies are increasingly transported across the placenta as pregnancy progresses, with the largest amount transferred during the third trimester. Administration of TROGARZO during pregnancy may affect immune responses in the in utero-exposed infant. For infants with perinatal exposure to TROGARZO, immune phenotyping of the peripheral blood, including CD4+ T cell and B cell counts, is recommended. Expert consultation is also recommended to provide guidance on monitoring and management (e.g., need for antibiotic or immunoprophylaxis) of exposed infants based on the degree of immunosuppression observed. The safety of administering live or live-attenuated vaccines in exposed infants is unknown.
In an enhanced pre- and post-natal development (ePPND) study, pregnant cynomolgus monkeys were administered intravenous doses of either vehicle or 110 mg/kg ibalizumab-uiyk every week from Gestation Day 20-22 (GD 20-22) until parturition on GD 160 ± 10. Significant changes in infant monkey immune cell levels on Postnatal Day (PND) 14 (mean decreases of 78% in CD4+ T cells and 46% in B cells and increases of 2.3-fold in CD8+ T cells) and PND 28 (mean decreases of 73% in CD4+ T cells and increases of 2.2-fold in CD8+ T cells), attributed to in utero ibalizumab-uiyk exposure, were observed relative to concurrent controls. The lymphocyte changes correlated with infant ibalizumab-uiyk serum concentrations and appeared to return to near normal levels between PND 28-91, when ibalizumab-uiyk concentrations were nearly undetectable. Although ibalizumab-uiyk exposure in these infant monkeys may be significantly higher than in human infants following in utero exposure at the recommended human maintenance dose, the risk of ibalizumab-uiyk-induced immunosuppression in human infants is possible. No meaningful differences in infant monkey lymphocyte counts were observed on PND 180. Further, no differences in immune cell function were observed in a T cell-dependent response assay conducted on PND 138 to 180 ± 2 following immunization of the infant monkeys with keyhole limpet hemocyanin. One treatment-group infant monkey died on PND 24 from a systemic viral infection with secondary superficial bacterial infection which was acquired during the postnatal period. Despite the low incidence (1 of 20 infants), the death may be related to ibalizumab-uiyk-induced immunosuppression. Decreases in CD4+ T cells (93%), and B cells (92%) were observed in this infant on PND 14, and decreased cellularity was observed in the spleen, thymus and mandibular lymph node. Unlike the rest of the ibalizumab-exposed infant monkey population, this infant also exhibited a decrease in CD8+ T cells of 71% on PND 14. Body weight was also decreased in this infant between PND 14 and 24. No structural abnormalities were observed among the ibalizumab-uiyk-exposed infants. In addition, no maternal toxicities, including no changes in maternal lymphocyte subsets or effects on embryo-fetal survival, were observed.