As with all therapeutic proteins, there is a potential for immunogenicity. The clinical significance of antibodies to Kepivance is unknown but may include decreased activity and/or cross reactivity with other members of the FGF family of growth factors.
In clinical trials, serum samples from patients treated with Kepivance were tested for antibodies to Kepivance using an electrochemiluminescence-based binding assay. Twelve of 645 patients (2%) tested positive; none had evidence of neutralizing activity in a cell-based assay.
The incidence of antibody positivity is highly dependent on the specific assay and its sensitivity. Additionally, the observed incidence of antibody positivity in an assay may be influenced by several factors including sample handling, timing of sample collection, concomitant medications and underlying disease. For these reasons, comparison of the incidence of antibodies to Kepivance with the incidence of antibodies to other products may be misleading.
The following adverse reactions have been identified during postapproval use of Kepivance in the stem cell transplant setting. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
- Vaginal edema and erythema;
- Palmar-plantar Erythrodysaesthesia Syndrome (also known as “hand-foot syndrome”)
In vitro and in vivo data showed that palifermin interacts with unfractionated as well as low molecular weight heparins with no noticeable effect on the pharmacodynamics of either drug. If heparin is used to maintain an intravenous line, rinse the line with saline prior to and after Kepivance administration [see Clinical Pharmacology ( 12.3)] .
Do not administer Kepivance within 24 hours before, during infusion of, or within 24 hours after administration of myelotoxic chemotherapy [see Dosage and Administration ( 2.1) and Clinical Studies ( 14)]. In a clinical trial, administration of Kepivance within 24 hours of chemotherapy resulted in increased severity and duration of oral mucositis.
Based on findings in animal studies, Kepivance may cause fetal harm when administered to pregnant women. There are no data available on Kepivance use in pregnant women to inform a drug-associated risk of major birth defects and miscarriage or adverse maternal or fetal outcomes. In animal reproduction studies, intravenous administration of palifermin to pregnant rabbits and rats during the period of organogenesis resulted in embryo-fetal mortality and alterations to growth [see Data].
The estimated background risk of major birth defects and miscarriage for the indicated populations 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 embryo-fetal development studies, palifermin was administered intravenously to pregnant rabbits and rats during the perid of organogenesis. Doses were 5, 60, and 150 μg/kg/day in rabbits (gestation days 6-18) and 100, 300, and 1000 μg/kg/day in rats (gestation days 6 through 17). Increased post-implantation loss and decreased fetal body weights occurred along with maternal toxicity (clinical signs and reductions in body weight gain and food consumption) at doses of 150 μg/kg/day in rabbits and 1000 μg/kg/day in rats. Increased skeletal variations was noted in rats at 1000 μg/kg/day. Doses of 150 μg/kg/day in rabbits and 1000 μg/kg/day in rats are approximately 5-times (rabbits) and 35-times (rats) the exposure (AUC) in patients receiving the recommended dose of 60 μg/kg/day.
There are no data on the presence of Kepivance in human milk, the effect on the breastfed child, or the effect on milk production. Since many drugs are secreted into human milk, and because of the potential for serious adverse reactions in a nursing child, breastfeeding should be discontinued during treatment and for at least 2 weeks after the last dose.
Based on findings from animal studies, palifermin may impair fertility in females and males of reproductive potential [see Nonclinical Toxicology (13.1)]. The reversibility of the effects on fertility is unknown.
Information on the dosing and safety of Kepivance in the pediatric population is limited. However, use of Kepivance in pediatric patients ages 1 to 16 years is supported by evidence from adequate and well-controlled studies of Kepivance in adults and a phase 1 study that included 27 pediatric patients with acute leukemia undergoing hematopoietic stem cell transplant. Three age groups were studied: ages 1 to 2 (n=9), ages 3 to 11 (n=9), and ages 12 to 16 (n=9); 56% were male, 26% were Caucasian, 63% Hispanic; 81% ALL, 19% AML. The patients received high-dose cytotoxic therapy consisting of fractionated total body irradiation (TBI) (12 Gy total dose), high dose etoposide (1500 mg/m 2), and high dose cyclophosphamide (120 mg/kg) followed by allogeneic hematopoietic stem cell support. The dose intensity of this preparative regimen is comparable to the dose intensity of the Study 1 preparative regimen. See Clinical Studies [14.1]. Kepivance was administered as a daily intravenous injection for 3 consecutive days prior to initiation of cytotoxic therapy and for 3 consecutive days following infusion of hematopoietic stem cells. Three dose levels, 40, 60, and 80 mcg/kg/dose, were evaluated. There was no dose limiting toxicity identified at any dose level. Adverse events were similar to those reported in adult studies. The incidence of palifermin related adverse events was highest in the 80 μg/kg cohort. The overall incidence of WHO grade 3 and 4 oral mucositis was 10/27 (37%).
The pharmacokinetics of Kepivance was evaluated in the phase 1 study. Age (1 to 16 years) did not affect the pharmacokinetics of palifermin over the dose range (40 to 80 mcg/kg). Palifermin concentrations declined in the first 30 minutes after dosing. An increase in palifermin concentrations occurred at around 2 to 4 hours post-dose for some subjects, which was followed by a second, slow decline phase. A similar trend has been observed in adult patients. The mean half-life range was 2.6 to 5.6 hours in pediatric patients following the first 60 mcg/kg dose of Kepivance. No accumulation was observed following 3 consecutive doses of Kepivance. Palifermin exposure did not increase linearly with increasing doses. The first dose AUC 0-inf (mean) of Kepivance 60 mcg/kg/day in adult patients (18 to 63 years) was 38.2 ng*hr/mL compared to 46.1 ng*hr/mL (range of means: 22.8 to 81.6) for pediatric patients (1 to 16 years). The mean clearance was 1730 mL/hr/kg for adults and 2481 mL/hr/kg (range of means: 1700 to 3460) in pediatric patients.
Clinical studies of Kepivance did not include sufficient numbers of subjects aged 65 years and older to determine whether they responded differently from younger subjects [see Clinical Pharmacology ( 12.3)].
Kepivance (palifermin) is a truncated human KGF produced by recombinant DNA technology in E coli. Kepivance is a water soluble, 140 amino acid protein with a molecular weight of 16.3 kilodaltons. It differs from endogenous human KGF in that the first 23 N terminal amino acids have been deleted to improve protein stability.
Kepivance is supplied as a sterile, white, preservative-free, lyophilized powder for intravenous injection after reconstitution with 1.2 mL of Sterile Water for Injection, USP. Reconstitution yields a clear, colorless solution of Kepivance (5 mg/mL) with a pH of 6.5. Each single-dose vial of Kepivance contains palifermin (6.25 mg),with L histidine (1.94 mg), mannitol (50 mg), polysorbate 20 (0.13 mg or 0.01% w/v), and sucrose (25 mg).
KGF is an endogenous protein in the fibroblast growth factor (FGF) family that binds to the KGF receptor. Binding of KGF to its receptor has been reported to result in proliferation, differentiation, and migration of epithelial cells. The KGF receptor, one of four receptors in the FGF family, has been reported to be present on epithelial cells in many tissues examined including the tongue, buccal mucosa, esophagus, stomach, intestine, salivary gland, lung, liver, pancreas, kidney, bladder, mammary gland, skin (hair follicles and sebaceous gland), and the lens of the eye. The KGF receptor has been reported to not be present on cells of the hematopoietic lineage. Endogenous KGF is produced by mesenchymal cells and is upregulated in response to epithelial tissue injury.
In mice and rats, Kepivance enhanced proliferation of epithelial cells (as measured by Ki67 immunohistochemical staining and BrDU uptake) and demonstrated an increase in tissue thickness of the tongue, buccal mucosa, and gastrointestinal tract. Kepivance has been studied in murine models of chemotherapy and radiation-induced gastrointestinal injury. In such models, administration of Kepivance prior to and/or after the cytotoxic insult improved survival and reduced weight loss compared to control animals.
Kepivance has been shown to enhance the growth of human epithelial tumor cell lines in vitro at concentrations ≥ 10 mcg/mL (> 15-fold higher than average therapeutic concentrations in humans). In nude mouse xenograft models, three consecutive daily treatments of Kepivance at doses of 1,500 and 4,000 mcg/kg (25- and 67-fold higher than the recommended human dose, respectively) repeated weekly for 4 to 6 weeks were associated with a dose-dependent increase in the growth rate of 1 of 7 KGF receptor-expressing human tumor cell lines.
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