Trials 2 and 3 included the active comparator, ustekinumab.
Adverse reactions that occurred in less than 1% of subjects in the SILIQ group through Week 12 were conjunctivitis and candida infections (including oral [0.2%], genital [0.1%], and esophageal [0.1%] versus none in the placebo group).
Week 0 to End of Trial:
Through Week 52, exposure-adjusted rates of serious adverse events were similar between subjects treated with SILIQ and those treated with ustekinumab. Through the end of the trial, the exposure-adjusted rates of treatment-emergent serious adverse events were similar to those seen in the 52-week period in the subjects treated with SILIQ.
Specific Adverse Reactions:
Suicidal Ideation and Behavior
During the 12-week randomized treatment period in the pooled trials, one subject in the SILIQ group attempted suicide and none in the placebo or ustekinumab groups. From initiation through Week 52 of the trials, suicidal ideation or behavior occurred in 7 of 4019 subjects (0.2 per 100 subject-years) treated with SILIQ and in 2 of 613 subjects (0.4 per 100 subject-years) treated with ustekinumab.
During the course of the clinical trials for plaque psoriasis, suicidal ideation or behavior occurred in 34 of 4464 subjects treated with SILIQ (0.37 per 100 subject-years). Eight of the 10 subjects who attempted or completed suicide had a history of depression and/or suicidal ideation or behavior [see Warnings and Precautions (5.1, 5.2)].
During the 12-week randomized treatment period, infections occurred in 25.4% of the SILIQ group compared to 23.4% of the placebo group. The majority of infections consisted of nasopharyngitis, upper respiratory tract infection, pharyngitis, urinary tract infections, bronchitis, and influenza, and did not necessitate treatment discontinuation. The SILIQ group had a higher rate of fungal infections compared to the placebo group (1.8% vs 0.9%). The fungal infections were primarily non-serious skin and mucosal candida infections [see Warnings and Precautions (5.3)].
During the 12-week randomized treatment period, neutropenia occurred in 0.7% of subjects in the SILIQ group. Most adverse reactions of neutropenia were transient. In subjects with normal absolute neutrophil count (ANC) at baseline, a reduction in ANC occurred in 6.8% of subjects in the SILIQ group, compared to 3.3% in the ustekinumab group, and 3.6% in the placebo group. Neutropenia ≥ Grade 3 (< 1000/mm3) occurred in 0.5% of subjects in the SILIQ group compared to 0.2% of subjects in the ustekinumab group and none in the placebo group. From Week 0 to end of trial, the exposure-adjusted rate of treatment-emergent neutropenia was 0.4 per 100 subject-years (0.1 per 100 subject-years were ≥ Grade 3). No serious infections were associated with cases of neutropenia.
As with all therapeutic proteins, there is potential for immunogenicity with SILIQ. Approximately 3% of subjects treated with SILIQ developed antibodies to brodalumab through the 52-week treatment period. Of the subjects who developed antibodies to brodalumab, none had antibodies that were classified as neutralizing. However, the assay to test for neutralizing antibodies had limitations detecting neutralizing antibodies in the presence of brodalumab; therefore, the incidence of neutralizing antibody development could be underestimated.
The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors, including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to SILIQ with the incidence of antibodies to other products may be misleading.
7 DRUG INTERACTIONS
7.1 Live Vaccinations
Avoid use of live vaccines in patients treated with SILIQ [see Warnings and Precautions (5.6)].
7.2 CYP450 Substrates
The formation of CYP450 enzymes can be altered by increased levels of certain cytokines (e.g., IL-1, IL-6, IL-10, TNFα, IFN) during chronic inflammation. Treatment with SILIQ may modulate serum levels of some cytokines.
Therefore, upon initiation or discontinuation of SILIQ in patients who are receiving concomitant drugs which are CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for effect (e.g., for warfarin) or drug concentration (e.g., for cyclosporine) and consider dosage modification of the CYP450 substrate [see Clinical Pharmacology (12.3)].
8 USE IN SPECIFIC POPULATIONS
There are no human data on SILIQ use in pregnant women to inform a drug associated risk. Human IgG antibodies are known to cross the placental barrier; therefore, SILIQ may be transmitted from the mother to the developing fetus. In a combined embryofetal development and pre- and post-natal development study, no adverse developmental effects were observed in infants born to pregnant monkeys after subcutaneous administration of brodalumab during organogenesis through parturition at doses up to 26 times the maximum recommended human dose (MRHD) [see Data].
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.
A combined embryofetal development and pre- and post-natal development study was conducted in cynomolgus monkeys administered brodalumab. No brodalumab-related effects on embryofetal toxicity or malformations, or on morphological, functional or immunological development were observed in infants from pregnant monkeys administered weekly subcutaneous doses of brodalumab up to 26 times the MRHD from the beginning of organogenesis to parturition (on a mg/kg basis of 90 mg/kg/week).
There are no data on the presence of brodalumab in human milk, the effects on the breastfed infant, or the effects on milk production. Brodalumab was detected in the milk of lactating cynomolgus monkeys. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for SILIQ and any potential adverse effects on the breastfed infant from SILIQ or from the underlying maternal condition.
8.4 Pediatric Use
The safety and effectiveness of SILIQ have not been evaluated in pediatric patients.
8.5 Geriatric Use
Of the 3066 plaque psoriasis subjects initially randomized to SILIQ in clinical trials, 192 (6%) were ≥ 65 years old and no subjects were ≥ 75 years old. Although no differences in safety or efficacy were observed between older and younger subjects, the number of subjects aged 65 years and older was not sufficient to determine whether they responded differently from younger subjects [see Clinical Pharmacology (12.3)].
Brodalumab is a human monoclonal IgG2κ antibody directed against human interleukin-17 receptor A (IL-17RA). It is expressed in a Chinese Hamster Ovary (CHO) cell line. Brodalumab is comprised of 1312 amino acids and has an estimated molecular mass of 144,000 Daltons.
SILIQ (brodalumab) Injection is a sterile, preservative-free, clear to slightly opalescent, colorless to slightly yellow solution, delivered via subcutaneous injection. A few translucent to white, amorphous particles may be present. SILIQ is supplied in a single-dose 2.25 mL syringe made from type 1 glass with stainless steel 27G x ½" needle. Each SILIQ single-dose prefilled syringe delivers 1.5 mL of solution containing 210 mg of brodalumab formulated in glutamate (6.5 mg), polysorbate 20 (0.15 mg), proline (36 mg), and Water for Injection, USP at pH 4.8.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
Brodalumab is a human monoclonal IgG2 antibody that selectively binds to human IL-17RA and inhibits its interactions with cytokines IL-17A, IL-17F, IL-17C, IL-17A/F heterodimer and IL-25. IL-17RA is a protein expressed on the cell surface and is a required component of receptor complexes utilized by multiple IL-17 family cytokines. Blocking IL-17RA inhibits IL-17 cytokine-induced responses including the release of pro-inflammatory cytokines and chemokines.
Elevated levels of IL-17A, IL-17C and IL-17F are found in psoriatic plaques. Serum IL-17A levels, measured at Weeks 12, 24, and 48 of SILIQ 210 mg every 2 weeks of treatment, were higher than the baseline levels in subjects with moderate to severe plaque psoriasis. The relationship between the pharmacodynamic activity and the mechanism(s) by which brodalumab exerts its clinical effects is unknown.
Following a single subcutaneous dose of 210 mg in subjects with plaque psoriasis, brodalumab reached peak mean (±SD) serum concentration (Cmax) of 13.4±7.3 mcg/mL by approximately 3 days post dose. The mean (±SD) area-under-the-concentration-time curve (AUC) of brodalumab was 111±64 mcg•day/mL.
Following multiple subcutaneous doses of 210 mg every 2 weeks, steady-state was achieved by Week 4. The mean (±SD) Cmax was 20.6±14.6 mcg/mL and the mean (±SD) AUC over the two week dosing interval was 227±167 mcg•day/mL.
Following subcutaneous administration, brodalumab bioavailability was approximately 55%.
Following a single subcutaneous administration of brodalumab 210 mg in subjects with plaque psoriasis, the mean (±SD) apparent volume of distribution (Vz/F) of brodalumab was 8.9±9.4 L.
The metabolic pathway of brodalumab has not been characterized. As a human monoclonal IgG2 antibody, brodalumab is expected to be degraded into small peptides and amino acids via catabolic pathways in a manner similar to endogenous IgG.
Following a single subcutaneous administration of brodalumab 210 mg in subjects with plaque psoriasis, the mean (±SD) apparent total clearance (CL/F) was 3.0±3.5 L/day. The clearance of brodalumab increased with decreasing doses due to nonlinear elimination.
Brodalumab exhibited non-linear pharmacokinetics with exposures that increased greater than dose-proportionally over a dose range from 140 mg (approximately 0.67 times the recommended dose) to 350 mg (approximately 1.67 times the recommended dose) following subcutaneous administrations in subjects with plaque psoriasis.
Brodalumab trough concentrations were lower in subjects with higher body weight.
Hepatic or Renal Impairment
No trials were conducted to assess the effect of hepatic or renal impairment on the pharmacokinetics of brodalumab.
Age: Geriatric Population
Population pharmacokinetic analysis indicated that age did not significantly influence the clearance of brodalumab in subjects with plaque psoriasis. Subjects who were 65 years or older had a similar brodalumab clearance as compared to subjects less than 65 years old.
Drug Interaction Studies
In subjects with plaque psoriasis, one week following a single subcutaneous administration of 210 mg brodalumab, the exposure of midazolam (CYP3A4 substrate) was increased by 24% [see Drug Interactions (7.2)].
13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
Animal studies have not been conducted to evaluate the carcinogenic or mutagenic potential of SILIQ. The published literature is mixed on the potential effects on malignancy risk due to the inhibition of the IL-17RA, the pharmacological action of SILIQ. Some published literature suggests that IL-17A directly promotes cancer cell invasion, which suggests a potential beneficial effect of SILIQ. However, other reports indicate IL-17A promotes T-cell mediated tumor rejection, which suggests a potential adverse effect by SILIQ. However, inhibition of the IL-17RA with SILIQ has not been studied in these models. Therefore, the relevance of experimental findings in these models for malignancy risk in humans is unknown.
In cynomolgus monkeys, there were no effects on fertility parameters such as changes in reproductive organs or sperm analysis following subcutaneous administration of brodalumab at dose levels up to 90 mg/kg/week for six months (26 times the MRHD on a mg/kg basis). The monkeys were not mated in this study to evaluate effects on fertility.
14 CLINICAL STUDIES
Three multicenter, randomized, double-blind, controlled trials (Trials 1, 2, and 3) enrolled a total of 4373 subjects 18 years of age and older with at least a 6-month history of moderate to severe plaque psoriasis, defined as having a minimum affected body surface area (BSA) of 10%, a Psoriasis Area and Severity Index (PASI) score ≥ 12, a static Physician’s Global Assessment (sPGA) score ≥3 in the overall assessment (plaque thickness/induration, erythema, and scaling) of psoriasis on a severity scale of 0 to 5, and who were candidates for systemic therapy or phototherapy. In all three trials, subjects were randomized to subcutaneous treatment with placebo or SILIQ 210 mg at Weeks 0, 1, and 2, followed by treatments every 2 weeks [Q2W] through Week 12. In the two active comparator trials (Trials 2 and 3), subjects randomized to ustekinumab received a 45 mg dose if their weight was less than or equal to 100 kg and a 90 mg dose if their weight was greater than 100 kg at Weeks 0, 4, and 16, followed by the same dose every 12 weeks.
All three trials assessed the change from baseline to Week 12 compared to placebo in the two co-primary endpoints: 1) PASI 75, the proportion of subjects who achieved at least a 75% reduction in the PASI composite score that takes into consideration both the percentage of body surface area affected and the nature and severity of psoriatic changes (induration, erythema, and scaling) within the affected region, and 2) the proportion of subjects with an sPGA of 0 (clear) or 1 (almost clear), and at least a 2-point improvement from baseline. In Trials 2 and 3, comparisons were also made to ustekinumab for the primary endpoint of the proportion of subjects who achieved a reduction in PASI score of 100% (PASI 100) from baseline at Week 12.
Other evaluated outcomes included the proportion of subjects who achieved an sPGA of 0 (clear) at Week 12, and the proportion of subjects who achieved a Psoriasis Symptom Inventory (PSI) score of 0 (not at all) or 1 (mild) on every item (itch, redness, scaling, burning, stinging, cracking, flaking, and pain) at Week 12. Baseline demographics and disease characteristics were generally consistent across all treatment groups in all three trials. Subjects were predominantly men (69%) and white (91%), with a mean age of 45 years. The mean baseline body weight was 90.5 kg and 28% of subjects had body weight greater than 100 kg. The baseline PASI score ranged from 9.4 to 72 (median: 17.4) and the baseline affected BSA ranged from 10 to 97% (median: 21%). Baseline sPGA scores ranged from “3 (moderate)” (58%) to “5 (very severe)” (5%).
Approximately 21% of subjects had a history of psoriatic arthritis. Approximately 30% of subjects had previously received a biologic therapy and 12% of subjects had failed previous biologic therapy.
Clinical Response at Week 12
The results of Trials 1, 2, and 3 are presented in Table 2.
Table 2: Efficacy Results at Week 12 in Adults with Plaque Psoriasis in Trials 1, 2, and 3 (NRI*)
Examination of age, gender, race, use of prior systemic or phototherapy, and use of prior biologics did not identify differences in response to SILIQ among these subgroups.
At Week 12, compared to subjects in the placebo group, a greater proportion of subjects in SILIQ 210 mg Q2W group achieved a Psoriasis Symptom Inventory (PSI) score of 0 (not at all) or 1 (mild) on every item (itch, redness, scaling, burning, stinging, cracking, flaking, pain).
Maintenance of Effect
In Trial 1, subjects randomized to receive SILIQ and who were responders at Week 12 (i.e., sPGA of 0 or 1) were re-randomized to receive either placebo or SILIQ. Among responders at Week 12, 83% (69/83) of subjects re-randomized to continued treatment with SILIQ 210 mg Q2W maintained this response (sPGA of 0 or 1) at Week 52 compared to none (0/84) who were re-randomized to placebo and withdrawn from SILIQ. In addition, 87% (72/83) of subjects re-randomized to continued treatment with SILIQ 210 mg Q2W achieved PASI 75 response at Week 52 compared to none (0/84) who were re-randomized to placebo and withdrawn from SILIQ.
Trials 2 and 3 included a re-randomized phase during which subjects originally randomized to receive SILIQ during the first 12 weeks were re-randomized to one of four SILIQ regimens at the Week 12 visit and placebo subjects were crossed over to receive SILIQ 210 mg Q2W. Subjects receiving ustekinumab continued the same treatment until crossed over at Week 52 to SILIQ 210 mg Q2W. For sPGA 0 or 1 responders at Week 12, the percentage of subjects who maintained this response at Week 52 was 79% for subjects treated with SILIQ 210 mg Q2W. For PASI 100 responders at Week 12, 72% of the subjects who continued on SILIQ 210 mg Q2W maintained the response at Week 52.
16 HOW SUPPLIED/STORAGE AND HANDLING
16.1 How Supplied
SILIQ (brodalumab) Injection is available in a single-dose prefilled syringe containing a sterile, preservative-free clear to slightly opalescent, colorless to slightly yellow solution that may contain a few translucent to white, amorphous particles.
• NDC 0187-0004-02: Carton of two 210 mg/1.5 mL single-dose prefilled syringes
16.2 Storage and Handling
• Store refrigerated at 2°C to 8°C (36°F to 46°F) in the original carton to protect from light and physical damage during storage.
• When necessary, prefilled syringes can be stored at room temperature up to a maximum of 77°F (25°C) in the original carton for a maximum single period of 14 days with protection from light and sources of heat. Once the prefilled syringe has reached room temperature, do not place back into the refrigerator. Discard after 14 days at room temperature.
• Do not freeze.
• Do not shake.
17 PATIENT COUNSELING INFORMATION
Advise the patient to read the FDA-approved patient labeling (Medication Guide and Instructions for Use) before the patient starts using SILIQ, and each time the prescription is renewed, as there may be new information they need to know.
Suicidal Thoughts and Behavior
Instruct patients and their caregivers to monitor for the emergence of suicidal thoughts and behavior and promptly seek medical attention if the patient experiences suicidal thoughts, new or worsening depression, anxiety, or other mood changes [see Warnings and Precautions (5.1)].
Instruct patients to carry the wallet card provided and to call the National Suicide Prevention Lifeline at 1-800-273-8255 if they experience suicidal thoughts.
SILIQ REMS Program
Because of the observed suicidal thoughts and behavior in subjects treated with SILIQ, SILIQ is available only through a restricted program called the SILIQ REMS Program [see Warnings and Precautions (5.2)]. Inform the patient of the following:
• Patients must enroll in the program [see Warnings and Precautions (5.1, 5.2)].
• Patients will be given a SILIQ Patient Wallet Card that they should carry with them at all times. This card describes symptoms which, if experienced, should prompt the patient to immediately seek medical evaluation. Advise the patient to show the SILIQ Patient Wallet Card to other treating healthcare providers.
SILIQ is available only from certified pharmacies participating in the program. Therefore, provide patients with the telephone number and website for information on how to obtain the product.
Inform patients that SILIQ may lower the ability of their immune system to fight infections. Instruct patients of the importance of communicating any history of infections to their healthcare providers and to contact their healthcare providers if they develop any signs or symptoms of infection [see Warnings and Precautions (5.3)].
Instruct patients to seek medical advice if they develop signs and symptoms of Crohn’s disease [see Warnings and Precautions (5.5)].
Instructions for Injection
Instruct the patient to perform the first self-injection under the guidance and supervision of a qualified healthcare professional for proper training in subcutaneous injection technique.
Instruct patients who are self-administering to inject the full dose of SILIQ [see Dosage and Administration (2.1) and Instructions for Use].
Instruct patients or caregivers in the technique of proper syringe and needle disposal [see Instructions for Use].