CLINICAL PHARMACOLOGY
Mechanism Of Action
Dupilumab is a human monoclonal IgG4 antibody that inhibits interleukin-4 (IL-4) and interleukin-13 (IL-13) signaling by specifically binding to the IL-4Rα subunit shared by the IL-4 and IL-13 receptor complexes. Dupilumab inhibits IL-4 signaling via the Type I receptor and both IL-4 and IL-13 signaling through the Type II receptor.
Blocking IL-4Rα with dupilumab inhibits IL-4 and IL-13 cytokine-induced responses, including the release of proinflammatory cytokines, chemokines and IgE.
Pharmacodynamics
Consistent with receptor blockade, serum levels of IL-4 and IL-13 were increased following dupilumab treatment. The relationship between the pharmacodynamic activity and the mechanism(s) by which dupilumab exerts its clinical effects is unknown.
Pharmacokinetics
Absorption
Following an initial subcutaneous (SC) dose of 600 mg, dupilumab reached peak mean ±SD concentrations (Cmax) of 70.1±24.1 mcg/mL by approximately 1 week post dose.
Steady-state concentrations were achieved by Week 16 following the administration of 600 mg starting dose and 300 mg dose either weekly (twice the recommended dosing frequency) or every other week. Across clinical trials, the mean ±SD steady-state trough concentrations ranged from 73.3±40.0 mcg/mL to 79.9±41.4 mcg/mL for 300 mg administered every 2 weeks and from 173±75.9 mcg/mL to 193±77.0 mcg/mL for 300 mg administered weekly.
The bioavailability of dupilumab following a SC dose is estimated to be 64%.
Distribution
The estimated total volume of distribution was approximately 4.8±1.3 L.
Elimination
The metabolic pathway of dupilumab has not been characterized. As a human monoclonal IgG4 antibody, dupilumab is expected to be degraded into small peptides and amino acids via catabolic pathways in the same manner as endogenous IgG. After the last steady-state dose of 300 mg Q2W or 300 mg QW dupilumab, the median times to non-detectable concentration (<78 ng/mL) are 10 and 13 weeks, respectively.
Dose Linearity
Dupilumab exhibited nonlinear target-mediated pharmacokinetics with exposures increasing in a greater than dose-proportional manner. The systemic exposure increased by 30-fold when the dose
increased 8-fold following a single dose of dupilumab from 75 mg to 600 mg (i.e., 0.25-times to 2times the recommended dose).
Weight
Dupilumab trough concentrations were lower in subjects with higher body weight.
Immunogenicity
Development of antibodies to dupilumab was associated with lower serum dupilumab
concentrations. A few subjects who had high antibody titers also had no detectable serum dupilumab concentrations.
Specific Populations
Geriatric Patients
In subjects who are 65 years and older, the mean ±SD steady-state trough concentrations of dupilumab were 69.4±31.4 mcg/mL and 166±62.3 mcg/mL, respectively, for 300 mg administered every 2 weeks and weekly. No dose adjustment in this population is recommended.
Renal Or Hepatic Impairment
No formal trial of the effect of hepatic or renal impairment on the pharmacokinetics of dupilumab was conducted.
Drug Interaction Studies
Cytochrome P450 Substrates
The effects of dupilumab on the pharmacokinetics of midazolam (metabolized by CYP3A4), warfarin (metabolized by CYP2C9), omeprazole (metabolized by CYP2C19), metoprolol (metabolized by CYP2D6), and caffeine (metabolized by CYP1A2) were evaluated in a study with 12-13 evaluable subjects with atopic dermatitis (a SC loading dose of 600 mg followed by 300 mg SC weekly for six weeks). No clinically significant changes in AUC were observed. The largest effect was observed for metoprolol (CYP2D6) with an increase in AUC of 29%.
Clinical Studies
Three randomized, double-blind, placebo-controlled trials (Trials 1, 2, and 3) enrolled a total of 2119 subjects 18 years of age and older with moderate-to-severe atopic dermatitis (AD) not adequately controlled by topical medication(s). Disease severity was defined by an Investigator’s Global Assessment (IGA) score ≥3 in the overall assessment of AD lesions on a severity scale of 0 to 4, an Eczema Area and Severity Index (EASI) score ≥16 on a scale of 0 to 72, and a minimum body surface area involvement of ≥10%. At baseline, 59% of subjects were male, 67% were white, 52% of subjects had a baseline IGA score of 3 (moderate AD), and 48% of subjects had a baseline IGA of 4 (severe AD). The baseline mean EASI score was 33 and the baseline weekly averaged peak pruritus Numeric Rating Scale (NRS) was 7 on a scale of 0-10.
In all three trials, subjects in the DUPIXENT group received subcutaneous injections of DUPIXENT 600 mg at Week 0, followed by 300 mg every other week (Q2W). In the monotherapy trials (Trials 1 and 2), subjects received DUPIXENT or placebo for 16 weeks.
In the concomitant therapy trial (Trial 3), subjects received DUPIXENT or placebo with concomitant topical corticosteroids (TCS) and as needed topical calcineurin inhibitors for problem areas only, such as the face, neck, intertriginous and genital areas for 52 weeks.
All three trials assessed the primary endpoint, the change from baseline to Week 16 in the proportion of subjects with an IGA 0 (clear) or 1 (almost clear) and at least a 2-point improvement. Other endpoints included the proportion of subjects with EASI-75 (improvement of at least 75% in EASI score from baseline), and reduction in itch as defined by at least a 4-point improvement in the peak pruritus NRS from baseline to Week 16.
Clinical Response At Week 16 (Trials 1, 2, And 3)
The results of the DUPIXENT monotherapy trials (Trials 1 and 2) and the DUPIXENT with concomitant TCS trial (Trial 3) are presented in Table 2.
Table 2: Efficacy Results of DUPIXENT With or Without Concomitant TCS at Week 16 (FAS)
|
Trial 1 |
Trial 2 |
Trial 3 |
DUPIXENT 300 mg Q2W |
Placebo |
DUPIXENT 300 mg Q2W |
Placebo |
DUPIXENT 300 mg Q2W + TCS |
Placebo + TCS |
Number of subjects randomized (FAS)a |
224 |
224 |
233 |
236 |
106 |
315 |
IGA 0 or 1b,c |
38% |
10% |
36% |
9% |
39% |
12% |
EASI-75c |
51% |
15% |
44% |
12% |
69% |
23% |
EASI-90c |
36% |
8% |
30% |
7% |
40% |
11% |
Number of subjects with baseline Peak Pruritus NRS score ≥4 |
213 |
212 |
225 |
221 |
102 |
299 |
Peak Pruritus NRS
(≥4-point improvement)c |
41% |
12% |
36% |
10% |
59% |
20% |
aFull Analysis Set (FAS) includes all subjects randomized.
b Responder was defined as a subject with IGA 0 or 1 (“clear” or “almost clear”) with a reduction of ≥2 points on a 0-4 IGA scale.
c Subjects who received rescue treatment or with missing data were considered as non-responders. |
Figure 1: Proportion of Subjects with ≥4-point Improvement on the Pruritus NRS in Trial 1a and Trial 2a Studies (FAS)b
a In the primary analyses of the efficacy endpoints, subjects who received rescue treatment or with missing data were considered non-responders.
b Full Analysis Set (FAS) includes all subjects randomized.
In Trial 3, of the 421 subjects, 353 had been on study for 52 weeks at the time of data analysis. Of these 353 subjects, responders at Week 52 represent a mixture of subjects who maintained their efficacy from Week 16 (e.g., 53% of DUPIXENT IGA 0 or 1 responders at Week 16 remained responders at Week 52) and subjects who were non-responders at Week 16 who later responded to treatment (e.g., 24% of DUPIXENT IGA 0 or 1 non-responders at Week 16 became responders at Week 52). Results of supportive analyses of the 353 subjects in the DUPIXENT with concomitant TCS trial (Trial 3) are presented in Table 3.
Table 3: Efficacy Results (IGA 0 or 1) of DUPIXENT with Concomitant TCS at Week 16 and 52
|
DUPIXENT
300 mg Q2W + TCS |
Placebo + TCS |
Number of Subjectsa |
89 |
264 |
Responderb,c at Week 16 and 52 |
22% |
7% |
Responder at Week 16 but Non-responder at Week 52 |
20% |
7% |
Non-responder at Week 16 and Responder at Week 52 |
13% |
6% |
Non-responder at Week 16 and 52 |
44% |
80% |
Overall Responderb,c Rate at Week 52 |
36% |
13% |
a In Trial 3, of the 421 randomized and treated subjects, 68 subjects (16%) had not been on study for 52 weeks at the time of data analysis.
b Responder was defined as a subject with IGA 0 or 1 (“clear” or “almost clear”) with a reduction of ≥2 points on a 0-4 IGA scale.
c Subjects who received rescue treatment or with missing data were considered as non-responders. |
Treatment effects in subgroups (weight, age, gender, race, and prior treatment, including immunosuppressants) in Trials 1, 2, and 3 were generally consistent with the results in the overall study population.
In Trials 1, 2, and 3, a third randomized treatment arm of DUPIXENT 300 mg QW did not demonstrate additional treatment benefit over DUPIXENT 300 mg Q2W.
Subjects in Trials 1 and 2 who had an IGA 0 or 1 with a reduction of ≥2 points were re-randomized into Trial 5. Trial 5 evaluated multiple DUPIXENT monotherapy dose regimens for maintaining treatment response. The study included subjects randomized to continue with DUPIXENT 300 mg Q2W (62 subjects) or switch to placebo (31 subjects) for 36 weeks. IGA 0 or 1 responses at Week 36 were as follows: 33 (53%) in the Q2W group and 3 (10%) in the placebo group.