Clinical Pharmacology for Orladeyo
Mechanism of Action
Berotralstat is a plasma kallikrein inhibitor that binds to plasma kallikrein and inhibits its proteolytic activity. Plasma kallikrein is a protease that cleaves high-molecular-weight kininogen (HMWK) to generate cleaved HMWK (cHMWK) and bradykinin, a potent vasodilator that increases vascular permeability resulting in swelling and pain associated with HAE. In patients with HAE due to C1-inhibitor (C1-INH) deficiency or dysfunction, normal regulation of plasma kallikrein activity is not present, which leads to uncontrolled increases in plasma kallikrein activity and results in angioedema attacks. Berotralstat decreases plasma kallikrein activity to control excess bradykinin generation in patients with HAE.
Pharmacodynamics
Concentration-dependent inhibition of plasma kallikrein, measured as a reduction from baseline of specific enzyme activity, was demonstrated after oral administration of ORLADEYO once daily in patients with HAE.
Cardiac Electrophysiology
At the maximum recommended dosage of 150 mg once daily in adults, clinically significant QTc interval prolongation was not observed. At 3-times the maximum recommended dosage, the mean (upper 90% confidence interval) increase in QTcF was 15.9 msec (23.5 msec). The observed increase in QTcF was concentration dependent.
Pharmacokinetics
Following oral administration of berotralstat 150 mg once daily in adults, the geometric mean steady-state Cmax is 158 ng/mL (range: 110 to 234 ng/mL) and steady-state area under the curve over the dosing interval (AUCtau) is 2770 ng*hr/mL (range: 1880 to 3790 ng*hr/mL). Following oral administration of berotralstat 110 mg once daily, the geometric mean steady-state Cmax is 97.8 ng/mL (range: 63 to 235 ng/mL) and steady-state AUCtau is 1600 ng*hr/mL (range: 950 to 4170 ng*hr/mL).
Berotralstat exposure (Cmax and AUC) increases in a greater than dose-proportional manner and steady state is reached in approximately 6 to 12 days. Berotralstat accumulation at steady state is approximately 5-fold at the recommended dosage.
No clinically significant difference in the pharmacokinetics of berotralstat was observed between healthy adult subjects and patients with HAE.
Absorption
The median time to maximum plasma concentration (Tmax) of berotralstat when administered with food is 5 hours (range: 1 to 8 hours).
No clinically significant difference in ORLADEYO exposure was observed following oral administration of either the pellets or capsules at the recommended adult dosage for 7 days.
Effect of Food
No clinically significant differences in the Cmax and AUC of berotralstat were observed following administration with a high-fat meal, however the median Tmax was delayed by 3 hours, from 2 hours (fasted) to 5 hours (fed).
Distribution
Plasma protein binding is approximately 99%. After a single dose of radiolabeled berotralstat at 2-times the maximum recommended dosage of 150 mg, the blood to plasma ratio was approximately 0.92.
Elimination
The median elimination half-life of berotralstat is approximately 93 hours (range: 39 to 152 hours).
Metabolism
Berotralstat is metabolized by CYP2D6 and by CYP3A4 with low turnover in vitro. After a single oral dose of radiolabeled berotralstat at 2-times the maximum recommended dosage of 150 mg, berotralstat represented 34% of the total plasma radioactivity, with 8 metabolites, each accounting for between 1.8 and 7.8% of the total radioactivity.
Excretion
After a single oral dose of radiolabeled berotralstat at 2-times the maximum recommended dosage of 150 mg, approximately 9% was excreted in urine (3.4% unchanged; range: 1.8 to 4.7%) and 79% was excreted in feces.
Specific Populations
In adults and pediatric patients 12 to <18 years of age, no clinically significant differences in the pharmacokinetics of ORLADEYO were observed based on age (12 to 74 years), sex, race, and body weight.
Pediatric Patients
Based on population pharmacokinetic analyses that included pediatric patients 12 to <18 years of age, exposure at steady state following oral administration of berotralstat 150 mg once daily was approximately 20% higher compared to adults. The higher exposure in pediatric patients 12 to <18 years of age is not considered to be clinically significant.
Based on population pharmacokinetics analyses that included pediatric patients 2 to <12 years of age, body weight was the only covariate with a clinically significant impact on the systemic exposure of berotralstat. In pediatric patients 2 to <12 years of age at the recommended dosage based on body weight, median Cmax at steady state is expected to be up to 24% higher compared to adults. However, this difference is not considered to be clinically significant [see Dosage and Administration and Use in Special Populations].
Patients with Renal Impairment
The pharmacokinetics of a single oral dose of berotralstat at 1.33-times the highest recommended dosage of 150 mg were studied in adult subjects with severe renal impairment (CLCR less than 30 mL/min, estimated by Cockcroft-Gault). When compared to a concurrent cohort with normal renal function (CLCR greater than 90 mL/min, estimated by Cockcroft-Gault), no clinically significant difference was observed; Cmax was increased by 47%, while AUC0-last was increased by 14% [see Use in Specific Populations].
The pharmacokinetics of berotralstat has not been studied in patients with End-Stage Renal Disease (CLCR less than 15 mL/min or eGFR less than 15 mL/min/1.73 m2 or patients requiring hemodialysis).
Patients with Hepatic Impairment
The pharmacokinetics of a single 150 mg oral dose of berotralstat were studied in adult subjects with mild, moderate, and severe hepatic function (Child-Pugh Class A, B, and C, respectively). The pharmacokinetics of berotralstat were unchanged in subjects with mild hepatic impairment compared to subjects with normal hepatic function. In subjects with moderate hepatic impairment, Cmax was increased by 77%, while AUC0-inf was increased by 78%. In subjects with severe hepatic impairment, Cmax was increased by 27%, while AUC0-last was decreased by 5%. The median half-life of berotralstat was increased by 37% and 22% in patients with moderate and severe hepatic impairment, respectively, in comparison to healthy subjects. The percent of unbound berotralstat increased 2-fold from a mean of 1.2% in healthy subjects to a mean of 2.4% in subjects with severe hepatic impairment [see Use in Specific Populations].
Drug Interaction Studies
Effect of Other Drugs on the Pharmacokinetics of ORLADEYO
Berotralstat is a P-gp and BCRP substrate. Cyclosporine, a P-gp and BCRP inhibitor, decreased berotralstat 150 mg Cmax by 7%, while AUC0-last and AUC0-inf increased by 27% and 24%, respectively.
Effect of ORLADEYO on the Pharmacokinetics of Other Drugs
Berotralstat 150 mg once daily is a moderate inhibitor of CYP2D6 and CYP3A4, and a weak inhibitor of CYP2C9 and CYP2C19.
At 2-times the maximum recommended dosage of 150 mg, berotralstat is an inhibitor of P-gp and is not an inhibitor of BCRP (rosuvastatin exposure was decreased by approximately 20%).
In a drug interaction study conducted in healthy females of reproductive potential (N=22), concomitant administration of berotralstat 150 mg once daily with 0.15 mg/0.03 mg desogestrel/ethinyl estradiol led to a 2.6-fold increase in the AUC0-last of etonogestrel, the active metabolite of desogestrel.
The effect of berotralstat on the pharmacokinetics of other drugs are presented in Figure 1 [see Drug Interactions].
Figure 1: Effect of ORLADEYO on Concomitant Medications
CLINICAL STUDIES
The efficacy of ORLADEYO for the prevention of angioedema attacks in adult and pediatric patients 12 years of age and older with Type I or II HAE was demonstrated in Part 1 of a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial (Trial 1 [NCT3485911]).
The trial included 120 adults and pediatric patients 12 to <18 years of age who experienced at least two investigator-confirmed attacks within the first 8 weeks of the run-in period and took at least one dose of study treatment. Patients were randomized into 1 of 3 parallel treatment arms, stratified by baseline attack rate, in a 1:1:1 ratio (ORLADEYO 110 mg, ORLADEYO 150 mg, or placebo by oral administration once daily, with food) for the 24-week treatment period (Part 1).
Patients discontinued other prophylactic HAE medications prior to entering the trial; however, all patients were allowed to use rescue medications for treatment of breakthrough HAE attacks.
A history of laryngeal angioedema attacks was reported in 74% of patients and 75% reported prior use of long-term prophylaxis. The median attack rate during the prospective run-in period (baseline attack rate) was 2.9/month. Seventy percent of patients enrolled had a baseline attack rate of ≥2 attacks/month.
ORLADEYO 150 mg and 110 mg produced statistically significant reductions in the rate of HAE attacks compared to placebo for the primary endpoint in the Intent-to-Treat (ITT) population as shown in Table 3. The percent reductions in HAE attack rate were greater with ORLADEYO 150 mg and 110 mg relative to placebo, regardless of attack rate during the run-in period.
Table 3. Primary Efficacy Endpoint (Trial 1): Reduction in HAE Attack Rate - ITT Population (Adult and Pediatric Patients 12 Years of Age and Older)
| Outcome |
ORLADEYO |
Placebo |
| 110 mg QD |
150 mg QD |
| N = 41 |
N = 40 |
N = 40* |
| HAE Attack Rate, rate per 28 days† |
1.65 |
1.31 |
2.35 |
| % Rate Reduction ‡ (95% CI) |
30.0%
(4.6, 48.7) |
44.2%
(23.0, 59.5) |
- |
| p-value |
0.024 |
<0.001 |
- |
* One patient in the ITT analysis was randomized to placebo but was not treated.
† Statistical analysis based on a negative binomial regression model; number of attacks included as dependent variable, treatment included as fixed effect, baseline attack rate included as covariate, and logarithm of duration on treatment included as offset variable.
‡ Percent reduction relative to placebo. |
Reductions in attack rates were observed in the first month of treatment with ORLADEYO 150 mg and 110 mg and were sustained through 24 weeks as shown in Figure 2.
Figure 2. Mean (+/- SEM) HAE Attack Rate/Month Through 24 Weeks (Trial 1) - ITT Population (Adult and Pediatric Patients 12 Years of Age and Older)
Pre-defined exploratory endpoints included the proportion of responders to ORLADEYO, defined as at least a 50% relative reduction in HAE attacks during treatment compared with the baseline attack rate; 58% of patients who received ORLADEYO 150 mg and 51% of patients who received ORLADEYO 110 mg had a ≥50% reduction in their HAE attack rates compared to baseline versus 25% of placebo patients. In post hoc analyses, 50% and 23% of patients who received ORLADEYO 150 mg, and 27% and 10% of patients who received ORLADEYO 110 mg, had a ≥70% or ≥90% reduction in their HAE attack rates compared to baseline versus 15% and 8% of placebo-treated patients, respectively. The rate of HAE attacks rated as moderate or severe was reduced by 40% and 10% in patients who received ORLADEYO 150 mg and 110 mg, respectively, versus placebo-treated patients.