Sequence 1
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Donidalorsen is an ASO‑GalNAc conjugate that causes ribonuclease H1 (RNase H1)‑mediated degradation of PKK mRNA through binding to PKK mRNA, which results in reduced production of PKK protein. PKK is a pro‑enzyme for plasma kallikrein, which results in the release of bradykinin, a potent vasodilator causing swelling and pain in HAE. In patients with HAE, C1‑inhibitor (C1‑INH) deficiency or dysfunction leads to excessive plasma kallikrein activity, bradykinin generation, and angioedema attacks. Donidalorsen lowers PKK concentration, preventing excessive bradykinin production in patients with HAE. 12.2 Pharmacodynamics In OASIS-HAE in adult and pediatric patients (≥12 years) with HAE‑1 or HAE‑2 [see Clinical Studies (14) ] , a decrease in plasma PKK concentrations was observed at the first assessment (Week 4) following treatment with DAWNZERA 80 mg. The mean percentage reduction from baseline at Week 4 across both treatment groups was 48%. The mean percentage change from baseline to Week 24 in trough plasma PKK concentrations indicated reductions of 73% and 47% following treatment with DAWNZERA 80 mg every 4 weeks and every 8 weeks, respectively, compared with a slight increase (2%) observed in the placebo group. Cardiac Electrophysiology At the maximum recommended dose of DAWNZERA 80 mg every 4 weeks, clinically significant QTc interval prolongation was not observed. 12.3 Pharmacokinetics The pharmacokinetic properties of DAWNZERA were evaluated following subcutaneous administration of multiple doses every 4 weeks in healthy subjects and every 4 weeks or every 8 weeks in patients with HAE. The pharmacokinetics of DAWNZERA were similar between healthy subjects and patients with HAE. Donidalorsen exposure (area under the plasma concentration‑time curve [AUC]) at steady state following subcutaneous administration in healthy subjects increased in a greater than dose‑proportional manner over the dose range of 0.25 times the maximum recommended dosage to 80 mg every 4 weeks. Geometric Mean (Coefficient of Variation [CV%]) of steady‑state maximum plasma concentration (C max,ss ), trough plasma concentration (C trough,ss ), and area under the plasma concentration‑time curve over the dosing interval (AUC τ ,ss ) are presented in Table 2. No accumulation of donidalorsen C max and AUC was observed in plasma after repeated dosing every 4 weeks. However, a 2-fold increase of plasma donidalorsen C trough was observed following repeated dosing every 4 weeks. Table 2: Summary of Geometric Mean (CV%) Steady-State Donidalorsen Pharmacokinetic Parameters Following Dosage of DAWNZERA 80 mg Every 4 Weeks or 80 mg Every 8 Weeks in Patients with HAE AUC τ,ss = area under the plasma concentration time curve over each dosing interval at steady state; C max,ss = maximum plasma concentration at steady state; C trough,ss = trough plasma concentration at steady state; q4wks = every 4 weeks; q8wks = every 8 weeks. Pharmacokinetic Parameters (Geometric Mean) DAWNZERA 80 mg q4wks 80 mg q8wks C max,ss (ng/mL) 417 (81%) 416 (78%) C trough,ss (ng/mL) 0.755 (63%) 0.255 (73%) AUC τ,ss (ng·h/mL) 5240 (52%) 5210 (52%) Absorption Following subcutaneous administration, donidalorsen is absorbed with the median (range) time to maximum plasma concentration of approximately 2 (0.25, 8) hours post dose. Distribution Donidalorsen is expected to distribute primarily to the liver and kidney cortex after subcutaneous dosing. The apparent volume of distribution for the central (V c /F) and peripheral (V p /F) compartment were 69.8 L and 1840 L, respectively. Donidalorsen is highly bound to human plasma proteins (>98% bound) in vitro. Elimination The terminal plasma elimination half-life of donidalorsen in a typical patient with HAE is approximately 1 month. The half-life of the initial rapid clearance phase, reflecting tissue distribution, was approximately 5 hours. Metabolism The oligonucleotide moiety of donidalorsen is expected to be metabolized by endo‑ and exonucleases to short oligonucleotide fragments of varying sizes within the liver. Based on in vitro studies, donidalorsen is not a substrate of cytochrome P450 (CYP) enzymes. The linker that covalently connects the ASO to the GalNAc residues is cleaved via hydrolysis and undergoes dephosphorylation and subsequent oxidative metabolism to form inactive metabolites, which are minimally released in circulation. The most abundant linker-related metabolite (M8) is a substrate of CYP3A4. Excretion The mean fraction of unchanged ASO eliminated in urine was less than 1% of the administered dose in healthy subjects within 24 hours post-dose. The renal route of elimination is minor for linker-related metabolites. Specific Populations No clinically meaningful differences in the pharmacokinetics or pharmacodynamics of donidalorsen were observed based on age (12 to 68 years), body weight (37 to 152 kg), sex, race (68% White, 24% Black, and 4% Asian), ethnicity, disease status (healthy subjects or subjects with HAE), mild renal impairment (eGFR ≥60 to <90 mL/min/1.73 m 2 ), or mild hepatic impairment (defined using NCI-ODWG Criteria: total bilirubin ≤1 × ULN and AST >1 × ULN, or total bilirubin >1 to 1.5 × ULN and any AST). Donidalorsen has not been studied in patients with moderate or severe renal impairment, end‑stage renal disease, or moderate or severe hepatic impairment. Drug Interaction Studies No clinical drug‑drug interaction studies have been performed with donidalorsen. In vitro studies show that donidalorsen is not a substrate or inhibitor of transporters, does not interact with highly plasma protein bound drugs, and is not an inhibitor/inducer of CYP enzymes. In vitro studies show that linker-related metabolite M8 is not an inhibitor or inducer of CYP enzymes. M8 is a substrate of transporters bile salt export pump (BSEP) and organic anion transporting polypeptide 1B3 (OATP1B3), and is an inhibitor of multidrug and toxin extrusion protein 1 (MATE1) transporter. 12.6 Immunogenicity The observed incidence of anti‑drug antibodies (ADAs) is highly dependent on the sensitivity and specificity of the assay. Differences in assay methods preclude meaningful comparisons of the incidence of anti-drug antibodies in the studies described below with the incidence of anti-drug antibodies in other studies, including those of donidalorsen or of other donidalorsen products. In OASIS-HAE, with a treatment duration up to 24 weeks, the incidence rate of treatment‑emergent ADAs in adult and pediatric patients (≥12 years of age) with HAE was 20% (9 of 45 patients) in the DAWNZERA 80 mg every 4 weeks group and 22% (5 of 23 patients) in the DAWNZERA 80 mg every 8 weeks group. In an open‑label extension trial, patients that rolled over from OASIS-HAE continued treatment with DAWNZERA in the 80 mg every 4 weeks or every 8 weeks groups for up to 3 years (median exposure duration of 227 days). The incidence rate of treatment‑emergent ADAs was 35% (22 of 63 patients) in the DAWNZERA 80 mg every 4 weeks group, including patients initially randomized to DAWNZERA 80 mg every 4 weeks in OASIS-HAE (36%, 16/44) and patients initially randomized to placebo in OASIS-HAE (32%, 6/19). The incidence rate of treatment-emergent ADAs was 21% (3 of 14 patients) among patients who received DAWNZERA 80 mg every 8 weeks in OASIS-HAE and open-label extension. In general, the development of ADAs was not found to affect the pharmacodynamics, safety, or efficacy of DAWNZERA. An increase in donidalorsen plasma C trough was observed in ADA-positive patients with high titers. Because of small sample size, the effect of ADA on the pharmacokinetics, pharmacodynamics, safety and effectiveness of DAWNZERA is inconclusive.