Clinical Pharmacology for Evkeeza
Mechanism Of Action
Evinacumab-dgnb is a recombinant human monoclonal antibody that binds to and inhibits ANGPTL3. ANGPTL3 is a member of the angiopoietin-like protein family that is expressed primarily in the liver and plays a role in the regulation of lipid metabolism by inhibiting lipoprotein lipase (LPL) and endothelial lipase (EL). Evinacumab-dgnb inhibition of ANGPTL3 leads to reduction in LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG). Evinacumab-dgnb reduces LDL-C independent of the presence of LDL receptor (LDLR) by promoting very low-density lipoprotein (VLDL) processing and clearance upstream of LDL formation. Evinacumab-dgnb blockade of ANGPTL3 lowers TG and HDL-C by rescuing LPL and EL activities, respectively.
Pharmacodynamics
Administration of evinacumab-dgnb in HoFH patients resulted in reductions in LDL-C, total cholesterol (TC), HDL-C, apolipoprotein B and TG [see Clinical Studies].
Pharmacokinetics
The pharmacokinetic parameters described in this section are presented following administration of evinacumab-dgnb 15 mg/kg intravenously every 4 weeks, unless otherwise specified.
Steady-state is reached after 4 doses, and the accumulation ratio is 2. According to population pharmacokinetic modeling, the mean (standard deviation) steady-state trough concentration is 266 (120) mg/L in adult patients, whereas the mean (standard deviation) Cmax at the end of infusion is 718 (183) mg/L in adult patients. Due to non-linear clearance, a 4.3-fold increase in area under the concentration-time curve at steady-state (AUCtau.ss) for a 3-fold increase in evinacumab-dgnb dose up to 15 mg/kg IV every 4 weeks was predicted in patients with HoFH.
Distribution
The steady-state volume of distribution estimated via population pharmacokinetic analysis was approximately 4.7 L in adult patients.
Elimination
Evinacumab-dgnb elimination is mediated via parallel linear and non-linear pathways. At higher concentrations, evinacumab-dgnb elimination is primarily through a non-saturable proteolytic pathway, whereas at lower concentrations, the non-linear, saturable ANGPTL3 target-mediated elimination predominates. The elimination half-life is a function of serum evinacumab-dgnb concentrations and is not a constant.
Based on a population pharmacokinetic analysis, the median time for serum evinacumab-dgnb concentrations to decrease below the lower limit of quantitation (78 ng/mL) is approximately 20 weeks after the last steady-state dose of 15 mg/kg IV every 4 weeks.
Metabolism
The exact pathway through which evinacumab-dgnb is metabolized has not been characterized. As a human monoclonal IgG4 antibody, evinacumab-dgnb is expected to be degraded into small peptides and amino acids via catabolic pathways in the same manner as endogenous IgG.
Excretion
Evinacumab-dgnb, a monoclonal antibody, is not likely to undergo renal excretion.
Specific Populations
A population PK analysis conducted on data from 183 healthy subjects and 95 patients with HoFH suggests that the following factors have no clinically significant effect on the exposure of evinacumab-dgnb: age (12 to 75 years), gender, body weight (42 to 152 kg), and race (White, Asian, Black or African American, and other races).
Pediatric Patients
Three (3) patients aged 12 to 17 years with HoFH received evinacumab-dgnb at 15 mg/kg IV every 4 weeks. Steady-state trough and end-of-infusion concentrations were within the range observed in adult patients.
Twenty (20) patients aged 5 to 11 years with HoFH received evinacumab-dgnb at 15 mg/kg IV every 4 weeks. According to population pharmacokinetic modeling, the mean (standard deviation) steady-state trough concentration is 174 (74.1) mg/L in pediatric patients, whereas the mean (standard deviation) Cmax at the end of infusion is 444 (111) mg/L in pediatric patients. Steady-state trough and end-of-infusion concentrations were lower but within the range observed in adult patients.
Patients With Renal Impairment
Observed trough serum evinacumab-dgnb concentrations at steady-state were comparable between patients with mild or moderate renal impairment and patients with normal renal function. No data are available in patients with severe renal impairment.
Patients With Hepatic Impairment
No data are available in patients with hepatic impairment.
Drug Interaction Studies
Drug interaction studies have not been conducted with evinacumab-dgnb. In a clinical trial, the concentrations of statins (atorvastatin, rosuvastatin, simvastatin) were not meaningfully altered in patients taking statins prior to and post administration of evinacumab-dgnb. Concentrations of evinacumab-dgnb were comparable in patients with HoFH taking or not taking background lipid-lowering therapy.
Immunogenicity
The observed incidence of anti-drug antibodies 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 trials described below with the incidence of anti-drug antibodies in other trials, including those of EVKEEZA or of other evinacumab-dgnb products. During the 24-week treatment period in the trials in:
- Adult and pediatric patients aged 12 years and older with HoFH (Trials 1 and 2) [see Clinical Studies], the incidence of anti-evinacumab-dgnb antibody formation was 0% (0 of 56) in EVKEEZA-treated patients.
- Pediatric patients aged 5 to 11 years with HoFH (Trial 3) [see Clinical Studies], the incidence of anti-evinacumab-dgnb antibody formation was 5% (1 of 20) in EVKEEZA-treated patients. In the one patient that developed anti-evinacumab-dgnb antibodies, there were no effects on efficacy or evinacumab-dgnb concentrations.
- Because of the low occurrence of anti-evinacumab-dgnb antibodies, the effect of these antibodies on the pharmacokinetics, pharmacodynamics, safety, and/or effectiveness of evinacumab products is unknown.
Clinical Studies
Adult and Pediatric Patients Aged 12 Years And Older With HoFH
Trial ELIPSE-HoFH (NCT03399786; Trial 1) was a multicenter, double-blind, randomized, placebo-controlled trial that evaluated the efficacy of EVKEEZA compared to placebo in 65 patients with HoFH (63 adult patients and 2 pediatric patients). During the 24-week, double-blind treatment period, patients were randomized to receive EVKEEZA 15 mg/kg given intravenously every 4 weeks (n=43) or placebo given intravenously every 4 weeks (n=22). After the double-blind treatment period, 64 of 65 patients entered a 24-week open-label extension period in which all patients received EVKEEZA 15 mg/kg given intravenously every 4 weeks.
Patients were on a background of other lipid-lowering therapies, including maximally tolerated statins, ezetimibe, PCSK9 inhibitor antibodies, lomitapide, and lipoprotein apheresis. Enrollment was stratified by apheresis status and geographical region. The diagnosis of HoFH was determined by genetic testing or by the presence of the following clinical criteria: history of an untreated total cholesterol (TC) >500 mg/dL and either xanthoma before 10 years of age or evidence of TC >250 mg/dL in both parents.
Baseline Disease And Demographic Characteristics
In this trial, 40% (26 of 65) patients had limited LDL receptor (LDLR) function, defined by either <15% receptor function by in vitro assays or by genetic variants likely to result in minimal to no LDLR function by mutation analysis.
The mean LDL-C at baseline was 255 mg/dL (in patients with limited LDLR function, the mean LDL-C at baseline was 307 mg/dL). At baseline, 94% of patients were on statins, 75% on ezetimibe, 77% on a PCSK9 inhibitor antibody, 22% on lomitapide, and 34% were receiving lipoprotein apheresis. The mean age at baseline was 42 years (range 12 to 75) with 12% ≥65 years old; 54% females, 3% Hispanic, 74% White, 15% Asian, 3% Black or African American, and 8% other races or race was not reported.
Endpoint Results
The primary efficacy endpoint was percent change in LDL-C from baseline to Week 24. At Week 24, the least squares (LS) mean treatment difference between the EVKEEZA and placebo groups in mean percent change in LDL-C from baseline was -49% (95% confidence interval: -65% to -33%; p <0.0001). After 24 weeks of open-label EVKEEZA treatment (Week 24 to Week 48), the observed LDL-C reduction from baseline was similar in patients who crossed over from placebo to EVKEEZA and was maintained in patients who remained on EVKEEZA for 48 weeks. For efficacy results see Table 2.
At Week 24, the observed reduction in LDL-C with EVKEEZA was similar across predefined subgroups, including age, sex, limited LDLR activity, concomitant treatment with lipoprotein apheresis, and concomitant background lipid-lowering medications (statins, ezetimibe, PCSK9 inhibitor antibodies, and lomitapide).
Table 2: Lipid Parameters in Patients (63 Adults and 2 Pediatric Patients) with HoFH on Other Lipid-Lowering Therapies in Trial ELIPSE-HoFH (Trial 1)
|
LDL-C |
ApoB |
Non-HDL-C |
TC |
TGa |
HDL-Ca |
| Baseline (mean), mg/dL (N=65) |
255 |
171 |
278 |
322 |
124 |
44 |
| LS Mean: EVKEEZA (N = 43) |
-47% |
-41% |
-50% |
-47% |
-55% |
-30%b |
| LS Mean: Placebo (N = 22) |
+2% |
-5% |
+2% |
+1% |
-5% |
+1%b |
| LS Mean Difference from Placebo (95% CI) |
-49%
(-65 to -33) |
-37%
(-49 to -25) |
-52%
(-65 to -39) |
-48%
(-59 to -38) |
-50%
(-66 to -35) |
-b |
a Neither TG nor HDL-C were pre-specified in the hypothesis testing
bMean percent change, based on safety population (EVKEEZA, n=44; placebo, n=21); HDL-C is presented for completeness but was not an efficacy endpoint that was statistically analyzed.
One subject in the placebo group discontinued the trial before Week 24. The treatment difference and 95% confidence interval (CI) were estimated using a mixed model repeated measures analysis.
Abbreviations: HoFH=homozygous familial hypercholesterolemia, ITT=intent-to-treat, LS mean=least squares mean, N=number of randomized patients, CI=confidence interval |
The LS mean LDL-C percent changes over time are presented in Figure 1.
Figure 1: Calculated LDL-C LS Mean Percent Change from Baseline Over Time Through Week 24 in Patients (63 Adults and 2 Pediatric Patients) with HoFH in Trial ELIPSE-HoFH (Trial 1)
Abbreviations: LS mean=least squares mean, HoFH=homozygous familial hypercholesterolemia, DBTP=doubleÂblind treatment period, SE=standard error
Pediatric Patients (aged 12 to 17 years) With HoFH
In an open-label trial (Trial 2), 13 pediatric patients with HoFH (aged 12 to 17 years) received 15 mg/kg of EVKEEZA given intravenously every 4 weeks as an adjunct to other lipid-lowering therapies (e.g., statins, ezetimibe, PCSK9 inhibitor antibodies and lipoprotein apheresis) for a median treatment duration of 33 weeks. The mean percent change from baseline in LDL-C at Week 24 was -52% in the 9 patients who completed treatment and had a lipid assessment at Week 24. Overall, the effect of EVKEEZA on lipid parameters in pediatric patients aged 12 to 17 years with HoFH was generally similar to that seen in adults with HoFH.
Pediatric Patients (aged 5 to 11 years) With HoFH
Trial R1500-CL-17100 (NCT04233918; Trial 3) was a multicenter, three-part, single-arm, open-label trial in pediatric patients aged 5 to 11 years with HoFH [see ADVERSE REACTIONS]. Part B of this trial evaluated the efficacy of EVKEEZA 15 mg/kg given intravenously every 4 weeks as an adjunct to other lipid-lowering therapies (e.g., statins, ezetimibe, lomitapide, and lipoprotein apheresis) for 24 weeks in 14 patients with HoFH.
Baseline Disease And Demographic Characteristics
In Part B, the mean LDL-C at baseline was 264 mg/dL.
At baseline, 86% of patients were on statins, 93% on ezetimibe, 14% on lomitapide, and 50% were receiving lipoprotein apheresis.
The mean age at baseline was 9 years (range 5 to 11); 57% females; 0% Hispanic; 57% White, 14% Asian, 7% Black or African American, 7% American Indian or Alaska Native, and 14% other races. Mean body weight was 40 kg. Body mass index (BMI) was 20 kg/m².
Endpoint Results
The primary efficacy endpoint was percent change in calculated LDL-C from baseline to Week 24. At Week 24, the mean percent change in calculated LDL-C from baseline was -48% (95% confidence interval: -69% to -28%). For efficacy results see Table 3. HDL-C and TG reductions observed in this trial were similar to changes seen in Trial 1, see Table 2.
At Week 24, the reduction in LDL-C with EVKEEZA was similar across baseline characteristics, including age, sex, limited LDLR activity, concomitant treatment with lipoprotein apheresis, and concomitant background lipid-lowering medications (statins, ezetimibe, and lomitapide).
Table 3: Lipid Parameters in EVKEEZA-Treated Pediatric Patients (aged 5 to 11 years) with HoFH Who Received Concomitant Lipid-Lowering Therapies (Trial 3)
|
LDL-C |
ApoB |
Non-HDL-C |
TC |
| Baseline (mean) (N=14) |
264mg/dL |
168mg/dL |
282mg/dL |
316mg/dL |
| Percent Change from Baseline at Week 24 (95% CI) |
-48
(-69 to -28) |
-41
(-59 to -24) |
-49
(-68 to -30) |
-49
(-65 to -33) |
| Abbreviations: HoFH=homozygous familial hypercholesterolemia, N=number of randomized patients, CI=confidence interval |