Dataset Information

Pharmacokinetics and Exposure-Response Relationship of Teprotumumab, an Insulin-Like Growth Factor-1 Receptor-Blocking Antibody, in Thyroid Eye Disease.

ABSTRACT:

Background and objective

Thyroid eye disease (TED) is characterized by inflammation/expansion of orbital tissues, proptosis, and diplopia. Teprotumumab is the first US Food and Drug Administration-approved therapy for TED, administered as an initial intravenous infusion of 10 mg/kg followed by 20 mg/kg every 3 weeks for an additional seven infusions. The objective of this article is to discuss the pharmacokinetics and exposure-response profile for teprotumumab in patients with TED.

Methods

A population pharmacokinetic analysis was performed to characterize pharmacokinetics and select dosing in patients with TED. Exposure-response was evaluated for efficacy (proptosis response, clinical activity score categorical response, and diplopia response) and safety (hyperglycemia, muscle spasms, and hearing impairment) parameters.

Results

Teprotumumab pharmacokinetics was linear in patients with TED, with low systemic clearance (0.334 L/day), low volume of distribution (3.9 and 4.2 L for the central and peripheral compartment, respectively), and a long elimination half-life (19.9 days). The approved dosing regimen provided > 20 µg/mL for > 90% insulin-like growth factor 1 receptor saturation throughout the dosing interval. Model-predicted mean (± standard deviation) steady-state area under the concentration-time curve, peak, and trough concentrations in patients with TED were 131 (± 30.9) mg∙h/mL, 643 (± 130) µg/mL, and 157 (± 50.6) µg/mL, respectively. Female patients had a 15% higher steady-state peak concentration but a similar steady-state area under the concentration-time curve vs male patients. No other covariates affected teprotumumab pharmacokinetics. No meaningful correlations between teprotumumab exposures and efficacy or safety parameters were observed.

Conclusions

Teprotumumab pharmacokinetics was well characterized in patients with TED, and generally consistent with other IgG1 antibodies. Efficacy was consistent across the exposure range with a well-tolerated safety profile supporting the current dose regimen for patients with TED.

SUBMITTER: Xin Y

PROVIDER: S-EPMC8332554 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Abstract Introduction: Teprotumumab treatment resulted in statistically and clinically meaningful improvements across multiple facets of active TED and was generally well-tolerated in Phase 2 and 3 trials.1,2 An initial intravenous infusion of 10 mg/kg followed by 20 mg/kg every 3 weeks was selected based on in vitro activity and clinical PK profile, to maintain pharmacologically active exposures and >90% saturation of IGF-1R over dosing intervals and to achieve efficacy at a well-tolerated dose for this vision-threatening disease. Methods: Population PK analysis were performed on data from a Phase 1 oncology study (n=60)3 and Phase 2 and 3 trials in active TED (N=83)2,3 and covariate effect on PK was assessed. Exposure-response relationship was evaluated in TED studies for key efficacy endpoints (proptosis response rate, % patients with a clinical activity score value of 0 or 1, and diplopia responder rate) and selected safety variables (hyperglycemia and muscle spasms). Results: Teprotumumab PK was linear in TED patients and consistent with other immunoglobulin G1 monoclonal antibodies (IgG1 mAbs), with low systemic clearance (0.334 L/day), low volume of distribution (3.9 L for central compartment and 4.2 L for peripheral compartment), and long elimination half-life (19.9 days). 4,5 Model-predicted mean (± standard deviation) steady-state area under the concentration curve (AUCss), peak (Cmax,ss), and trough (Cmin,ss) concentrations in TED patients were 131 (± 30.9) mg∙hr/mL, 643 (± 130) µg/mL and 157 (± 50.6) µg/mL, respectively, suggesting low inter-subject variability. Population PK analysis indicated no significant impact of baseline age, gender, race, weight, smoking status, renal impairment (mild/moderate), and hepatic function (total bilirubin, aspartate and alanine aminotransferases) on teprotumumab PK. Female patients had 15% higher Cmax,ss but similar AUC compared to male patients, which is not considered clinically relevant. Exposure-response analysis from the TED dose regimen indicated no meaningful correlations between exposures (AUCss, Cmax,ss and Cmin,ss) and key efficacy endpoints or selected safety variables, supporting the demonstrated, favorable benefit-risk profile of the TED dose regimen.2 Conclusion: Teprotumumab PK was characterized in TED patients by long elimination half-life, low systemic clearance and low volume of distribution, consistent with other IgG1 mAbs. There was no meaningful exposure-response relationship at the selected TED dose regimen for both efficacy and safety endpoints, supporting the teprotumumab dose regimen used in TED patients. Reference: (1) Smith TJ, et al. N Engl J Med 2017;376:1748-1761. (2) Douglas RS, et al. AACE 2019 late-breaking abstract. (3) ClinicalTrials.gov: NCT00400361. (4) Dirks NL et al. Clin Pharmacokinet. 2010;49(10):633-59. (5) Ryman JT et al. CPT Pharmacometrics Syst Pharmacol. 2017;6(9):576-88.

Project description:PurposeIn recent trials, 50% of patients treated with teprotumumab for thyroid eye disease had significant improvements in proptosis at 6 weeks. However, a small subgroup of patients did not have a significant response by week 12. We examine the outcomes at week 24 in patients from both trials who had little or no proptosis response at week 12.DesignIn this post hoc analysis, data from teprotumumab-treated patients in the placebo-controlled randomized phases 2 and 3 trials were reviewed.MethodsPatients treated with teprotumumab or placebo with a ≤2 mm reduction from baseline in proptosis at week 12 and completed assessments at both the weeks 12 and 24 visits were included. The main outcome measures were a change in proptosis, clinical activity score (CAS) and diplopia in response to teprotumumab therapy at baseline and weeks 6, 12, 18, and 24.ResultsFrom the phases 2 and 3 studies, 24 patients from the treated and placebo groups were included for analysis (48 total). In the teprotumumab group, of the 24 who had no improvement in proptosis (≥2 mm from baseline) at 12 weeks, 15 (63%) demonstrated a clinically significant improvement at week 24. No patients from the 24 placebo patients had a clinically significant improvement in proptosis at 12 weeks, and 24 weeks. At week 12, 22 patients (92%) in the teprotumumab group had a significant reduction in the CAS (≥2 points) and at 24 weeks all patients achieved this reduction. At week 12, 11 (46%) patients from the placebo group had a significant improvement, while 10 (42%) had a significant improvement at 24 weeks. 22 of the 24 patients (92%) in the teprotumumab group had a diplopia grade > 0 at baseline. At week 12, 12 of the 22 (55%) had improvement in diplopia ≥ 1 grade. By week 24, 16 patients (73%) had an improvement in diplopia ≥ 1 grade. In the placebo group, 15 (63%) had significant diplopia. At week 12, 3 (20%) from this group had improvement in diplopia ≥ 1 grade, while at 24 weeks this number rose to 4 (27%).ConclusionsThere is variability in the time taken to manifest a clinically significant response to teprotumumab, some patients my need a longer time to respond.