FRI057 Drug Concentrations And Dosing Considerations For Mibavademab, A Novel Leptin Receptor Agonist, In Individuals With Generalized Lipodystrophy

Abstract Disclosure: J. Mendell: Employee; Self; Regeneron Pharmaceuticals. Stock Owner; Self; Regeneron Pharmaceuticals. Y. Wang: Employee; Self; Regeneron Pharmaceuticals. Stock Owner; Self; Regeneron Pharmaceuticals. B.A. Olenchock: Employee; Self; Regeneron Pharmaceuticals. Stock Owner; Self; Regeneron Pharmaceuticals. S. Podgrabinska: Employee; Self; Regeneron Pharmaceuticals. Stock Owner; Self; Regeneron Pharmaceuticals. O.E. Pagovich: Employee; Self; Regeneron Pharmaceuticals. Stock Owner; Self; Regeneron Pharmaceuticals. E.A. Oral: Advisory Board Member; Self; Regeneron Pharmaceuticals. Consulting Fee; Self; Third Rock Ventures, Rejuvenate Inc. Grant Recipient; Self; Amryt Pharamceuticals, Ionis Pharmaceuticals Inc., Gemphire Theraputics. Research Investigator; Self; Regeneron Pharmaceuticals, Novo Nordisk, Rhythm pharmaceuticals, Fractyl Laboratories, GI Dynamics. Other; Self; Has IP rights to Metreleptin manufactured by Amryt Pharmaceuticals and receives royalty payments. R.J. Brown: Research Investigator; Self; Regeneron Pharmaceuticals. J. Davis: Employee; Self; Regeneron Pharmaceuticals. Stock Owner; Self; Regeneron Pharmaceuticals. Background: Generalized lipodystrophy (GLD) is characterized by deficiency of adipose tissue and, consequently, low levels of the adipose-derived hormone leptin. Leptin deficiency in GLD causes metabolic abnormalities and complications that are often refractory to treatment with usual glucose/lipid-lowering agents. Mibavademab is a first-in-class human leptin receptor (LEPR) agonist monoclonal antibody that activates LEPR. We investigated baseline serum leptin in patients with GLD, pharmacokinetics (PK) of mibavademab, and soluble LEPR (sLEPR) levels from a phase 2 study. Methods: In this phase 2 trial (NCT04159415), patients with GLD (≥12 yrs old) underwent a single-blind placebo run-in, followed by 1:1 randomization to one of two fixed sequence arms: Treatment A (placebo for 8 weeks, then mibavademab low dose for 8 weeks, then mibavademab high dose for 20 weeks) or Treatment B (mibavademab low dose for 8 weeks, then mibavademab high dose for 28 weeks). A loading dose of intravenous mibavademab was administered before low-dose treatment. Mibavademab and sLEPR concentrations in serum were serially measured during mibavademab treatment using validated bioanalytical methods. Results: Sixteen patients were enrolled with median body weight (BW) of 51 kg, corresponding to the approximate BW cut point for mibavademab. Baseline serum leptin was below the lower limit of quantitation (0.078 mg/L) in 5 patients with a median concentration of 0.345 mg/L (n=15). Baseline sLEPR concentrations with Treatments A and B were 30.6 and 33.9 μg/L, respectively. At Week 8, mean (SD) mibavademab trough concentrations (Ctrough) with Treatments A and B were 0 (0) and 1.61 (1.71) mg/L, respectively. Low-dose PK were less than predicted from a first in human study in healthy volunteers with higher leptin levels, reflecting higher target mediated clearance in patients with GLD. At Week 16, Ctrough for Treatments A and B increased to 2.31 and 43.0 mg/L, respectively, but were still below predicted. At Week 36, Ctrough for Treatments A and B were 60 (35.3) and 67.7 (44.2) mg/L, respectively. Clinically meaningful metabolic benefit (i.e reflected by reductions in fasting triglycerides and glycated hemoglobin) was observed at Week 36 with both Treatments A and B. Conclusions: Mibavademab concentrations by Week 36 were associated with clinically meaningful improvement in metabolic parameters. Presentation: Friday, June 16, 2023