A multipart phase 1 study of the safety, pharmacodynamics and pharmacokinetics of ALG-055009, a novel thyroid hormone receptor beta (THR-β) agonist for metabolic dysfunction-associated steatohepatitis (MASH), in healthy participants.

ALG-055009 is an oral thyroid hormone receptor beta (THR-β) agonist being evaluated for treating metabolic dysfunction-associated steatohepatitis (MASH). This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of ALG-055009 and bioavailability/food effect. Part 1 was a single-ascending dose study in healthy participants randomized to ALG-055009 (0.1 to 4.0 mg) or placebo. Part 2 was a multiple-ascending dose study in participants with mild hyperlipidemia randomized to ALG-055009 (0.3 to 1.0 mg) or placebo once daily for 14 days. Part 3 was an open-label study to determine relative bioavailability and food effect of 0.6 mg ALG-055009 solution versus soft gelatin (softgel) capsule formulation. Among 78 participants, ALG-055009 was well tolerated, and most adverse events were mild or moderate with no clinically meaningful safety issues. Transient reductions in thyroid hormone levels were observed with no clinical manifestation of hypo/hyperthyroidism. Plasma ALG-055009 exposure increased in a dose-proportional manner with rapid absorption, low variability, accumulation ranging from 1.6-2.6-fold, and t_1/2 of 20 h. Relative bioavailability of the softgel capsule was 86% versus solution, with no food effect. Dose-dependent decreases in atherogenic lipids and increases in sex hormone binding globulin were observed. These results support further development of ALG-055009 for patients with MASH.