Oral orismilast: Efficacy and safety in moderate-to-severe psoriasis and development of modified release tablets

Background: Orismilast is a high-potency phosphodiesterase 4 (PDE4) inhibitor with enhanced selectivity for the PDE4B and PDE4D subtypes.

Objectives: The objective of this phase 2a trial was to examine the efficacy and safety of orismilast for psoriasis using a first-generation immediate-release (IR) formulation. The objective of the subsequent phase 1 trial was to test new formulations designed to minimize the gastrointestinal (GI)-related adverse events (AEs) observed with the first-generation IR formulation. We examined the following: (1) pharmacokinetic (PK) properties of orismilast modified release (MR) and IR, (2) food effects on PK properties of orismilast MR or IR, (3) safety of orismilast MR compared to placebo.

Methods: In a phase 2a prospective, randomized, double-blind, placebo-controlled trial, patients with moderate-to-severe psoriasis were randomized to receive 30 mg oral orismilast IR or placebo over 16 weeks. The single-site phase 1 trial consisted of three parts: (1) participants received a single 30 mg dose of orismilast MR and IR (open-label), (2) participants received 30 mg orismilast MR or IR under either fasting condition, following a high-fat meal or low-fat meal (open-label) and (3) participants received up to 60 mg orismilast MR twice-daily or a placebo for 17 days (double-blind).

Results: In the phase 2a trial, treatment with orismilast IR significantly improved the mean Psoriasis Area Severity Index score at week 16 compared to placebo. The phase 1 trial revealed comparable PK properties of the orismilast MR and IR formulations, with participants in the orismilast MR group experiencing fewer GI-related AEs than those receiving orismilast IR (16.7% vs. 33.3%).

Conclusion: Orismilast IR displayed higher efficacy compared to placebo in patients with moderate-to-severe psoriasis at week 16. Orismilast MR had similar PK properties and fewer GI disorders compared to the IR formulation in healthy participants. Future development of orismilast will be based on the MR formulation.