Iberdomide in patients with systemic lupus erythematosus: a randomised, double-blind, placebo-controlled, ascending-dose, phase 2a study.

Objective: To evaluate safety, pharmacokinetics, pharmacodynamics and efficacy of iberdomide in patients with SLE. Iberdomide is a high-affinity cereblon ligand that targets the hematopoietic transcription factors Ikaros and Aiolos for proteasomal degradation.

Methods: A 12-week, multicentre, double-blind, placebo-controlled, dose-escalation study in active SLE was followed by a 2-year, open-label active treatment extension phase (ATEP) (NCT02185040). In the dose-escalation phase, adults with active SLE were randomised to oral placebo or iberdomide (0.3 mg every other day, 0.3 mg once daily, 0.6 mg and 0.3 mg alternating once daily, or 0.6 mg once daily). Primary endpoints were safety and tolerability.

Results: The dose-escalation phase enrolled 42 patients, with 33 completing this phase and 17 patients enrolling into the ATEP. In the dose-escalation phase, the most common treatment-emergent adverse events (TEAEs; iberdomide/placebo groups) were nausea (20.6%/12.5%), diarrhoea (17.6%/12.5%) and upper respiratory tract infection (11.8%/12.5%). Most TEAEs were mild or moderate in severity and more common in the highest dose groups in both study phases. In the dose-escalation phase, Physician's Global Assessment and Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) activity scores improved relative to baseline and placebo in all iberdomide groups, with a trend toward continued score improvements in the ATEP. In the dose-escalation phase, iberdomide treatment resulted in dose-dependent reductions in total B cells and plasmacytoid dendritic cells in blood. Improvements in CLASI activity scores correlated with plasmacytoid dendritic cell depletion.

Conclusions: These proof-of-concept findings suggest a favourable benefit/risk ratio in SLE for iberdomide, a drug with a novel immunomodulatory mechanism of action, supporting further clinical investigation.