A Phase III Multicenter Randomized Double-Blind Placebo-Controlled Study Evaluating the Efficacy and Safety of Lenalidomide in Patients With IgG4-Related Disease

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory disorder characterized by lymphoplasmacytic infiltration, IgG4-positive plasma cell accumulation, storiform fibrosis, and involvement of multiple organs. Although glucocorticoids remain the standard first-line therapy for induction of remission, a substantial proportion of patients experience disease relapse during glucocorticoid tapering or after treatment discontinuation. In addition, prolonged glucocorticoid exposure is associated with clinically significant adverse effects, including metabolic complications, osteoporosis, cardiovascular risks, and increased susceptibility to infection. Therefore, effective and well-tolerated maintenance therapies are urgently needed to sustain remission and reduce relapse risk in patients with IgG4-RD.

Accumulating evidence indicates that persistent immune dysregulation contributes to disease recurrence in IgG4-RD even after clinical remission has been achieved. Aberrant B-cell activation, expansion of plasmablasts and plasma cells, dysregulated T-cell responses, and remodeling of the immune microenvironment are considered key components underlying disease persistence and relapse. Therapeutic strategies targeting pathogenic immune pathways, particularly those involving B-cell and plasma cell responses, have shown potential clinical benefits, supporting the concept that immune modulation during the remission phase may prevent disease recurrence.

Lenalidomide is an immunomodulatory agent with established clinical activity in plasma cell disorders and emerging applications in immune-mediated diseases. Through binding to cereblon (CRBN), lenalidomide promotes the degradation of specific immune regulatory transcription factors, including IKZF1 and IKZF3, thereby modulating B-cell activation, plasma cell differentiation, inflammatory cytokine production, and T-cell function. Given the central role of B-cell/plasma cell dysregulation in IgG4-RD pathogenesis, these immunomodulatory properties provide a scientific rationale for evaluating lenalidomide as a maintenance therapy in patients with IgG4-RD who have achieved sustained clinical remission.

This is a phase III, multicenter, randomized, double-blind, placebo-controlled, parallel-group clinical trial designed to evaluate the efficacy and safety of lenalidomide as maintenance therapy for relapse prevention in patients with IgG4-RD in sustained clinical remission.

Approximately 146 participants will be enrolled. Eligible participants are adults with IgG4-RD who meet the 2019 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria and have achieved sustained disease control following glucocorticoid therapy. Participants must have no documented disease relapse within the preceding year, an IgG4-RD Responder Index (IgG4-RD RI) score of 0, and be receiving a stable low-dose glucocorticoid regimen before randomization.