Pharmacodynamic effects and exploratory efficacy of afimetoran, a TLR7/8 inhibitor, in patients with cutaneous lupus erythematosus
Authors: Saini Jasmine , Ignatenko Stanislav , Chadwick Kristina , Zhu Lin , Bach Huynh Yen Thanh , Karabeber Hazem , Dawes Michelle , Harrison Melanie , Carayannopoulos Leon , Krishna Gopal , Hosein Fareeda , Baribaud Frédéric 
Published: November 2024

Background: Cutaneous lupus erythematosus (CLE) is a chronic inflammatory skin condition occurring alone or as a manifestation of systemic lupus erythematosus (SLE). There is an unmet need for safe and effective CLE-focused treatments. Afimetoran is an investigational, first-in-class, potent oral inhibitor of toll-like receptors (TLRs) 7/8. Given the involvement of TLRs 7/8 in SLE, afimetoran may have therapeutic potential for CLE. A phase 1b randomized, double-blind, placebo-controlled study (NCT04493541) demonstrated preliminary safety and efficacy of afimetoran in patients with active CLE. We assessed the pharmacodynamics, safety, and efficacy of afimetoran and its impact on CLE pathobiology. 
Methods: Patients aged 18–65 years with SLE and cutaneous manifestations by EULAR/ACR 2019 classification criteria or biopsy-proven CLE, and modified CLE Disease Area and Severity Index-Activity (CLASI-A) score ≥6, were randomized 2:1 to once-daily afimetoran (30 mg) or placebo for 16 weeks with a 4-week post-treatment follow-up period. The primary endpoints were safety and tolerability; efficacy was exploratory. Transcriptomics and cytokine analyses were performed using peripheral whole blood and serum, respectively, at baseline (pre-dose) and each study visit (weeks 1, 2, 4, 8, 12, 16, and 20 [post-dose]). Statistical analyses compared data from the 13 randomized patients with thirteen age-, ethnicity-, and gender-matched healthy volunteers. Treatment responses were evaluated longitudinally in each treatment arm. The dataset was analyzed using a linear regression model. Gene set variation analysis (GSVA) was performed for pathway enrichment.
Results: 13 patients with CLE were randomized (afimetoran, n=8; placebo, n=5); 12 patients completed 16 weeks of treatment and 1 discontinued after 6 weeks due to COVID-19. Compared with placebo, afimetoran demonstrated a favorable safety profile with no serious adverse events, and showed a greater reduction in CLASI-A scores as early as week 4, which persisted to week 20. Improvement in the molecular disease profile was rapid (week 1), sustained through the 16-week treatment period, and the 4-week post-treatment follow-up period. Expression of interferon (IFN) pathway genes was significantly reduced with afimetoran compared with baseline (ΔGSVA enrichment score [ES]=1.57, P<0.0001) and placebo (ΔGSVA ES=0.56, P<0.01); this effect was maintained through week 16 and ≥4 weeks post-treatment. Expression of TLR7 and TLR8 pathway genes and key cytokines (interleukin [IL]-6, tumor necrosis factor α, IL-18, IFNγ, macrophage inflammatory protein-1 alpha [CCL3/MiP1α] or beta [CCL4/MiP1β]) were greatly reduced with afimetoran treatment. GSVA demonstrated robust pharmacodynamic activity on immune cell populations, including immature and activated dendritic cells, macrophages, and inflammatory pathway signatures.
 Conclusion: In patients with CLE, afimetoran was safe, well tolerated, and demonstrated durable efficacy beyond the treatment period. Afimetoran’s clinical effects and potent pharmacodynamic impact on the molecular disease profile suggest a substantial therapeutic benefit for patients with CLE.