IFN-α kinoid in systemic lupus erythematosus: results from a phase IIb, randomised, placebo-controlled study

Objective To evaluate the efficacy and safety of the immunotherapeutic vaccine interferon-α kinoid (IFN-K) in a 36-week (W) phase IIb, randomised, double-blind, placebo (PBO)-controlled trial in adults with active systemic lupus erythematosus (SLE) despite standard of care. Methods Patients with SLE (185) with moderate to severe disease activity and positive interferon (IFN) gene signature were randomised to receive IFN-K or PBO intramuscular injections (days 0, 7 and 28 and W12 and W24). Coprimary endpoints at W36 were neutralisation of IFN gene signature and the BILAG-Based Composite Lupus Assessment (BICLA) modified by mandatory corticosteroid (CS) tapering. Results IFN-K induced neutralising anti-IFN-α2b serum antibodies in 91% of treated patients and reduced the IFN gene signature (p<0.0001). Modified BICLA responses at W36 did not statistically differ between IFN-K (41%) and PBO (34%). Trends on Systemic Lupus Erythematosus Responder Index-4, including steroid tapering at W36, favoured the IFN-K and became significant (p<0.05) in analyses restricted to patients who developed neutralising anti-IFN-α2b antibodies. Attainment of lupus low disease activity state (LLDAS) at W36 discriminated the two groups in favour of IFN-K (53% vs 30%, p=0.0022). A significant CS sparing effect of IFN-K was observed from W28 onwards, with a 24% prednisone daily dose reduction at W36 in IFN-K compared with PBO (p=0.0097). The safety profile of IFN-K was acceptable. Conclusions IFN-K induced neutralising anti-IFN-α2b antibodies and significantly reduced the IFN gene signature with an acceptable safety profile. Although the clinical coprimary endpoint was not met, relevant secondary endpoints were achieved in the IFN-K group, including attainment of LLDAS and steroid tapering. Trial registration number NCT02665364 .