DARMSTADT, Germany, November 14, 2016 /PRNewswire/ -- Merck KGaA, Darmstadt, Germany, a leading science and technology company, today announced the results of the ADDRESS II Phase IIb, multicenter study on atacicept in patients with systemic lupus erythematosus (SLE). Patients on standard-of-care therapy (n=306) were randomized to weekly subcutaneous injections of atacicept (75 or 150 mg) or placebo for 24 weeks. The primary endpoint was the proportion of patients achieving a clinical response as defined by a composite SLE Responder Index (SRI)-4 at week 24. Secondary endpoints included SRI-6 response rate and time to severe flare, assessed by SLEDAI flare index (SFI) or BILAG. Although the primary endpoint was not met in the overall study population, there was a trend favoring atacicept with statistical significance achieved in a pre-specified sensitivity analysis of the primary endpoint using treatment Day 1 as baseline (rather than screening visit); atacicept 75 mg (55.9%, adjusted odds ratio/OR 1.88, p=0.029) and 150 mg (55.8%, adjusted OR 1.96, p=0.020) compared with placebo (41.0%). BILAG A flare was significantly reduced compared to placebo with atacicept 75 mg (p=0.019), and severe SFI flare reduced with 150 mg (p=0.002). Additionally, analyses of a predefined subpopulation of patients with high disease activity (HDA; SLEDAI-2K=10, n=158) demonstrated statistically significant treatment effects of atacicept when compared to placebo. SRI-6 response at week 24 was significantly greater with atacicept 150 mg (54.9%, adjusted OR 3.30, p=0.005) compared with placebo (28.8%). Both atacicept doses led to significant reductions in the incidence of severe flare versus placebo, BILAG A flare (150 mg, hazard ratio/HR 0.32, p=0.038; 75 mg, HR 0.08, p=0.002) and SFI flare (150 mg, HR 0.19, p=0.004; 75 mg, HR 0.33, p=0.029). "This is an impressive result, and particularly remarkable for having been achieved in a small study and in 24 weeks," said Dr. Joan Merrill, Coordinating Investigator for the ADDRESS II study. "If confirmed in future studies, this could hold exciting possibilities for our patients." Luciano Rossetti, Head of Global Research & Development for the biopharma business of Merck KGaA, Darmstadt, Germany added, "Building on the results of the APRIL SLE study, the results of ADDRESS II show that atacicept has the potential to become an important option for patients with lupus. We are particularly encouraged by the results in patients with high disease activity — which was approximately 50% of the patients in the ADDRESS II study. We are looking forward to discussions with the regulatory authorities." Atacicept was also associated with increased serum complement C3 and C4, and decreased IgG, IgM, IgA, and anti-dsDNA antibodies over time. Treatment-emergent adverse event incidence was slightly higher with atacicept (150 mg, 80.8%; 75 mg, 81.4%) than placebo (71.0%), however, the risks of serious adverse events or serious/severe infections were not increased with atacicept versus placebo, and there were no deaths. The safety findings were comparable for the high disease activity subpopulation, in that the risks of serious adverse events or serious/severe infections were not increased with atacicept versus placebo.