GSK announced results from the BLISS-SC Phase III pivotal study in patients with active, autoantibody-positive systemic lupus erythematosus (SLE). These results, which are being presented at the American College of Rheumatology/Association for Rheumatology Health Professionals Annual Meeting, showed that Benlysta® (belimumab) 200mg administered weekly via subcutaneous injection plus standard of care (SoC), showed significantly greater reductions in disease activity compared to placebo plus SoC.

For the primary efficacy endpoint (Systemic Lupus Erythematosus Responder Index (SRI) at Week 52), significantly more patients treated with belimumab administered subcutaneously plus SoC (60.8%) showed reduced disease activity compared to placebo plus SoC (48.47%, p=0.0011). SRI is a comprehensive composite endpoint measure, used in the pivotal Phase III BLISS clinical trial programme for belimumab administered intravenously. The SRI components measure reduction in disease activity defined as clinical improvement (SELENA-SLEDAI) with no significant worsening in any organ system (BILAG) and no worsening in overall patient condition (PGA).

For the two pre-specified secondary efficacy endpoints, the study showed that the time to severe flare was significantly delayed in patients receiving belimumab administered subcutaneously plus SoC (170 days, p=0.0003) compared to those on placebo plus SoC (116.5 days). In addition, in patients receiving more than 7.5mg/day of prednisone (n=503),18.2% of patients receiving belimumab administered subcutaneously plus SoC in the study were able to reduce their steroid dose by 25% or more to <7.5mg/day during Weeks 40-52, compared with 11.9% of those on placebo plus SoC, but this did not reach statistical significance (p=0.0732).

'Despite use of current standard of care, such as glucocorticosteroids and immunosuppressants, about 60% of lupus patients continue to experience persistent symptoms and severe disease flares,' said Paul-Peter Tak, Senior Vice-President and Head of the Immuno-Inflammation Therapy Area Unit at GSK. 'This is GSK's third successful Phase III study of belimumab in patients with lupus, the results of which reinforce our belief in the BLyS pathway as a means of reducing underlying disease activity. On the basis of these data, we expect to progress towards global regulatory filings for a belimumabsubcutaneous formulation, which if approved, will provide appropriate patients with a new approach to treatment administration.'

The overall safety profile of belimumab in BLISS-SC was consistent with that observed in the two previous BLISS studies (BLISS-52 and BLISS-76). The overall incidence of treatment-related adverse events (AEs) was 31.3% with belimumab administered subcutaneously plus SoC vs 26.1% with placebo plus SoC [the most common of which were infections/infestations (belimumab administered subcutaneously plus SoC 18.7% vs placebo plus SoC 18.9%) and general disorders and administration site conditions, primarily injection site-related events (belimumab administered subcutaneously plus SoC 6.3% vs placebo plus SoC 3.6%)]. Incidence of AEs leading to discontinuation in the belimumabadministered subcutaneously plus SoC group was 7.2% compared to 8.9% with placebo plus SoC. The percentage of patients experiencing a serious AE was 10.8% with belimumab administered subcutaneously plus SoC compared with 15.7% with placebo plus SoC. A total of 5 deaths were reported; 3 (0.5%) with belimumab administered subcutaneously plus SoC, and 2 (0.7%) with placebo plus SoC. The overall incidence of death in all the randomised controlled studies of belimumab in lupus was 0.7% for the belimumab group, which is similar to that in the placebo group (0.5%).

Belimumab subcutaneous formulation is currently not approved for use anywhere in the world.