Clinical response to belimumab in academic clinical practices

Background

Belimumab is a human monoclonal antibody that inhibits soluble B-lymphocyte stimulator and improves systemic lupus erythematosus (SLE) disease activity. This study was initiated to evaluate the use and efficacy of belimumab in academic SLE clinical practices.

Methods

An invitation to participate was sent to 16 physicians experienced in SLE phase III clinical trials. All agreeing to participate completed a one-page questionnaire for each patient prescribed belimumab that includes demographic and SLE characteristics, and information about belimumab administration. The questionnaire completed every 3 months by the physicians also captured clinical responses and belimumab safety. Clinical response was defined as a ≥50% improvement in the initial clinical manifestation being treated without worsening in other organ systems.

Results

Of 16 invitations sent, nine investigators participated. Questionnaires on 150 patients treated with belimumab for at least 3 months were available for analysis. The mean age was 41.9 ± 12.6 years. 92.0% were female, 67.1% White, 24.7% Black, 5.7% Asian, and 5.3% Hispanic. The average SLE disease duration was 12.2 ± 8.2 years. Concomitant medications included: prednisone in 73.3% (mean dose of 12.2 ± 10.9, 41.7% on ≥10 mg), antimalarials in 71.7%, and immunosuppressants in 66.3% (mycophenolate mofetil 34.2%, azathioprine 20.3%, methotrexate 11.8%). Only 3.7% of patients were not on any background SLE medications, 8.0% were on antimalarials alone. The dominant clinical manifestations driving treatment were arthritis in 69.5%, rash in 44.4%, and inability to taper steroids in 27.3%. Other SLE manifestations were serositis 16.0%, hematological 13.9%, and renal 10.7%. A total 65.2% of patients had ≥2 active manifestations. Of the 150 patients on belimumab for at least 3 months, 69 (46.0%) clinically responded by 3 months with marked improvement in arthritis and/or rash. Similarly, of the 112 patients on belimumab for at least 6 months for whom follow-up data were available, 54 (48.2%) clinically responded with improvements in arthritis, rash and/or nephritis. While the numbers are limited, black patients showed improvement at 6 months, with 19/26 (73%) of patients responding, P = 0.05.

Conclusions

These observational data support the use of belimumab across all racial/ethnic groups and efficacy similar to that reported in the phase III trials. Relevant to physician and patient decision-making, improvement was seen as early as 3 months.