Background/Purpose: Belimumab is an anti-BAFF monoclonal antibody approved for the treatment of auto-antibody positive patients with SLE. In two large phase 3 clinical trials, belimumab plus standard of care reduced SLE disease activity compared with standard of care alone. However, African-American SLE patients in these studies had no such improvements resulting in clinicians unsure of the efficacy of belimumab in this group. This study examines the effect of belimumab on clinical outcomes and disease activity in a cohort of African- American patients with SLE being treated at an academic medical center.

Methods: All SLE patients who were African-American and who had been prescribed belimumab as part of their medical care at our center were identified in a retrospective chart review. Data was analyzed for up to 24 months of therapy. Patient demographics, disease manifestations, medication usage, and labs were recorded for visits at Day 0 (day of initial belimumab infusion), and at months 3, 6, 12, 18, and 24. Whenever all appropriate labs, clinical exam and history were available, a SLEDAI was calculated. For any patient who discontinued belimumab therapy at any time point prior to 24 months, additional information as to reason was recorded.

Results:  23 African-American SLE patients were identified; mean age 38.9 years (22-58), 87% female, with a mean duration of disease of 12.7 years (4-31). At the time of their initial belimumab infusion, 91.3% of the patients were on prednisone at an average dose of 20 mg /day (5-60), 78.3% of patients were taking lupus DMARDs, and 91.3% were on HCQ. The mean SLEDAI score was 8.5 (2-20) with 39% of patients having a score ≥10. 65% of patients were hypocomplementemic (low C3/C4) at baseline, 60% had elevated anti-dsDNA titers, and 47% had both. The most common clinical disease manifestation at belimumab initiation was arthritis (56.5%) followed by cutaneous (47.8%). Over the subsequent observation period, 5 patients (22%) discontinued belimumab therapy at a mean duration of 8.4 months, 2 due to inefficacy, 1 secondary to abnormal LFTs, one patient moved away, and 1 patient self-discontinued secondary to feeling well. For the remainder of the patients, by month 3 the mean SLEDAI had decreased 3.6 points (8.5 to 4.9) and by month 24 the mean SLEDAI was 3.5 (p < 0.001). Prednisone dose among those still taking the medication also decreased, going from a mean of 20 mg/day to 8.06 mg/day by month 24 (p < 0.001). Four patients came off of prednisone completely. 53.8% of those patients with low C3/C4 normalized their levels and 25% of those with elevated anti-dsDNA titers became undetectable. One patient was hospitalized for community acquired pneumonia during the observation period but no other major infections were noted.

Conclusion:  Belimumab is well tolerated and may be effective in African-American patients with SLE. Prednisone doses as well as SLEDAI scores decreased significantly and were maintained through 2 years of treatment in most patients. Ongoing prospective placebo controlled studies with belimumab in African-American SLE patients will hopefully provide more definitive answers.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/belimumab-use-in-african-american-patients-in-an-u-s-academic-medical-center/