Background/Purpose: Randomized clinical trials have reported that 56-68% of patients with lupus nephritis treated with mycophenolate mofetil (MMF) respond to therapy, and a randomized clinical trial has suggested that African-American patients respond better to MMF than Caucasians. However, data on rates and the role of ethnicity on MMF response in routine clinical practice are limited. As part of initial efforts to improve prediction models and personalized medicine in patients with systemic lupus erythematosus (SLE), we calculated the response rate and defined the role of ethnicity on response to MMF in patients with lupus nephritis at a tertiary center.

Methods: This is a retrospective study using a de-identified version of patients’ electronic health records (EHR) at a University-based Medical Center. We completed EHR review and identified a cohort of patients who met the following inclusion criteria: (1) diagnosed with lupus nephritis; (2) received treatment with MMF for lupus nephritis; (3) were new users of MMF; and (4) had laboratory data available at baseline. All patients had confirmed diagnoses of SLE by clinical record review; they also presented with proteinuria (urine protein-to-creatinine ratio or 24-hour proteinuria >0.5 g/g or g/d, respectively) or a renal biopsy indicating lupus nephritis. Response was defined as: (1) a decrease in urine protein/creatinine ratio (uPCR) to < 3.0 g/g in patients with baseline nephrotic range uPCR (≥3.0 g/g), or by ≥50% in patients with sub-nephrotic baseline uPCR (< 3.0 g/g); and (2) stabilization (±25%) or improvement in serum creatinine at six month. For patients who were lost to follow up prior to six months, we used the last observation carried forward as a method of imputing missing data. Univariate analysis was calculated using Fisher’s exact text. To adjust for multiple potential confounders, we used propensity scores including age, baseline creatinine, calendar year, baseline proteinuria, use of hydroxychloroquine, use of methylprednisolone, use of prednisone, and history of prior immunosuppressant use.

Results: 93 patients met inclusion criteria; 31 (33%) were African-American, and 62 (67%) reported a different race or did not report race. Patient characteristics are presented in Table 1. A total of 32 (34.4%) patients were classified as MMF responders and 61(65.6%) as non-responders. Among African-American patients, the response rate was 25.8%; among other patients, it was 38.7% (p=0.25). After adjusting for the propensity score and sex, African-American patients had lower odds of responding to MMF than patients from other races [OR: 0.34, 95% CI (0.11 – 0.99) p=0.049].

Conclusion: A total of 34% patients with lupus nephritis responded to MMF at six months of treatment in routine clinical practice at a tertiary center. Our results suggest that—in contrast to what has been reported in a previous randomized control clinical trial—African-American patients with lupus nephritis had lower odds of responding to MMF than patients who reported other races.

MMF-LN-Table1

MMF-LN-Table 2

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/therapy-of-lupus-nephritis-with-mycophenolate-mofetil-in-routine-clinical-practice-response-rates-and-role-of-ethnicity/