Treatment for lupus nephritis has changed dramatically in recent years. Only 10 years ago, rheumatologists and nephrologists, whether specializing in adult or pediatric medicine, treated lupus nephritis with a similar regimen of monthly intravenous cyclophosphamide (Cytoxan) and glucocorticoids. Although the regimen is effective, side effects such as infection, hair loss, and infertility were extremely common.
Effective but very toxic therapy is common in autoimmune diseases. In the last decade, clinical trials have shown that less toxic drugs are as effective for treating lupus nephritis. This article will review new developments in therapy for lupus nephritis, which can be viewed as a prototype for other fields of medicine.
DEMOGRAPHICS ARE IMPORTANT
Although numerous factors have prognostic value in lupus nephritis (eg, serum creatinine, proteinuria, renal biopsy findings), the most important to consider when designing and interpreting studies are race and socioeconomic variables.
A retrospective study in Miami, FL,1 evaluated 213 patients with lupus nephritis, of whom 47% were Hispanic, 44% African American, and 20% white. At baseline, African Americans had higher blood pressure, higher serum creatinine levels, and lower household income. After 6 years, African Americans fared the worst in terms of doubling of serum creatinine, developing end-stage renal disease, and death; whites had the best outcomes, and Hispanics were in between. Low income was found to be a significant risk factor, independent of racial background.
In a similar retrospective study in New York City in 128 patients (43% white, 40% Hispanic, and 17% African American) with proliferative lupus nephritis,2 disease was much more likely to progress to renal failure over 10 years in patients living in a poor neighborhood, even after adjustment for race.
We need to keep in mind that racial and socioeconomic factors correlate with disease severity when we design and interpret studies of lupus nephritis. Study groups must be carefully balanced with patients of similar racial and socioeconomic profiles. Study findings must be interpreted with caution; for example, whether results from a study from China are applicable to an African American with lupus nephritis in New York City is unclear.
OLDER STANDARD THERAPY: EFFECTIVE BUT TOXIC
The last large National Institutes of Health study that involved only cyclophosphamide and a glucocorticoid was published in 2001,3 with 21 patients receiving cyclophosphamide alone and 20 patients receiving cyclophosphamide plus methylprednisolone. Although lupus nephritis improved, serious side effects occurred in one-third to one-half of patients in each group and included hypertension, hyperlipidemia, valvular heart disease, avascular necrosis, premature menopause, and major infections, including herpes zoster.
Less cyclophosphamide works just as well
The multicenter, prospective Euro-Lupus Nephritis Trial4 randomized 90 patients with proliferative lupus nephritis to receive either standard high-dose intravenous (IV) cyclophosphamide therapy (six monthly pulses and two quarterly pulses, with doses increasing according to the white blood cell count) or low-dose IV cyclophosphamide therapy (six pulses every 2 weeks at a fixed dose of 500 mg). Both regimens were followed by azathioprine (Imuran).
At 4 years, the two treatment groups were not significantly different in terms of treatment failure, remission rates, serum creatinine levels, 24-hour proteinuria, and freedom from renal flares. However, the rates of side effects were significantly different, with more patients in the low-dosage group free of severe infection.
One problem with this study is whether it is applicable to an American lupus nephritis population, since 84% of the patients were white. Since this study, others indicate that this regimen is probably also safe and effective for different racial groups in the United States.
At 10-year follow-up,5 both treatment groups still had identical excellent rates of freedom from end-stage renal disease. Serum creatinine and 24-hour proteinuria were also at excellent levels and identical in both groups. Nearly three quarters of patients still needed glucocorticoid therapy and more than half still needed immunosuppressive therapy, but the rates were not statistically significantly different between the treatment groups.
The cumulative dose of cyclophosphamide was 9.5 g in the standard-treatment group and 5.5 g in the low-dose group. This difference in exposure could make a tremendous difference to patients, not only for immediate side effects such as early menopause and infections, but for the risk of cancer in later decades.
This study showed clearly that low-dose cyclophosphamide is an option for induction therapy. Drawbacks of the study were that the population was mostly white and that patients had only moderately severe disease.
Low-dose cyclophosphamide has largely replaced the older National Institutes of Health regimen, although during the last decade drug therapy has undergone more changes.
MYCOPHENOLATE AND AZATHIOPRINE: ALTERNATIVES TO CYCLOPHOSPHAMIDE
In a Chinese study, mycophenolate was better than cyclophosphamide for induction
In a study in Hong Kong, Chan et al6 randomized 42 patients with severe lupus nephritis to receive either mycophenolate mofetil (available in the United States as CellCept; 2 g/day for 6 months, then 1 g/day for 6 months) or oral cyclophosphamide (2.5 mg/kg per day for 6 months) followed by azathioprine (1.5–2.0 mg/kg per day) for 6 months. Both groups also received prednisolone during the year.
At the end of the first year, the two groups were not significantly different in their rates of complete remission, partial remission, and relapse. The rate of infection, although not significantly different, was higher in the cyclophosphamide group (33% vs 19%). Two patients (10%) died in the cyclophosphamide group, but the difference in mortality rates was not statistically significant.
Nearly 5 years later,7 rates of chronic renal failure and relapse were still statistically the same in the two groups. Infections were fewer in the mycophenolate group (13% vs 40%, P = .013). The rate of amenorrhea was 36% in the cyclophosphamide group and only 4% in the mycophenolate group (P = .004). Four patients in the cyclophosphamide group and none in the mycophenolate group reached the composite end point of end-stage renal failure or death (P = .062).
This study appeared to offer a new option with equal efficacy and fewer side effects than standard therapy. However, its applicability to non-Chinese populations remained to be shown.