Cyclophosphamide and Fludarabine to Treat Lupus Nephritis

This study will test the safety and effectiveness of combination therapy with cyclophosphamide (Cytoxan) and fludarabine in treating lupus nephritis (kidney inflammation). This condition, common in patients with systemic lupus erythematosus, is caused by abnormal action of immune cells called lymphocytes against the kidneys. Left untreated, severe cases can result in loss of kidney function. The current treatment of choice-intermittent high doses (pulses) of cyclophosphamide-does not work in all patients and causes infertility in many women. The rate of infertility in men is not known. This study will examine whether fludarabine can safely be given with significantly lower doses of cyclophosphamide, and if this combination controls kidney inflammation. Patients 18 years of age and older with severe lupus nephritis (called proliferative lupus nephritis) may be eligible for this study. Candidates will have a history and physical examination; blood and urine tests; chest X-ray; electrocardiogram; cancer screening that may include a Pap smear, mammogram, rectal examination, PSA testing, and sigmoidoscopy. Participants will be divided into one of the following treatment groups: Group 1-Patients undergo three treatment cycles of cyclophosphamide, taken by mouth, and fludarabine, injected subcutaneously (under the skin). Patients receive both drugs on day 1 of the cycle, and fludarabine alone on days 2 and 3. This regimen is repeated once every 5 weeks for three cycles. Group 2-Same as for Group 1, except fludarabine injections are given intravenously (through a vein) for the second treatment cycle. Patients in this group have frequent blood sampling during the first and second treatment cycles to monitor blood levels of the drug. Samples are collected before the first injection is given and at 0.5, 1, 1.5, 2, 4, 8, 24 and 48 hours after the third injection. A total 12 tablespoons of blood is drawn over a 2-month period. All patients will have blood drawn once or twic