Although interest in the use of high-dose cytotoxic therapy followed by autologous stem-cell transplantation to treat autoimmune disease is increasing, disease progresses or relapses early in many patients [7, 8]. It is unclear whether reappearance of the disease after autologous transplantation results from failure of high-dose therapy to eradicate autoaggressive lymphocytes, reinfusion of autoaggressive lymphocytes with the autograft, or renewed challenge from the autoantigen [7, 8]. However, the success of syngeneic transplantation in animal models and allogeneic transplantation in patients with autoimmune diseases suggests that high-dose cytotoxic therapy may be sufficient to eradicate autoaggressive lymphocytes [8].

We previously found that the immunoablative doses of cyclophosphamide used for transplantation can induce durable, complete remission (median follow-up > 10 years) without stem-cell rescue in most patients with severe aplastic anemia [9]. Because most cases of aplastic anemia result from immune suppression of hematopoiesis [10], high-dose cyclophosphamide without the addition of other cytotoxic immunosuppressive agents seems to ablate the autoaggressive lymphocytes. We also reported that high-dose cyclophosphamide spared hematopoietic stem cells because full hematopoietic recovery occurred [9]. Hematopoietic stem cells express high levels of aldehyde dehydrogenase, an enzyme responsible for cellular resistance to cyclophosphamide, and are therefore resistant to the cytotoxic effects of cyclophosphamide [11, 12]. We investigated the efficacy of high-dose cyclophosphamide without stem-cell rescue in patients with various severe autoimmune diseases.

Methods

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Treatment Schedule

Our study was approved by the institutional review boards of Johns Hopkins University and Hahnemann University. After giving informed consent, eight patients (Table 1 and Table 3) with refractory autoimmune disorders received cyclophosphamide (50 mg/kg of body weight per day) intravenously for 4 consecutive days. Granulocyte colony-stimulating factor therapy (5 µg/kg per day) was started 6 days after the last dose of cyclophosphamide and was continued until the absolute neutrophil count reached 10⁹ cells/L. Inclusion in the study required failure of two previous therapies. Patients were excluded if their cardiac ejection fraction was less than 0.45, their serum creatinine level was greater than 176.8 µmol/L, or they were older than 70 years of age. Red blood cell transfusions were administered to patients with a hematocrit less than 0.25, and platelet transfusions were given to patients with platelet counts less than 20 x 10⁹ cells/L or clinically significant bleeding. Complete remission required the absence of any clinical or serologic evidence of disease. Complete remission from lupus nephritis was defined as fewer than 10 dysmorphic erythrocytes per high-powered field, absence of cellular casts, and excretion of less than 1 g of protein per day without doubling of the serum creatinine level [13]. For patients with systemic lupus erythematosus, daily activity indices [14] were measured at 3-month intervals.

Selected Case Reports

Patient 1 was a 64-year-old man with a 35-year history of rheumatoid arthritis treated with prednisone and gold. The Felty syndrome had been diagnosed 3 years earlier when the patient developed a perirectal abscess and profound neutropenia (neutrophil count < 0.2 x 10⁹ cells/L). Examination of bone marrow showed hypercellularity with myeloid maturation arrest. The patient was treated with myeloid growth factors and steroids but showed no response. He required frequent hospitalizations for recurrent infections. Before the patient received high-dose cyclophosphamide, he was positive for antineutrophil antibodies, the neutrophil count was 0.1 x 10⁹ cells/L, the rheumatoid factor level was elevated, complement levels were depressed, and the Karnofsky score [15] was 40%. The patient tolerated high-dose cyclophosphamide well and had few side effects other than alopecia; he achieved a neutrophil count greater than 0.5 x 10⁹ cells/L by day 15, and infections (perirectal abscess, pneumonia, and sinusitis) that were present at the time of treatment resolved. Two units of red blood cells and five platelet transfusions were required. The patient is in complete remission 21 months after treatment and has normal peripheral blood counts, has normal complement levels, and is negative for antineutrophil antibodies. He has not been receiving any immunosuppressive agents for more than 15 months.

Patient 6 was a 23-year-old woman in whom lupus was diagnosed at 12 years of age after she presented with the Raynaud phenomenon and stomatitis. She later developed severe proteinuria, hyperlipidemia, polyarthralgia, and an extensive skin rash. Renal biopsy performed 4 years before initiation of high-dose cyclophosphamide therapy showed membranous nephropathy. The patient required hospitalization for lupus flares three to four times per year despite treatment with methylprednisolone (4 mg/d), hydroxychloroquine (400 mg/d), azathioprine (150 mg/d), and pulse-dose cyclophosphamide. Before high-dose cyclophosphamide therapy began, the hematocrit was 0.27, the leukocyte count was 2.8 x 10⁹ cells/L, the platelet count was 278 x 10⁹ cells/L, and the erythrocyte sedimentation rate was 104 mm/h. Anti-DNA antibodies were present at a titer of 1:320, the C3 level was 0.41 g/L, and the 24-hour urine protein level was 2 g. The patient tolerated high-dose cyclophosphamide well; side effects were alopecia and febrile neutropenia. A neutrophil count greater than 0.5 x 10⁹ cells/L was reached on day 18, and only six units of red blood cells and three platelet transfusions were needed. The patient is in continuous complete remission 12 months after treatment; the erythrocyte sedimentation rate is 20 mm/h, no anti-DNA antibodies are present, the C3 level is 1.49 g/L, and the 24-hour urine protein level is 86 mg. Immunosuppressive therapy has been tapered to 1 mg of prednisone daily.

Results

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High-dose cyclophosphamide was well tolerated and was associated with rapid hematologic recovery in all eight patients despite their poor medical condition at time of treatment. Four patients were hospitalized for complications of their autoimmune disease, and four patients were being treated for active infections at the time of cyclophosphamide therapy; the median Karnofsky score was 40% (range, 20% to 70%). The median time to achievement of a neutrophil count greater than 0.5 x 10⁹ cells/L was 17 days (range, 11 to 22 days), and the median time to the last platelet transfusion was 16 days (range, 12 to 33 days). All patients experienced complete alopecia, and six patients required antibiotics for febrile neutropenia. No patient developed hemorrhagic cystitis or mucositis.

Patients 2 and 4 eventually died of complications of autoimmune disease. Patient 2, who was treated for autoimmune hemolytic anemia, died of complications of immune thrombocytopenic purpura, which was not present when she was treated with high-dose cyclophosphamide. Autoimmune hemolytic anemia remained in complete remission until the patient's death, 16 months after cyclophosphamide therapy. Patient 4 achieved brief remission of immune thrombocytopenic purpura and died of her disease 8 months later.

Six patients remain alive, and five (patients 1, 3, 6, 7, and 8) have no symptomatic manifestations of their disease. In addition, four patients have no laboratory or clinical evidence of disease (Table 2). Patient 3, who has the Evans syndrome, shows continued improvement in blood counts; prednisone therapy is being tapered to 10 mg every other day. Patient 3 has been independent of transfusion for more than 10 months and has a normal hemoglobin level and a platelet count of 66 x 10⁹ cells/L. One of the patients with lupus achieved complete remission; the other still has clinical and serologic evidence of the disease but continues to improve 14 months after treatment. Patient 7, who has the Felty syndrome, is in complete remission 3 months after cyclophosphamide therapy. Patient 10, who has chronic inflammatory demyelinating polyneuropathy, had progressive upper- and lower-extremity paralysis and was unable to walk. Plasmapheresis, intravenous immunoglobulin, and pulse-dose cyclophosphamide therapy had proven ineffective. Three months after therapy with high-dose cyclophosphamide, he has no neurologic manifestations, is not receiving immunosuppressive therapy, and can walk normally.

Discussion

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Most immunoablative therapy for severe autoimmune disease uses autologous stem-cell rescue after high-dose therapy with cyclophosphamide in combination with other immunosuppressive agents [8]. Although our study was small and the follow-up was relatively short, the results indicate that high-dose cyclophosphamide alone can be effective therapy for some patients with severe autoimmune disease. In addition, our study confirms that high-dose cyclophosphamide (50 mg/kg per day for 4 days) spares hematopoietic stem cells; the kinetics of bone marrow recovery after high-dose cyclophosphamide therapy without stem-cell rescue are similar to those of engraftment after autologous transplantation. Autografting was not necessary because interventions toxic to stem cells, such as total-body irradiation or busulfan, were not included in our protocol.

The two patients who achieved partial remission (patients 3 and 5) continue to show slow, progressive improvement 19 months and 14 months after treatment, respectively. We previously demonstrated that high-dose cyclophosphamide produces a slow but progressive response in another autoimmune disease, severe aplastic anemia. All patients with severe aplastic anemia who responded to high-dose cyclophosphamide eventually achieved complete remission (although sometimes after many months); none of these patients have had relapse (median follow-up > 10 years) [9]. The kinetics and duration of the response suggest that high-dose cyclophosphamide may induce both immunologic tolerance to the autoantigen and potent immunosuppression. High-dose cyclophosphamide has induced immunologic tolerance in various animal models, although the precise mechanism is unknown [16, 17].

Lower doses of cyclophosphamide (0.5 to 1.5 g/m² of body surface area) can induce remission in some autoimmune diseases, but relapse is common; therapy needs to be repeated to sustain a response [13, 18]. Lower-dose cyclophosphamide therapy had failed in four patients in our series, but three of these patients subsequently demonstrated major clinical improvement after receiving immunoablative doses of cyclophosphamide. In addition, a single course of immunoablative cyclophosphamide may be associated with fewer late complications than are multiple courses at lower doses. High-dose cyclophosphamide without stem-cell rescue also has several important advantages over autologous transplantation regimens as treatment for autoimmune disease. It is less toxic than regimens that include total-body irradiation and is associated with a low incidence of infertility [19] and secondary malignant conditions [20]. High-dose cyclophosphamide without stem-cell rescue also avoids the problem of reinfusing autoaggressive lymphocytes with the autograft, which may play a role in relapse of autoimmune diseases after autologous transplantation.

Dr. Petri: Department of Internal Medicine, Division of Rheumatology, Johns Hopkins University School of Medicine, 1830 East Monument Street, Suite 7500, Baltimore, MD 21205.

Dr. Spivak and Dr. Dang: Division of Hematology, Johns Hopkins University School of Medicine, 1025 Ross Building, 720 Rutland Avenue, Baltimore, MD 21205.

Dr. Styler and Dr. I. Brodsky: Hahnemann University, Broad and Vine Streets, Mailstop 412, Philadelphia, PA 19102.