Clinical Efficacy of Combined Pentoxifylline and Conventional Immunosuppressive Regimens on Patients With Rapidly Progressive Glomerulonephritis

Corticosteroids and cytotoxic agents such as cyclophosphamide remain the most commonly used regimens for crescentic glomerulonephritis. However, their use is often limited by adverse effects, most notably life-threatening opportunistic infections due to generalized immunosuppression. Over the past decade, a number of novel experimental therapeutic agents have been shown to ameliorate the severity of experimental crescentic glomerulonephritis. Unfortunately, none of these measures is currently available for clinical use. Other potential agents such as mycophenolate, cyclosporin, and tacrolimus , while clinically available, share similar adverse effects with corticosteroid- and cyclophosphamide-based regimens. PTX is a methylxanthine phosphodiesterase inhibitor that has been widely used to treat peripheral vascular diseases and cerebrovascular disorders. In addition to its well-known hemorheologic activity, accumulating evidence suggests that PTX also possesses potent anti-inflammatory and/or immunoregulatory activities. For examples, PTX has shown its efficacy in different animal models of renal diseases where tumor necrosis factor (TNF)-alpha, monocyte chemoattractant protein (MCP)-1, or intercellular adhesion molecule-1 is involved. Moreover, clinical trials in patients with diabetic nephropathy and membranous glomerulonephritis have shown that PTX can lower endogenous TNF-alpha and attenuate proteinuria. These data raise the possibility that PTX may have promise as an anti-inflammatory agent via its ability to antagonize inflammatory mediators. Consistent with this idea, we have demonstrated this potential usefulness of PTX in a rat model of accelerated anti-GBM glomerulonephritis. More recently, we have reported that PTX is capable of inhibiting proteinuria via renal MCP-1 production in subnephrotic primary glomerular diseases. In this study, we aim to investigate the potential benefit of combined PTX and conventional immunosuppressive regimens, compared to conventional immunosuppressive therapy, in patients with rapidly progressive glomerulonephritis.

This study is a randomized, open-label, comparative study. Group A is treated by three monthly standard intravenous pulse-dose methylprednisolone (15 mg/kg/day or a maximum of 1 g/day from days 1 to 3) followed by oral prednisolone 0.5-1.0 mg/kg/day (from days 4-30). Group B is treated by the same corticosteroid regimen plus intravenous PTX (0.33-0.66 mg/kg/h from days 1 to 7) followed by oral PTX 400-800 mg/day (from days 8-90). The dose of intravenous PTX will be determined by estimated GFR, patients whose GFRs are 30-59 ml/min/1.73 m2 will be given 0.66 mg/kg/h, and those below 30 ml/min/1.73 m2 will be given 0.33 mg/kg/h. The oral dose of PTX will also be determined by estimated GFR. Patients whose estimated glomerular filtration rates (GFRs) are between 30-59 ml/min/1.73 m2 will be given 800 mg/day, and those below 30 ml/min/1.73 m2 will be given 400 mg/day. If the patients cannot tolerate oral medications, either PTX or corticosteroids can be administered intravenously until patients can resume oral intakes. Serum and single-voided urine specimens will be collected at the hospital before initiation of therapy (day 0), and at days 8, 15, 30, and 90 after the commencement of therapy. Renal function will be calculated by Cockcroft-Gault and simplified Modification of Diet in Renal Disease formula. All biochemical and immunological analyses will be performed by the Department of Laboratory Medicine, National Taiwan University Hospital. Serum and urine samples will be measured for inflammatory mediators using commercial ELISA kits.