Newer Insights into Cisplatin Nephrotoxicity

A clinical trial was undertaken to improve the therapeutic index of cis-platinum diammine dichloride with a concomitantly administered mannitol induced diuresis. Sixty patients, heavily pretreated, were entered; fifty-one are evaluable. The technique of concomitant osmotic diuresis and CPDD administration is described in detail. Doses ranged from 3 mg/kg to 5 mg/kg. At 5 mg/kg, dose-limiting renal, marrow and ototoxicity were seen, and resulted in one drug death. Marrow toxicity was moderate. Renal toxicity was limited to transient elevations in serum creatinine levels, except in some patients who had renal impairment prior to CPDD treatment. These patients had moderate renal toxicity. Serial treatments as frequently as once every 3 weeks were used to maintain responses. Serial high dose CPDD produced only mild renal dysfunction. Ototoxicity, usually subclinical, was quantitated audiometrically, and found to be dose related, but not clinically prohibitive at 4 mg/kg or less. The overall response rate (PR/MR) was 42%. Clinically significant responses in epidermoid carcinoma of the head and neck, adenocarcinoma of the ovary, and germ cell tumors of the testis were seen. All six responding patients with germ cell tumor of the testis, had been resistant to low dose (1mg/kg) CPDD. Two responding patients with ovarian adenocarcinoma had been resistant to alkylating agents.

The effect of three cycles of high-dose cisplatin (40 mg/m2 day for 5 days) on renal tubular function was evaluated in 30 patients. A significant impairment of proximal tubular salt and water reabsorption rates was observed, but also distal tubular function seemed to be affected. These changes were also present 6 months after termination of treatment. Sodium and magnesium clearance increased significantly during treatment. Magnesium clearance normalized shortly after treatment but sodium clearance was significantly elevated 6 months after treatment. Proteinuria, albuminuria, and amino aciduria, together with an increase of beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) excretion rates, were observed during each treatment cycle. A good correlation was registered between the increase in urinary excretion rates of protein, NAG, and magnesium and the decrease in proximal tubular salt and water reabsorption during cisplatin administration.