The effects of oral pentoxifylline on interleukin-2 toxicity in patients with metastatic renal cell carcinoma.

Interleukin-2 (IL-2) mediates the regression of metastatic renal cell carcinoma, but clinical application has been limited by associated toxicities. Preclinical studies show that pentoxifylline (PTXF), a methylxanthine derivative, inhibits IL-2 toxicity while preserving anti-tumour efficacy. This study was designed to determine whether oral PTXF would alter IL-2-induced toxicities. Patients with disseminated renal cell carcinoma were treated with continuous infusion of 18 x 10(6) IU/m2/24 h for 4 days followed by 3 days without treatment, for 4 consecutive weeks. After a 2-week interval, the 4-week treatment cycle was repeated. All patients concomitantly received oral PTXF (2000 mg/24 h) in five divided doses. Despite the co-administration of PTXF, all patients demonstrated a spectrum and severity of toxicities consistent with previous reports of continuous infusion of IL-2 alone. There was considerably more nausea and vomiting associated with the administration of PTXF which improved on withdrawal of PTXF. Oral PTXF in IL-2 therapy did not show any substantiated benefit. Indeed, patients suffered more severe nausea and vomiting than if they had received IL-2 alone, resulting in the early termination of the trial.