Biological therapy

Biological therapy has been extensively tested in renal cancer, partly because of its chemo-resistance, but mainly because of the presumption that immunological mechanisms underly the occasional spontaneous regression of metastases. In addition, the very late relapses seen in some patients and the increased incidence of renal cancers in immunosuppressed patients suggest that some intrinsic immuno-logical surveillance can operate in patients with renal cancer.

Interleukin-2 (IL-2) is the most widely tested biological agents and induces responses in 10-25% of patients with advanced disease. Those patients with a complete radiological response have a significant survival benefit, with durable remissions in a few.

The original studies of IL-2 employed high-dose intravenous IL-2, either alone or in combination with lymphokine-activated killer cells (LAK). These regimens are associated with considerable morbidity, in particular capillary leak syndrome, and some mortality.

Less toxic subcutaneous (SC) IL-2 regimens are probably equally effective and can be combined with interferon-a (IFN) and/or cyto-toxics, although comparative studies are lacking to confirm a benefit for combination regimens. As a single agent, SC IFN also provides a response rate of approximately 15% and use of this agent has a proven survival advantage over endocrine therapy in an important MRC trial.

Prognostic factors that predict better response and survival time after biological therapy include:

♦ Long time for diagnosis to relapse

♦ Nephrectomy

♦ Good performance status

♦ Pulmonary metastases as the sole site of disease

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