Interleukin-2 is one of the most active anti-cancer agents for the treatment of patients with metastatic renal cell cancer. Interleukin-2 induces remissions in approximately 15% and cures approximately 5% of patients. Alfa interferon is another biologic anti-cancer therapy that produces responses in a similar fraction of patients. In some, but not all clinical trials, the combination of interleukin-2 and alfa interferon appears superior to treatment with either drug alone.
In order to clarify this situation, physicians in France performed a comparative clinical trial in 425 patients with metastatic renal cell cancer. Patients were treated with either interleukin-2, alfa interferon, or both. The response rates were 6.5% to interleukin-2, 7.5% to alfa interferon, and 18.6% to the combination of interleukin-2 and alfa interferon. At one year, the survival rates were 15% for interleukin-2, 12% for alfa interferon, and 20% for the combination. Interleukin-2 was more toxic than alfa interferon and the drug combination more toxic than either single drug regimen.
While patients with metastatic renal cell cancer responded to treatment with any of the 3 regimens, only a modest benefit occurred with the combination of interleukin-2 and alfa interferon. The higher response rate and the longer event-free survival obtained with the combination regimen has to be weighed against the additional toxicity of such treatment. (
New England Journal of Medicine; Vol 338, No 18, pp 1272-8, 1998)