Subcutaneous Recombinant Interleukin 2 in a Dose Escalating Regimen in Patients with Metastatic Renal Cell Adenocarcinoma

Abstract

Recombinant human interleukin 2 (rIL-2) was administered by s.c. injection daily, 5 days/week to patients with metastatic renal cell carcinoma in an escalating dose regimen. Fifteen patients were entered in this study and are evaluable for toxicity with one patient not evaluable for response because of lack of measurable disease. The patient population had a median age of 63 years with initial performance status (Southwest Oncology Group criteria) of 0 in one patient, 1 in eight patients, and 2 in six patients. The starting dose was 5 × 10⁵ Cetus units/m²/day with dose escalation to 1 × 10⁶, 2 × 10⁶, 4 × 10⁶, and 5 × 10⁶ Cetus units/m²/day scheduled at 2-week intervals if no significant toxicity or response was noted. Six patients were treated with drug doses of 2 × 10⁶ Cetus units/m²/day or higher with a maximum daily dose achieved of 2 × 10⁶ units/m² in two patients, 4 × 10⁶ units/m² in two patients, and 5 × 10⁶ units/m² in two patients. Fatigue with decrease in performance status and elevations in serum creatinine were the most common reasons for limiting the dose or removing a patient from the study. Only one minor antitumor response was seen.

Subcutaneously administered rIL-2 was able to alter immunological parameters. In two of the three patients tested, development of lymphokine-activated killer cell activity in vivo was seen, and statistically significant enhancement of natural killer cell activity compared to values from a concurrently run normal control was demonstrated. With treatment, there was a trend toward increased numbers of circulating total lymphocytes, OKT 8+, OKT 11+, Leu 7+, and Leu 11a+ cells and decreased numbers of circulating OKT 3+ and OKT 4+ cells. However, for the heterogeneous group of six patients monitored, results were not statistically significant compared to pretreatment values.

The levels of rIL-2-specific antibodies were followed in the sera of 10 patients. Six of the 10 developed rIL-2-specific IgG during treatment with five of the six patients also developing neutralizing activity.

Recombinant human interleukin 2 given by the s.c. route in the doses and schedule used in this trial can safely be given as an outpatient regimen with manageable toxicity. It may result in enhanced immune function in some patients but also results in a high incidence of antibody formation.