Combination therapy with interferon alfa-2a and interleukin-2 for the treatment of metastatic cancer.

PURPOSE

Here we report the long-term follow-up evaluation of a phase I/II study of toxicity and response of combination interferon alfa-2a (IFN alpha) and interleukin-2 (IL-2) in patients with metastatic cancer.

PATIENTS AND METHODS

From November 1987 through October 1990, 189 patients were treated with 379 courses. IFN alpha (3 x 10(6) U/m2) was administered three times per day as an intravenous (IV) bolus with IV IL-2 2.6 x 10(6) IU/m2 (six patients, group 1), 7.8 x 10(6) IU/m2 (32 patients, group 2), or 11.7 x 10(6) IU/m2 (26 patients, group 3). Subsequently, IFN alpha dose was escalated to 6 x 10(6) U/m2 plus IL-2 11.7 x 10(6) IU/m2 (22 patients, group 4). Two further dosage schedules of IL-2 were tested at 7.8 x 10(6) IU/m2 (29 patients, group 5) and 15.6 x 10(6) IU/m2 (74 patients, group 6); however, because of IFN alpha-related toxicity, these two groups received IFN alpha once per day (6 x 10(6) U/m2). A treatment course consisted of two cycles (maximum, 15 doses per cycle) separated by a 10-day interval.

RESULTS

All patients were assessable for response: 82 patients had melanoma, 75 renal cell carcinoma (RCC), and 16 colorectal cancer. There were two treatment-related deaths. The objective response rate was 23% (43 patients). Response rates were 17%, 19%, 19%, 32%, 41%, and 16%, respectively, for groups 1 through 6. Ten responses are still ongoing (nine in RCC patients) at 57 to 74 months, and 21 patients are alive, for an overall 5-year survival rate of 11%. The median potential follow-up period was 65 months. Although a significantly higher response rate was noted for group 4 (highest dose of IFN alpha three times per day), no benefit for survival and increased toxicity were noted in this group.

CONCLUSION

Based on these findings, we conclude that further studies of this combination treatment are not warranted.