Continuous Infusion Interleukin-2 and Antihistamines in Melanoma: A Retrospective Review Showing Activity of This Combination

Abstract

A recent randomized trial suggests that there may be an advantage in terms of survival with the combination of histamine and subcutaneous interleukin-2 (IL-2), compared to IL-2 alone. It has been postulated, then, that antihistamines may actually be antagonistic to IL-2 and, therefore, interfere with its antitumor activity. Because antihistamines such as cimetidine and ranitidine are commonly used as prophylaxis against gastrointestinal toxicity commonly seen with IL-2, and, because antihistamines may increase natural killer cell activity, it is reasonable to examine the response rate for this combination. An OVID Medline literature search between 1985 and 2003 was done. Continuous infusion (CIV) interleukin- 2 was used as the reference therapy because of the relatively constant IL-2 levels generated by this approach. Included studies were those in which either cimetidine, ranitidine, or famotidine were regularly scheduled and administered concurrently with IL-2, typically for gastrointestinal ulcer prophylaxis. Six (6) studies were identified. A total of 21 patients responded to therapy. Total response rate was 11%, with a 95% Confidence Interval: 7-17%. Four (4) complete responses were noted. Complete response rate was 2%, with a 95% Confidence Interval: 1-6%. These response rates are consistent with previously noted IL-2 response rates. In this retrospective review of CIV IL-2 and antihistamines, this combination appears to be active in melanoma. There appears to be no deleterious effect of routine antihistamine on the CIV IL-2 response rate.