Recombinant interferon alfa-2b in plaque-phase mycosis fungoides. Intralesional and low-dose intramuscular therapy.

A two-part clinical trial was conducted to determine the therapeutic efficacy of recombinant interferon alfa-2b in plaque-phase mycosis fungoides. In an initial randomized double-blind study, each of six patients had two representative plaques injected intralesionally with 1 X 10(6) U of recombinant interferon alfa-2b per site and two control plaques injected with placebo three times weekly for four consecutive weeks. Complete clinical regression of disease was observed at ten of 12 recombinant interferon alfa-2b sites compared with one of 12 placebo-treated sites four weeks after treatment with injections was stopped. Subsequently, in an open-labeled study, five of these patients were treated intramuscularly with 5 X 10(6) U of recombinant interferon alfa-2b three times weekly for four weeks and two patients were treated with a second, more extended course of therapy lasting 12 to 16 weeks. Three of the five patients treated systemically showed some improvement overall, but the responses were judged not to be clinically significant. The differential response observed from intralesional and intramuscular injections may be related to differences in concentration of recombinant interferon alfa-2b achieved in lesional skin by the two methods of administration.