CURRENT THERAPEUTIC RESEARCH@ VOL. 61, No. 9, SEFTEMBER 2000

Editorial Comment

Immune-Response Modifiers and Imiquimod

In his article on immune-response modifiers, Dr. Tyring takes on a daunt- ing task. He attempts to build a case for the immune system’s role in fighting human papillomavirus infection. Having done that to his own satisfaction, he then places imiquimod in the therapeutic spectrum and shows its value against genital/perianal warts by its actions in increasing local cytokine production. Dr. Tyring’s interpretation may well be correct. Still, in the more conservative view of the US Food and Drug Administra- tion (FDA), while imiquimod is indeed an immune-response modifier, a more precise definition of its mechanism of action cannot be made. Some studies do indicate induction of cytokines. However, the FDA could not establish the clinical relevance of these data. Often, when the science may not be absolutely clear, the FDA will make statements like those on the imiquimod label to prevent unwarranted claims.

As with other immune-response modifiers, scientists have recom- mended using imiquimod 3 times per week. Partly this interrupted sched- ule would reduce imiquimod’s local adverse reactions. Also, it is difficult to establish the most effective dose and dose interval when the clinical re- sponse is delayed and the outcome encompasses partial clearing. Clinical trialists then have to attempt intermittent long-term therapy. The recom- mended duration of therapy is a total of 16 weeks. Using imiquimod is facilitated by its provision in single-dose packets to standardize the amount of medication and avoid the chance of overdose or excessive use.

Dr. Tyring has created a well-written exposition of the data and his interpretation of them. We at Current Therapeutic Research@ felt readers should have the opportunity to read it and see if they are persuaded.

Michael Weintraub, MD Editor-in-Chief

583