IL-12 Deaths: Explanation and a Puzzle

Abstract

Researchers investigating toxic reactions that killed two patients in a trial of interleukin-12 earlier this year have reached a surprising conclusion: The drug is highly toxic if it is given in multiple high doses, but those effects can be avoided if the multiple doses are preceded by a single dose followed by a rest period. The initial dose apparently imprints a memory on the immune system, but the mechanism is unclear.