To keep immune cells from reacting to inappropriate triggers or dragging out their response for too long, they’re equipped with sundry molecular safeguards called immune checkpoints that nearby immune cells can flip on. As important as these checkpoints are, many tumors take advantage of them, throwing on these molecular brakes to dampen the antitumor immune response. A common form of immunotherapy called immune checkpoint blockade, or checkpoint inhibition, seeks to counter this kind of immunosuppression by physically blocking the immune checkpoint molecules so they can’t relay inhibitory signals. But while this treatment is successful in some patients, it fails in many others, and scientists don’t entirely know why—or more importantly, how to overcome the tumor’s immunosuppression. Key clues to solving this mystery are coming from an unexpected source: the brain-dwelling parasite Toxoplasma gondii.
The idea of tackling cancer with a brain parasite arose in the 1960s and 1970s when scientists ...
