Está no New York Times de hoje (aqui).
Gostei da descrição que a droga é anti-frenagem:
“The answer is that tumors activate brakes on the immune system, preventing it from attacking them. Keytruda is the first drug approved that inhibits the action of one of those brakes, a protein known as PD-1, or programmed death receptor 1.”
Figura do papel de PD-1 (aqui)