TL;DR
The tiny medical robots of science fiction are starting to show up in real experiments, and the first ones are made partly of living things. Researchers have now steered a swarm of magnetized, cancer-hunting immune cells up the spinal canal of mice and confirmed the same navigation works in a monkey, the first step of its kind in a primate. Separately, swarms of drug-carrying algae robots left mice with bladder cancer with less than 3% of the tumor burden that standard treatment did after one week. No microrobot has entered a confirmed human trial. But if these results carry over, cancer drugs could be driven precisely to tumors in places surgeons and pills reach poorly, instead of flooding the whole body and hoping enough arrives.
Below the line, for paid subscribers: The full story: where it stands, how we got here and what's dated next; our Odds board on 5 milestones, starting with "Robeauté starts its brain-microrobot human trial by 2027"; our labeled speculation on what it adds up to; and every source.