A San Francisco startup with ties to Elon Musk’s Neuralink has started testing its brain implant to detect and treat cancer in humans.

Coherence Neuro says it temporarily placed its coin-sized implant in the brains of three people undergoing surgery to have brain tumors removed at the Royal Melbourne Hospital in Australia. The implant was in place for roughly 30 minutes before being removed, providing an important safety check before the device can be implanted long-term in patients with brain cancer.

Known as a brain-computer interface, the Coherence Neuro device is designed to sense the unique electrical signals of tumors and deliver mild electrical stimulation to prevent their growth. In the time the implant was in the patients’ brains, the company was able to see how it performed for a short period. (The patients had consented prior to surgery.)

Matthew MacDougall, Neuralink’s head neurosurgeon, is an adviser and investor in Coherence. Rory Murphy, a neurosurgeon at the Barrow Neurological Institute in Arizona who is an investigator in one of Neuralink’s trials, is also slated to be involved in future trials of the Coherence device.

The idea behind treating brain tumors with electrical stimulation comes from the long-held observation that cancerous tissue has distinctive electrical properties. “These are electrical conditions, just like epilepsy, just like depression. This is a network problem in the brain,” says Ben Woodington, chief executive officer and cofounder of Coherence.

In 2019, researchers at Stanford University found that a group of aggressive brain tumors called high-grade gliomas drive their own growth by forming synapses with healthy neurons. In that study, researchers showed that giving a seizure drug to mice successfully interrupted electrical signals to tumors and slowed their growth. Applying low-intensity electricity has also been shown to disrupt cancer cell division in brain tumors.

A wearable device called Optune, developed by Novocure, was first approved in 2011 to treat adults with glioblastoma, which makes up about half o...