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 of cancerous brain tumors. Earlier this year, the company received regulatory approval to treat pancreatic cancer with its device, which is attached to either the scalp or stomach with adhesive patches depending on the type of cancer.

The Optune device can improve survival by several months if it’s worn for most of the day, but people have to shave their heads to use it and carry a battery around in a backpack or on a hip belt.

Coherence wants to deliver electrical stimulation in a more convenient way. Its implant sits in the skull and has 16 extending threads that extend into the brain tissue. It’s designed to be implanted during a brain tumor resection surgery, when a tumor is removed. Even when tumors can be fully removed, it’s common for them to come back after surgery, something Coherence’s device is designed to protect against.

The company is initially aiming to treat glioblastoma, which has a higher risk of coming back compared to lower-grade tumors. Glioblastoma patients have few options and a grim prognosis. Most patients live for just 15 to 18 months after being diagnosed, with a five-year survival rate of less than 10 percent.

Right now, glioblastoma patients get an MRI of their brain every two to three months so doctors can monitor tumor growth and tweak their drug regimen as needed. But Woodington doesn’t think that’s frequent enough. Brain tumors can suddenly become more aggressive, and clinicians don’t have a good idea of what’s going on between scans. The Coherence device is designed to monitor people continuously and deliver customized electrical stimulation.

A connected app will let patients log their symptoms, which get sent to clinicians along with their disease state and the amount of stimulation they’re receiving. Doctors can fine-tune the therapy remotely or let the device do so automatically. And by detecting rapid tumor growth, the device could signal to doctors when to intervene with surgery before an MRI could.

The company plans to begin a trial next year in glioblastoma patients in which they will have the device permanently implanted.