a cylindrical magnetic coil that’s about 15 inches in diameter. It’s placed on a patient’s head, above the eyes. The coil produces a specific, time-varying magnetic field that in turn, induces a time-varying electric field in the brain. Miller says the patient doesn’t feel any sensation associated with treatment—the only indication the device is running is a beep, or tone. That’s important, because it means patients won’t be able to tell the difference between Tal’s device and a sham treatment in a blinded trial, Miller says.
If this type of device sounds familiar, that’s because Tal isn’t the first to try this sort of approach. Depression patients who don’t respond to drugs already have the option to undergo another brain stimulation technique, called, repetitive transcranial magnetic stimulation (rTMS), which is delivered via devices marketed by Neuronetics and Brainsway. Both of those, similarly, involve a magnetic coil and a therapy session conducted in a clinician’s office. Then, of course, there’s electroconvulsive therapy (ECT), which is much more invasive and essentially induces a seizure in a patient under anesthesia.
Tal, however, is trying to show that its method is both safe and works much faster than these other options. Miller says rTMS takes several weeks of five treatments per week to achieve a clinical benefit, while ECT typically requires two or more weeks of two to three treatment sessions.
The very early data Tal is encouraged by have shown a treatment effect, by comparison, within 20 to 30 minutes, he says. Tal also hasn’t seen any side effects that it can directly attribute to the device as of yet, and there haven’t been any seizures reported—always a risk when trying to electrically stimulate the brain.
Those data came from three small studies researchers at McLean and the NIH had already either finished, or were underway, before Tal licensed the technology. Miller says two of those were “pilot-style efficacy studies” done at the hospital, while the other was a PET imaging study done by a researcher at the NIH that looked at the technology’s impact on the glucose metabolism of healthy volunteers—a trial done to try to begin to understand the physiological impact of magnetic stimulation.
That data, according to Miller, indicated that Tal’s technology might work, on a physiological level, in a completely different way than rTMS and ECT. While Tal’s device hyperpolarizes neurons, for instance, the other methods depolarize them. Though its unclear at this point whether Tal’s technology is better or worse for patients than rTMS or ECT, Miller nonetheless says that the differentiation is significant.
“It implies that the physiological impact of [low-field magnetic stimulation] is different, and thus provides a rationale as to why the efficacy and safety profile may also be different from [those other methods],” he says.
Of course this is something that Tal has a long way to go to prove. Neuronetics’ device has been FDA approved since 2008, and regulators cleared Brainsway’s a year ago. Tal, meanwhile, is running its proof-of-concept trial, as well as a second small, single-site biomarker study. The results of the former, however, will be critical. If Tal sees positive signs that it’s got a truly differentiated therapy, it’ll likely move from there to a larger, randomized trial—the kind that Neuronetics and Brainsway ran before getting the nod from regulators.
“Both [of their] regulatory paths provide us with what we believe will be a good benchmark for what would be our own regulatory path,” Miller says.
