The stock of psychedelics giant Atai is tumbling after a treatment failed to help patients in a trial

• Atai Life Sciences said that its ketamine therapy failed to help patients in a trial.
• Ketamine is being tested as a treatment for severe forms of depression.
• Atai's stock tumbled 39%.

Atai Life Sciences' stock tumbled 39% after the company said that a ketamine-based therapy failed to help patients with treatment-resistant depression in a trial.

Perception Neuroscience, a subsidary of Atai, was testing a form of ketamine called PCN-101, compared to a placebo, in 102 patients in a mid-stage trial. Patients who received ketamine didn't fare better than those who got the placebo, Atai said in a press release. 

Ketamine, a surgical anesthetic, is currently being tested as a possible treatment option for patients with severe depression that has not responded to other kinds of therapy. It is fast-acting, which could make it useful for patients experiencing sudden bouts of suicidality.

Spravato, a drug based on ketamine developed by Johnson & Johnson, was approved by the FDA in 2019 to treat severe forms of depression. According to Insider's tracker, there are four other mid-stage trials of ketamine underway for conditions such as treatment-resistant depression and alcohol-use disorder. 

In the Perception Neuroscience trial, 102 patients with treatment-resistant depression were given 60mg of PCN-101, 30mg of the therapy, or a placebo group. The patients got the treatment via IV, and their depression symptoms were evaluated 24 hours later using a survey called the Montgomery-Åsberg Depression Rating Scale.

Patients who got the 60mg dose didn't improve more than those who received the placebo, according to the press release. The company didn't detail results for patients who got the 30mg dose.

Atai said it plans to continue reviewing the data and determine its next steps.