Intra-Cellular Therapies said a higher dose of its experimental lead drug met the main goal of reducing the severity of schizophrenia symptoms in its first late-stage study.

The company's shares rose about 34 percent to $35.01 in premarket trading on Wednesday.

Patients treated with 60 mg of the drug, ITI-007, showed improvement over placebo. The 40 mg dosage, however, failed to achieve statistical significance, the company said in a statement.

Schizophrenia is characterized by reduced brain function, with patients experiencing a range of psychological symptoms such as hallucinations, delusions and changes in behavioral patterns.

The disorder affects over 20 million people worldwide, according to the World Health Organization.

Intra-Cellular also reported results from another trial, which showed the drug could have reduced risks of side effects such as movement and metabolic disorders or cardiovascular effects often observed with other antipsychotics.

The company is also evaluating ITI-007 in another late-stage study to treat depression associated with bipolar disorder.